Magnesium Cations Research Articles

Synthesis of carbonate hydroxyapatite contained magnesium cations by dry mechano-milling

The B-type carbonate hydroxyapatite (CHA) containing Mg cations was synthesized through the dry mechano-milling between Indonesian limestone-based hydroxyapatite (HA) and magnesium carbonate (MgCO3). The novelty in this research is the selection of MgCO3 as a precursor that will donate CO32− and Mg2+ to the HA structure to form CHA-containing Mg cations. The crystalline phases and chemical structure of synthesized CHA were studied by X-ray diffraction, X-ray fluorescence, scanning electron microscope, and a particle size analyzer. The feasibility of this work is to be able to produce B-type CHA containing Mg cations that have the potential to be developed for biomaterial application.

Cationic lipid membranes condense double-strand DNA through ion bridging.

Cationic lipid (CL)-DNA complexes have attracted much attention due to their potential application in somatic gene therapy, such as nonviral transfection vectors. The rational design of efficient synthetic vectors requires a systematic understanding of the underlying mechanisms governing CL-DNA assembly. Experimental studies show that DNA double strands form assemblies in divalent cations when confined between CL lipid systems. The physical mechanism of membrane-induced condensation is not well understood. Herein, we present a computational study of a simplified vector system, quasi-random genomic DNA chains intercalated into DOPC/DOTAP membrane bilayers. Using all-atom molecular dynamics simulations and free energy calculations, we observe attraction between dsDNA pairs when the ionic strength of the solution and mole fraction of DOPC mimic experimental conditions. Strikingly, the same salt conditions favoring condensation in CL lead to repulsion without the lipid. We investigated the role of lipids and confined cations to understand the differences in DNA-DNA interactions. Simulations suggest that the head groups of the lipids in contact with the DNA backbone reduce the DNA charges. The cationic DOTAP and zwitterionic DOPC head groups form direct contact with the DNA backbone. In addition, the DOPC phosphate head groups are glued to the DNA backbone by magnesium cations. The already reduced opposite surface of DNA double strands are brought together with dynamically bridging magnesium cations confined between the two helices. Our study offers physical insight into the mechanism of CL-DNA assembly and may help to facilitate the development of liposome transfer vectors for gene delivery.

The electrostatic basis of diacylglycerol pyrophosphate-protein interaction.

Phosphatidic acid (PA) is an anionic lipid with a simple phosphate headgroup that recruits multiple proteins for its diverse functional roles in all eukaryotes. Its charge, shape and Electrostatic Hydrogen bond switch mechanism forms the basis of its interaction with membrane components. PA is phosphorylated to Diacylglycerol pyrophosphate (DGPP) in many signaling events in plants, yeast, and some parasites. DGPP has a pyrophosphate headgroup with similar ionization properties to PA, except that its charge at any given physiological pH is higher. The synthesis of DGPP in the signaling cascade potentially alters membrane dynamics and properties due to the differences in the physicochemical parameters between the two lipids. Thus, DGPP is expected to differ from PA in its interaction with membrane components. However, the overall effect on the biophysical properties of DGPP's interactions with proteins and ions are unexplored. In this study, we investigated the effect of the interactions of DGPP with model peptides KALP23 and WALP23 by 31P MAS NMR spectroscopy. In addition, we also analyzed the effect of DGPP with two positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and ethyl -phosphatidylcholine (EtPC) as well as with Magnesium and Calcium cations. Results from this study highlight a unique model for DGPP-protein interactions and has important implications in how DGPP interacts with membrane components in the signaling pathway.

