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Human carbonic anhydrase II (hCAII) naturally catalyzes the reaction between two achiral molecules—water and carbon dioxide—to yield the achiral product carbonic acid through a zinc hydroxide intermediate. We have previously shown that a zinc hydride, instead of a hydroxide, can be generated in this enzyme to create a catalyst for the reduction of aryl ketones. Dialkyl ketones are more challenging to reduce, and the enantioselective reduction of dialkyl ketones with two alkyl groups that are similar in size and electronic properties, is a particularly challenging transformation to achieve with high activity and selectivity. Here, we show that hCAII, as well as a double mutant of it, catalyzes the enantioselective reduction of dialkyl ketones with high yields and enantioselectivities, even when the two alkyl groups are similar in size. We also show that variants of hCAII catalyze the site‐selective reduction of one ketone over the other in an unsymmetrical aliphatic diketone. Computational docking of a dialkyl ketone to variants of hCAII containing the zinc hydride provides insights into the origins of the reactivity of various substrates and the high enantioselectivity of the transformations and show how a confined environment can control the enantioselectivity of an abiological intermediate. [ABSTRACT FROM AUTHOR]

Antibiotics produced by soil microorganisms, are crucial for treating bacterial and fungal diseases. Due to antibiotic resistance, a broad spectrum of antibiotics from bacteria is needed. Soil samples from Zamfara state were used for detecting antibiotic-producing bacteria. The study involved physico-chemical analysis, pour plate methods, biochemical tests and molecular characterization using 16s rRNA. Agar well diffusion method was employed to test isolates' ability to inhibit pathogens growth and their potential for antibiotic production. Antibiotics production was assessed through small-scale submerged fermentation condition. Compounds were extracted using solvent extraction method, thin layer chromatography and GC-MS analysis were used for separation and identification. Data analysis were done using SPSS and were presented as mean, standard error of mean, and Anova. The soil samples exhibited light brown to dark brown colors, indicating clay-loamy, loamy-sandy and sandy-loamy. Sample C had the highest pH (7.31±.03), Sample H had the highest temperature (26°C), sample D had the highest electrical conductivity (108µs/m), and sample B had the highest moisture content (5.6). Six bacteria were identified and these include; Bacillus cereus, Bacillus pumilus, Providencia stuartii, Providencia alcalificiens, Pseudomonas aeruginosa, and Micrococcus luteus. All the organisms inhibited at least one pathogen, with Bacillus cereus showing the highest zone of inhibition. GC-MS analysis revealed diverse bioactive compounds namely, Carbonic acid, Glycerin, Nonadecane, 5-hydroxymethyl furfural, L-arabinitol, and Methylchloroformate. This study has demonstrated the diversity of bacterial population in the local soils and potential production of antibiotics that can be useful for many medical applications and further studies are recommended. [ABSTRACT FROM AUTHOR]

The article presents the results of the study of the oil collecting and oil dispersing properties of the quaternary ammonium salts formed by undecanoic and tetradecanoic acids, which are monobasic carboxylic acids, with triethanolamine (TEA) in distilled, drinking, and sea waters contaminated with Balakhani Oil. The surface activity property of the products of different concentrations of these complexes was calculated using a tensiometer, and the elemental composition was calculated using the calculation method. A comparative study of the element composition of the salts of both acids formed with TEA shows that the mass fraction of carbon in the complex formed by tetradecanoic acid with TEA is higher than in the other complex. Comparison of the surface activity property of the complexes formed by undecane and tetradecanoic acid with TEA shows that the complex compound formed by tetradecanoic acid with TEA shows more surface activity property. Therefore, as the mass fraction of carbon element increases in the complexes formed by undecane and tetradecanoic acid with TEA, the complex compound shows more surface activity properties. [ABSTRACT FROM AUTHOR]

The sensitivity of the fugacity of carbon dioxide in seawater (fCO2) to temperature (denoted υ , reported in %°C-1) is critical for the accurate fCO2 measurements needed to build global carbon budgets and for understanding the drivers of air–sea CO2 flux variability across the ocean. However, understanding and computing υ have been restricted to either using empirical functions fitted to experimental data or determining it as an emergent property of a fully resolved marine carbonate system, and these two approaches are not consistent with each other. The lack of a theoretical basis and an uncertainty estimate for υ has hindered resolving this discrepancy. Here, we develop a new approach for calculating the temperature sensitivity of fCO2 based on the equations governing the marine carbonate system and the van 't Hoff equation. This shows that, to first order, ln⁡(fCO2) should be proportional to 1/tK (where tK is temperature in kelvin), rather than to temperature, as has previously been assumed. This new approach is, to first order, consistent with calculations from a fully resolved marine carbonate system, which we have incorporated into the PyCO2SYS software. Agreement with experimental data is less convincing but remains inconclusive due to the scarcity of direct measurements of υ , particularly above 25 °C. However, the new approach is consistent with field data, performing better than any other approach for adjusting fCO2 by up to 10 °C if spatiotemporal variability in its single fitted coefficient is accounted for. The uncertainty in υ arising from only measurement uncertainty in the main experimental dataset where υ has been directly measured is in the order of 0.04 %°C-1 , which corresponds to a 0.04 % uncertainty in fCO2 adjusted by +1 °C. However, spatiotemporal variability in υ is several times greater than this, so the true uncertainty due to the temperature adjustment in fCO2 adjusted by +1 °C using the most widely used constant υ value is around 0.24 %. This can be reduced to around 0.06 % using the new approach proposed here, and this could be further reduced by more measurements. The spatiotemporal variability in υ arises mostly from the equilibrium constants for CO2 solubility and carbonic acid dissociation (K1∗ and K2∗), and its magnitude varies significantly depending on which parameterisation is used for K1∗ and K2∗. Seawater fCO2 can be measured accurately enough that additional experiments should be able to detect spatiotemporal variability in υ and distinguish between different parameterisations for K1∗ and K2∗. Because the most widely used constant υ was coincidentally measured from seawater with roughly global average υ , our results are unlikely to significantly affect global air–sea CO2 flux budgets, but they may have more important implications for regional budgets and studies that adjust by larger temperature differences. [ABSTRACT FROM AUTHOR]

This paper aims to study the changes in the Indian Ocean seawater pH in response to the changes in sea‐surface temperature, sea‐surface salinity, dissolved inorganic carbon (DIC), and total alkalinity (ALK) over the period 1980–2019 and its driving mechanisms using a high‐resolution regional model outputs. The analysis indicates that the rate of change of declining pH in the Arabian Sea (AS), the Bay of Bengal (BoB), and the Equatorial Indian Ocean (EIO) is −0.014 ± $\pm $ 0.002, −0.014 ± $\pm $ 0.001, and −0.015 ± $\pm $ 0.001 unit dec−1, respectively. Both in AS and BoB (EIO), the highest (lowest) decadal DIC trend is found during 2000–2009. The surface acidification rate has accelerated throughout the IO region during 2010–2019 compared to the previous decades. Further, our analysis indicates that El Ninõ and positive Indian Ocean Dipole events lead to an enhancement of the Indian Ocean acidification. The increasing anthropogenic CO2 uptake by the ocean dominantly controls 80% (94.5% and 85.7%) of the net pH trend (1980–2019) in AS (BoB and EIO), whereas ocean warming controls 14.4% (13.4% and 7.0%) of pH trends in AS (BoB and EIO). The changes in ALK contribute to enhancing the pH trend of AS by 5.0%. ALK dominates after DIC in the EIO and, similar to the AS, contributes to increasing the negative pH trend by 10.7%. In contrast, it has a buffering effect in the BoB, suppressing the pH trend by −5.4%. Plain Language Summary: The oceans play a significant role in regulating the amount of CO2 in the atmosphere. The increasing oceanic uptake of CO2 counterbalances the increase in atmospheric CO2. This uptake has a considerable impact on marine biogeochemistry, leading to pH and alkalinity imbalances in the water column, commonly referred to as ocean acidification. In an acidic ocean, excess CO2 reacts with seawater to form carbonic acid, which is highly unstable and undergoes further reduction by releasing hydrogen ions (H+) and acidifying the seawater (reduces the pH). Several studies have projected a decline of upper ocean pH by 0.3–0.4 by the end of the 21st century, which has the potential to reduce oceanic biological production considerably. The number of available observations to study Indian Ocean acidification is limited. There is a critical need to understand the status of Indian Ocean acidification and identify its key drivers. This article consolidates the current level of understanding about the Indian Ocean acidification based on the available field observations, reconstructed data sets, and model simulations. Key Points: The Indian Ocean pH is decreasing at an average rate of 0.015 dec−1 from 1980 to 2019The trend of dissolved inorganic carbon primarily drives an increasing ocean acidification trend in the Indian OceanEl Ninõ and positive Indian Ocean Dipole events lead to an enhancement of the Indian Ocean acidification [ABSTRACT FROM AUTHOR]

