Polyvalent Metal Research Articles

СНИЖЕНИЕ ЖЁСТКОСТИ ОРОСИТЕЛЬНОЙ ВОДЫ ОЗОНИРОВАНИЕМ

Abstract. The article presents the research on the effect of ozone treatment on the hardness of irrigation water. The effect of hard water on plant growth and development has been analyzed. It has been revealed that excessive magnesium and calcium ions in irrigation water lead to the suppression of agricultural crops and a decrease in their yield. To conduct laboratory studies, water was taken from a natural reservoir located near the village of Gvazda, Buturlinovsky District, Voronezh Region, which is used by local farmers to irrigate agricultural land. The sample was divided into two parts, one of which was subjected to ozone treatment, and the second was a control variant. Laboratory studies have established that the total water hardness in the natural reservoir was 21 dH, which corresponds to 7.5 mg eq / l. This level of hardness is excessive and will negatively affect plants. Ozonation at an average ozone concentration in the ozone-air mixture of 4.67 mg/m3 allowed to reduce the total water hardness to 14 dH, which is comparable to 5 mg eq/l. Intensive water softening occurred at ozone treatment doses of up to 840 mg min/m3. Consequently, ozonation reduces the content of polyvalent metal ions, which in high concentrations have a negative effect on plants. Modern compact, energy-efficient, high-performance ozonizers can be easily integrated into the design of sprinkler machines. Softer water will have a positive effect on the efficiency of irrigation and the reliability of irrigation systems. In addition, ozone water treatment will have a bactericidal and disinfectant effect, which will prevent the development of various diseases and pests.

Polydopamine functionalized dendritic fibrous silica nanoparticles as a generic platform for nucleic acid-based biosensing

Accurate and rapid detection of nucleic acid sequences is of utmost importance in various fields, including disease monitoring, clinical treatment, gene analysis and drug discovery. In this study, we developed a "turn-on" fluorescence biosensor that enables simple and highly efficient detection of nucleic acid biomarkers. Our approach involves the utilization of 6-carboxyfluorescein modified single-stranded DNA (FAM-ssDNA) as molecular recognition element, along with polydopamine-functionalized dendritic fibrous nanosilica (DFNS). FAM-ssDNA serves as both specific molecular recognition element for the target analyte and reporter capable of transducing a detectable signal through Watson–Crick base pairing. The polydopamine-functionalized DFNS (DFNS@DA) exhibits strong binding to FAM-ssDNA via polyvalent metal mediated coordination leading to effective quenching by fluorescence resonance energy transfer. In the presence of a complementary target sequence, FAM-ssDNA forms hybridized structure and detaches from DFNS@DA, which causes an increased fluorescence emission. The analytical system based on FAM-ssDNA and DFNS@DA demonstrates exceptional sensitivity, selectivity, and rapid response for the detection of nucleic acid sequences, leveraging the high adsorption and quenching properties of DFNS@DA. For the first proof of concept, we demonstrated the successful detection of microRNA (miR-21) in cancer cells using the FAM-ssDNA/DFNS@DA system. Our results highlight the promising capabilities of DFNS@DA and nucleic acid-based biosensors, offering a generic and cost-effective solution for the detection of nucleic acid-related biomarkers.Graphical abstract

Mg2+- or Ca2+-regulated aptamer adsorption on polydopamine-coated magnetic nanoparticles for fluorescence detection of ochratoxin A.

