Decrease In pH Research Articles

PH-Driven Rotational Configuration of Keggin-Fe13 Clusters and Their Transformations.

Keggin-Fe13 clusters are considered foundational building blocks or prenucleation precursors of ferrihydrite. Understanding the factors that influence the rotational configuration of these clusters, and their transformations in water, is vital for comprehending the formation mechanism of ferrihydrite. Here, we report syntheses and crystal structures of four lanthanide-iron-oxo clusters, namely, [Dy6Fe13(Gly)12(μ2-OH)6(μ3-OH)18(μ4-O)4(H2O)17]·13ClO4·19H2O (1), [Dy6Fe13(Gly)12(μ3-OH)24(μ4-O)4(H2O)18]·13ClO4·14H2O (2), [Pr8Fe34(Gly)24(μ3-OH)28(μ3-O)30(μ4-O)4(H2O)30]·6ClO4·20H2O (3), and [Pr6Fe13(Gly)12(μ3-OH)24(μ4-O)4(H2O)18]·13ClO4·22H2O (4, Gly = glycine). Single-crystal analyses reveal that 1 has a β-Keggin-Fe13 cluster, marking the first documented instance of such a cluster to date. Conversely, both 2 and 4 contain an α-Keggin-Fe13 cluster, while 3 is characterized by four hexavacant ε-Keggin-Fe13 clusters. Magnetic property investigations of 1 and 2 show that 2 exhibits ferromagnetic interactions, while 1 exhibits antiferromagnetic interactions. An exploration of the synthetic conditions for 1 and 2 indicates that a higher pH promotes the formation of α-Keggin-Fe13 clusters, while a lower pH favors β-Keggin-Fe13 clusters. A detailed analysis of the transition from 3 to 4 emphasizes that lacunary Keggin-Fe13 clusters can morph into Keggin-Fe13 clusters with a decrease in pH, accompanied by a significant change in their rotational configuration.

Urine pH as predictor of blood acid-base status in dairy cattle fed acidogenic diets

We determined the association between urine pH and blood acid-base indicators and assessed a urine pH cut-off value to predict severe metabolic acidosis under field conditions in cows fed acidogenic diets. Eighty-six cows were sampled for urine and blood. Urine pH was evaluated immediately after collection, and blood acid-base status was evaluated within 2 hours of collection using a portable blood analyzer. Twenty-five cows were classified as having severe metabolic acidosis (blood pH ≤ 7.4; bicarbonate < 24 mmol/L, base excess ≤ −0.5; PCO2 low to normal concentrations and urine pH between 4.88 and 5.71. There was a positive linear association between urine pH and blood pH (r = 0.46), and between urine pH and base excess (r = 0.74). The area under the ROC curve was 0.91 (CI 95 %= 0.84–0.96; good-excellent test). The optimal cut-off value for urine pH to categorize a cow with severe metabolic acidosis was 5.5 (94 % specificity and 72 % sensitivity). For each 0.1 unit of decrease in urine pH below 5.5, cows were 1.6 times (95 % CI= 1.3–2.1) more likely to exhibit a severe metabolic acidosis. We conclude that a urine pH of 5.5 or less is indicative of more life-threatening metabolic acidosis in dairy cows.

Exogenous putrescine plays a switch-like influence on the pH stress adaptability of biofilm-based activated sludge.