Despite the abundance of shale-oil and tight-oil reserves in the Fengcheng Formation within the Mahu Sag, exploration and development efforts for both types of reservoir are still in their early stages. A comprehensive examination and comparison of the pore structures of these reservoirs can establish rational classification and evaluation criteria. However, there is a dearth of comparative analyses focusing on the pore structures of shale-oil and tight-oil reservoirs within the Fengcheng Formation. This study addresses this gap by systematically analyzing and comparing the pore structures of these reservoirs using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), low-temperature nitrogen adsorption, and mercury intrusion capillary pressure experiments (MICP). The results show that the shale oil within the Fengcheng Formation exhibits a higher content of carbonic acid compared to the tight-oil samples. Furthermore, it demonstrates smaller displacement pressure and median pressure, a larger sorting coefficient, and superior permeability in contrast to tight oil. Notably, the shale oil within the Fengcheng Formation is characterized by abundant striated layer structures and micro-fractures, which significantly contribute to the microstructural disparities between shale-oil and tight-oil reservoirs. These differences in microstructures between shale oil and tight oil within the Fengcheng Formation in the Mahu Sag region delineate distinct criteria for evaluating sweet spots in shale-oil and tight-oil reservoirs. [ABSTRACT FROM AUTHOR]

At present, the wide application of surfactants in various fields such as detergents, foam and emulsion stabilizers, fluorogens, hydrophobizers, corrosion inhibitors makes their synthesis considered one of the urgent issues. In the article, the results of the study of oil collecting and oil dispersing properties of the quaternary ammonium salt formed by triethanolamine (TEA) of heptanoic acid, which is a monobasic carbonic acid, in distilled, drinking, and seawater contaminated with Balakhani oil are given. The surface activity property of the products of different concentrations of this complex was calculated using a tensiometer, and the element content was calculated using the calculation method. The complex formed by heptanoic acid with TEA shows high surface activity by reducing the surface tension from 71.98 mN/m to 26.3 mN/m at that boundary. In the quaternary ammonium salt of heptanoic acid with TEA, the mass fraction of carbon is 55.9%, the mass fraction of hydrogen is 10.5%, the mass fraction of oxygen is 28.6%, and the mass fraction of nitrogen is 5%. The complex of heptanoic acid and TEA exhibits the ability to accumulate oil in seawater, both in the pure and 5% percent form of the reagent. Solutions of various concentrations of the complex formed by heptanoic acid with triethanolamine are well soluble in ethyl and isopropyl alcohols. [ABSTRACT FROM AUTHOR]

Soursop leaves (Annona muricata) contain various secondary metabolite compounds with pharmacological benefits. This study foccused on the activity and chemical components cytotoxic active fraction of soursop leaf dichloromethane extract. From maceration of 535.8 g dried sample of A. muricata leaves we obtained extracts of n-hexane (18.4 g; 3.43 %). dichloromethane (11.4 g; 2.23 %). and methanol (48.7 g; 9.95 %). The dichloromethane extract was separated for its chemical components using gravity column chromatography resulting in 9 combined fractions. Toxicity screening test was done based on Bhrine Shrimp Lethality Test (BSLT) and cytotoxic test using MTT method 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide. The highest toxicity and cytotoxic test results were found in DMD 1 dichloromethane extract of A. muricata leaves with LC50 of 19.05 µg/mL and IC50 of 824.09 µg/mL. The results of DMD 1 gravity column re-chromatography produced 6-combined subfractions with the best separation pattern on DMD 1.4 and the results of GC-MS chromatogram analysis showed 29 peaks with the main component of fatty acid compounds namely Carbonic acid. but-2-yn-1-yl octadecyl ester (70.46 %). Potential anticancer compounds found were Phytol; 2-Hydroxy-1.1.10-trimethyl-6.9-epidioxydecalin and 2-Piperidinone. N-(4-bromo-n-butyl). [ABSTRACT FROM AUTHOR]

This study investigates the process of optimizing the injection rates of carbonic acid during matrix acidizing in carbonate formations, highlighting its impact on wormhole formation, dissolution, and the changes in rock petrophysical properties. Indiana limestone core samples, with porosity ranging from 14 % to 16 % and permeability from 7 to 12 mD, were flooded using diffrent injection rates (0.5, 1, 2, and 5 cm³/min) to determine the optimal injection velocity. The carbonic acid is prepared by mixing 70 % fresh water with 30 % sc-CO2 at 1500 psi and room temperature. A micro-CT scan was employed to visualize the wormhole patterns, measure its size, and calculate the optimum Damköhler Number. Moreover, inductively coupled plasma (ICP) was used to measure the calcium concentrations from effluents collected at different intervals. Two models were used to ascertain the optimum injection rate; the first model based on PVBT as a function of injection rate, indicated that 2 cm³/min is the optimum injection rate with 22 pore volumes to breakthrough (PVBT). The second model considered the relationship between PVBT and interstitial velocity (Vi), leading to an optimum injection rate of 1.7 cm³/min, corresponding to an interstitial velocity of 1 cm/min. Calculations of the optimum Damkhöler number reveal a value significantly different from the 0.29 proposed by Fredd and Fogler. This study provides valuable insights into the utilization of CO2 to enhance well productivity as a replacement for conventional acids.

The high primary porosity and permeability of eogenetic karst aquifers permit water recharged through secondary dissolution features to be temporarily stored in aquifer matrix porosity. The recharged water contains elevated dissolved organic carbon (DOC) concentrations that, when oxidized, enhance limestone dissolution and impact carbon cycling. We evaluate the relationship between DOC oxidation and limestone dissolution using observations at a stream sink‐rise system and reversing spring in the Floridan aquifer, north‐central Florida, USA, where subsurface residence times of recharged water are days and months, respectively. We estimate water chemical compositions during surface water‐groundwater interactions at these two systems with mixing models of surface water and groundwater compositions and compare them with measured DOC, dissolved inorganic carbon (DIC), Ca2+ and dissolved organic nitrogen (DON) concentrations. Differences between measured and modelled concentrations represent net changes that can be attributed to calcite dissolution and redox reactions, including DOC oxidation. DOC losses and Ca2+ gains exhibit significant (p < 0.01) inverse linear correlations at both the reversing spring (slope = −0.9, r2 = 0.99) and the sink‐rise system (slope = −0.4, r2 = 0.72). DOC oxidation in both systems was associated with decreases in the molar C:N ratio (DOC:DON). Significant (p < 0.01) positive linear correlations between increases in Ca2+ and DIC concentrations after correcting for DIC derived from calcite dissolution occurred at both the reversing spring (slope = 1.3, r2 = 0.99) and the sink‐rise system (slope = 1.61, r2 = 0.75). Greater deviations from the expected slope of −1 or +1 at the sink‐rise system than at the reversing spring indicate DOC oxidation contributes less dissolution at the sink‐rise system than at the reversing spring, likely from shorter storage in the subsurface. A portion of the deviation from expected slope values can be explained by the dissolution of Mg‐rich carbonate or dolomite rather than pure calcite dissolution. Despite this, slope values reflect kinetic effects controlling incomplete consumption of carbonic acid during dissolution reactions. [ABSTRACT FROM AUTHOR]

The commercial tin oxide (SnO2) colloidal suspension is widely utilized as an electron transport layer (ETL) in high‐performance perovskite solar cells (PSCs). However, despite significant efforts have been proposed to address bulk transport and interface recombination issues, the PSC efficiency is still limited to around 25%. In this study, the crucial role of the physicochemical characteristics of the SnO2 colloidal suspension in shaping the morphology, electrical properties, and optical properties of the SnO2 ETL is investigated. By controlling the pH value of the SnO2 solution with weak acids such as carbonic acid, the reassembly of metal oxide nanoparticles into smaller sizes with more homogeneous dispersion and dense interconnections is successfully induced. Consequently, the resulting SnO2 ETL exhibits enhanced crystallinity, high conductivity, low surface defects, and high optical transmittance. As a result, the efficiency of the target PSC is increased from 23.10% (control device) to 24.70%. This improvement is attributed to higher voltage, photocurrent, and fill factor compared to the relevant control samples. A similar device improvement using phosphoric acid is observed, indicating that the approach represents a universal technique to further enhance the quality of SnO2 ETL for large‐area, high‐efficiency, and stable PSCs. [ABSTRACT FROM AUTHOR]

