Alkaline pH Research Articles

Comparative evaluation of pH and Ca + ion release from MTA on interaction with platelet-rich fibrin and blood clot: an in vitro study.

Background: 'Regenerative endodontics' using host-derived scaffolds and biomaterials (MTA) is popular in the management of teeth with open apex. Alkaline pH and bioactivity contribute to tissue healing and remineralization. We assessed the influence of PRF and Blood Clot on the pH and Ca + ion release from MTA. Methods: A total of 15 single-rooted human extracted teeth were sectioned at the level of the cementoenamel junction. Based on the type of scaffolds used, samples were divided into three groups. Group 1 (MTA+ PRF), Group 2 (MTA + Blood Clot), Group 3 (control MTA). The prepared specimens were transferred to a fresh falcon tube containing 10mL of distilled water and the collected solutions were analysed for pH and Ca + ion release at 3h, seventh day and 14 th day. Results: It was observed that the mean pH and Ca + ion release were significantly lower in the experimental groups as compared to the control group. Though there was an increase in the pH recorded in Group 1 and 2 at all time periods, the difference was not significant. Ca + ion release peaked at Day 7 (Group3 > Group2 > Group1) and reduced significantly on the 14 th day for all groups. Conclusions: Within the limitations of the study, it can be concluded that PRF and blood clot influence the pH and Ca + ion release from MTA.

Plant protein hydrogel as a delivery system of curcumin: Characterization and in vitro release Kinetics

In recent years, non-animal protein sources have led many consumers to eat plant-based alternatives. The Green gram protein is more biocompatible, highly sustainable and safer than animal proteins. Nutraceuticals have drawbacks such as poor water solubility, chemical instability at neutral and alkaline pH, auto-oxidation and poor absorption. Hydrogels are used to enhance the efficiency of these bioactive compounds. In this study, Green gram protein hydrogel enriched with curcumin was prepared. Protein was extracted from Green gram seeds using alkaline extraction and acid precipitation. Curcumin was extracted from turmeric using a Soxhlet Apparatus. A hydrogel was prepared using a sodium hydroxide concentration of 0.5 M to efficiently encapsulate curcumin and was characterized. The physicochemical properties of green gram protein hydrogels were evaluated by entrapment efficiency, swelling degree, FTIR, XRD, DSC, SEM, in vitro release and free radical scavenging assessment method. The encapsulation efficiency was 89.02 ± 0.56% respectively. The successful incorporation of curcumin in the hydrogel was confirmed by FTIR analysis. The surface properties of hydrogels were investigated using the SEM technique. The synthesized hydrogels are highly porous in nature and form cross linked structures. Moreover, hydrogels have a high swelling capacity. The swelling behaviour was due to the presence of hydrogen bonding interaction with the aqueous media. The hydrogel possesses a hydrophilic character when investigated by the contact angle. The contact angle of curcumin-loaded green gram hydrogel was increased by 9 °. The inhibition zone of 30 ± 03 mm was effective against E. coli. bacteria. The antioxidant property of the hydrogel gets increased by 50.46% after the addition of curcumin. Slow release of curcumin from hydrogel was studied using UV–vis Spectroscopy and it was inferred that it follows Korsmeyer-Peppas Kinetics model. The hydrogel was applied to tomato and apple as a coating. Generally, the results emphasised the potential use of Green gram protein hydrogel as a coating on fruits and vegetables.

Synthesis and physicochemical characterization of carbon quantum dots produced from folic acid