Microbial community adaptability to pH stress plays a crucial role in biofilm formation. This study aims to investigate the regulatory mechanisms of exogenous putrescine on pH stress, as well as enhance understanding and application for the technical measures and molecular mechanisms of biofilm regulation. Findings demonstrated that exogenous putrescine acted as a switch-like distributor affecting microorganism pH stress, thus promoting biofilm formation under acid conditions while inhibiting it under alkaline conditions. As pH decreases, the protonation degree of putrescine increases, making putrescine more readily adsorbed. Protonated exogenous putrescine could increase cell membrane permeability, facilitating its entry into the cell. Subsequently, putrescine consumed intracellular H+ by enhancing the glutamate-based acid resistance strategy and the γ-aminobutyric acid metabolic pathway to reduce acid stress on cells. Furthermore, putrescine stimulated ATPase expression, allowing for better utilization of energy in H+ transmembrane transport and enhancing oxidative phosphorylation activity. However, putrescine protonation was limited under alkaline conditions, and the intracellular H+ consumption further exacerbated alkali stress and inhibits cellular metabolic activity. Exogenous putrescine promoted the proportion of fungi and acidophilic bacteria under acidic stress and alkaliphilic bacteria under alkali stress while having a limited impact on fungi in alkaline biofilms. Increasing Bdellovibrio under alkali conditions with putrescine further aggravated the biofilm decomposition. This research shed light on the unclear relationship between exogenous putrescine, environmental pH, and pH stress adaptability of biofilm. By judiciously employing putrescine, biofilm formation could be controlled to meet the needs of engineering applications with different characteristics.IMPORTANCEThe objective of this study is to unravel the regulatory mechanism by which exogenous putrescine influences biofilm pH stress adaptability and understand the role of environmental pH in this intricate process. Our findings revealed that exogenous putrescine functioned as a switch-like distributor affecting the pH stress adaptability of biofilm-based activated sludge, which promoted energy utilization for growth and reproduction processes under acidic conditions while limiting biofilm development to conserve energy under alkaline conditions. This study not only clarified the previously ambiguous relationship between exogenous putrescine, environmental pH, and biofilm pH stress adaptability but also offered fresh insights into enhancing biofilm stability within extreme environments. Through the modulation of energy utilization, exerting control over biofilm growth and achieving more effective engineering goals could be possible.

Elucidating the Activation Mechanism of the Proton-sensing GPR68 Receptor

GPR68 is a proton-sensing G-protein Coupled Receptor (GPCR) involved in a variety of physiological processes and disorders including neoplastic pathologies. While GPR68 and few other GPCRs have been shown to be activated by a decrease in the extracellular pH, the molecular mechanism of their activation remains largely unknown. In this work, we used a combined computational and in vitro approach to provide new insight into the activation mechanism of the receptor. Molecular Dynamics simulations of GPR68 were used to model the changes in residue interactions and motions triggered by pH. Global and local rearrangements consistent with partial activation were observed upon protonation of the inactive state. Selected extracellular histidine and transmembrane acidic residues were found to have significantly upshifted pKa values during the simulations, consistently with their previously hypothesised role in activation through changes in protonation state. Moreover, a novel pairing between histidine and acidic residues in the extracellular region was highlighted by both sequence analyses and simulation data and tested through site-directed mutagenesis. At last, we identified a previously unknown hydrophobic lock in the extracellular region that might stabilise the inactive conformation and regulate the transition to the active state.

Effect of guar gum and fortification by haritaki (Terminalia chebula) extract and its encapsulates on physicochemical, textural, and rheological properties of yogurt

AbstractIn the present study functional yogurt was prepared by addition of guar gum (0.5% and 1.5%) and fortification by phytochemical extract of haritaki (Terminalia chebula) extracted using supercritical CO2 and freeze dried encapsulates of the extracts. The results indicated that the addition of guar gum led to a concentration‐dependent reduction in pH, with yogurt containing 1.5% guar gum exhibiting the highest acidity. During a 24‐day storage period at 4°C, all samples displayed a decrease in pH and an increase in acidity. Notably, all variations exhibited sporadic syneresis patterns, with higher syneresis observed on the 1st day, followed by a decline on the 12th day and a subsequent rise on the 24th day of storage. The color of haritaki encapsulated yogurt appeared greener and more yellowish compared to the control samples on the 1st day, with noticeable changes in L*, a*, and b* values during storage. Texture analysis revealed that encapsulation significantly affected textural characteristics, with reduced firmness but comparable adhesiveness in some cases. The firmness of plain yogurt ranged from 0.69 to 0.72 N, while its adhesiveness was between 6.14 × 10−2 and 8.51 × 10−2 N.s. The stiffness of the samples made with encapsulates (E1–E6) ranged from 0.38 to 0.70 N, while their adhesiveness was 5.74 × 10−2 to 8.78 × 10−2 N.s. The findings demonstrate that encapsulation significantly affected the textural characteristics. However, the samples' firmness (F1–F3) was less than the control, ranging from 0.36 to 0.54 N. Encapsulated haritaki extract outperformed nonencapsulated haritaki extract in terms of phenolic and antioxidant activities, making it a preferred option for yogurt fortification. Furthermore, yogurt enriched with up to 0.5% guar gum exhibited sensory qualities similar to or even better than the control sample.