Transient receptor potential (TRP) ion channels are involved in the surveillance or regulation of the acid-base balance. Here, we demonstrate that weak carbonic acids, including acetic acid, lactic acid, and CO2 activate and sensitize TRPV2 through a mechanism requiring permeation through the cell membrane. TRPV2 channels in cell-free inside-out patches maintain weak acid-sensitivity, but protons applied on either side of the membrane do not induce channel activation or sensitization. The involvement of proton modulation sites for weak acid-sensitivity was supported by the identification of titratable extracellular (Glu495, Glu561) and intracellular (His521) residues on a cryo-EM structure of rat TRPV2 (rTRPV2) treated with acetic acid. Molecular dynamics simulations as well as patch clamp experiments on mutant rTRPV2 constructs confirmed that these residues are critical for weak acid-sensitivity. We also demonstrate that the pore residue Glu609 dictates an inhibition of weak acid-induced currents by extracellular calcium. Finally, TRPV2-expression in HEK293 cells is associated with an increased weak acid-induced cytotoxicity. Together, our data provide new insights into weak acids as endogenous modulators of TRPV2. Synopsis: The transient receptor potential vanilloid 2 (TRPV2) ion channel controls important physiological and pathophysiological processes, but its regulation by acid species remains unclear. Here, combined structure-function work uncovers activation of rat TRPV2 by endogenous weak acids and offers a detailed characterization of its membrane permeation-dependent acid sensitivity. Weak, but not strong acids activate and sensitize TRPV2. Membrane permeability of weak acids is required for TRPV2 activation. Positively charged S4-S5 linker residue His521 controls TRPV2 weak acid-sensitivity. Extracellular calcium inhibits weak acid-induced TRPV2 activation. Weak acetic acids are endogenous agonists of rat TRPV2 acting via permeation through the cell membrane. [ABSTRACT FROM AUTHOR]

Aggressiveness of ground water to concrete in Germany – part 1: origin and spatial distribution of relevant groundwater constituents Groundwater quality needs to be assessed for geotechnical reports by determining the concentrations of magnesium, sulphate, ammonium and lime‐dissolving carbonic acid and their aggressiveness to concrete acc. to DIN 4030‐1. Aggressiveness to concrete can be a significant cost factor, as in particularly aggressive environments some tiebacks will not be suitable for construction projects. Furthermore, in some cases important decisions on construction planning and execution may be required at an early planning stage because of the groundwater quality. The "Groundwater background values" web map service, which is part of a geographic information system (GIS) and is provided for free via the geoportal of the German Federal Institute for Geosciences and Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe, BGR), shows the concentration distributions of the relevant water constituents. The data are shown separately for each constituent in the form of thematic maps and, for purposes of the exposure classes defined in DIN 4030‐1, as aggregate values. The thematic maps can be used to check analysis results for plausibility and to make a preliminary assessment of the constituent's aggressiveness to concrete. A spatial analysis shows that in Germany the aggressiveness of groundwater to concrete is mainly due to elevated concentrations of sulphate and/or lime‐dissolving carbonic acid, and the combined effect of both constituents. By contrast, both magnesium and ammonium are groundwater constituents that only play a minor role in the aggressiveness to concrete. [ABSTRACT FROM AUTHOR]

Aggressiveness of groundwater to concrete in Germany – part 2: validation of spatial analyses based on analysis results Groundwater quality needs to be assessed for geotechnical reports pursuant to DIN 4020 by determining the concentrations of magnesium, sulphate, ammonium and lime‐dissolving carbonic acid and their aggressiveness to concrete acc. to DIN 4030‐1. In this context, the first part of this publication introduced thematic maps that show concentration distributions separately for each of the relevant water constituents and, for purposes of the exposure classes defined in DIN 4030‐1, as aggregate values. To underline the importance of the thematic maps, these are compared with analysis results obtained by the German Federal Waterways and Shipping Administration (WSV) from 23 construction projects. The analysis results show very good agreement with the results derived from the thematic maps: the evaluations based on the analysis results and those based on the thematic maps are identical except for two sites, for which the maps nevertheless also enable reliable assessments of the aggressiveness to concrete. However, it is recommended that the maps should not be used as a substitute for groundwater sampling and analysis but rather as an additional, valuable method to be included in plausibility checks of analysis results and preliminary assessments of groundwater attack on concrete. [ABSTRACT FROM AUTHOR]

By preparation of 4-amino-3-nitrobenzoic acid (4-A3NBA-P) in the triclinic crystal form in contrast to known monoclinic crystals polymorphism of this compound has been established. The monoclinic form is called polymorph I, while triclinic crystals are designated as polymorph II. In the former polymorph, 4-A3NBA molecules are associated with the 3D network by H-bonds, while in the case of the latter polymorph, the H-bonded layers are incorporated into crystal structure by π•••π interactions. Therefore, Hirshfeld surface analyses indicate that the percentage of the O•••H/H•••O interactions of polymorph II (~ 39.1%) is less than that of polymorph I (54.5%). The TG-DTA studies attest that there is no "polymorph II → polymorph I" phase transition. [ABSTRACT FROM AUTHOR]

The utilization of CO2 is crucial for the sustainable growth of human society. Herein, we present the direct esterification of potassium lactate (KL) with butanol under CO2 pressurization, resulting in the synthesis of butyl lactate (BL). The pressurized CO2 reacts with water to generate carbonic acid, thereby facilitating esterification. A single batch reaction yielded 17% of BL, which could be augmented to 36% via two successive operations. Ultimately, through the utilization of a minimal quantity of H2SO4 in the final step, the complete conversion of KL to BL was achieved with a selectivity exceeding 99%. The proposed integrated process necessitates approximately 63% less mineral acid compared to conventional lactate separation. An exploration of the effect of various reaction parameters, including reaction temperature, duration, CO2 pressure, and H2O content in the KL, was also conducted. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) is widespread in astrochemically relevant environments, often coexisting with water (H2O) ices and thus triggering a great interest regarding the possible formation of their adducts under various thermodynamic conditions. Amongst them, solid carbonic acid (H2CO3) remains elusive, yet being widely studied. Synthetic routes followed for its production have always been characterised by drastic irradiation on solid ice mixtures or complex procedures on fluid samples (such as laser heating at moderate to high pressures). Here we report about a simpler yet effective synthetic route to obtain two diverse carbonic acid crystal structures from the fast, cold compression of pristine clathrate hydrate samples. The two distinct polymorphs we obtained, differing in the water content, have been deeply characterised via spectroscopic and structural techniques to assess their composition and their astonishing pressure stability, checked up to half a megabar, also highlighting the complex correlations between them so to compile a detailed phase diagram of this system. These results may have a profound impact on the prediction and modelisation of the complex chemistry which characterises many icy bodies of our Solar System. [ABSTRACT FROM AUTHOR]

Non-acidic hydrogen evolution systems have a low concentration of hydrogen ions, and the H2 evolution reaction (HER) is often limited by the water dissociation step. Preparing catalysts that can accelerate water dissociation is a common method for achieving high-efficiency evolution of hydrogen. In the current work, the performance of a hydrogen evolution system was first improved by introducing CO2 to transform the presence status of H2O. According to density functional theory (DFT) calculations, water reacts with CO2 to produce carbonic acid which can reduce the barrier of adsorbed H generation. Subsequently, under same pH conditions, a constructed dye-sensitized Ni–CO2 system shows an H2 evolution rate 1.5 times higher than that shown by dye-sensitized Ni. This result indicates that transforming the presence status of H2O may be a new strategy for further improving H2 evolution efficiency. [ABSTRACT FROM AUTHOR]

In the article, the results of the study of the quaternary ammonium salt formed by hexadecanoic acid, a monobasic carbonic acid, with monoethanolamine, in laboratory conditions, in distilled, drinking, and sea waters contaminated with Balakhani oil with different degrees of mineralization, are given. The surface activity property of the products of different concentrations of this complex was studied using a tensiometer, the element composition was calculated by calculation, and the composition and structure were confirmed by infrared spectroscopy. The result of investigating the composition of the complexes formed by hexadecanoic acid with monoethanolamine by infrared spectroscopy proves that the reaction proceeds according to the scheme indicated in the article. As a result of the research, it was determined that the mass share of carbon in the salt obtained on the basis of hexadecanoic acid and monoethanolamine is 68%, the share of hydrogen is 12.6%, the share of oxygen is 15%, and the share of nitrogen is 4.4%. The salt obtained on the basis of hexadecanoic acid and monoethanolamine shows high surface activity by reducing the surface tension at the water-air interface from 71.98 mN/m to 30.9 mN/m. The synthesized reagent has strong oil-collecting and oil-dispersing properties. With the application of this complex, it is possible to remove thin layers of oil from the water surface. The obtained complex is well soluble in ethyl and isopropyl alcohols. [ABSTRACT FROM AUTHOR]