The rising interest in carbon dots (c-dots) is driven by their remarkable potential in the field of biomedical applications. This is due to their distinctive and adjustable photoluminescence characteristics, outstanding physicochemical properties, excellent photostability, and biocompatibility. Herein, carbon dots were successfully produced via the heat synthesis method and characterization for physical and chemical properties using UV–Vis spectrophotometer, photoluminescence spectroscopy, Fourier Transform Infrared and Raman spectroscopy, Energy-dispersive X-ray analysis, and quantum yield. The resulting carbon dots exhibited a distinct blue fluorescence upon exposure to ultraviolet radiation with a 366 nm wavelength. The photoluminescence spectrum of carbon dots displayed a fluorescence peak around 470 nm when excited with a 325 nm wavelength. The synthesized carbon dots demonstrated thermal stability and maintained photoluminescence intensity under different pH conditions, including neutral and alkaline mediums, and good salt resistance ability. Raman spectroscopy confirmed the presence of structural defects within the carbon dots, which are associated with the presence of hybrid groups on their surface. Fourier-transform infrared analysis detected various carbon-bonded, nitrogen-bonded, and oxygen-bonded units. The quantum yield was around 8.9%. These findings from our experiments indicate that the manufactured carbon dots possess substantial promise for a wide range of applications within the biotechnology field.

A mechano- and heat-gated two-pore domain K+ channel controls excitability in adult zebrafish skeletal muscle.

TRAAK channels are mechano-gated two-pore-domain K+ channels. Up to now, activity of these channels has been reported in neurons but not in skeletal muscle, yet an archetype of tissue challenged by mechanical stress. Using patch clamp methods on isolated skeletal muscle fibers from adult zebrafish, we show here that single channels sharing properties of TRAAK channels, i.e., selective to K+ ions, of 56 pS unitary conductance in the presence of 5 mM external K+, activated by membrane stretch, heat, arachidonic acid, and internal alkaline pH, are present in enzymatically isolated fast skeletal muscle fibers from adult zebrafish. The kcnk4b transcript encoding for TRAAK channels was cloned and found, concomitantly with activity of mechano-gated K+ channels, to be absent in zebrafish fast skeletal muscles at the larval stage but arising around 1 mo of age. The transfer of the kcnk4b gene in HEK cells and in the adult mouse muscle, that do not express functional TRAAK channels, led to expression and activity of mechano-gated K+ channels displaying properties comparable to native zebrafish TRAAK channels. In whole-cell voltage-clamp and current-clamp conditions, membrane stretch and heat led to activation of macroscopic K+ currents and to acceleration of the repolarization phase of action potentials respectively, suggesting that heat production and membrane deformation associated with skeletal muscle activity can control muscle excitability through TRAAK channel activation. TRAAK channels may represent a teleost-specific evolutionary product contributing to improve swimming performance for escaping predators and capturing prey at a critical stage of development.

Ammonia water as a biobased fertiliser: Evaluating agronomic and environmental performance for Lactuca sativa compared to synthetic fertilisers

The European Union is actively promoting circular agriculture, aiming to reduce external inputs, close nutrient cycles, and minimise harmful emissions. This shift has spotlighted bio-based fertilisers (BBFs) as a potential substitute for energy-intensive and environmentally detrimental synthetic fertilisers. Nevertheless, research on resilience and eco-friendliness of BBFs remains limited. To address this, novel manure-derived BBF - ammonia water (AW) was examined in terms of agronomic (crop yield, nitrogen (N) fertiliser replacement value (NFRV)) and environmental (N2O, CO2, CH4, NH3) parameters in a lettuce pot cultivation. The AW had an initial alkaline pH of 11.2 (AWpHini), and another variant with pH adjusted to 5 (AWpH5) was tested for performance comparison against calcium ammonium nitrate (CAN). The agronomic efficiency was tested at three incremental N rates (30%, 60%, and 100% of crop N demand). AWpHini resulted in similar crop yield and N uptake compared to CAN for all N rates. NFRV for all N rates of AWphini exceeded 90%, however, significant reverse trend was noted for AWph5 (NFRV <90% for all rates) likely due to product's low pH affecting soil microbes. In terms of environmental performance, gaseous emissions for AWphini (52.2 CO2eq) showed significantly lower (p < 0.05) trend in comparison to CAN (120.2 CO2eq), AWph5 (114.1 CO2eq) and urea (101.3 CO2eq). The effect of acidification was observed in NH3 emissions, where AWpH5 resulted in significantly lower (p < 0.05) emissions compared to AWpHini. More research in real-world field conditions with different crops is needed to confirm ammonia water's potential as a synthetic nitrogen fertiliser replacement.