English

In Rwanda, the traditional fired solid bricks embody high fuel consumption and quantity of clay during their molding. Traditional solid bricks are also heavy compared to perforated bricks. This study aimed at investigating the performance of perforated clay bricks made of clay soil (CS) mixed with charcoal waste (CW) as an additive. The physical, chemical and mechanical properties of CS mixed with 0, 10, 30, 40 and 50% of CW were determined. The bricks were extruded manually with the inclusion of a varied number of perforations: 4, 8, 12 and 15 number perforations. The chemical analysis included the determination of organic carbon, exchangeable acidity and chemical components (through XRD) in the soil matrix. The chemical analysis depicted an increase in CaO proportions with an increase in charcoal waste content. There was also an increase in the amounts of exchangeable cations. The research found that with an increase in perforations, weight loss is reduced. However, non-perforated bricks depicted the least abrasion resistance, followed by bricks with 4 perforations. As the CW content increased from 0 to 50%, bricks with 15 and 12 perforations displayed the highest abrasion resistance. The research concludes that an increase in charcoal waste led to an increase in the linear shrinkage of clay soil bricks due to increased calcium cations and reduced magnesium cations in the soil. An optimum of 30% of charcoal waste was identified for the linear shrinkage of clay soil bricks. Bricks having 12 perforations and below with 30% charcoal waste additive can be categorized as category I (load-bearing) bricks.

Study to improve the reactivity of magnesium cations to CO2 for carbon capture and utilization technology using edible salt manufacturing plant wastewater

Study to improve the reactivity of magnesium cations to CO2 for carbon capture and utilization technology using edible salt manufacturing plant wastewater

ХЕЛАТУВАННЯ ДВОВАЛЕНТНИХ КАТІОНІВ ТА АНТИРАКОВА АКТИВНІСТЬПОХІДНИХ 8-ГІДРОКСИСТИРИЛХІНОЛІНІВ IN VITRO

Background. The search for new methods of cancer treatment and diagnosis are important. The disadvantages of chemotherapy drugs are the rapid acquisition of resistance and high toxicity. 8-hydroxyquinoline derivatives have a wide spectrum of biological activity and have the necessary properties for fluorescent cancer diagnosis. The aim of the study was to determine the chelation of calcium, magnesium and zinc cations by hydrophobic derivatives of 8-hydroxystyrylquinolines (8HQ) 2-(4-chlorostyryl)quinolin-8-ol (STQ-Cl) and 2-(4-nitrostyryl)quinolin-8-ol (STQ-NO2) in physiological solution, the stability of the complexes and the cytotoxicity of the compounds to prostate and breast cancer cell lines in vitro. Methods. 8HQ derivatives STQ-Cl and STQ-NO2 were used. Solutions of Ca2+, Mg2+, Zn2+ cations were prepared by the method of two-fold dilutions in 0.5-0.0078125 mM concentration range based on 0.9 % NaCl. Both individual solutions of each cation and a mixture in an equivalent molar ratio were used. The concentration of 8HQ derivatives were 0.05 mM. Optical absorption was registered in 200-700 nm wavelength range. Cytotoxicity was investigated on breast (MDA-MB-231) and prostate (DU-145) cancer cell lines. STQ-Cl and STQ-NO2 derivatives in DMSO were added to the incubation solution by four-fold dilutions (0.125–0.00003 mM). For luminescence studies, MDA-MB-231 and DU-145 cells were grown on coverslips. The final concentration of 8HQ derivatives were 5 mM. Cells were kept for 5, 10, 20 and 30 min. Luminescence was recorded under the same conditions for all samples, with an exposure time of 10 ms. Results. Mg2+ and Ca2+ (0.03125 mM) were contributed to reduce the intensity of optical absorption maxima of STQ-Cl by 1.6 and 1.3 times, respectively. The effect was most pronounced at 0.015625 mM Zn2+. Weak differences in the optical absorption of solutions were detected when STQ-NO2 was incubated with different concentrations of Mg2+ and Ca2+. The optical absorption intensity of the STQ-NO2 aqueous solution was increased at 0.015625 and 0.03125 mM Zn2+. The maximum cytotoxicity against MDA-MB-231 cells for STQ-Cl was about 80 %, and STQ-NO2 was 60 % at 0.04 mM Zn2+. DU-145 cells were more sensitive to STQ-NO2 (EC50 = 0.011 mM), but weakly sensitive to STQ-Cl (50 % at 0.125 mM). The maximum luminescence intensity was after 20 min of incubation with STQ-Cl and STQ-NO2 (5 mM) for both cells lines and was not change over time. Conclusions. The decrease of optical absorption maxima of STQ-Cl aqueous solutions in the presence of magnesium, calcium, and zinc cations was a consequence of aggregation processes. This phenomenon was probably the reason for the different cytotoxicity of STQ-Cl and STQ-NO2, as well as the presence of other mechanisms of action to cancer cells. Results was a consequence of different affinity of 8-hydroxyquinoline derivatives to magnesium, calcium and zinc cations, solubility in water, stability, aggregation of metal complexes and free compounds.