The sensitivity of the fugacity of carbon dioxide in seawater (ƒCO2) to temperature (denoted ?, reported in % °C-1) is critical for the accurate ƒCO2 measurements needed to build global carbon budgets and for understanding the drivers of air sea CO2 flux variability across the global ocean. Yet understanding and computing this property have until now been restricted to either using purely empirical functions fitted to experimental data or determining it as an emergent property of a fully resolved marine carbonate system, and these two approaches are not consistent with each other. The lack of a theoretical basis and an uncertainty estimate for υ has hindered resolving this discrepancy. Here, we develop a new approach to calculating the temperature sensitivity of ƒCO2 based on the equations governing the marine carbonate system and the van 't Hoff equation. This shows that ln(ƒCO2) should be proportional to 1/tK (where tK is temperature in K) to first order, rather than to temperature as has previously been assumed. Our new approach is consistent with experimental data, although more measurements are needed to confirm this, particularly at temperatures above 25 °C. It is consistent with field data, performing better than any other approach for adjusting ƒCO2 data by up to 10 °C. It is also consistent with calculations from a fully resolved marine carbonate system, which we have incorporated into the PyCO2SYS software. The uncertainty in υ arising from only measurement uncertainty in the scarce experimental data with which υ has been directly measured is on the order of 0.04% °C-1, which corresponds to a 0.04% uncertainty in ƒCO2 adjusted by +1 °C. However, spatiotemporal variability in υ is several times greater than this, so the true uncertainty due to the temperature adjustment in ƒCO2 adjusted by +1 °C using the most widely used constant υ value is around 0.24%. This can be reduced to around 0.06% by using the new approach proposed here, and this could be further reduced with more measurements. The spatiotemporal variability in υ arises from the equilibrium constants for CO2 solubility and carbonic acid dissociation (K1* and K2*) and its magnitude varies significantly depending on which parameterisation is used for K1* and K2*. Seawater ƒCO2 can be measured accurately enough that additional experiments should be able to detect spatiotemporal variability in υ and distinguish between the different parameterisations for K1* and K2*. Because the most widely used constant υ was coincidentally measured from seawater with roughly global average υ, our results are unlikely to significantly affect global air-sea CO2 flux budgets, but may have more important implications for regional budgets and studies that adjust by larger temperature differences. [ABSTRACT FROM AUTHOR]

An analysis of an out‐of‐equilibrium cyclic reaction network which continuously converts a minor undesired product enantiomer to the desired major enantiomer by irreversible addition of chemical fuel and irreversible elimination of spent fuel is presented. The reaction network is maintained as long as fuel is added; interrupted fuel addition drives the system towards equilibrium, but the cyclic process restarts upon resumed fuel addition, as demonstrated by three consecutive fuel cycles. The process is powered by the hydrolysis of methyl cyanoformate to HCN and monomethyl carbonic acid, which decomposes to CO2 and MeOH. The time it takes to reach steady state depends on the rate of conversion of the fuel and decreases with increased conversion rate. Three catalysts, one metal catalyst and two enzymes, together constitute an efficient regulation system allowing control of the forward, backward and waste‐forming steps, thereby assuring the production of high yields of products with high enantiopurity. [ABSTRACT FROM AUTHOR]

Human carbonic anhydrase IX (hCA IX) is a zinc(II)-dependent metalloenzyme that plays a critical role in the conversion of carbon dioxide and water to protons and bicarbonate. It is a membrane-bound protein with an extracellular catalytic center that is predominantly overexpressed in solid hypoxic tumors. Sulfamates and sulfonamides, for example acetazolamide (AZA), have been used to inhibit hCA IX in order to improve the response to solid hypoxic tumors. In the present study, we propose a new drug targeting approach by attaching the natural cytotoxic substances betulin and betulinic acid (BA) via a linker to sulfonamides. The conjugate was designed with different spacer lengths to accumulate at the target site of hCA IX. Computational and cell biological studies suggest that the length of the linker may influence hCA IX inhibition. Cytotoxicity tests of the newly synthesized bifunctional conjugates 3, 5, and 9 show effective cytotoxicity in the range of 6.4 and 30.1 µM in 2D and 3D tumor models. The hCA IX inhibition constants of this conjugates, measured using an in vitro enzyme assay with p-nitrophenyl acetate, were determined in a low µM-range, and all compounds reveal a significant inhibition of hypoxia-induced CA activity in a cell-based assay using the Wilbur–Anderson method. In addition, the cells respond with G1 increase and apoptosis induction. Overall, the dual strategy to produce cytotoxic tumor therapeutics that inhibit tumor-associated hCA IX was successfully implemented. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review addresses the important bioactive ingredients recovered from different major crustacean's by-products. • A comprehensive application of crustacean's by-products in various fields is presented. • Nowadays, many newly developed techniques have been applied in crustacean's by-products recovery. • A combination of innovative extraction techniques with industrially applicable technologies can efficiently recover these valuable components. The processing of the three major crustaceans (shrimp, lobster, and crab) is associated with inevitable by-products, high waste disposal costs, environmental and human health issues, loss of multiple biomaterials (chitin, protein hydrolysates, lipids, astaxanthin and minerals). Nowadays, these bioresources are underutilized owing to the lack of effective and standardized technologies to convert these materials into valued industrial forms. This review aims to provide a holistic overview of the various bioactive ingredients and applications within major crustaceans by-products. This review aims to compare various extraction methods in crustaceans by-products, which will aid identify a more workable platform to minimize waste disposal and maximize its value for best valorization practices. The fully integrated applications (agriculture, food, cosmetics, pharmaceuticals, paper industries, etc.) of multiple biomaterials from crustaceans by-products are presented. The pros and cons of the various extraction methods, including chemical (acid and alkali), bioprocesses (enzymatic or fermentation), physical (microwave, ultrasound, hot water and carbonic acid process), solvent (ionic liquids, deep eutectic solvents, EDTA) and electrochemistry are detailed. The rapid development of corresponding biotechnological attempts present a simple, fast, effective, clean, and controllable bioprocess for the comprehensive utilization of crustacean waste that has yet to be applied at an industrial level. One feasible way for best valorization practices is to combine innovative extraction techniques with industrially applicable technologies to efficiently recover these valuable components. [ABSTRACT FROM AUTHOR]

NMR spectroscopy has become a standard technique in studies both on carbon capture and storage. 13C NMR allows the detection of two peaks for carbonated aqueous samples: one for CO2(aq) and another one for the species H2CO3, HCO3−, and CO32−—herein collectively named HxCO3x‐2. The chemical shift of this second peak depends on the molar fraction of the three species in equilibrium and has been used to assess the equilibrium between HCO3− and CO32−. The detection of H2CO3 at low pH solutions is hindered, because of the concurrent liberation of CO2 when the medium is acidified. Herein, a valved NMR tube facilitates the detection of the HxCO3x‐2 peak across a wide pH range, even at pH 1.8 where the dominant species is H2CO3. The method employed the formation of frozen layers of NaH13CO3 and acid solutions within the tube, which are mixed as the tube reaches room temperature. At this point, the tube is already securely sealed, preventing any loss of CO2 to the atmosphere. A spectrophotometry approach allowed the measurement of the actual pH inside the pressurized NMR tube. The chemical shift for H2CO3 was determined as 160.33 ± 0.03 ppm, which is in good agreement with value obtained by DFT calculations combined with Car–Parrinello molecular dynamics. The H2CO3 pKa value determined by the present method was 3.41 ± 0.03, for 15% D2O aqueous medium and 0.8 mol/L ionic strength. The proposed method can be extended to studies about analogs such as alkyl carbonic and carbamic acids. [ABSTRACT FROM AUTHOR]