Kinetics, stoichiometry, and mechanism of arsenopyrite-water interaction under anoxic conditions

Arsenopyrite dissolution is an important source of arsenic’s environmental occurrence and is well-studied under oxidative conditions. However, little is known of anoxic leaching of arsenopyrite by water, though it is probably one of the dominant abiotic processes controlling arsenic mobility in oxygen-limited environments such as groundwaters and paddy fields. The present study attempts to probe the mechanism of arsenopyrite-water interaction in anoxic environment through examining the pH dependence of dissolution kinetics and stoichiometry, as well as speciation changes both on the surface and in solution. Batch and flow-through experiments were first carried out to measure dissolution rates and the results showed alkaline pH mildly encourages As release. Furthermore, the dissolution was found to be near stoichiometric with respect to As and S but not with Fe/As or Fe/S, and the non-stoichiometry exhibited a negative dependence on pH. Combining speciation analyses that revealed the presence of H2O2, SO42− and S2O32− in solutions and a positive correlation of surface species Fe(III)-O, S(-II), and As(I), As(III), As(V), and As(-III) to solution pH, we interpreted the anoxic dissolution behavior of arsenopyrite through a mechanism that combines surface complexation and interfacial redox reactions. The kinetic measurements came to be concerning as data indicates arsenopyrite dissolution in anoxic environment can lead to water having arsenic concentrations above the 10 ppb WHO guideline value in one day at the experimental conditions. The observed H2O2 production indicated the dissolution is associated with or initiated by electron transfer despite the anoxic condition, further suggesting that a more comprehensive theory other than surface complexation model may be needed to better understand the geochemical behavior of As and possibly S in the context of sulfide mineral–water interactions.

Microbially-driven alkaline regulation: Organic acid secretion behavior of Penicillium oxalicum and charge neutralization in bauxite residue

Microbially-driven alkaline neutralization in bauxite residue by functional microorganisms is a promising approach for the ecological rehabilitation on alkaline disposal areas. However, the alkali resistance and acid secretion mechanism of functional microorganisms are still unknown, which limits their application. Here, saline-alkaline resistance, acid production performance, and differentially expressed genes of Penicillium oxalicum (P. oxalicum, a functional fungus screened from a typical disposal area) were investigated and its bio-neutralization efficiency was evaluated. This fungus exhibited high tolerance to alkalinity (pH 12), and salinity (NaCl 2.0 M), and produced a large amount of oxalic acid to reduce the medium pH to 2.0. Transcriptome showed that alkali stress induced the overexpression of genes related to antioxidant and stress-resistant enzymes (GST, KatE) and glycolytic pathway rate-limiting enzymes (HK). The rate of glycolysis and other organic acid metabolism processes was increased with higher stress resistance of P. oxalicum. The integrated application of P. oxalicum and maize straw accelerated the dissolved organic carbon content and stabilized the leachate pH of bauxite residue at about 7.4. 3DEEM and BIOSEM analysis indicated that P. oxalicum maintained high activity in the residue leachate and continuously decomposed the maize straw for their metabolism. P. oxalicum showed strong alkaline resistance, biomass degradation capacity, and alkaline regulation potential, which should be beneficial for microbial-driven alkaline regulation in bauxite residue.

The Influence of Spent Portable Battery Waste on the Aquatic Environment

Spent portable batteries belong to the category of hazardous waste, sometimes dumped together with non-hazardous municipal waste in landfills, resulting in various aquatic environments. Their presence in the aquatic environment leads to changes in its quality and its contamination with heavy metals or other toxic elements. This paper highlights the portable battery waste’s influence on the aquatic environment in stagnant conditions. Therefore, three types of batteries and three solutions with different pH values were used to represent the possible media existing in nature: acid (pH = 4.00), rainwater (pH = 5.63), and alkaline (pH = 8.00). After 180 days, the results showed changes in the chromatics and composition of the initial solutions. The analyses showed decreased pH, increased conductivity, and the transfer of several heavy metals into solutions (Cu, Pb, Zn, Ni, and Fe). Thus, there were slight exceedances of the maximum allowed values for water quality class I (Order no. 161/2006) in the case of Cu and Pb and higher exceedances in the case of Zn, Ni, and Fe. Zinc–carbon batteries stand out because of the release of Pb and Fe ions. The same applies to lithium manganese dioxide batteries because of Ni ions as well as zinc–manganese alloy batteries because of Cu and Zn ions. Altogether, the negative influence of spent batteries on the aquatic environment is noticed, and the measures for the implementation of safe disposal and processing are necessary.

