Bicarbonate Concentration Research Articles

Flood-spreading effects on the chemical properties of the soil: a case study of the Tasuj station, Iran

ABSTRACT The objective of this paper is to determine whether the flood-spreading system at the Tasuj station in east Azerbaijan, Iran, has caused inappropriate chemical alterations to the properties of the soil. One question is whether the flood-spreading system was constructed at an inappropriate location leading to unintentional consequences. Composite soil samples were taken from three flooded areas, from three grids in each flooding area, and from two depths. Chemical characteristics of the soil including electrical conductivity, pH, concentrations of bicarbonate, chloride, sodium, calcium, and magnesium ions, and the sodium adsorption ratio in the flooded areas were measured. Because of calcareous, gypsum, shale, and marl formations in the first flooded area, dissolution of solutes of these formations increased the concentration of ions in the runoff (especially sodium and chlorine, to 19.50 and 21.90 mmol (charge) L−1, respectively). These high ion concentrations caused the electrical conductivity of the runoff to increase significantly (up to 2.03 dS/m) compared to the other areas. High amounts of lime in the soil caused increasing buffering capacity of the area soil, as a consequence the flood-spreading did not cause significant changes to the soil pH and showed a difference of only 0.3–0.2 in the first flooded area compared to other areas.

Urinary acid-base excretion deciphers high acid load from colonic bicarbonate loss in intestinal failure patients with ileocolonic anastomosis – Guidance for composition of parenteral support

Background & AimsAcid-base disturbances are common in short bowel (SB) patients due to increased intestinal bicarbonate loss. However, the resulting systemic acid load has not been quantified. Base excess is used to monitor metabolic acid-base disturbances but inadequately reflects the acid load. Our aim was to investigate the systemic acid/base load in SB-patients to obtain quantitative estimates to guide the composition of parenteral support. MethodsWe calculated total acid load in SB patients by summing 24-hour urinary net acid excretion (NAE) and the provision of base equivalents in parenteral support. We then compared differences among anatomical SB-types: jejunostomy (SB-J), jejunocolostomy (SB-JC), and jejunoileostomy (SB-JIC). 47 urine samples from 34 SB patients were analyzed for bicarbonate (HCO3-), ammonium (NH4+), and titratable acidity (TA) concentrations. NAE was calculated as (TA + NH4+) - HCO3-. Mixed-effects repeated-measures models were used to statistically examine differences between SB-types and associations with parenteral nutrition and NAE. A healthy cohort served as control. ResultsIn comparison to SB-J, SB-JC patients had a 4.1 mmol/l lower base excess (95% CI: -6.3 to -1.8) and an 84.5 mmol/day higher total acid load (CI: 41.3 to 127.7). There were no significant differences between SB-JIC and SB-J regarding base excess, NAE, or total acid load. Higher amounts of infused acetate, sodium, and chloride, but not the acetate/chloride ratio, were associated with lower NAE and higher base excess. ConclusionsDue to increased colonic bicarbonate loss, patients with SB-JC have a ∼4.4-fold higher acid load than healthy controls. The ion transport mechanisms mediating this bicarbonate loss from the remaining colon need further experimental investigation. NAE could be a useful tool to adjust base infusion in SB.

Retrospective study of acid-base disturbances in patients with chronic kidney disease