The equilibrium oxygen isotope fractionation factor is widely used in geological thermometry. However, under most natural conditions, the oxygen isotope exchange is rare to reach equilibrium. Especially for the complex water–rock interaction process, the contribution of the H2CO3 solution, CO32− solution, Ca(HCO3)2 solution, and CaCO3 solution to the equilibrium oxygen isotope fractionation factor of this process is poorly understood. In view of this predicament, these key parameters are obtained by ab initio calculations. The results showed that the contributions of different carbonate minerals and different aqueous solutions to the equilibrium oxygen isotope fractionation factor were different. Among all nine carbonate minerals (dolomite, calcite, aragonite, magnesite, siderite, otavite, smithsonite, ankerite, and strontianite), the minerals with the highest and lowest reduced partition function ratios (RPFR) were siderite and strontianite, respectively. At the same time, the RPFR of nitratine, which has the same structure as carbonate, was studied. The RPFRs of the three most widely distributed carbonates in nature (dolomite, calcite, and aragonite) were dolomite > calcite > aragonite. Among the H2CO3 solution, CO32− solution, Ca(HCO3)2 solution, and CaCO3 solution, the H2CO3 solution had the strongest ability to enrich 18O. In addition, the equilibrium oxygen isotope fractionation factors between aqueous solutions and gas phase species (CO2(g), H2O(g), and O2(g), etc.) were calculated systematically. The results showed that the oxygen isotope fractionation factors between solutions and gas phases were often inconsistent with the temperature change direction and that the kinetic effects played a key role. These theoretical parameters obtained in this study will provide key equilibrium oxygen isotope constraints for water-rock interaction processes. [ABSTRACT FROM AUTHOR]

An economical 2Cr steel tubing was prepared for application in a certain downhole corrosion condition, and the CO2 corrosion behaviour was investigated by employing the 25Mn2 steel for comparative study. The corrosion films of the two steels under different corrosion conditions were analysed by optical microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). It is revealed that the corrosion rate of 25Mn2 steel at static solution is about 2.5 times higher than that at the dynamic solution with the flow velocity of 1 m/s, while the corrosion rate of 2Cr steel keeps almost the same. It is found that both steels show two layers of corrosion film at static corrosion, and the corrosion film is mainly composed of FeCO3, α-FeOOH and dotted Fe3C in the inner layer. It is inferred that carbon pickup phenomenon observed in the corrosion film is attributed to the formation of FeCO3, as well as may also be due to phenomenologically the reaction of Fe3C with carbonic acid. [ABSTRACT FROM AUTHOR]

Understanding the flow characteristics of supercritical CO2 in dry sandstones or those with low water content provides crucial information on the flow behavior in near‐wellbore zone. We conducted supercritical CO2 core flooding experiments using sandstone cores extracted from potential CO2 reservoirs in the Ordos Basin, China. During the experiments, we reduced the water content of saturated cores by flushing with dry CO2 and subsequently vacuumizing them at a temperature of 35°C to simulate sandstones with low water content. The experimental results demonstrate that the CO2 permeability was initially high during the low differential pressure stage and remained constant as the differential pressure increased. In the carbonic acid solution injection experiment, we observed an increase in the flow rate of the solution with the continuous interaction in the cores from the Shanxi and Shihezi groups, while the Yanchang group exhibited the opposite effect. This increase in permeability can be attributed to mineral dissolution and the loss of fine particles. Conversely, the blockage of fine particles or the precipitation of dissolved minerals may lead to a decrease in permeability. After the CO2–water–rock interaction, the CO2 permeability decreased compared to before the interaction, indicating that adsorbed water, the precipitation of dissolved mineral, or pore throat blockage by fine particles could induce this permeability decrease. The impact of adsorbed water on the decrease in CO2 permeability is significant. Additionally, the CO2–water–rock interaction caused corrosion on the anorthite surface. Furthermore, calcite dispersed in connected pores displayed a more pronounced dissolution compared to cemented calcite. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Due to thiolation of poly‐ and oligosaccharides numerous favorable properties for tissue engineering and wound healing can be introduced. Poly‐ and oligosaccharides can be thiolated via hydroxyl‐to‐thiol conversions or the covalent attachment of sulfhydryl ligands to hydroxyl, carbonic acid or amino groups on them. Since thiolated poly‐ and oligosaccharides can cross‐link via disulfide bonds, they form stable 3D networks with defined microarchitecture, stiffness, elasticity, and degradability. Furthermore, thiol groups can enhance cell adhesion since cells exhibit cysteine‐rich subdomains on their surface that form disulfide bonds with them. Sulfhydryl groups can also participate in cell signaling pathways favoring various cellular processes like proliferation, migration, spreading, and differentiation that are beneficial for tissue engineering and wound healing. In addition, a controlled release of active ingredients such as growth factors being bound via disulfide bonds to thiolated poly‐ and oligosaccharides can be achieved via thiol/disulfide exchange reactions. Over the last two decades, the number of thiolated poly‐ and oligosaccharides such as thiolated hyaluronic acid and thiolated chitosan used for tissue engineering and wound healing has increased tremendously. Within this review, an overview is provided about the chemistry of thiolated poly‐ and oligosaccharides, their key properties, applications and performance in clinical trials and as marketed products. [ABSTRACT FROM AUTHOR]

Shale oil resources are abundant, but reservoirs exhibit strong heterogeneity with extremely low porosity and permeability, and their development is challenging. Carbon dioxide (CO2) injection technology is crucial for efficient shale oil development. When CO2 is dissolved in reservoir formation water, it undergoes a series of physical and chemical reactions with various rock minerals present in the reservoir. These reactions not only modify the reservoir environment but also lead to precipitation that impacts the development of the oil reservoir. In this paper, the effects of water–rock interaction on core porosity and permeability during CO2 displacement are investigated by combining static and dynamic tests. The results reveal that the injection of CO2 into the core leads to reactions between CO2 and rock minerals upon dissolution in formation water. These reactions result in the formation of new minerals and the obstruction of clastic particles, thereby reducing core permeability. However, the generation of fine fractures through carbonic acid corrosion yields an increase in core permeability. The CO2–water–rock reaction is significantly influenced by the PV number, pressure, and temperature. As the injected PV number increases, the degree of pore throat plugging gradually increases. As the pressure increases, the volume of larger pore spaces gradually decreases, resulting in an increase in the degree of pore blockage. However, when the pressure exceeds 20 MPa, the degree of carbonic acid dissolution will be enhanced, resulting in the formation of small cracks and an increase in the volume of small pores. As the temperature reaches the critical point, the degree of blockage of macropores gradually increases, and the blockage of small pores also occurs, which eventually leads to a decrease in core porosity. [ABSTRACT FROM AUTHOR]

The geochemistry of rivers draining into the Arabian Sea has received lesser attention than their eastern counterparts draining into the Bay of Bengal. The major ion concentrations in the third-major river (Mahi) draining into the Arabian Sea have been reported. Hydrochemistry of seasonally collected samples (n = 67) during two consecutive years reveals that the average solute export and the cationic charges are ~ 1.2 and ~ 4 times their corresponding global average values. Generally, lower solute levels (except Ca) in the rainy season reflect the dilution effect. In contrast, the higher intensity of carbonate weathering out-weighing the dilution effect, aided by CaCO3 precipitation in summer, dominates the Ca dynamics. Chemical weathering in the catchment is mediated predominantly by carbonic acid, as evident from the alkalinity/(Ca + Mg) and SO4/(Ca + Mg) molar ratios. Using a forward model, the estimated average contributions from various sources to the cationic composition are atmospheric (5 ± 1%), evaporites and soil salts (27 ± 9%), silicates (39 ± 12%), and carbonates (29 ± 13%). Runoff exerts the dominant control on the weathering rates, with the best estimated average silicate (11 t km−2 yr−1), carbonate (22 t km−2 yr−1), and evaporite and soil-salt (8 t km−2 yr−1) weathering rates, which sums up to a dissolved chemical flux of ~ 41 t km−2 yr−1. The lower-bound estimate of CO2 consumption by silicate weathering of the Mahi basin is ~ 2.8 × 105 mol km−2 yr−1, translating into CO2 consumption of ~ 9.7 × 109 mol yr−1. This is ~ 0.08% of the global average value (by silicate weathering) and is disproportionately higher than its fractional continental drainage area (~ 0.03%). Integrating the data of Mahi with those available for the other two major rivers (Narmada & Tapti), this study underscores the prominent role of these rivers in supplying solutes to the Arabian Sea and controlling the biogeochemistry of the Arabian Sea. [ABSTRACT FROM AUTHOR]

Plant cells are capable of uptaking exogenous organic substances. This inherited trait allows the development of heterotrophic cell cultures in various plants. The most common of them are Nicotiana tabacum and Arabidopsis thaliana. Plant cells are widely used in academic studies and as factories for valuable substance production. The repertoire of compounds supporting the heterotrophic growth of plant cells is limited. The best growth of cultures is ensured by oligosaccharides and their cleavage products. Primarily, these are sucrose, raffinose, glucose and fructose. Other molecules such as glycerol, carbonic acids, starch, and mannitol have the ability to support growth occasionally, or in combination with another substrate. Culture growth is accompanied by processes of specialization, such as elongation growth. This determines the pattern of the carbon budget. Culture ageing is closely linked to substrate depletion, changes in medium composition, and cell physiological rearrangements. A lack of substrate leads to starvation, which results in a decrease in physiological activity and the mobilization of resources, and finally in the loss of viability. The cause of the instability of cultivated cells may be the non-optimal metabolism under cultural conditions or the insufficiency of internal regulation. [ABSTRACT FROM AUTHOR]