Nutrient Diagnostics and Biochemical Indicators of Oat Grain Quality Predicted by Leaf Juice Amino Acid Concentration

In order to find out the relationship between the level of nitrogen nutrition of oat plants of the Yakov variety and the content of amino acids in leaf juice, as well as the possibility of using this indicator to assess the content and composition of proteins, the activity of amylases, catalases and peroxidases in ripe grain and the activity of theseenzymes in germinating grain, a field experiment was carried out at the Field Experimental Station of Russian State Agrarian University – Moscow Timiryazev Agricultural Academy, on sod-podzolic medium loamy soil. In the field experiment, variants with different levels of nitrogen nutrition of oat plants that had passed post-harvest ripening were tudied. Ammonium nitrate, double superphosphate, and potassium chloride were applied in advance. As a result, it was found that as the level of nitrogen nutrition of plants increased, the concentration of amino acids in the juice of oat leaves at the stage of formation of the first stem node decreased, which was closely correlated with the nitrogen doses. These data indicate the possibility of using this indicator for the diagnosis of nitrogen nutrition in oat plants. The studies also revealed a reliable correlation between the content of amino acids in leaf juice and the concentration of proteins soluble in water and solutions of 10% KCl, 0.2% NaOH, as well as the activity of acid (pH 5.5), neutral (pH 7) and alkaline (pH 8) isoenzymes of α-amylase and acid isoforms of β-amylase in ripe grain. In addition, the amino acid content of leaf juice was found to be significantly correlated with the activity of acidic α-amylase, acidic and neutral β-amylase in germinated grain. The results obtained demonstrate the possibility of predicting the level of protein accumulation in oat grains. It is also possible to predict the protein composition, activity of α- and β-amylase, catalase, and peroxidase isoenzymes from the content of amino acids in leaf juice in the phase of the first stem node formation. A reliable correlation was also found for the activity of acid and neutral isoenzymes of α-amylase, catalase, and peroxidase in ripe and germinated oat grain.

The pH tolerance range of the airborne species Tetracystis vinatzeri (Chlorophyceae, Chlamydomonadales)

ABSTRACT To decipher the dispersal range of the cosmopolitan green microalga Tetracystis vinatzeri, two airborne-collected strains were barcoded using the 18S ribosomal DNA gene (18S) and the mitochondrial cytochrome c oxidase I subunit (COI), and their survival capacities were investigated across a stepwise acidic to alkaline pH gradient. Genetic fingerprinting confirmed the identity of the strains as representing the same biological species. Investigations of the tolerance of T. vinatzeri to pH levels refined the delimitation of its ecological niche. T. vinatzeri showed optimal growth in freshwater habitats at pH 4.3–9.6 and strains could cope with exposure to slightly more acidic (down to 3.8) and alkaline (up to 10.4) conditions. However, organismal survival was drastically affected by exposure to pH < 3 and > 11. Morphological observations showed that T. vinatzeri could better cope with exposure to acidic pH, exhibiting less cell membrane damage. Genetic analysis showed that the two airborne strains shared the same haplotype, suggesting that they either originated from the same air mass or that the haplotype has a widespread distribution. Further phylogeographic and physiological investigations are required to define the spreading dynamic of T. vinatzeri.