It has been observed that polyvalent metal ions can mediate the adsorption of DNA on polydopamine (PDA) surfaces. Exploiting this, we used two divalent metal ions (Mg2+ or Ca2+) to promote the adsorption of fluorescence-labelled ochratoxin A (OTA) aptamers on PDA-coated magnetic nanoparticles (Fe3O4@PDA). Based on the different adsorption affinities of free aptamers and OTA-bound aptamers, a facile assay method was established for OTA detection. The aptamers adsorbed on Fe3O4@PDA were removed via simple magnetic separation, and the remaining aptamers in the supernatant exhibited a positive correlation with the OTA concentration. The concentrations of Mg2+ and Ca2+ were finely tuned to attain the optimal adsorption affinity and sensitivity for OTA detection. In addition, other factors, including the Fe3O4@PDA dosage, pH, mixing order, and incubation time, were studied. Finally, under optimized conditions, a detection limit (3σ/s) of 1.26ng/mL was achieved for OTA. Real samples of spiked red wine were analysed with this aptamer-based method. This is the first report of regulating aptamer adsorption on the PDA surface with polyvalent metal ions for OTA detection. By changing the aptamers, the method can be easily extended to other target analytes.

Mg2+-promoted high-efficiency DNA conjugation on polydopamine surfaces for aptamer-based ochratoxin A detection

BackgroundSurface immobilization of DNA is the foundation of a broad range of applications in biosensing and specific DNA extraction. Polydopamine (PDA) coatings can serve as intermediate layers to immobilize amino- or thiol-labelled molecules, including DNA, onto various materials through Michael addition and/or Schiff base reactions. However, the conjugation efficiency is limited by electrostatic repulsion between negatively charged DNA and PDA. Recently, it has been reported that polyvalent metal ions (such as Mg2+ and Ca2+) can mediate the adsorption of DNA on PDA surfaces. Inspired by this, in this work we aimed to exploit polyvalent metal ions to facilitate the conjugation of DNA on PDA. ResultsMg2+ was used to promote the conjugation of amino-terminated DNA complementary to ochratoxin A (OTA) aptamer (cDNA-NH2) on PDA-coated magnetic nanoparticles (Fe3O4@PDA). After the reaction, the unlinked cDNA-NH2 adsorbed on Fe3O4@PDA mediated by Mg2+ was removed with EDTA. In the presence of 20 mM Mg2+, the amount of covalently linked cDNA-NH2 increased approximately 11-fold compared to that in the absence of Mg2+. The resulting Fe3O4@PDA@cDNA conjugates exhibited superior hybridization capacity towards OTA aptamers, minimal nonspecific adsorption, and excellent chemical stability. The conjugates combined with fluorophore-labelled aptamers were employed for OTA detection, achieving a limit of detection (LOD) of 2.77 ng mL−1. To demonstrate versatility, this conjugation method was extended to Ca2+-promoted conjugation of cDNA-NH2 on Fe3O4@PDA nanoparticles and Mg2+-promoted conjugation of cDNA-NH2 on PDA-coated 96-well plates. SignificanceThe conjugation efficiency of DNA on PDA was significantly improved with the assistance of polyvalent metal ions (Mg2+ and Ca2+), providing a facile and efficient method for DNA immobilization. Due to the substrate-independent adhesion property of PDA, this method demonstrates versatility in DNA surface modification and holds great potential for applications in target extraction, biosensing, and other fields.

Easy-regeneration Mn-doped ZIF-67 derivate adsorbent with ultra-high adsorption capacity for tetracycline hydrochloride in wastewater

Adsorption capacity and reusability are critical to the practical applications of metal–organic framework (MOF)-based adsorbents. In this work, an easy-regeneration ZIF-67 derivate adsorbent (Mn-ZIF-400) was synthesized by calcining the manganese-modified MOF ZIF-67 (Mn-ZIF-67) precursor at 400 °C in air for the first time. Mn-ZIF-400 reveals an ultra-high adsorption capacity for tetracycline hydrochloride (TCH) (qmax = 1191.5 mg⋅g−1 at 308 K at pH = 4) in a wide pH range (pH = 3–10) owing to its great surface area (816.2 m2⋅g−1), surface polyvalent metal ions (Co2+/Co3+, Mn2+/ Mn 3+/ Mn4+), abundant surface oxygen species (including –COOH, –OH etc.) and π-electrons from benzene-ring. The adsorption mechanism of TCH on Mn-ZIF-400 belongs to the monolayer chemisorption mainly by π-π conjugation/π-cation interactions, hydrogen/coordination bonding, and pore filling. It also can maintain high adsorption performance in an actual aqueous environment. More importantly, Mn-ZIF-400 showed enhanced water stability and reusability after modification and no obvious loss in adsorption capacity in four recycles via simple water washing, being a promising adsorbent for antibiotic elimination.