Blastocystis sp. are the most common, unicellular, anaerobic parasites of the intestinal tract of many animal and human species that can cause various digestive diseases. Metronidazole has long been used as a first-line treatment for blastocystosis, but recent clinical and in vitro studies have demonstrated its low efficacy against Blastocystis sp. The aim of this study was to determine the in vitro sensitivity of Blastocystis sp. clinical isolates to carbonic acid hop extracts and alcohol hop extracts in comparison with metronidazole. Five cultures of Blastocystis sp. were isolated from faecal samples from patients with irritable bowel syndrome with predominant diarrhoea (IBS-D, Rome IV). The parasites were identified by microscopy of faecal smears permanently stained with trichrome, Wheatley’s modification and Heidenhain’s iron-haematoxylin. Blastocystis sp. was cultivated at 37°C under anaerobic conditions on RPMI-1640 with antibiotics and horse serum, taking into account their growth characteristics. To detect the antiblastocystic activity hop extracts and metronidazole were tested in the range from 1000 μg/ml to 1 μg/ml.The presence and number of viable Blastocystis sp. cells were determined after 24, 48, 72 and 96 hours. Blastocystis sp. cells were counted in a hemocytometer using the trypan blue dye exclusion test. All experiments were performed in triplicate. According to the results of in vitro sensitivity of 5 clinical isolates of Blastocystis sp. to the action of carbonic acid hop extract, alcohoicl hop extract and metronidazole, a direct positive pattern in the dose-response and contact time-response effects was established. Alcoholic hop extract showed the highest level of antiblastocystic activity with indicators (for 72- hour parasite cultures) of the minimum inhibitory concentration (which inhibits the parasite cultures growth by 50%) (2.8±0,8) μg/ml and the minimum lethal concentration (which destroys parasite cells by 100%) – 8 μg/ml, being 2.4 and 4.5 times lower than the minimum inhibitory concentration and 8 and 62.5 times lower, than the minimum lethal concentration for hop extract and metronidazole, respectively (p<0.05). It has been shown that alcoholic hop extract (≥16 μg/ml) causes gradual morphological changes in Blastocystis sp. cells, leading to their complete destruction.In contrast to metronidazole, subinhibitory concentrations of hop extract (<2 μg/ml) do not stimulate the proliferation of Blastocystis sp. cells in vitro. [ABSTRACT FROM AUTHOR]

Dissolved oxygen plays a central role for all organisms dwelling in water. However, the flux of oxygen by ebullition has not received much attention in environmental science. For a better quantitative understanding of the oxygen flux due to ebullition, we conducted a series of laboratory experiments, where we forced macrophytes to produce photosynthetic gas bubbles. Raising the CO2 concentration in the water greatly increased bubble formation. Depth was varied to compare the results with theoretically predicted composition of photosynthetic bubbles forming at minimum required gas pressure. Oxygen concentrations lay between this theoretical line as lower boundary (ca. 21% O2 at 0.3 m depth and 45% of O2 at 4.5 m) and 45% of oxygen as the purely empirical upper limit for all depths. As a consequence, no bubble formation was observed at depths below 4.5 m. Plain Language Summary: Under light, green plants produce oxygen, when they grow. Submerged plants can produce bubbles under these conditions. Some of these bubbles rise to the surface and hence transport oxygen out of the water into the atmosphere. We studied this process by measuring the composition of such bubbles in a laboratory experiment. Adding carbonic acid to the water boosted the bubble production a lot. Depending of depth, there is a minimum of gases required for bubble formation, which yields a theoretical minimum concentration for oxygen. In all experiments, the oxygen concentration of bubbles was above atmospheric percentage of 21%, but always below 45%. Key Points: Photosynthetic gas bubbles from submerged macrophytes contain other gases beyond oxygenThe depth‐dependent lower limit can be derived from minimum gas pressure consideration for the formation of bubblesEmpirically we find an upper limit of 45% of oxygen in the collected gas bubbles [ABSTRACT FROM AUTHOR]

A parallel, rapid, efficient, one-pot and three-component synthesis of α-aminonitriles designed for the Strecker reaction starting from the corresponding carbonyl compounds, amines, and trimethylsilyl cyanide catalyzed by carbonic acid produced in-situ from dry ice has been devised. Carbonic acid is a non-toxic and eco-friendly catalyst. Carbonic acid is readily accessible and does not leave any residual traces. The main advantages of the current method include high yields, a reduced reaction time, an easy experimental method, a simple workup procedure, and the suitability of the catalyst to withstand a wide range of substrate scopes. Various aldehydes and aliphatic ketone reacted well with aromatic amines to give Strecker product in a shorter reaction time in the presence of carbonic acid as a green catalyst. This provides economic and environmental benefits.

A theoretical investigation of the microsolvation effect on proton exchange (PE) between carbonic acid and methylamine (CA-MTA) has been explored by quantum dynamics simulations. The structural, energy, and dynamic properties of the CA-MTA complex with and without an explicit water molecule are elucidated at the molecular level. The reactions from this study have been clarified into different types: single-step PE (SSPE) and stepwise PE (SWPE). Without the water molecule, the SSPE mechanism is hardly found but observable with a low probability of 0.2. In particular, the water molecule interacting through intermolecular hydrogen-bonded network between CA and MTA in CA-MTA-Win could affect PE by showing both SSPE and SWPE mechanisms. In addition, the existing water molecule plays the significant role in shortening intermolecular hydrogen bonding interactions within the complex resulting in increasing the probability of PE up to 0.92 especially in CA-MTA-Wout. Hence, one water molecule could be used to provide reliable results to represent the significant activity that occurs for the proton exchangeability of the CA and MTA complex.

Carbon dioxide and the related species bicarbonate and carbonate are known for centuries and are deeply involved with modern chemistry knowledge from the beginning. Carbonic acid, by its turn, was intuited more than a century before being synthesized for the first time, which was not obtained, however, without stumbles and mistakes. The equilibrium between HCO3− and CO32− in aqueous medium is free of disputes. However, the interconversion of the other three species is rather controversial. Several papers starting in the beginning of the 19th century until the present days are critically reviewed in order to understand the controversial history of the CO2/H2O system. Finally, experimental evidence and theoretical calculations allow us to place HCO3− as the central species as the conjugate acid for CO32− and conjugate base for two different acids: H2CO3 and CO2.

Relevance. The need to ensure the integrity of the wellbore, composed of clay rocks, and the stability of drilling fluid when drilling in conditions of carbon dioxide and bicarbonate aggression. Aim. To determine experimentally the effect of carbonic acid, bicarbonate and carbonate ions on clay depending on the presence of calcium ions in the dispersion medium. Objects. Water contaminated with carbonic acid, bicarbonate and carbonate ions with different equivalent concentrations of calcium ions. Methods. Inhibitory and peptizing properties of the objects of study in relation to the clay rock were studied by the method of clay swelling when it was in the water under study (on the Zhigacha-Yarov device); methods of chemical analysis (complexometric and acid-base titration) and potentiometry were used to control water composition and properties. Results. The peptizing and inhibiting properties of drilling fluid depend significantly on the form of carbonic acid present in the dispersion medium and the equivalent content of calcium ions (Ca2+). It was found that carbonic acid (H2CO3) contributes to clay inhibition (coagulation), bicarbonate ions (HCO3–) and carbonate ions (CO32–) – clay peptization. Calcium ions (Ca2+) do not have an inhibitory effect in the presence of carbonic acid (H2CO3) – hydrogen ions (H+) displace exchangeable cations from the interlayer space of clays and, due to their small diameter, independently inhibit clay swelling. In the presence of bicarbonate ions (HCO3–), calcium ions (Ca2+) also do not have an inhibitory effect – bicarbonate ions (HCO3–), being in a dispersion medium, draw calcium ions (Ca2+) from the clay surface, increasing the thickness of the electrical double layer. In the presence of carbonate ions (CO32–) the calcium ions (Ca2+) precipitate and effectively prevent clay peptization only in the presence of hydroxide ions (OH–). The authors proved experimentally that calcium ions (Ca2+) in the presence of hydroxide ions (OH–) have a better inhibitory ability than hydrogen ions (H+) of dissociated carbonic acid (H2CO3). A mechanism was proposed for inhibiting the swelling of clays by calcium ions (Ca2+) in the presence of hydroxide ions (OH-), based on the adsorption of the hydrated calcium ion (Ca2+) on a silica tetrahedral sheet due to the preliminary protonation of its oxygen atoms by water molecules. The conditions required for clay effective peptization are formulated: [CO32–]≥0; [OH–]>0, [Ca2+]=0, pH>11.5; for clay swelling inhibition: [CO32–]=0; [OH–]>0, [Ca2+]>0 and pH>11.5.