Background. Impaired kidney function has a negative effect on the body’s acid-base status (ABS). However, a violation of ABS can worsen the course of chronic kidney disease (CKD). Therefore, during the examination and treatment of patients with CKD, it is necessary to take into account the ABS. The purpose of the study: to conduct a retrospective analysis of the dynamics of ABS indicators in patients with stage 1–5 CKD who sought outpatient medical care in a medical institution in Kyiv. Materials and methods. A retrospective, randomized, cohort study was performed of 53 medical records of patients (form 025/o) who sought outpatient medical care at the Professor Dmytro Ivanov Nephrological Clinic LLC with a diagnosis of stage 1–5 CKD from February 2022 to February 2023. Participants were examined for ABS indicators three times. They were divided into 2 groups: group 1 (n = 31) — stage 1–3 CKD and group 2 (n = 22) — stage 4–5 CKD. An analysis of ABS indicators was carried out in dyna­mics. Results. Results of multiple linear regression for patients with stage 1–5 CKD (n = 53) showed that there was a strong significant effect between potassium (K+) and glomerular filtration rate (GFR) (F(1, 13) = 10.59, p = 0.006, R2 = 0.45, R2 adj = 0.41). The results of multiple linear regression of indicators in patients with stage 1–3 CKD (group 1) demonstrated a weak insignificant influence between lactate and GFR (F(1, 15) = 1.11, p = 0.310, R2 = 0.07, R2 adj = 0.01). The results of multiple linear regression of indicators in patients with stage 4–5 CKD (group 2) showed that there is a very strong combined insignificant influence between the hydrogen index, partial pressure of carbon dioxide, partial pressure of oxygen, bicarbonate concentration, base excess of extracellular fluid, K+, total carbon dioxide, anion gap with K concentration included in the equation, base excess, lactate and GFR (F(10, –3) = 0.3, p = 58.099, R2 = –65.23, R2 adj = 155.53). Conclusions. When studying ABS in patients with stage 1–5 CKD, a correlation was found between K+ and GFR using the multiple linear regression tool. In the first group, the relationship between lactate and GFR, in the second one, all predictors had a relationship with GFR.

Production of ammonium bicarbonate from the condensate of the upgrading biogas-pipelines

Developing a suite of biofuels for different applications relies heavily on upgrading technologies to remove nitrogen compounds and carbon dioxide. Particularly in the upgrading of biogas to biomethane, simple water scrubbing is the most widely used technology for biogas upgrading. This technology can be synergistically implemented without the need for additional equipment for processing steps, although this design has not been conceived yet. Samples of biogas-pipeline condensates were collected from 3 different anaerobic digestion plants processing 3 different feedstocks (i.e., food waste, agrowaste, and manure) at 3 different locations in each plant (i.e., biodigester and postdigester condensate pits, digestate pasteurizer, and biogas booster and chiller). The methodology for the analysis of the 5-mL biogas-pipeline condensates was acid-base titration with 0.06 M hydrochloric acid and 0.13 M sodium hydroxide solutions as titrants, and induction of crystallization by cooling at 3 °C, adding up to 40 mL of acetone as antisolvent, and settling for 12 h. The results showed that the concentration of ammonium bicarbonate in the condensates ranged from 0.75 to 50 g/L. The most suitable location to enhance the upgradation of biogas, formation of condensate, and precipitation of ammonium bicarbonate was the pit after the anaerobic digester and before the biogas storage. The most concentrated condensate was retrieved from the biogas-pipeline coming out of the pasteurization tank, but the operation at 70.5 °C also led to volatilization of organic compounds that negatively affected the biogas quality. Future work aims to investigate coating and granulation of ammonium bicarbonate crystals to improve their stability and commercialization.

Photosynthetic response of Chara braunii towards different bicarbonate concentrations.

A variety of inorganic carbon acquisition modes have been proposed in Characean algae, however, a broadly applicable inorganic carbon uptake mechanism is unknown for the genus Chara. In the present study, we analyzed if C. braunii can efficiently use HCO3 - as a carbon source for photosynthesis. For this purpose, C. braunii was exposed to different concentrations of NaHCO3 - at different time scales. The photosynthetic electron transport through photosystem I (PSI) and II (PSII), the maximum electron transport rate (ETRmax ), the efficiency of the electron transport rate (α, the initial slope of the ETR), and the light saturation point of photosynthesis (Ek ) were evaluated. Additionally, pigment contents (chlorophyll a, chlorophyll b, and carotenoids) were determined. Bicarbonate addition positively affected ETRmax , after direct HCO3 - application, of both PSII and PSI, but this effect seems to decrease after 1 h and 24 h. Similar trends were seen for Ek , but no significant effect was observed for α. Pigment contents showed no significant changes in relation to different HCO3 - concentrations. To evaluate if cyclic electron flow around PSI was involved in active HCO3 - uptake, the ratio of PSI ETRmax /PSII ETRmax was calculated but did not show a distinctive trend. These results suggest that C. braunii can utilize NaHCO3 - in short-term periods as a carbon source but could rely on other carbon acquisition mechanisms over prolonged time periods. These observations suggest that the minor role of HCO3 - as a carbon source for photosynthesis in this alga might differentiate C. braunii from other examined Chara spp.