Determination of the mechanical composition and salinity of the Bukhara Gijduvan district of the Bukhara region

In the article, the mechanical composition and type and level of salinity of meadow-alluvial soils of Gijduvan district of Bukhara region were determined. According to the obtained data, this type of soil is mostly non-saline, salinity is found in the layer below 1 meter. The mechanical composition is moderate in the driving layer, but heavy in the lower layers. In different soil-climatic conditions of our republic, including determining the general properties of irrigated soils of Gijduvon district of Bukhara region, determining the state of land reclamation, reducing the effects of degradation processes occurring in oasis soils, maintaining, increasing and protecting soil fertility, and carrying out research on effective use of land going is important. The reclamation condition of Bukhara oasis soils, their mechanical composition, their origin and causes of formation, the reclamation condition of meadow alluvial soils with different levels of salinity, the melioration condition of the soils of the meadow alluvial soils are noted to be better than that of other meadow alluvial soils. The change in the composition of the absorption complex of saline soils and the increase in the share of sodium and magnesium cations in it is due to the movement of salts in the Aral Sea with the help of the wind. It is necessary to take into account not only the mechanical composition of the soil, the level of salinity, but also the type and chemistry of salinity in salt washing. It is highlighted that special agrotechnical activities are carried out on these soils.

Reactivity of a quasi-four-coordinate butylmagnesium cation.

We present the reactivity of the Mg-C and the β-CH bonds in the trigonal pyramidal [(pmdta)Mg(nBu)]+ exhibiting a weak Mg⋯F interaction with counter anion, [B(C6F5)4]-. Instantaneous β-hydride reactivity with benzophenone, reductive alkylation of phenyl benzoate, and straightforward synthesis of [(pmdta)MgH]+via metathesis with pinacolborane/phenylsilane are discussed.

Development of technology for reuse of collector trench waters

It is known that water in nature has the property of self-purification. But by our century, the level of water pollution exceeded the norm. As a result, water could not completely eliminate the contaminants contained in its composition. This also defines the problem of solving on self-purification of water. There are various ways to control the quality of water, from which it is possible to list the following: reduce the number of dissolved salts contained in the water or dilute the water, reduce the hardness of the water, reduce the amount of iron contained in it, reduce the number of floating substances hanging in the water, etc. Therefore, in this proposed method, salt underground water sources are used, and the problems of water for use in rural areas, farms, and similar enterprises have been solved. The degree of desalination depends on the content of water. Magnesium cation water is sufficient to separate the gypsum compounds, which are found to be unfavorable for this method. This requires a method and technology that will distinguish only these salts from water. In this article, the process of adding irrigation water to groundwater, treating it, and reusing it for irrigation has been implemented. An experiment was conducted using Faraday's law. The experiment was mainly to remove unwanted salt content from the water through plates and check the quality of the water. As a result, the excess amount of salt in the water was removed, and it was reused and used for irrigation.

Atom-economic access to cationic magnesium complexes.

Cationic alkaline-earth complexes attract interest for their enhanced Lewis acidity and reactivity compared with their neutral counterparts. Synthetic protocols to these complexes generally utilize expensive specialized reagents in reactions generating multiple by-products. We have studied a simple ligand transfer approach to these complexes using (NacNac)MgR and ER3 (NacNac = β-diketiminate anion; E = group 13 element; R = aryl/amido anion) which demonstrates high atom economy, opening up the ability to target these species in a more sustainable manner. The success of this methodology is dependent on the identity of the group 13 element with the heavier elements facilitating faster ligand exchange. Furthermore, while this reaction is successful with aromatic ligands such as phenyl and pyrrolyl, the secondary amide piperidide (pip) fails to transfer, which we attribute to the stronger 3-centre-4-electron dimerization interaction of Al2(pip)6.