Introduction: Carbon dioxide (CO2) is a critical biological signal that is noxious to many animals at high concentrations. The earthworm Dendrobaena veneta lives in subterranean burrows containing high levels of CO2 and respires through its skin. Despite the ecological and agricultural importance of earthworms, relatively little is known about how they make decisions in their environment, including their response to elevated levels of CO2. Methods: To examine CO2 detection in this species, we designed the exudate assay, in which we placed an earthworm in a sealed container, exposed it to varying concentrations of CO2 for one minute, and recorded the amount of exudate secreted. Because earthworms excrete exudate in response to noxious stimuli, we hypothesized that the amount of exudate produced was proportional to the amount of irritation. We repeated these experiments after treatment with several blockers for molecules with potential involvement in CO2 detection, including carbonic anhydrases, guanylate cyclase, TRPA1, ASICs, and OTOP channels. We also confirmed the presence of homologous transcripts for each of these gene families in an epithelial transcriptome for D. veneta. Additionally, since organisms often detect CO2 levels indirectly by monitoring the conversion to carbonic acid (a weak acid), we used the exudate assay to evaluate aversion to additional weak acids (formic acid, acetic acid, and propionic acid). Results: Earthworms excreted significantly more exudate in response to CO2 in a dosage-dependent manner, and this response was muted by the general carbonic anhydrase inhibitor acetazolamide, the carbonic anhydrase IX/XII inhibitor indisulam, the calcium channel blocker ruthenium red, the sodium channel blocker amiloride, and the acid-sensing ion channel blocker diminazene aceturate. Discussion: These data provide evidence of the role of carbonic anhydrase and epithelial sodium channels in earthworm CO2 detection, establish that, similar to other subterranean-dwelling animals, earthworms are extremely tolerant of CO2, and contribute to our understanding of the mechanisms used by earthworms to detect and react to weak acids in their environment. [ABSTRACT FROM AUTHOR]

Design and synthesis of three novel series of aryl enaminones (3a–f and 5a–c) and pyrazole (4a-c) linked compounds with sulphonamides, sulfaguanidine, or carboxylic acid functionalities were reported as carbonic anhydrase inhibitors (CAIs) using the "tail approach" strategy in their design to achieve the most variable amino acids in the middle/outer rims of the hCAs active site. The synthesised compounds were assessed in vitro for their inhibitory activity against the following human (h) isoforms, hCA I, II, IX, and XII using stopped-flow CO2 hydrase assay. Enaminone sulphonamide derivatives (3a–c) potently inhibited the target tumour-associated isoforms hCA IX and hCA XII (KIs 26.2–63.7 nM) and hence compounds 3a and 3c were further screened for their in vitro cytotoxic activity against MCF-7 and MDA-MB-231 cancer cell lines under normoxic and hypoxic conditions. Derivative 3c showed comparable potency against both MCF-7 and MDA-MB-231 cancer cell lines under both normoxic ((IC50 = 4.918 and 12.27 µM, respectively) and hypoxic (IC50 = 1.689 and 5.898 µM, respectively) conditions compared to the reference drug doxorubicin under normoxic (IC50 = 3.386 and 4.269 µM, respectively) and hypoxic conditions (IC50 = 1.368 and 2.62 µM, respectively). Cell cycle analysis and Annexin V-FITC and propidium iodide double staining methods were performed to reinforce the assumption that 3c may act as a cytotoxic agent through the induction of apoptosis in MCF-7 cancer cells. [ABSTRACT FROM AUTHOR]

As part of our ongoing endeavour to identify novel inhibitors of cancer-associated CA isoforms IX and XII as possible anticancer candidates, here we describe the design and synthesis of small library of 2-aryl-quinazolin-4-yl aminobenzoic acid derivatives (6a–c, 7a–c, and 8a–c) as new non-classical CA inhibitors. On account of its significance in the anticancer drug discovery and in the development of effective CAIs, the 4-anilinoquinazoline privileged scaffold was exploited in this study. Thereafter, the free carboxylic acid functionality was appended in the ortho (6a–c), meta (7a–c), or para-positon (8a–c) of the anilino motif to furnish the target inhibitors. All compounds were assessed for their inhibitory activities against the hCA I, II (cytosolic), IX, and XII (trans-membrane, tumour-associated) isoforms. Moreover, six quinazolines (6a–c, 7b, and 8a–b) were chosen by the NCI-USA for in vitro anti-proliferative activity evaluation against 59 human cancer cell lines representing nine tumour subpanels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calcite and dolomite dissolves faster in acetic acid than in carbonic acid. • Activity of calcite and dolomite plane follows: (1 1 0) > (1 1 6) > (1 0 1) > (1 1 3) > (0 1 8) > (1 0 4). • Ions on (1 1 0) plane diffuse faster than those on (1 0 4) plane. • Ca2+ dissolves faster than Mg2+ on both (1 1 0) and (1 0 4) planes of dolomite. • Crystal calcite with preferential (1 0 4) plane is precipitated at 423.15 K. Geologic carbon sequestration (GCS) via injecting CO 2 into deep carbonate reservoirs (mainly calcite and dolomite) is a promising strategy to reduce CO 2 level. However, the dissolution or precipitation of calcite/dolomite planes on minerals/solution interface during long-term GCS process develops intergranular porosity and thus affects the permeability and stability of reservoirs. To investigate this process, both calcite and dolomite were dissolved in acetic and carbonic acids. A diffusion-controlled process was identified, with greater diffusion rates in acetic acid than that in carbonic acid. Quantified planes activity of both minerals follows (1 1 0) > (1 1 6) > (1 0 1) > (1 1 3) > (0 1 8) > (1 0 4) through density functional theory. Accomplished with preferential dissolution of calcite (1 1 0) planes in carbonic acid, calcite crystals precipitated with (1 0 4) planes at 423.15 K, under which, more calcite crystals were observed on dolomite surface, producing Ca-deplete surface. Molecular dynamic calculations showed higher dissolution rates of calcite/dolomite (1 1 0) planes than (1 0 4). In addition, the dissolution coefficients of Ca2+ were approximately triple of that Mg2+. Therefore, this study reveals the interface dissolution mechanisms of calcite and dolomite, especially on (1 1 0) and (1 0 4) planes at an atomic level, for the first time, providing better understanding for the stability of long-term GCS process. [ABSTRACT FROM AUTHOR]

Perfluoroalkylated carboxylic acids (PFCAs) are a subclass of man-made chemicals that have been widely used in industrial production and consumer products. As a result, PFCAs have been found to accumulate in the environment and bioaccumulate in organisms, leading to potential health and environmental impacts. This study investigated the inhibition of 11 PFCAs on gonadal 3β-hydroxysteroid dehydrogenases in humans, rats, and mice. We observed a V-shaped inhibition pattern against human granulosa (KGN) cell 3β-HSD2 starting from C9 (half-maximal inhibitory concentration, IC 50 , 100.8 μM) to C11 (8.92 μM), with a V-shaped turn. The same V-shaped inhibition pattern was also observed for PFCAs against rat testicular 3β-HSD1 from C9 (IC 50 , 50.43 μM) to C11 (6.60 μM). Mouse gonadal 3β-HSD6 was insensitive to the inhibition of PFCAs, with an IC 50 of 50.43 μM for C11. All of these PFCAs were mixed inhibitors of gonadal 3β-HSDs. Docking analysis showed that PFCAs bind to the nicotinamide adenine dinucleotide (NAD+)/steroid binding sites of these enzymes and bivariate correlation analysis showed that molecular length determines the inhibitory pattern of PFCAs on these enzymes. In conclusion, the carbon chain length determines the inhibitory strength of PFCAs on human, rat, and mouse gonadal 3β-HSDs, and the inhibitory strength of PFCAs against human and rat 3β-HSD enzymes shows V-shaped turn. [Display omitted] • PFAS inhibit human and rat 3β-HSDs. • The potency of perfluoroalkyl carbonic acids is increased from C9 to C11 and then is declined. • Carbon chain length determines the potency of PFAS with a V-shaped pattern. [ABSTRACT FROM AUTHOR]