Effects of acute and multi-day low-dose sodium bicarbonate intake on high-intensity endurance exercise performance in male recreational cyclists

PurposeThis study aimed to compare the effects of acute and multi-day low-dose sodium bicarbonate (SB) intake on high-intensity endurance exercise performance.MethodsIn a randomized, double-blind, cross-over design, twelve recreational male cyclists (age: 31.17 ± 4.91 years; V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{{\ ext{V}}}$$\\end{document}O2peak: 47.98 ± 7.68 ml·kg−1·min−1) completed three endurance performance tests following acute SB (ASB, 0.2 g·kg−1 SB), multi-day SB (MSB, 0.2 g·kg−1·day−1 SB for four days), and placebo (PLA) intake. The high-intensity endurance performance was assessed with a cycling exercise test, wherein participants cycled on a bicycle ergometer at 95% of the predetermined anaerobic threshold for 30 min, followed by a time-to-exhaustion test at 110% of the anaerobic threshold. Data were analyzed using one-way and two-way repeated-measures ANOVA.ResultsSignificant main effects of supplementation protocol were evident in pre-exercise bicarbonate concentrations (F = 27.93; p < 0.01; partial eta squared (η2) = 0.72; false discovery rate (FDR)-adjusted p value = 0.001). Prior to performance test, blood bicarbonate concentrations were significantly higher in MSB (25.78 ± 1.63 mmol·L−1 [95% CI 26.55–28.44] (p < 0.001; FDR-adjusted p value = 0.001)) and ASB (27.49 ± 1.49 mmol·L−1 [95% CI 24.75–26.81] (p < 0.001; FDR-adjusted p value = 0.007)) compared to PLA (23.75 ± 1.40 mmol·L−1 [95% CI 22.86 to 24.64]). Time-to-exhaustion increased in MSB (54.27 ± 9.20 min [95% CI 48.43–60.12]) compared to PLA (49.75 ± 10.80 min [95% CI 42.89–56.62]) (p = 0.048); however, this increase in MSB did not reach the significance threshold of 1% FDR (FDR-adjusted p value = 0.040). No significant difference was noted in exhaustion times between ASB (51.15 ± 8.39 min [95% CI 45.82–56.48]) and PLA (p > 0.05).ConclusionBoth acute and multi-day administration of low-dose SB improves buffering system in cyclists; nevertheless, neither intervention demonstrates sufficient efficacy in enhancing high-intensity endurance performance.

Aragonite crystallization in a sulfate-rich hypersaline wetland under dry Mediterranean climate (Laguna Honda, eastern Guadalquivir basin, S Spain)

This research investigates the influence of water composition, the presence of seasonal algal mats, detrital inputs and the activity of microorganisms on the crystallization of aragonite in the sediments deposited in the hypersaline Laguna Honda wetland (S of Spain). The high alkaline and hypersaline waters (pH > 9.2 and C.E. > 70 mS/cm) of the wetland lake are rich in SO42− (>24,000 mg/l), Cl− (>21,000 mg/l), Na+ (>11,000 mg/l) Mg2+ (>8400 mg/l) and Ca2+ (>1000 mg/l), and are supersaturated for dolomite, calcite and aragonite. Sediments have lower pH values than column waters, oscillating from 8.54 in the low Eh (up to −80.9 mV) central deep sediments and 6.33 in the shallower higher Eh (around −13.6 mV) shore sediments. Erosion of the surrounding olive groves soils produced detrital silicates rich sediments with concretions of carbonate or sulfate. Aragonite (up to 19 %) and pyrite (up to 13 %) are mainly concentrated in the organic matter rich samples from the upper part of the sediment cores, whereas gypsum is preferably concentrated in low organic matter content samples. Mineral crusts containing a MgAl silicate phase, epsomite, halite and gypsum are precipitated on the floating algal mats covering the wetland waters. Floating algal mats deposit increased the organic matter content of the upper sediments which promoted the presence of fermentative microorganisms, sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) communities and variations of Eh that influence the authigenesis of carbonate and S-bearing minerals. Replacement of poorly crystalline MgSi phases infilling algal cells by aragonite was favored in the organic matter rich sediments with low Eh values and important SRB communities that promoted sulfate bioreduction processes to form pyrite. Aragonite precipitation was favored by the increase of carbonate and bicarbonate concentration produced by the SRB oxidation of organic matter, the CO2 degassing by high summer temperatures and the CO2 uptake by photosynthesis of the algal mats.