Patterns of carbonate chemistry in mangroves of the Northern Persian Gulf

The mangroves located in the Northern Persian Gulf are reeling from anthropogenic pressures including from intense industrial activities (Pars Special Economic Energy Zone-PSEEZ). Given the unique geographical location of these mangroves, understanding the initial basis of seawater carbonate chemistry is key to link with global patterns of coastal ocean carbonate dynamics. In this study, water samples were collected from pre-designated stations representing the mangrove forest and nearshore water namely Nayband, Mel-e-Gonzeh and Bardestan of the Persian Gulf in September of 2016. Based on extensive carbonate chemistry measurements, the results show that the pCO2 at the Nayband site (13217.9±5841.5 µatm) was significantly higher than the other two sites (Mel-e-Gonzeh: 416.4±49.3 µatm and Bardestan: 294.3±95.0 µatm) while pH (6.92±0.18) was significantly lower than the two other sites (Mel-e-Gonzeh: 8.18±0.02, Bardestan: 8.26±0.04). The observed increase of pCO2 and decrease of surface water pH at the Nayband site compared to other two sites may have due to the emission of CO2 originating from oil and gas refining facilities located PSEEZ. Moreover, surface water in Nayband was undersaturated with respect to aragonite (Ωarg<1) and supersaturated (Ωarg>1) in case of the Mel-e-Gonzeh and Bardestan sites. This study although preliminary provides much-needed baseline information to address issues of changing carbonate chemistry and can help towards understanding the basis of coastal ocean acidification.

Ultrasonic-assisted nanofiltration separation recovering salvianolic acid B from ethanol wastewater

The transformation of salvianolic acid B brought on by heat treatment recovery of ethanol eluent, which is a difficult problem in pharmaceutical technology, affects the purity of raw material when the medicinal raw material salvianolic acid B is purified by resin. Ultrasonic-assisted nanofiltration separation (UANS) was first employed to improve efficiency of resource utilization by regulating rejection and separating salvianolic acid B and rosmarinic acid from organic pharmaceutical wastewater. The rejection was related to three variables: ultrasonic power, pH, and ethanol concentration. But there were differences in the effects of variables on the rejections of salvianolic acid B and rosmarinic acid. The rejections of rosmarinic acid and salvianolic acid B showed a decreasing trend with an increase in ultrasonic power or a decrease in pH; however, when the concentration of ethanol was increased from 5 % to 35 %, the salvianolic acid B rejection increased from 84.96 % to 96.60 % and the rosmarinic acid rejection decreased from 35.09 % to 17.51 %. On the basis of response surface methodology (RSM), the optimal UANS parameters for solution conditions involving different ethanol concentrations are as follows: 10 % ethanol solution (ultrasonic power 500 W and pH 6.15), 20 % ethanol solution (ultrasonic power 500 W and pH 6.54), and 30 % ethanol solution (ultrasonic power 460 W and pH 6.34). The molecular proportions of salvianolic acid B were 10.75 %, 7.13 %, and 8.27 % in 10 %, 20 %, and 30 % ethanol wastewater, while the molecular proportions of rosmarinic acid were 40.52 %, 33.83 %, and 69.87 %, respectively. And the recoveries of salvianolic acid B in 10 %, 20 %, and 30 % ethanol wastewater were 93.56 %, 95.04 %, and 97.30 %, respectively, while the recoveries of rosmarinic acid were 3.19 %, 2.27 %, and 0.56 %. The molecular proportion and the rejection are correlated exponentially. In comparison with conventional nanofiltration separation (CNS), UANS is able to resolve the conflict between rosmarinic acid and salvianolic acid B in pharmaceutical wastewater, as well as enhance resource recycling and separation efficiency to prevent pollution of the environment from pharmaceutical wastewater. Experiments using UANS at different power intensities suggest that the ultrasonic at a power intensity of 46–50 W/L and the power density of 0.92–1.00 W/cm2 may resolve the separation conflict between rosmarinic acid and salvianolic acid B. This work suggests that UANS may be a significant advancement in the field of ultrasonic separation and has several potential uses in the water treatment industry.