Usnic Acid-Mediated Exchange of Protons for Divalent Metal Cations across Lipid Membranes: Relevance to Mitochondrial Uncoupling.

Usnic acid (UA), a unique lichen metabolite, is a protonophoric uncoupler of oxidative phosphorylation, widely known as a weight-loss dietary supplement. In contrast to conventional proton-shuttling mitochondrial uncouplers, UA was found to carry protons across lipid membranes via the induction of an electrogenic proton exchange for calcium or magnesium cations. Here, we evaluated the ability of various divalent metal cations to stimulate a proton transport through both planar and vesicular bilayer lipid membranes by measuring the transmembrane electrical current and fluorescence-detected pH gradient dissipation in pyranine-loaded liposomes, respectively. Thus, we obtained the following selectivity series of calcium, magnesium, zinc, manganese and copper cations: Zn2+ > Mn2+ > Mg2+ > Ca2+ >> Cu2+. Remarkably, Cu2+ appeared to suppress the UA-mediated proton transport in both lipid membrane systems. The data on the divalent metal cation/proton exchange were supported by circular dichroism spectroscopy of UA in the presence of the corresponding cations.

Structures of Fission Yeast Inositol Pyrophosphate Kinase Asp1 in Ligand-Free, Substrate-Bound, and Product-Bound States.

Expression of the fission yeast Schizosaccharomyces pombe phosphate regulon is sensitive to the intracellular level of the inositol pyrophosphate signaling molecule 1,5-IP8. IP8 dynamics are determined by Asp1, a bifunctional enzyme consisting of an N-terminal kinase domain and a C-terminal pyrophosphatase domain that catalyze IP8 synthesis and catabolism, respectively. Here, we report structures of the Asp1 kinase domain, crystallized with two protomers in the asymmetric unit, one of which was complexed with ligands (ADPNP, ADP, or ATP; Mg2+ or Mn2+; IP6, 5-IP7, or 1,5-IP8) and the other which was ligand-free. The ligand-free enzyme adopts an "open" conformation that allows ingress of substrates and egress of products. ADPNP, ADP, and ATP and associated metal ions occupy a deep phospho-donor pocket in the active site. IP6 or 5-IP7 engagement above the nucleotide favors adoption of a "closed" conformation, in which surface protein segments undergo movement and a disordered-to-ordered transition to form an inositol polyphosphate-binding site. In a structure mimetic of the kinase Michaelis complex, the anionic 5-IP7 phosphates are encaged by an ensemble of nine cationic amino acids: Lys43, Arg223, Lys224, Lys260, Arg274, Arg285, Lys290, Arg293, and Lys341. Alanine mutagenesis of amino acids that contact the adenosine nucleoside of the ATP donor underscored the contributions of Asp258 interaction with the ribose 3'-OH and of Glu248 with adenine-N6. Changing Glu248 to Gln elicited a gain of function whereby the kinase became adept at using GTP as phosphate donor. Wild-type Asp1 kinase can utilize N6-benzyl-ATP as phosphate donor. IMPORTANCE The inositol pyrophosphate signaling molecule 1,5-IP8 modulates fission yeast phosphate homeostasis via its action as an agonist of RNA 3'-processing and transcription termination. Cellular IP8 levels are determined by Asp1, a bifunctional enzyme composed of an N-terminal kinase and a C-terminal pyrophosphatase domain. Here, we present a series of crystal structures of the Asp1 kinase domain, in a ligand-free state and in complexes with nucleotides ADPNP, ADP, and ATP, divalent cations magnesium and manganese, and inositol polyphosphates IP6, 5-IP7, and 1,5-IP8. Substrate binding elicits a switch from open to closed conformations, entailing a disordered-to-ordered transition and a rearrangement or movement of two peptide segments that form a binding site for the phospho-acceptor. Our structures, along with structure-guided mutagenesis, fortify understanding of the mechanism and substrate specificity of Asp1 kinase, and they extend and complement structural and functional studies of the orthologous human kinase PPIP5K2.