Using ultrasonic-assisted sodium bicarbonate treatment to improve the gel and rheological properties of reduced-salt pork myofibrillar protein

To study the impact of ultrasonic duration (0, 30, and 60 min) and sodium bicarbonate concentration (0% and 0.2%) on the gel properties of reduced-salt pork myofibrillar protein, the changes in cooking yield, colour, water retention, texture properties, and dynamic rheology were investigated. The findings revealed that added sodium bicarbonate significantly increased (P < 0.05) cooking yield, hardness, springiness, and strength of myofibrillar protein while reducing centrifugal loss. Furthermore, the incorporation of sodium bicarbonate led to a significant decrease in L⁎, a⁎, b⁎, and white values of cooked myofibrillar protein; these effects were further amplified with increasing ultrasonic duration (P < 0.05). Additionally, storage modulus (G') significantly increased for myofibrillar protein treated with ultrasonic-assisted sodium bicarbonate treatment resulting in a more compact gel structure post-cooking. In summary, the results demonstrated that ultrasonic-assisted sodium bicarbonate treatment could enhance the tightness of reduced-salt myofibrillar protein gel structure while improving the water retention and texture properties.

Early Blood Gas Analysis in SARS-COV-2 Infected Patients Admitted to SMHS Hospital: A Tertiary Care Hospital in Kashmir

Inroduction: Blood gases are a measurement of how much oxygen and carbon dioxide is in blood. These determine the acidity of blood. The blood gas testing is generally used for detecting and monitoring lung and kidney problems. The blood gas testing measures partial pressure of oxygen (o2), partial pressure of carbon dioxide (CO2),oxygen saturation(O2Sat), bicarbonate(HCO3) concentration .&#x0D; Materials and Methods: Here in study Patients aged more than 18 years confirmed Covid 19 positive by reverse transcription, PCR (RT-PCR). Patients suffering from moderate to severe Covid 19 as per WHO diagnostic guidelines and underwent at least one ABG were included in the analysis. The ABG test was done on ABG analyzer in department of Biochemistry, SMHS hospital. All the data which was related to study was gathered and recorded in case record forms using files. As well as reports of patients from medical record section.&#x0D; Results: Alkaline pH was found in 57.33% individuals.36% individuals were having normal pH and the percentage of individuals having acidic pH was 6.66%. Low PaO2 was found in 45.33% individuals. Normal PaO2 levels were found in 21.33% and high PaO2 levels were found in 33.33% individuals .Low PaCO2 (&lt;35 mmHg) were found in 56%, normal (35-45mmHg) levels were found in 37.33% and high levels (&gt;45mmHg) were found in 6.66%. Low HCO3- (&lt;22mmol/L) were found in 16%, normal (22-26mmol/L) in 38.66% individuals and high (&gt;26mmol/L) were found in 45.33% individuals would be expected in the case of respiratory alkalosis.&#x0D; Conclusion: Regular ABG monitoring can aid in the early detection of silent hypoxia, and respiratory injury. With early management start-up, many lives can be spared with early diagnosis.

Pathophysiology of Diet-Induced Acid Stress.