The Antilisterial Effect of Latilactobacillus sakei CTC494 in Relation to Dry Fermented Sausage Ingredients and Temperature in Meat Simulation Media

Listeria monocytogenes, the causative agent of listeriosis, is a relevant pathogen in dry fermented sausages (DFSs), and the application of antilisterial starter cultures is an effective intervention strategy to control the pathogen during DFS production. The effect of factors in relation to DFS formulation and production, NaCl (0–40 g/L), Mn (0.08–0.32 g/L), glucose (0–40 g/L) and temperature (3–37 °C), on the behaviour of L. monocytogenes when cocultured with Latilactobacillus sakei 23K (non-bacteriocinogenic) and CTC494 (bacteriocinogenic) strains was studied through a central composite design in meat simulation media. L. sakei and L. monocytogenes counts, pH, lactic acid production and bacteriocin activity were determined in mono and coculture. The pH decrease and lactic acid production were highly influenced by glucose, while production of sakacin K by L. sakei CTC494 was observed at moderate (10 and 20 °C), but not at the lowest (3 °C) and highest (37 °C), temperatures. Coculture growth had no effect on the acidification and bacteriocin production but inhibited and inactivated L. monocytogenes when L. sakei 23K entered the early stationary phase and when L. sakei CTC494 produced sakacin K. Optimal conditions for achieving a 5-log units reduction of L. monocytogenes were at 20 °C, 20 g/L of NaCl, 0.20 g/L of Mn and 40 g/L of glucose, those highlighting the importance of considering product formulation and fermentation conditions for bioprotective starter cultures application.

PEMANFAATAN EKOENZIM DARI KULIT BUAH-SAYUR UNTUK PENINGKATAN KUALITAS AIR DANAU BATUR DI KECAMATAN KINTAMANI BANGLI, BALI

Eco enzyme production through the fermentation process of household waste, such as leftover fruit and vegetables can also be a solution to minimize waste from its source. This research aims to determine the effect of a mixture of organic materials, fruit and vegetable waste eco enzyme on pH, and the effect of eco enzyme dosage on improving the water quality of Lake Batur, Kintamani Bali. Making eco enzymes using vegetable and fruit waste. water, molasses in a ratio of 3: 10: 1. The liquid is fermented for 3 months while observing the fermentation process. Eco enzyme is harvested and filtered, ready for testing to improve the water quality of Lake Batur. The results of observations of making eco enzyme can be explained that in the first 4 weeks, there was a change in colour with shades of brown to reddish, after the fourth week the colour was relatively stable (no colour change. Changes in pH during the process of making eco enzymes were related to variations in the composition of organic material (vegetable residues. There was a decrease in pH). with an average of up to 1 digit, the highest reduction occurred in ingredients containing papaya, mango and mustard greens. Eco enzymes can improve water quality as indicated by several water quality parameters, but are not enough to achieve conformity with the established quality standards. Keyword: Eco Enzyme; Water Quality; Batur Lake

D-Tagatose: A Rare Sugar with Functional Properties and Antimicrobial Potential against Oral Species.

Carbohydrates have a dietary role, but excessive consumption of high-calorie sugars can contribute to an increased incidence of metabolic diseases and dental caries. Recently, carbohydrates with sweetening properties and low caloric value, such as D-tagatose, have been investigated as alternative sugars. D-tagatose is a rare sugar that has nutritional and functional properties of great interest for health. This literature review presents an approach to the biological effects of D-tagatose, emphasizing its benefits for oral health. Studies report that D-tagatose has antioxidant and prebiotic effects, low digestibility, reduced glycemic and insulinemic responses, and the potential to improve the lipid profile, constituting an alternative for diabetes mellitus and obesity. It can also be observed that D-tagatose has an antioxidant action, favoring the elimination of free radicals and, consequently, causing a reduction in cellular oxidative stress. Furthermore, it also has antibacterial potential against oral species. Regarding oral health, studies have shown that D-tagatose efficiently reversed bacterial coaggregations, including periodontopathogenic species, and impaired the activity and growth of cariogenic bacteria, such as S. mutans. D-tagatose significantly inhibited biofilm formation, pH decrease and insoluble glucan synthesis in S. mutans cultures. Salivary S. mutans counts were also significantly reduced by the consumption of chewing gum containing D-tagatose and xylitol. In addition, there is evidence that tagatose is effective as an air-polishing powder for biofilm decontamination. The literature indicates that D-tagatose can contribute to the prevention of systemic diseases, also constituting a promising agent to improve oral health.