Adsorption of Sodium of Polyaspartic Acid on Serpentine and Its Effects on Selective Pyrite/Serpentine Flotation

Due to the optimum dissolution of the hydroxyl ion, serpentine is positively charged and tends to cover the sulfide mineral surface as a slime coating through electrostatic attraction, which intensively worsens sulfide flotation. To handle this problem, the sodium of polyaspartic acid (PASP) was employed as the selective depressant for the flotation of pyrite from serpentine in this work. Micro-flotation results showed that the fine serpentine of −10 µm could intensively hinder pyrite flotation, with a maximum decrease of about 75.8% in pyrite recovery at pH 9. However, at this pH, pyrite recovery remarkably increased from 20.17% to 92.68% when 15 mg/L PASP was introduced. Zeta potential results depicted that the addition of PASP overcompensated the positive charge on the serpentine surface and rendered it negative, while it had little impact on that of pyrite. Hence, the hetero-coagulation between serpentine and pyrite was broken due to the electrostatic repulsion, which was further confirmed by turbidity results. After that, the adsorption of PAX on the pyrite surface was restored, and the selective flotation of pyrite from serpentine was obtained. XPS analyses revealed that the chelation interaction between the carboxylate groups in PASP and the magnesium cations that remained on the serpentine surface were the main driving forces for the adsorption of PASP on the serpentine surface.

COMBINED METHOD OF WASTEWATER TREATMENT OF A SMALL-CAPACITY BREWERY

With the help of the proposed circuit of EMT, the method of simultaneous measurements of the static characteristics of the magnetic fluid: specific electrical conductivity χt, magnetic susceptibility kt and temperature t of the magnetic fluid, which is recommended to be used for wastewater treatment of breweries, was investigated. A combined method of cleaning has been developed and the appropriate technological scheme has been improved, which provides, together with the use of mechanical cleaning devices, the use of an additional filter for magnetizing wastewater samples, which includes a special zone for the introduction of a pre-calculated magnetic liquid. Thus, in the process of wastewater treatment, mini-breweries using the proposed combined method, after applying methods of pre mechanical cleaning, use the wastewater interaction and the magnetic fluid: after intensive stirring of the mixture, the droplets of magnetic fluid dissolve in impurities and a weakly magnetic fluid is formed, which enters the magnetic separator for further cleaning. A rational ratio of wastewater: magnetic fluid (WW:MF), WW:MF = 8,7‧10-3: 1 was found. A comparison of the data obtained using informative methods with the data given in the regulatory documents witness the effectiveness of the proposed combined method of beer wastewater treatment in relation to the norms of water discharge into the city sewer, namely, the hydrogen pH indicator decreases as a result of the treatment by 34.6%, COD by 7.14 times, BOD5 by 1.52 times, suspended substances by 1.52 times, calcium cations Ca2+ by 1.53 times, magnesium cations Mg2+ by 1.51 times, total hardness dH by 1.64 times, carbonate hardness KH by 1, 86 times.

A Molybdenum Polysulfide In-Situ Generated from Ammonium Tetrathiomolybdate for High-Capacity and High-Power Rechargeable Magnesium Battery Cathodes.