Diets can influence the body's acid-base status because specific food components yield acids, bases, or neither when metabolized. Animal-sourced foods yield acids and plant-sourced food, particularly fruits and vegetables, generally yield bases when metabolized. Modern diets proportionately contain more animal-sourced than plant-sourced foods, are, thereby, generally net acid-producing, and so constitute an ongoing acid challenge. Acid accumulation severe enough to reduce serum bicarbonate concentration, i.e., manifesting as chronic metabolic acidosis, the most extreme end of the continuum of "acid stress", harms bones and muscles and appears to enhance the progression of chronic kidney disease (CKD). Progressive acid accumulation that does not achieve the threshold amount necessary to cause chronic metabolic acidosis also appears to have deleterious effects. Specifically, identifiable acid retention without reduced serum bicarbonate concentration, which, in this review, we will call "covert acidosis", appears to cause kidney injury and exacerbate CKD progression. Furthermore, the chronic engagement of mechanisms to mitigate the ongoing acid challenge of modern diets also appears to threaten health, including kidney health. This review describes the full continuum of "acid stress" to which modern diets contribute and the mechanisms by which acid stress challenges health. Ongoing research will develop clinically useful tools to identify stages of acid stress earlier than metabolic acidosis and determine if dietary acid reduction lowers or eliminates the threats to health that these diets appear to cause.

Serum Bicarbonate Levels Among Patients on Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome With and Without Kidney Replacement Therapy

OBJECTIVES: For patients with acute respiratory distress syndrome (ARDS) receiving venovenous extracorporeal membrane oxygenation (ECMO) who develop acute kidney injury (AKI) requiring kidney replacement therapy (KRT), the inability to renally compensate for respiratory acidosis could result in increased sweep gas flow to normalize arterial pH. Our objective was to examine the relationship of serum bicarbonate levels, arterial pH, sweep gas flow, and Paco 2. DESIGN: This is a retrospective cohort study. We compared patients who received KRT while undergoing venovenous ECMO to patients who did not. SETTING: Vanderbilt University Medical Center, February 2019 to February 2022. PATIENTS: We examined data from adult patients receiving venovenous ECMO for ARDS. INTERVENTIONS: Values for serum bicarbonate, arterial pH, Paco 2, and sweep gas flow were collected daily from time of cannulation until the earlier of decannulation, 30 days, or death. MEASUREMENTS AND MAIN RESULTS: Of the 126 patients included, 53 (42.1%) received KRT and 73 (57.9%) did not. In patients who received KRT, mean serum bicarbonate levels remained between 22 and 28 mmol/L throughout the study period. Patients who did not receive KRT experienced an increase in mean serum bicarbonate levels over time up to 40 mmol/L (mean difference = –4.4 mmol/L [95% CI, –6.3 to –2.5 mmol/L]; p &lt; 0.0001). Mean values for Paco 2 (–5.2 [95% CI, –8.8 to –1.7]; p = 0.004) and pH (–0.03 [95% CI, –0.03 to –0.02]; p &lt; 0.0001) were lower in patients who received KRT than in patients who did not, despite higher sweep gas flow rates in patients who received KRT than in patients who did not (mean difference = 1.5 [95% CI, 0.8–2.3]; p &lt; 0.001). CONCLUSIONS: ARDS patients on venovenous ECMO with preserved kidney function experience an increase in bicarbonate concentration over time, compared to patients with AKI on KRT. Whether this increase in bicarbonate concentration increases pH, decreases sweep gas flow requirements, and facilitate weaning from venovenous ECMO requires examination in future research.

Risk factors for hip and vertebral fractures in chronic kidney disease: the CRIC study.