Stainless steel as an electrocatalyst for overall water splitting under alkaline and neutral conditions

The development process for an effective catalyst for electrochemical water splitting must consider properties such as chemical and mechanical stability, corrosion resistance, and abundance alongside efficiency. In this work, a detailed electrochemical evaluation of four types of commercially available AISI stainless steel (302, 304, 316, and 321) was performed for their electrocatalytic activity, stability, and corrosion resistance in overall water splitting under alkaline (pH 14.00) and near-neutral conditions (pH 6.26). Using AISI plates directly as an anode or cathode, a current density of 10 mA cm−2 was obtained at η ≈ 0.38 V for OER and η ≈ 0.43 V for HER in 1 M KOH. Although all of the tested types have proved to be efficient electrocatalysts, detailed electrochemical studies have distinguished certain differences between the AISI types, depending mainly on the composition peculiarities. A detailed corrosion evaluation has revealed that although all measured stainless steels are sensitive to the oxidative environment, their corrosion rate does not exceed 3.3 µm per year.

Relationship of Urine Acidity to The Risk of Candidiasis Infection in Pregnant Mothers

Candidiasis is a disease caused by fungi and the most common cause is candida albicans. The aim of this study was to measure the relationship between the degree of urine acidity and the risk of candidiasis infection in pregnant women. The benefit of research is to determine the degree of acidity on the incidence of candidiasis in pregnant women. The results of research from 42 urine samples from pregnant women found urine with an acidic pH of 30 urines or 71.4% and from these 30 samples 19 urine samples were found to be positive for Candida albicans. A neutral pH was found in 5 urines with the sample test results not finding Candida albicans, but 1 sample was found with the fungus Candida Sp. The results of the urine measurements found 7 urine with an alkaline pH and no Candida albicans was found, but overall Esterococcus bacteria were found in the urine with a neutral and alkaline pH and no Candida albicans was found.

Influential Factors in Intestinal Absorption and Renal Reabsorption of Calcium

Calcium is one of the vital and essential elements in the body, serving as a primary constituent of bones and teeth. It plays a fundamental role in nerve signal transmission, muscle contractions, heart rate regulation, blood clotting, energy production, glandular secretion, and immune system maintenance. Calcium is abundantly found in dietary sources, with most of it residing in the teeth and bones within the body. Approximately 40% of daily dietary calcium is absorbed primarily at the beginning of the intestine and before gastric juice neutralization, while 60% of it is excreted through feces. Calcium absorption occurs in two forms, passive and active, through the intestines, and renal reabsorption takes place through the kidneys. Various factors such as intestinal environment, dietary components (including lactose, proteins, and amino acids),bile salts, parathyroid hormone, vitamin D, acidic pH, health status, age, and growth hormone influence intestinal calcium absorption positively. Conversely, fatty acids, phytic acid, aging, alkaline pH, iron, magnesium, calcitonin hormones, and glucocorticoids reduce calcium absorption. Parathyroid hormone, calcitonin hormone, vitamin D, and dietary regimen significantly contribute to the active reabsorption of calcium through renal tubules. Despite the considerable variations in the calcium content of dietary sources, a highly precise regulatory system controls vitamin D production, preventing fluctuations in plasma calcium ion concentrations. This regulation helps prevent hypocalcemia and hypercalcemia, which can lead to numerous irregularities in the body.

Autotrophic nitrogen polishing of secondary effluents: Alkaline pH and residual nitrate control S0-driven denitratation for downstream anammox treatment

Energy-lean nitrogen removal technologies, such as partial nitritation/anammox, often encounter effluent issues due to elevated nitrate and ammonium levels. This study proposed a novel autotrophic polishing strategy coupling sulfur-driven denitratation with anammox. To explore the denitratation potential in obtaining stable and sufficient nitrite accumulation, the effects of pH, residual nitrate level, and biomass-specific nitrate loading rate (BSNLR) were investigated in an S0-packed bed reactor at low hydraulic retention time (i.e., 0.2 h). Implementing pH and residual nitrate control strategies would be easier in practice than BSNLR control to polish secondary effluent. Alkaline pH values could realize successful nitrite accumulation without residual nitrate, and further intensify the accumulation under increased residual nitrate levels. The nitrate level was positively correlated with the nitrite accumulation efficiency. At pH 8.5 and nitrate concentration of 1.0 ± 0.8 mg N L−1, sulfur-driven denitratation could successfully maintain nitrite accumulation of 6.4 ± 1.0 mg NO2−-N L−1, ideally for the downstream anammox in case of residual ammonium levels of around 5 mg N L−1. Since Thiobacillus members play a key role in managing nitrite accumulation, their abundance should be guaranteed in the practical application.