As a subtropical and tropical tree, bayberry (Myrica rubra) is an important fruit tree grown commercially in southern China. Interestingly, our studies found that the fruit quality of bayberry with accompanying ryegrass was significantly improved, but its mechanism remains unclear. The aim of this study was to explore the mechanism of accompanying ryegrass on the beneficial effect of the fruit quality of bayberry by measuring the vegetative growth parameters, fruit parameters with economic impact, physical and chemical properties of rhizosphere soil, microbial community structure, and metabolites of the bayberry with/without ryegrass. Notably, the results revealed a significant difference between bayberry trees with and without accompanying ryegrass in fruit quality parameters, soil physical and chemical properties, microbial community structure, and metabolites. Compared with the control without accompanying ryegrass, the planting of ryegrass increased the titratable sugar, vitamin C, and titratable flavonoid contents of bayberry fruits by 2.26%, 28.45%, and 25.00%, respectively, and decreased the titratable acid contents by 9.04%. Furthermore, based on 16S and ITS amplicon sequencing of soil microflora, the accompanying ryegrass caused a 12.47% increment in Acidobacteriota while a 30.04% reduction in Actinobacteria was recorded, respectively, when compared with the bayberry trees without ryegrass. Redundancy discriminant analysis of microbial communities and soil properties indicated that the main variables of the bacterial community included available nitrogen, available phosphorus, exchangeable aluminum, and available kalium, while the main variables of the fungal community included exchangeable aluminum, available phosphorus, available kalium, and pH. In addition, the change in microbial community structure was justified by the high correlation analysis between microorganisms and secondary metabolites. Indeed, GC-MS metabolomics analysis showed that planting ryegrass caused a 3.83%–144.36% increase in 19 metabolites such as 1,3-Dipentyl-heptabarbital and carbonic acid 1, respectively, and a 23.78%–51.79% reduction of 5 metabolites compared to the bayberry trees without the accompanying ryegrass. Overall, the results revealed the significant change caused by the planting of ryegrass in the physical and chemical properties, microbiota, and secondary metabolites of the bayberry rhizosphere soils, which provides a new insight for the ecological improvement of bayberry. [ABSTRACT FROM AUTHOR]

Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO2. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms. [ABSTRACT FROM AUTHOR]

A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant. Under these conditions, cellulose was first hydrolysed to glucose by reversibly formed carbonic acid in water and then instantaneously hydrogenated on Ru/C. By tuning the reaction parameters, such as temperature, time and the relative pressure of CO2 and hydrogen gas, cellulose was fully converted at 220 °C in 18 h under 30 and 40 bar of H2 and CO2, respectively, with a sorbitol yield of 81%. Blank experiments revealed that without a catalyst and hydrogen, the reaction exhibited <5% conversion and glucose was the only detected product when the reaction was performed under CO2 pressure. XRD measurements on CO2-treated cellulose surprisingly revealed no noticeable changes in the crystallinity index (<10% with respect to microcrystalline cellulose), suggesting that hydrolytic hydrogenation took place on crystalline, not amorphous, cellulose. Furthermore, not only several cellulosic feedstocks, including filter paper, cotton wool, and cotton fiber, but also typical cellulose-based wastes such as a cardboard pizza box were also tested and under the optimized conditions sorbitol was obtained with yields ranging from 56% up to 72% in all cases. No less significant was the Ru/C catalyst stability, which could be recycled at least six times without any noticeable activity loss. [ABSTRACT FROM AUTHOR]

A quarter century after the detection of the last interstellar carboxylic acid, acetic acid (CH3COOH), we report the discovery of a new one, the cis-trans form of carbonic acid (HOCOOH), toward the Galactic center molecular cloud G+0.693–0.027. HOCOOH stands as the first interstellar molecule containing three oxygen atoms and the third carboxylic acid detected so far in the interstellar medium. Albeit the limited available laboratory measurements (up to 65 GHz), we have also directly identified several pairs of unblended lines in the astronomical data (between 75 and 120 GHz), which allowed us to slightly improve the set of spectroscopic constants. We derive a column density for cis-trans HOCOOH of N = (6.4 ± 0.4) × 1012 cm−2, which yields an abundance with respect to molecular H2 of 4.7 × 10−11. Meanwhile, the extremely low dipole moment (about 15 times lower) of the lower-energy conformer, cis-cis HOCOOH, precludes its detection. We obtain an upper limit to its abundance with respect to H2 of ≤1.2 × 10−9, which suggests that cis-cis HOCOOH might be fairly abundant in interstellar space, although it is nearly undetectable by radio astronomical observations. We derive a cis-cis / cis-trans ratio of ≤25, consistent with the smaller energy difference between both conformers compared with the relative stability of trans- and cis -formic acid. Finally, we compare the abundance of these acids in different astronomical environments, further suggesting a relationship between the chemical content found in the interstellar medium and the chemical composition of the minor bodies of the solar system, which could be inherited during the star formation process. [ABSTRACT FROM AUTHOR]

Chemical weathering processes has become a growing issue in research on carbon cycling, however, mineral weathering by sulfuric acid and carbonic acid and its possible impacts on carbon cycle are yet unknown over the typical glacial catchment. To investigate the mechanisms of mineral weathering processes and its influence, the spatial–temporal variations of the major ions in Mingyong River, a glacier‐originated river located on the southeastern edge of the Qinghai‐Tibetan Plateau, were investigated. The seasonal and spatial variations in river solutes were resulted from the hydrological conditions and different mineral weathering rates. The results showed that the major ion compositions of the river waters were characterized by the dominance of Ca2+, Mg2+, HCO3−, with a significantly rich in SO42−. A systematic increase in ionic concentrations (apart from NH4+ and NO3−) was observed in the river water from non‐monsoon to monsoon season as well as from upstream to downstream. Piper diagram results showed 100% (upstream‐midstream) and 72.5% (downstream) contributions to Ca‐HCO3 type, respectively, indicating that a dominated carbonate weathering to the river chemistry. The (Ca2++Mg2+)/HCO3− against (SO42−/HCO3−) scatter suggested that sulfuric and carbonic acid are responsible for chemical weathering. An increased contributions of sulfuric acid from upstream (43%) to downstream (87.3%) on the (Ca2++Mg2+) and from upstream (29.6%) to downstream (88.3%) on HCO3− using the stoichiometry analysis during the monsoon season. Contrarily, H2SO4‐related dissolution (>65%) processes controlled the carbonate weathering during the non‐monsoon season, which indicated that sulfuric acid played a significant part in the process of rock dissolution that intensifies weathering. The effects of accelerated weathering on drinking and irrigation suitability suggested that the Mingyong River water is subject to a salinity hazard. This research demonstrates that the weathering of catchments involving sulfuric acid has the potential to alter carbon cycle and should be considered in global carbon cycle models. [ABSTRACT FROM AUTHOR]

Supercritical CO2 (SC-CO2), as a new type of energizing fluid, has been widely applied in fracturing and acidizing treatment on tight sandstone, shale and carbonate formation. However, the effect of SC-CO2 on limestone's pore structure is unclear. To explore the effect, SC-CO2 reactor featuring high-temperature and high-pressure was used to carry out soaking experiments of SC-CO2-brine-limestone and SC-CO2-limestone respectively. With the help of NMR and SEM, this paper studies the effect of SC-CO2 on limestone's pore structure when the soaking time is different. It is found that in the experiment of SC-CO2-brine-limestone, SC-CO2 will react with brine to produce carbonic acid, which would react with calcite to augment limestone's porosity and permeability. Yet at the same time, Ca2+ and Mg2+ in the brine deposit continuously, which would lessen limestone's porosity and permeability. Besides, it is the generation of large pores that leads to augmentation of porosity, and more large pores are produced as time increases. While in the experiment of SC-CO2+-limestone, volume expansion caused by transforming SC-CO2+ into gaseous CO2+ also augments limestone's porosity, and the augmentation is due to small pores. However, the increase of porosity in experiments without brine is much lower than that with brine. [ABSTRACT FROM AUTHOR]

For the first time, condensations of amines with carbonyl compounds have been performed in supercritical carbon dioxide (sc‐CO2). The reactions with aldehydes or active ketones proceed at moderate temperatures (35–55 °C) without use of external catalysts. The process is autocatalytic: it is accelerated by the carbonic acid generated in situ by interaction between the released water and the CO2 medium. The imine products were obtained in high yields in a crystalline form and did not require further purification. The one‐pot transfer hydrogenation and [4+2] cycloaddition reactions performed in the CO2 medium have uncovered attractive prospects for facile green synthesis of more complex and valuable compounds from the generated in situ imine products. [ABSTRACT FROM AUTHOR]