Fracture risk is high in chronic kidney disease (CKD) and underlying pathophysiology and risk factors may differ from the general population. In a cohort study of 3939 participants in the chronic renal insufficiency cohort (CRIC), we used Cox regression to test associations of putative risk factors with the composite of first hip or vertebral fracture assessed using hospital discharge codes. Mean age was 58years, 45% were female, 42% were Black, and 13% were Hispanic. There were 82 hip and 24 vertebral fractures over a mean (SD) 11.1 (4.8) years (2.4 events per 1000 person-years [95% CI: 2.0, 2.9]). Measured at baseline, diabetes, lower body mass index (BMI), steroid use, proteinuria, and elevated parathyroid hormone (PTH) were each associated with fracture risk after adjusting for covariates. Lower time-updated estimated glomerular filtration rate (eGFR) was associated with fractures (HR 1.20 per 10mL/min/1.73m2 lower eGFR; 95% CI: 1.04, 1.38) as were lower time-updated serum calcium and bicarbonate concentrations. Among time-updated categories of kidney function, hazard ratios (95% CI) for incident fracture were 4.53 (1.77, 11.60) for kidney failure treated with dialysis and 2.48 (0.86, 7.14) for post-kidney transplantation, compared with eGFR ≥60. Proton pump inhibitor use, dietary calcium intake, measures of vitamin D status, serum phosphate, urine calcium and phosphate, and plasma fibroblast growth factor-23 were not associated with fracture risk. In conclusion, lower eGFR in CKD is associated with higher fracture risk, which was highest in kidney failure. Diabetes, lower BMI, steroid use, proteinuria, higher serum concentrations of PTH, and lower calcium and bicarbonate concentrations were associated with fractures and may be modifiable risk factors.

Facial fabrication of self‐healing natural rubber foam based on zinc thiolate ionic networks

AbstractIn this work, self‐healing natural rubber (SHNR) foam incorporating an intrinsic zinc thiolate ionic network was successfully prepared. The materials exhibited the ability to autonomously repair damage at room temperature without the need for external triggers. The investigation focused on the effect of sodium bicarbonate, employed as a blowing agent, on the self‐healing performance, as well as the physical and mechanical properties of the foam. Various concentrations of sodium bicarbonate (0, 1, 4, 8, and 10 phr) were employed. The conventional two‐roller mill was used for mixing and compounding, while compression molding was utilized for the vulcanization process. With increasing sodium bicarbonate concentration, the density, tensile strength, elongation at break, and compression set of the self‐healing NR foam were found to decreased. Conversely, the porosity, shrinkage, compressive strength, and water uptake of the SHNR foam increased as the concentration of sodium bicarbonate increased. Scanning electron microscopy analysis revealed that the optimal concentration of sodium bicarbonate (8 phr) resulted in smaller, finer, and more uniform porous structures. The self‐healing rubber foam incorporating 8 phr sodium bicarbonate exhibited improved properties in terms of tensile modulus, elongation at break, and tear strength, with healing efficiencies of 91.27%, 69.39%, and 83.99%, respectively.

Effect of time-dependent dialysate bicarbonate concentrations on acid–base and uremic solute kinetics during hemodialysis treatments

Recent studies have suggested benefits for time-dependent dialysate bicarbonate concentrations (Dbic) during hemodialysis (HD). In this clinical trial, we compared for the first time in the same HD patients the effects of time-dependent changes with constant Dbic on acid–base and uremic solute kinetics. Blood acid–base and uremic solute concentration were measured in twenty chronic HD patients during 4-h treatments with A) constant Dbic of 35 mmol/L; B) Dbic of 35 mmol/L then 30 mmol/L; and C) Dbic of 30 mmol/L then 35 mmol/L (change of Dbic after two hours during Treatments B and C). Arterial blood samples were obtained predialysis, every hour during HD and one hour after HD, during second and third treatments of the week with each Dbic concentration profile. Blood bicarbonate concentration (blood [HCO3]) during Treatment C was lower only during the first three HD hours than in Treatment A. Overall blood [HCO3] was reduced during Treatment B in comparison to Treatment A at each time points. We conclude that a single change Dbic in the middle of HD can alter the rate of change in blood [HCO3] and pH during HD; time-dependent Dbic had no influence on uremic solute kinetics.