Kinetics and mechanism of dissolved organic phosphorus (DOP) digestion by the UV/O3 process

AbstractIn this study, the kinetics and mechanism of UV/O3 synergistic oxidative digestion of dissolved organic phosphorus (DOP) were investigated, focusing on the ozone direct oxidation and hydroxyl radical oxidation parts of glufosinate and triphenyl phosphate (TPhP). The p‐chlorobenzoic acid (p‐CBA) was selected as the probe compound, and two kinds of reaction kinetic models were proposed by competitive kinetic method with Rct according to the different scale of rate constants of hydroxyl radical oxidation. Under the condition of weakly alkaline (pH = 9.0) and weakly acidic environment (pH = 5.0), the second‐order rate constants of glufosinate and TPhP was determined indirectly to be ko3/glufosinate = (2.903 ± 0.247)M−1s−1 and ko3/TPhP = (3.307 ± 0.204) M−1s−1 by ozone direct oxidation, and k·OH/glufosinate = (1.257 ± 1.031) × 109 M−1s−1 and k·OH/TPhP = (7.120 × 108 ± 0.963) M−1s−1 by hydroxyl radical oxidation, respectively. The comparison of the contribution levels of the two parts to the digestion process showed that the contribution levels in the digestion of glufosinate and TPhP processes both the contribution of ·OH were higher than those of ozone, 86.3% and 72.6%, respectively.

Study and Analysis on Groundwater Modelling in Watershed Area of the Wainganga River Gondia District Using GIS Techniques

Currently, Geographic information systems (GIS) are the most significant mapping and modelling tool for groundwater analysis.The determination of the groundwater level of In a few years, the availability of groundwater will be a problem in Kati Village, Gondia District, Maharashtra, India, a case study Wainganga River watershed area pre-monsoon and post-monsoon analysis.The monsoon rains in Gondia District are concentrated in the four months of June to September, with 90.81% rainfall, 1.86% post-monsoon, 4.83% pre-monsoon, and 2.48% winter. The annual rainfall distribution in Gondia is very irregular. The main river is Wainganga, and the tributaries are Bagh.The water has a neutral to alkaline pH range of 6.6 to 8.92 and a high TDS range of 140 to 2184 ppm. The suitability of the groundwater level must be established before using GIS interpolation model techniques to evaluate it. Groundwater level monitoring, hydrology, and other fields increasingly make use of geospatial techniques for Geographic information systems (GIS). Using this method of groundwater level monitoring to gather information on water level potential position conditions in the study area is crucial for effective analysis, prediction, and validation. The result is reached through statistically significant analysis of physicochemical parameters and groundwater modelling using GIS. This study's objective is to use GIS techniques to analyse groundwater modelling in the Wainganga River Gondia District.The information can be used in the future for studies on area management, resource conservation, and restoration.

Assessment of the in situ biomethanation potential of a deep aquifer used for natural gas storage