Rechargeable magnesium batteries (RMBs) are a promising large-scale energy-storage technology with low cost and high reliability. However, developing high-performance cathode materials remains the most prominent obstacle because of the insufficient magnesium-storage active sites and unfavorable magnesium cation transport paths, as well as the strong interaction between the cathode material and the bivalent magnesium cation. Herein, ammonium tetrathiomolybdate is demonstrated to be a high-performance RMB cathode material. Ammonium tetrathiomolybdate exhibits a high capacity of 333 mAh g-1 at 50 mA g-1 and a good rate performance of 129 mAh g-1 at 5.0 A g-1 (∼15 C). An amorphous structure with plenty of efficient magnesium-storage active sites and open magnesium transport paths is in situ formed during the first cycle via ammonium extraction. The covalent-like bond between the molybdenum and sulfur delocalizes the negative charge, weakening the interaction with the bivalent magnesium cation and accelerating the kinetics. The covalent-like molybdenum-sulfur bond also promotes the simultaneous redox of molybdenum and sulfur, leading to a high specific capacity. The present work introduces a high-capacity and high-power RMB cathode material, elucidates the origin of the high performance, and provides insights for the design and optimization of RMB cathode materials.

Experimental X-ray Charge-Density Studies─A Suitable Probe for Superconductivity? A Case Study on MgB2.

Case studies of 1T-TiSe2 and YBa2Cu3O7-δ have demonstrated that X-ray diffraction (XRD) studies can be used to trace even subtle structural phase transitions which are inherently connected with the onset of superconductivity in these benchmark systems. However, the utility of XRD in the investigation of superconductors like MgB2 lacking an additional symmetry-breaking structural phase transition is not immediately evident. Nevertheless, high-resolution powder XRD experiments on MgB2 in combination with maximum entropy method analyses hinted at differences between the electron density distributions at room temperature and 15 K, that is, below the Tc of approx. 39 K. The high-resolution single-crystal XRD experiments in combination with multipolar refinements presented here can reproduce these results but show that the observed temperature-dependent density changes are almost entirely due to a decrease of atomic displacement parameters as a natural consequence of a reduced thermal vibration amplitude with decreasing temperature. Our investigations also shed new light on the presence or absence of magnesium vacancies in MgB2 samples─a defect type claimed to control the superconducting properties of the compound. We propose that previous reports on the tendency of MgB2 to form non-stoichiometric Mg1-xB2 phases (1 - x ∼ 0.95) during high-temperature (HT) synthesis might result from the interpretation of XRD data of insufficient resolution and/or usage of inflexible refinement models. Indeed, advanced refinements based on an Extended Hansen-Coppens multipolar model and high-resolution X-ray data, which consider explicitly the contraction of core and valence shells of the magnesium cations, do not provide any significant evidence for the formation of non-stoichiometric Mg1-xB2 phases during HT synthesis.

Experimental study of effective compounds in a smart water injection process

The process of smart water injection into carbonate reservoirs has always faced many challenges. This study attempted to investigate this issue by examining two effective factors active ionic compounds in brine and active compounds in the oil phase. The potential for the reaction among three phases’ oil, rock, and brine in changing wettability requires the presence of active ionic compounds in the brine water and active compounds in the oil. These compounds in optimal concentrations are the driving force of the wettability alteration process. In the first step, the contact angle and the spontaneous imbibition process were performed on the outcrop samples and the limestone core to investigate the effect of the active compounds of smart water. The efficiency of calcium and divalent magnesium cations mainly depends on the sulfate ion concentration. However, reservoir physical condition and the presence of other effective compounds in the reactions network can be helpful in the determination of the essential active ions in the reaction. Finally, the optimal concentrations of these three ions lead to the formation of a stable water film and a change in the wettability of the rock, which leads to an increase in oil recovery. In this regard, cations in the presence of sulfate ions as much as the minimum concentration in seawater can have a positive function and have an acceptable efficiency compared to increased concentrations of sulfate ions in seawater. The cores were saturated with two oil samples for further investigation, and again, two tests of measuring contact angle and spontaneous imbibition were performed. The difference between imbibition rate and ultimate recovery illustrates that the carboxylic acid functional group in the original crude oil structure can facilitate displacement compared to oil-free acid components. Therefore, acidic components in crude oil affect the wettability alteration through electrostatic interaction with surface minerals and brine. Active components can act as a critical indicator in smart water injection processes.