A numerical study of CaCO3 deposition on the membrane surface of direct contact membrane distillation

This numerical study investigates the effect of CaCO3 deposition on the performance of direct contact membrane distillation (DCMD). It is the first numerical study to directly evaluate the deposition and film thickness of CaCO3 on the membrane surface. Therefore, a 3D computational fluid dynamics (CFD) model, which combines momentum, heat, species transport reaction, and the Eulerian wall film model, is used to analyze the CaCO3 mass deposition rate and scaling deposition thickness on the membrane surface. HSC Chemical Software is used to evaluate the ion compositions and reaction kinetics, including the activation energy (Ea) and pre-exponential factor (Ar). The CFD model is validated with experimental results. The results reveal that the CaCO3 deposition rate increases significantly at a high temperature, velocity, and salinity of the solution. The CaCO3 mass deposition increased by 15 times and scaling deposition thickness increased from 0.05 nm to 1 nm when the temperature was raised from 318.15 K to 348.15 K, whereas an increase of approximately 25 % in deposition was observed with an increase in velocity from 0.17 to 1.38 m/s at a concentration of calcium (Ca+2) ions, 0.03 % and bicarbonate (HCO3−) ions 0.004 %. The results also indicate that CaCO3 deposition decreases the flux and efficiency of the DCMD by 2 % with a low concentration of Ca+2 ions, 0.03 %, and HCO3− ions, 0.004 %. The findings indicate that the high feed salinity (75.23 g/l) increases CaCO3 mass deposition and scaling deposition thickness on the membrane surface due to the high concentration of Ca+2 ions, 0.07 %, and HCO3− ions, 0.01 %, significantly reducing the permeate flux by 14 %. The study's model development and implementation can be adjusted to offer guidance for studying the MD process in treating high saline water with fouling issues.

Optimizing Fast-Dissolving Tablets of Ketotifen: Impact of Sodium Bicarbonate and Citric Acid in Formulation and Evaluation

The research aimed to develop and assess fast-dissolving tablets (FDT) of ketotifen, a second-generation noncompetitive H1-receptor blocker, due to its poor oral bioavailability resulting from rapid first-pass effect (~50%) and poor solubility despite excellent permeability within the II-class of the biopharmaceutical classification system (BCS). The methodology involved formulating ketotifen with various excipients, including sodium bicarbonate, citric acid, menthol, polyvinyl pyrrolidone (PVP), aspartame, magnesium stearate, saccharin sodium, and dextrose. The combination of sodium bicarbonate and citric acid served as a fast-disintegrating agent by evolving carbon dioxide. Employing 23 factorial designs, the study assessed the impact of sodium bicarbonate (X1), citric acid (X2), and menthol (X3) on FDT performance. Batch A, exhibiting desirable characteristics, demonstrated weight variation (200±0.53), thickness (3.52±0.12 mm), hardness (2.87±0.23), friability (0.55±0.12), disintegration time (16±3 s), drug content uniformity (99.45±0.23), wetting time (3±1 s), and water absorption ratio (19.23±0.43). The primary contributor to fast tablet disintegration was identified as the high concentration of sodium bicarbonate rather than citric acid. All batches adhered to the Peppas Korsmeyer model, signifying Fickian Diffusion (Higuchi Matrix) as the drug release mechanism. In conclusion, the study underscored the pivotal role of sodium bicarbonate concentration in facilitating rapid tablet disintegration, emphasizing its significance over citric acid concentration.

Phenols and GABAA receptors: from structure and molecular mechanisms action to neuropsychiatric sequelae.

γ-Aminobutyric acid type A receptors (GABAARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABAARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl-) and bicarbonate (HCO3 -) ions by their passive permeability through the ion channel pore. GABAARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols. The wide chemical and structural variability of phenols suggest similar and different binding sites on GABAARs, allowing them to manifest themselves as activators, inhibitors, or allosteric ligands of GABAAR function. Interest in phenols is associated with their great potential for GABAAR modulation, but also with their subsequent negative or positive role in neurological and psychiatric disorders. This review focuses on the GABAergic deficit hypotheses during neurological and psychiatric disorders induced by various phenols. We summarize the structure-activity relationship of general phenol groups concerning their differential roles in the manifestation of neuropsychiatric symptoms. We describe and analyze the role of GABAAR subunits in manifesting various neuropathologies and the molecular mechanisms underlying their modulation by phenols. Finally, we discuss how phenol drugs can modulate GABAAR activity via desensitization and resensitization. We also demonstrate a novel pharmacological approach to treat neuropsychiatric disorders via regulation of receptor phosphorylation/dephosphorylation.