In response to the challenges of sustainable development and the H2 sector, it is foreseeable that H2 will be stored into geological storage, such as deep aquifers. However, CO2 evolves in deep aquifers because it may be naturally present there; it may also be a constituent of the stored gas mix, or could even be voluntarily stored in the context of the fight against global warming. Autochthonous microorganisms can consume them as sources of energy and carbon (methanogens, (homo)-acetogens and sulfate-reducers). This was already demonstrated in a previous experiment (Haddad 2022) and under operating conditions (Lobodice, Czech Republic ; Smigan 1990). Understanding these mechanisms and quantifying them appear necessary to assess the modifications generated by this type of microorganisms on the properties of the gas. The methanogenesis reaction (CO2 gas + 4H2 gas → CH4 gas + 2H2O liquid) induces a lowering of pressure, since 5 gas molecules are transformed into a single gas molecule: CH4 (water being condensed at subsurface conditions). In situ biomethanation technique could represent a potential on several scales larger than conventional catalytic or biological methanation reactors, due to the very large reservoir volumes involved. Biomethanation in geological reservoirs would enable us to reduce our consumption of fossil fuels, so as not to emit more CO2, while meeting the growing energy needs of a region and ensuring its independence from hydrocarbon-producing countries. A deep aquifer already used as UGS was selected for this study. Formation waters from 17 control wells in this aquifer (Fig. 1) were sampled to assess the potential activity of indigenous methanogenic populations, as well as sulfate-reducers. Despite relatively low sulfate concentrations for a deep aquifer (0.025-1.35 mM), sulfate reducers were found at all sites targeting and quantifying the dsrB gene, which is characteristic of this metabolic group (between 1.8∙101 ±2.0x100 and 1.3∙104 ±2.0∙103 dsrB gene copy numbers.mL-1). In contrast, methanogenic archaea based on the mcrA gene quantification were detected at only 10 of the 17 sites (up to 4.3∙102 ±8.3∙101 mcrA gene copy numbers.mL-1). The choice was made to focus the rest of the study on 7 of these 10 sites. The potential for methanogenesis was assessed on cultural tests with formation water alone or supplemented with calcite (CaCO3), a mineral present in the formation. Results indicate that initial times and controls are controlled by the sulfate variable, since the latter was not consumed by sulfate-reducers. Biotic trials in the presence of calcite and H2/CO2 (abiotic controls and final times) are logically characterized by higher concentrations of calcite, bicarbonate and calcium, but this is not the case for trials in the presence of H2 alone. We therefore deduce that methanogenesis took place mainly via gaseous CO2, but that without the latter, calcite was a source of carbon for lithoautotrophs. Cultures incubated with H2 as the sole gas phase have the highest methane concentrations, logically associated with the lowest sulfate concentrations (consumed by sulfate-reducers), the lowest Eh (probably due to the presence of sulfides) and more alkaline pH values up to 10 (which may have led to precipitation of carbonate and calcium ions). All the sites studied showed sulfate consumption and methane production. Analysis of taxonomic diversity (MiSeq; 16S rRNA gene V4-V5) showed the dominance of three genera of sulfate-reducers with Thermodesulfovibrio-Desulfovibrio-Desulfotomaculum and methanogenic populations belonging to the Methanobacterium genus. These initial results show a strong potential of in situ biomethanation for the deep aquifer studied. All these experiments were carried out at near-atmospheric pressure, and the results still need to be confirmed and refined in the laboratory under conditions that simulate real-life conditions as closely as possible (rock, pressure, nature of gases).