A comprehensive monitoring approach for a naturally anoxic aquifer beneath a controlled landfill

The processes leading to high levels of arsenic (As), iron (Fe), and manganese (Mn) in groundwater, in a naturally reducing aquifer at a controlled municipal landfill site, are investigated. The challenge is to distinguish the natural water-rock interaction processes, that allow these substances to dissolve in groundwater, from direct pollution or enhanced dissolution of hydroxides as undesired consequences of the anthropic activities above. Ordinary groundwater monitoring of physical-chemical parameters and inorganic compounds (major and trace elements) was complemented by environmental isotopes of groundwater (tritium, deuterium, oxygen-18 and carbon-13) and dissolved gases (carbon-13 of methane and carbon dioxide and carbon-14 of methane). Pearson/Spearman correlation indices, as well as Principal Component Analysis (PCA), were used to determine the main correlations among variables. The concurrent presence of As, Fe and CH4, as reported in similar anoxic environments, suggests that anaerobic oxidation of methane could drive the reductive dissolution of As-rich Fe(III)(hydro)oxides. Manganese is more sensitive to carbon dioxide, possibly due to a decrease in pH which accelerates the dissolution of Mn-oxides. Finally, we found that tritium and deuterium, which have been used for decades as leachate tracer in groundwater, may be subject to false positives due to the reuse of water recovered from leachate treatment (which has the same isotopic signature of leachate) within the plants, to comply with the requirements of the circular economy. The integration of the environmental isotope analysis into the traditional monitoring approach can effectively support the comprehension of processes. However, this strategy needs to be complemented by a good conceptual hydrogeological model and expert evaluation to avoid misinterpretations.

Acid Neutralization by Composite Lysine Nanoparticles for Spinal Cord Injury Recovery through Mitigating Mitochondrial Dysfunction.

After spinal cord injury (SCI), significant alterations in the tissue microenvironment lead to mitochondrial dysfunction, inducing apoptosis and inhibiting the remodeling of neural circuits, thereby impeding recovery. Although previous studies have demonstrated a marked decrease in pH at the injury site, creating an acidic microenvironment, the impact of improving this acidic microenvironment on SCI recovery has not been investigated. This study prepared a lysine@hollow mesoporous silica nanoparticle/gelatin methacrylate (GelMA) (L@H/G) composite hydrogel. The L@H/G composite hydrogel was demonstrated to release lysine and efficiently improve the acidic microenvironment slowly. Significantly, the composite hydrogel reduced cell apoptosis, promoted nerve regeneration, inhibited glial scar formation, and ultimately enhanced motor function recovery in mice with SCI. Mechanistically, the L@H/G hydrogel improved the mitochondrial tricarboxylic acid (TCA) cycle and fatty acid metabolism, restoring energy supply and facilitating mitochondrial function recovery. To the best of our knowledge, this is the first report confirming that improving the acidic microenvironment could promote SCI repair, providing a potential therapeutic strategy for SCI.

Isomerization of maltose to maltulose under microwave heating using uncalcined scallop shell powder

Uncalcined scallop shell powder, consisting mainly of calcium carbonate, and an aqueous maltose solution were placed in a pressure-resistant vessel and heated in a domestic microwave oven to isomerize maltose to maltulose. When a maltose solution (50 mL) was heated at a power of 700 W, a high maltulose yield of approximately 30 % was achieved in as short a time as 105 s. As the reaction progressed, the shell powder dissolved and neutralized acidic by-products to suppress the decrease in pH, keeping the pH above 7, where the isomerization by Lobry de Bruyn-Alberda van Ekenstein transformation proceeded. The average selectivity for isomerization of maltose to maltulose under various reaction conditions was 0.822. This would be because the shell powder kept the pH of the reaction solution in the range of 7–9 and suppressed the progression of side reactions. The coloration of the reaction solution increased rapidly when the yield of maltulose approached its maximum value. This indicated that if the reaction were to be stopped when the yield of maltulose was close to its maximum value, a high yield of maltulose solution with low coloration could be obtained.

Significant Factors for Modelling Survival of Escherichia coli in Lake Sediments.