SOLVATOCHROMIC PROPERTIES OF SOME 6,7-DIHYDROXYBENZOPYRYLLIUM PERCHLORATE DERIVATIVES

The creation of new reagents based on benzopyrylium derivatives with improved che­mical-analytical characteristics is of interest because their preparative synthesis is relatively simple and consists in the condensation of triatomic phenols with β-dicarbonyl compounds. Benzopyryllium derivatives are reactive compounds and are able to redox reactions, complexes formation with polyvalent metal ions, and are also prone to acid-base transformations in solutions. It should be noted separately that hydroxyderivatives of ben­zopyrylium during complex formation can turn into anhydro bases with a quinoid structure, which leads to a significant bathochromic shift of the absorption band and an increase in the contrast of analytical reactions. The current work is devoted to the study of solvatochromic pro­perties of a number of 6,7-dihydroxybenzopyrylium perchlorate derivatives: 6,7-dihyd­roxy-2,4-dimethylbenzopyrylium, 6,7-dihyd­roxy-2-phenyl-4-methylbenzopyrylium and 6,7-di­hyd­roxy-2,4 -diphenylbenzopyrylium. The presented work is a continuation of research on synthesis, acid-base and complexation of 6,7-­dihyd­roxybenzopyrylium derivatives. The influence of the nature of organic solvents was stu­died using the example of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, n-pentanol, iso-pentanol, n-hexanol, n-heptanol, n-nonanol, decanol, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, butyl acetate, toluene, and chloroform. It is shown that when a polar solvent is replaced by a less polar one, a bathochromic shift of the maximum of the absorption band of 6,7-dihydroxybenzopyrylium derivatives is observed, which corresponds to the n→π* electronic transition. It was noted that there is a satisfactory correlation (R = 0.795–0.993) between the position of the maximum absorption of the dye and the values of the Hansen parameter, Kamlet – Taft, donor and acceptor number according to Gutman.

Operando probing and adjusting of the complicated electrode process of multivalent metals at extreme temperature

Nearly half of the elements in the periodic table are extracted, refined, or plated using electrodeposition in high-temperature melts. However, operando observations and tuning of the electrodeposition process during realistic electrolysis operations are extremely difficult due to severe reaction conditions and complicated electrolytic cell, which makes the improvement of the process very blind and inefficient. Here, we developed a multipurpose operando high-temperature electrochemical instrument that combines operando Raman microspectroscopy analysis, optical microscopy imaging, and a tunable magnetic field. Subsequently, the electrodeposition of Ti-which is a typical polyvalent metal and generally shows a very complex electrode process-was used to verify the stability of the instrument. The complex multistep cathodic process of Ti in the molten salt at 823 K was systematically analyzed by a multidimensional operando analysis strategy involving multiple experimental studies, theoretical calculations, etc. The regulatory effect and its corresponding scale-span mechanism of the magnetic field on the electrodeposition process of Ti were also elucidated, which would be inaccessible with existing experimental techniques and is significant for the real-time and rational optimization of the process. Overall, this work established a powerful and universal methodology for in-depth analysis of high-temperature electrochemistry.

Localized Electron Density Regulation Effect for Promoting Solid-Liquid Ion Adsorption to Enhance Areal Capacitance of Micro-Supercapacitors.