The Geochemical Habitats that Favored the Origin of Thermophilic Lineages

Evidence in the fossil and isotopic records suggests that life inhabited hot springs by ~3.5 Ga. Further, phylogenetic evidence places Bacteria and Archaea from high temperature environments as among the earliest evolving lineages. Moreover, contemporary hot spring communities host an extensive level of biodiversity coinciding with extensive geochemical variation due to spatial and temporal heterogeneity in available oxidants and reductants generated by variable mixing of reduced volcanic and oxidized meteoric fluids. Thus, thermophilic archaeal and bacterial lineages have been co-evolving with their hydrothermal environments since early in the history of life and through dramatic changes in Earth’s geologic history. Yet, little is known of the environmental characteristics that enabled the extensive diversification of microbial life and their metabolic functionalities in these environments. To begin developing a framework to understand the environmental characteristics that enabled expansive microbial taxonomic and functional innovation in thermophilic lineages - coordinated geochemical, metagenomic, and phylogenetic analyses were conducted on 37 high-temperature Yellowstone National Park (YNP) hot spring ecosystems that spanned the range of geochemistry (pH ~1.5-10) in YNP springs. Considerable variation in dissolved solutes and gases were identified, consistent with spatial and temporal variation in the geological, geochemical, and hydrologic processes that influence the YNP hydrothermal system. Shotgun sequencing and bioinformatics analyses yielded 1,154 archaeal and bacterial metagenome-assembled-genomes (MAGs) from the 37 springs. Genomic diversity and metabolic functions encoded by the MAGs were not uniformly distributed among spring types based on geochemistry, with moderately acidic springs (pH 5-7) harboring the greatest overall diversity, despite these spring types being relatively rare among continental hydrothermal systems. Phylogenomic analyses of MAGs indicated that their divergence times (estimated by distance to phylogenetic roots) were variable, but highly associated with spring geochemistry. Specifically, spring types hosting the highest genomic, taxonomic, and functional diversity also predominantly harbored microbial lineages with the oldest inferred divergence times. In addition, MAG-encoded metabolic functions related to carbon fixation, methane, sulfur, iron, arsenic, hydrogen, and nitrogen metabolism were discretely distributed across spring geochemical types. The distribution of metabolic functions coincided with variation in spring geochemical parameters related to those metabolisms. For example, iron metabolism was most prevalent in acidic springs exhibiting the highest iron concentrations, gas metabolism was most prominent in moderately acidic springs that exhibited the highest dissolved gas concentrations, and arsenic metabolism was prevalent among alkaline pH springs where arsenic concentrations were highest. Lastly, preliminary comparisons of microbial communities from YNP and other global continental hydrothermal systems suggest that geologic setting (e.g., bedrock type) significantly influences hot spring geochemistry and ultimately, microbial compositional and functional profiles that coincide with distinct evolutionary trajectories of hot spring taxa and functional genes. Results will be discussed in the context of the early evolution of life and the co-evolution of microbial lineages and their geologic settings in hydrothermal systems.

Facts and Features of Gastroretentive Drug Delivery System

Oral drug delivery has gained a lot of popularity because of patient compliance and the simplicity of administration. It only provides a small number of benefits for medications with poor bioavailability because of inadequate digestion and absorption in the latter stages of the GI tract. In this scenario, GRDDS have emerged as a preferred choice for drug administration with unique qualities such as a narrow absorption window, avoiding metabolism, instability in high alkaline pH, and improved solubility in low pH. In this present review, we discuss the Merits and demerits, the physiology of the stomach, and factors affecting the grdds. Various gastrointestinal technologies, including floating, non-floating, expandable, superporous hydrogel; Bioadhesive, magnetic, and raft system, as well as their applications, is outlined. In addition, potential future developments on this technology to minimise stomach emptying rate in both fasting and fed stages are highlighted. In the end, this review might assist formulation scientists and researchers in designing the GRDDS.

Enrichment of resistant starch in starch-protein hydrolysate binary matrix by modulating pH during thermal processing

Controlling the digestion features of starch-based food matrices following thermal processing plays vital roles in reducing risks of metabolic diseases such as obesity and type II diabetes. To date, it remains largely unclear how regulating the pH during thermal processing alters the microstructure and digestion features of starch-based matrix including protein hydrolysates. Considering this, corn starch (CS) and soybean protein isolate (SPI) (or its hydrolysates (SPIH)) were used to prepare thermally-processed CS-SPI and CS-SPIH binary matrices under different pH values (3 to 9), followed by inspection of changes in the structures and digestibility using combined methods. It was found that including SPI (especially SPIH) caused structural changes of those binary systems, such as reduced network sizes, increased V-crystals and reduced nanoscale structures, which could allow more resistant starch (RS). This phenomenon was especially true when including SPIH with regulated pH value. For instance, SPIH inclusion at pH 5 caused the highest RS content (about 20.30%), presumably linked to the reduced molecule size of SPIH with strengthened aggregation at pH 5. In contrast, the acidic (pH 3) and alkaline (pH 9) conditions allowed reduced short-range orders and tailored porous networks and thus less RS (ca. 17.46% at pH 3 and 16.74% at pH 9).