Divalent cations of magnesium, iron and copper regulate oxidative responses and inflammatory cytokines in RAW 264.7 macrophages

The metal ions play a decisive role in regulating the redox balance of cells and subsequentially alter cellular functions. The pacifying (“cold”) or irritating (“hot”) effects of food on the human body have been traditionally recognized and utilized by Chinese for hundreds of years. The principal components of fruits and vegetables corresponding to these effects have been identified to be magnesium, iron, and copper cations in combination. This study aims to elucidate the regulatory effects of the three cations on the oxidative responses and inflammatory cytokines production in RAW264.7 macrophages. Two “cold” solutions and two “hot” solutions were prepared with MgSO4, FeSO4, and CuSO4. The contents of three cations were calculated with a previously established regression equation and set to the physiologically meaningful levels (at ppm). It was found that the “cold” solution exhibited antioxidant and anti-inflammatory effects in the macrophages. They reduced the intracellular ROS level and restored the mitochondrial respiratory of the AAPH-insulted macrophages, while suppressing the LPS-induced expression of TNF-α, IL-1β, and IL-6 in the cells. Conversely, the “hot” solutions exhibited pro-oxidative and pro-inflammatory effects as they increased the intracellular ROS and expression of inflammatory cytokines in normal cells. It demonstrates the bidirectional regulation of the Mg2+, Cu2+, and Fe2+ cocktails on oxidative and inflammatory responses of murine macrophages. Inspired by the traditional Chinese food concept, the outcome of this study provides a new perspective and useful tool for future research and innovations in healthy and sustainable food.

Chemical Analysis of Groundwater and Wastewater in the Area of the Tengiz Deposit of the Atyrau Region of the Republic of Kazakhstan

This article analyzes the content of the chemical composition of groundwater and wastewater of the Tengiz deposit located in the Zhyloy district of Atyrau region of the Republic of Kazakhstan. This analysis is necessary to determine the deposition of inorganic salts in oilfield equipment. The analysis shows that the content of chloride anions and magnesium cations prevails in groundwater and wastewater. Thus, the content of chloride anions exceeds the content of other anions up to 2-3 times of sulfate anions in groundwater and wastewater and up to 2.5-5 times of bicarbonate anions in groundwater and 17-27 times in wastewater. Among the cations, the maximum values are characteristic of magnesium cations, whose content exceeds the calcium content by more than 3.5 times in wastewater and more than 6.5 times in groundwater. In addition, the magnesium content exceeds more than 5 times the content of the sum of sodium and potassium ions. Thus, according to the results of the study, it was determined that the main salts affecting the oilfield equipment at the Tengiz field are magnesium chloride salts.

Enhanced Elastic Migration of Magnesium Cations in alpha‐Manganese Dioxide Tunnels Locally Tuned by Aluminium Substitution

AbstractThe harsh conditions of large hydrated ion radius of Mg2+ cations and the strong electrostatic interaction with the host material put forward higher requirements for high‐performance aqueous magnesium ion (Mg2+) energy storage devices. Herein, substituted aluminium ions (Al3+) doped α‐MnO2 materials are prepared. The introduction of Al3+ cations adjust the local chemical environment inside the tunnel structure of α‐MnO2 and precisely regulates the diffusion behavior of inserted Mg2+ cations. The shortened oxygens’ distance and abundant oxygen defects result in a substantially enhanced elastic migration pattern of Mg2+ cations driven by strengthened electrostatic attraction, which brings the lower diffusion energy barrier, improved reaction kinetics, and adaptive volume expansion as evidenced by Climbing Image‐Nudged Elastic Band density function theory calculations coupled with experimental confirmation in X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and galvanostatic intermittent titration technique. As a result, this rationally designed cathode exhibits a high reversible capacity of 197.02 mAh g‐1 at 0.1 A g‐1 and stable cycle performance of 2500 cycles with 82% retention. These parameters are among the best of Mg‐ion capacitors reported to date. This study offers a detailed insight into the local tunnel structure tunning effect and opens up a new path of modification for tunnel‐type structural materials.