Currently available numerical models that describe the fecal contamination of aquatic environments using Escherichia coli as an indicator bacterium did not consider its survival in sediments. We conducted a series of comparative experiments to reveal the independent and interactive effects of sediment factors, including temperature, pH, water-extractable total dissolved solids (TDSs), coexisting microbes, and sampling sites, in lake environments on E. coli survival. In experiments, E. coli survival was observed by controlling any two factors at a time. Consequently, the decrease in pH and presence of coexisting microbes enhanced E. coli die-off, whereas the addition of water-extractable TDSs promoted its growth. To select factors to be considered for modelling E. coli survival in sediments, the independent effects of each factor and the interaction effect of the two factors were statistically compared based on their effect sizes (η2). As a result, pH (η2 = 59.5-89.0%) affected E. coli survival most significantly, followed by coexisting microbes (1.7-48.4%). Among the interactions affecting E. coli survival, including pH or coexisting microbes-which had larger independent effects-relatively larger statistically significant interactions were observed between pH and coexisting microbes (31.1%), coexisting microbes and water-extractable TDSs (85.4%), and coexisting microbes and temperature (26.4%).

Impacts of microplastic decomposition using heat-activated persulfate on antibiotic adsorption and environmental toxicity

The objective of this study was to determine microplastic-antibiotic interaction by examining how heat-activated persulfate decomposed polyamide adsorbed antibiotics and explored the environmental consequences of treated water. Sulfate radicals roughened the microplastic surfaces, significantly enhancing the adsorption capacity of polyamide. The kinetic and isotherm studies provided confirmation that electrostatic interactions were the primary mechanisms, with a minor contribution from H-bonding, highlighting that antibiotic adsorption was prone to occur, especially on the aged surface. Thermodynamic data indicated that the process was spontaneous and exothermic. The results showed significant negative effects of treated water on seed germination, copepod survival, and cell lines at only a higher concentration, due to a decrease in pH and the potential presence of polymer degradates. Our findings revealed the significant impact of decomposed polyamide on the antibiotic adsorption and offered insight into the potential harm that microplastic-treated water might cause to aquatic and marine ecosystems.

Effects of florfenicol on the midgut physiological function of Bombyx mori, based on the diversity of intestinal microbiota

AbstractFlorfenicol (FF) is a new antibiotic commonly used in sericulture. This study aimed to examine the effects of low (LC: 0.06 g/L), medium (MC: 0.12 g/L), and high (HC: 1.2 g/L) concentrations of FF on the midgut physiological functions of the silkworm, Bombyx mori (L.) (Lepidoptera: Bombycidae). The results showed that the body weight and the whole cocoon weight of silkworms decreased and the development duration of the fifth instar was prolonged in the HC group. The structure of intestinal microbiota of silkworm larvae was changed by high FF exposure. Specifically, the abundance of conditional pathogens (Curtobacterium, Sanguibater, etc.) was significantly increased, whereas the abundance of Pseudomonas and Pedobacter was decreased significantly. Additionally, the intestinal reactive oxygen species level at 72 h was significantly elevated, and the muscle layer had become loose, together with the appearance of gut goblet cell atrophy. We observed that the increase in Lactobacillus abundance led to a reduction in intestinal fluid pH, resulting in decreased α‐amylase and protease activities, whereas lipase activity exhibited an elevation. The results demonstrated that the accumulation of peroxides induced by exposure to 1.2 g/L FF caused intestinal damage, and the decrease in pH resulting from alterations in microbial composition and structure affected digestive enzyme activity, collectively leading to physiological impairment of the silkworm midgut. These findings provide a valuable reference for the safe use of FF in sericulture.

Changes in proteolysis and volatile fraction of nitrite‐free Italian‐type salami modified in formulation and processing

SummaryNitrite in meat products exerts multiple functions in terms of safety and quality, but it has been related to an increased risk of health issues, and alternatives have been investigated. In this study, Italian‐style salamis were prepared with nitrite and ascorbate (CNO2), without nitrite and ascorbate (C0) and without nitrite and with ascorbate, green tea, grape seed and olive extracts (C0A). The products showed specific features in terms of peptides, free amino acids and volatiles, according to the technology applied for their production. The variations in peptides and free amino acids are likely due to process modifications, as the applied temperature and the time needed for pH decrease. Most volatile compounds, whether generated by known biochemical pathways or by ingredients (spices), differed between salami groups. The changes detected in the chemical parameters analysed provide some insights into the impact on product characteristics due to the process changes applied to replace nitrite removal.