Geochemical evolution of geothermal waters in the Pearl River Delta region, South China: Insights from water chemistry and isotope geochemistry

The Pearl River Delta (PRD) region in South China is abundant of geothermal water resources whereas geochemical evolution of the geothermal water is still poorly understood. In this study, geothermal water is sampled to investigate the provenance of CO2 and sulphate, residence time, recharge elevation, circulation depth, and water-interaction processes by analyzing chemistry of major ions and isotope geochemistry. The range of δ13C and content of bicarbonate reveal multiple sources of soil CO2, carbonate rocks, and small amounts of mantle CO2. The δ34S ratio and sulphate concentration are attributed to evaporites dissolution, input of atmospheric sulphur, seawater intrusion, and oxidation of pyrite. The residence time of up to 21.01 ka for geothermal water likely suggests the earliest precipitation recharge during the Late Pleistocene. Mountains or/and hills at an altitude of 300–760 m in north PRD region are currently the major recharge areas for the geothermal water which can circulate at the depths of up to 3000–4800 m along regional structures. The isotopic and hydrochemical analysis confirms that extensive water interaction with silicate rock, carbonate rock and evaporite, evaporation-crystallization process, and cation exchange are the key mechanisms that control the geochemical evolution of geothermal water in the PRD geothermal system.

Role of bicarbonate in CO2 corrosion of carbon steel

This study investigates the dual role of bicarbonate in the CO2 corrosion of carbon steel through electrochemical measurements and immersion tests conducted in a CO2-saturated solution. The results show that the critical bicarbonate concentration for the aggressive/inhibitive transition is approximately 0.03–0.05 mol·L−1. Above this concentration, bicarbonate exhibits an inhibitory effect on the CO2 corrosion of X65 steel. The size of FeCO3 particles decreases as the bicarbonate concentration increases, leading to a denser FeCO3 film and enhanced passivation of the steel. However, at concentrations below 0.03 mol·L−1, bicarbonate enhances the CO2 corrosion of carbon steel owing to its participation in cathodic processes.

Effects of climate and acidic deposition on interannual variations of stream water chemistry in forested watersheds in the Shimanto River Basin, southern Japan

AbstractAlthough the amount of acidic deposition has recently decreased in Japan, it has still deteriorated some forest ecosystems during the past several decades. Moreover, recent climate changes can affect stream water chemistry. We investigated the temporal trend and effects of climate conditions on stream water chemistry for more than 20 years in two areas (Yusuhara and Taisho) in the Shmanto River Basin, southern Japan, where the effects of acidic deposition are considered to be modest. Stream water samples were collected monthly from three forest watersheds selected at each site. The annual means of the stream chemistry were predicted by multiple regression analysis. The ammonium, nitrate, and sulfate concentrations in the bulk precipitation have decreased at Yusuhara, and the sodium, magnesium, calcium, chloride, nitrate, and sulfate concentrations in the stream water have decreased in both areas. The nitrate and sulfate concentrations apparently responded to the decreasing input of acidic deposition. The sunlight hours were positively related with the potassium, magnesium, calcium, nitrate, sulfate, and bicarbonate concentrations in stream water. The results suggest that long sunlight hours boost the photosynthetic activities, thus promoting soil respiration and decomposition of soil organic matter. Moreover, a higher carbonic acid concentration in the soil solution promotes cation weathering and carbonic acid dissociation to bicarbonate. Given the decreasing trends in magnesium and calcium concentration with no change in bicarbonate concentration, we inferred that previousinputs of acidic deposition enhanced the rate of rock weathering.