The Rare Earth Element Distribution in Marine Carbonates as a Potential Proxy for Seawater pH on Early Earth

Understanding the marine environment of early Earth is crucial for understanding the evolution of climate and early life. However, the master variable of Archean and Proterozoic seawater, the pH, is poorly constrained, and published ideas about the pH range encompass ~7 pH units from mildly acidic to hyperalkaline. To better infer ancient seawater pH, we examine the possibility of a seawater pH proxy using rare earth elements (REEs) in marine carbonates. The principle is based on increasing concentrations of heavy rare earth elements in solution relative to the light REEs with decreasing pH due to REE complexation and scavenging. We calibrated such an REE pH proxy using pH variability in modern seawater and tested the proxy with ~100 REE measurements from 13 separate carbonate formations. We compared our pH estimates derived from the REE proxy to published pH estimates of Cenozoic and Neoproterozoic seawater that use the established pH proxy of boron isotopes (δ11B). REE-pH estimates agree with the Cenozoic and the Ediacaran δ11B-pH proxy based on the type of carbonate and boron isotopic composition at corresponding times. The uncertainty in our REE-pH proxy can probably be explained by model assumptions, noise from freshwater influence, siliciclastic input, and diagenesis. This proof-of-concept study demonstrates that the REE-pH method provides pH estimates comparable to boron isotope pH estimates within uncertainties, which potentially could constrain changes in Precambrian seawater pH to better understand the coevolution of life and early Earth’s environment.

Enhancing the quality of highland barley noodles by Lactobacillus plantarum pre-fermentation: Insights into its underlying mechanism

To improve highland barley noodles (HBNs) quality, the highland barley flour (HBF) was pre-fermented by Lactobacillus plantarum in this study. The changes in the quality of HBNs, the hydration properties and microstructure of the dietary fiber (DF), and the conformation and cross-linking of the protein in HBNs were measured. With the extension of pre-fermentation time (0–4 h), the overall acceptance of HBNs increased from 7.83 to 8.27, along with a 5.9% reduction in hardness and a 4.5% increase in springiness of HBNs. Meanwhile, confocal laser scanning microscopy (CLSM) revealed that the physical structure of the DF gradually disintegrated, which caused a significant (p < 0.05) decrease in its water retention capacity. In addition, spectral analysis showed a continual increase (from 19.62% to 30.15%) in β-turn content of the protein. The content of the free sulfhydryl group and sodium dodecyl sulfate extractable protein (SDSEP) decreased by 18.1% and 4.12%, respectively. However, with the further extension of pre-fermentation time (6–8 h), the degradation in HBNs sensory quality occurred, accompanied by a significant (p < 0.05) decrease in pH (5.95–5.01). These findings suggested that a moderate duration (4 h) of HBF pre-fermentation could effectively improve the quality of HBNs.

Analysis of the Effects of Different Orthodontic Appliances on Salivary pH Levels: An In vitro Approach.

Orthodontic appliances can influence the oral environment, including salivary pH levels, which play a crucial role in maintaining oral health. Understanding how different orthodontic appliances affect salivary pH levels can help in improving treatment outcomes and minimizing potential side effects. In this in vitro study, we evaluated the effects of various orthodontic appliances on salivary pH levels using a simulated oral environment. Four different types of orthodontic appliances were tested: traditional metal braces, ceramic braces, lingual braces, and clear aligners. Saliva samples were collected and subjected to pH measurements using a standardized method. The pH measurements were recorded at three different time intervals: immediately after appliance placement, after 24 hours, and after 48 hours. The initial pH values varied among the different orthodontic appliances: metal braces (pH 7.2), ceramic braces (pH 7.4), lingual braces (pH 7.1), and clear aligners (pH 7.5). After 24 hours, there was a decrease in pH levels for all groups: metal braces (pH 6.8), ceramic braces (pH 7.0), lingual braces (pH 6.7), and clear aligners (pH 7.2). After 48 hours, the pH levels continued to decrease: metal braces (pH 6.5), ceramic braces (pH 6.8), lingual braces (pH 6.4), and clear aligners (pH 6.9). Our findings suggest that different orthodontic appliances have varying effects on salivary pH levels. Metal braces and lingual braces tend to cause a more pronounced decrease in salivary pH compared to ceramic braces and clear aligners. Monitoring salivary pH levels during orthodontic treatment may be beneficial in identifying potential risks to oral health and implementing appropriate interventions.