The development of flexible microelectronic systems requires the construction of high-energy-output planar micro-supercapacitors (MSCs). Herein, the localized electron density, by introducing graphene quantum dots (GQDs) on the surface of electrodes, is regulated. The enhanced local field intensity promotes ion electrostatic adsorption at the solid-liquid interface, which significantly improves the energy density of MSCs in the confined space. Local electronic structure has been investigated from the perspective of the topological analysis of the electron localization function (ELF) and the electron density. Impressively, the edges of the simulated structure exhibit a higher electron density distribution than the CC skeleton. This finding indicates that the introduced GQDs reinforce the intrinsic electrical double-layer capacitance (EDLC) and the oxygen-bearing functional groups at the edge, further increasing the pseudocapacitance performance. Moreover, the edge electron aggregation effect enables the all-carbon-based symmetric MSCs to exhibit ultra-high areal capacitance (21.78mFcm-2 ) and excellent cycle stability (86.74% retention after 25000 cycles). This novel surface local charge regulation strategy is also applied for intensifying ion electrostatic adsorption on Zn-ion hybrid MSCs (polyvalent metal ions) and ion-gel electrolyte MSCs (non-metallic ions). With excellent planar integration, this device demonstrates excellent flexibility and has potential applications in timing and environmental monitoring.

Ti4+-dopamine/sodium alginate multicomponent complex derived N-doped TiO2@carbon nanocomposites for efficient removal of methylene blue

A one-pot route for the preparation of TiO2@carbon nanocomposite from Ti4+/polysaccharide coordination complex has been developed and shown advantages in operation, cost, environment, etc. However, the photodegradation rate of methylene blue (MB) needs to be improved. N-doping has been proven as an efficient means to enhance photodegradation performance. Thus, the present study upgraded the TiO2@carbon nanocomposite to N-doped TiO2@carbon nanocomposite (N-TiO2@C) from Ti4+-dopamine/sodium alginate multicomponent complex. The composites were characterized by FT-IR, XRD, XPS, UV–vis DRS, TG-DTA, and SEM-EDS. The obtained TiO2 was a typical rutile phase, and the carboxyl groups existed on N-TiO2@C. The photocatalyst consequently showed high removal efficiency of MB. The cycling experiment additionally indicated the high stability of N-TiO2@C. The present work provided a novel route for preparing N-TiO2@C. Moreover, it can be extended to prepare N-doped polyvalent metal oxides@carbon composites from all water-soluble polysaccharides such as cellulose derivatives, starch, and guar gum.

Influence of the nutrition substrate concentration on sulfate reduction in denitrifying biofilter point of use

ABSTRACT The influence of bacterial nutrition (by ethanol) on the appearance of hydrogen sulfide and colloidal sulfur in the filtrate of innovative U-shaped small-sized (point-of-use) submersible denitrifying biofilter describes in the course of its regular operation. The device intends to get drinking water from groundwater sources contaminated with nitrates, sulfates, and heavy metal ions. Colonies of denitrifying bacteria occupy an ecological niche inside the filter bed in an anoxic medium in the inlet elbow of the biofilter and reduce the concentration of nitrates below of hygienic limit at the optimal feed by ethanol. Hydrogen sulfide and colloidal sulfur produce the sulfate-reducing and sulfur bacteria. Sulfate-reducing bacteria act in an anaerobic environment in the bottom conjunction zone of the inlet and outlet elbows of the biofilter. These bacteria release hydrogen sulfide when ethanol adds to filtering water in excess compared to the dosage required for denitrification. Colonies of sulfur bacteria occupy an ecological niche in the output zone of the biofilter exit elbow and oxidise hydrogen sulfide to elemental sulfur. Sulfate reduction associated with nitrates removal can be helpful for additional water purification from admixtures of heavy and polyvalent metal ions.

Saccharina japonica – её технохимическая характеристика для применения в технологии пищевых и лечебно-профилактических продуктов

Data are presented that determine the directions of processing and use of brown algae, including the hydration coefficient (HC) of dried thalli or crushed into pieces of various sizes, which is an important indicator used in setting the parameters of technological processes, as well as the yield of finished products. The results are presented demonstrating the ability of the dried algae Saccharina japonica to limit hydration. It has been shown that during deep treatment of S. japonica in order to increase the HC, about 80% of biologically active substances are lost, with the exception of fiber, some part of the protein, the organic form of iodine, as well as alginates associated with polyvalent metal cations in water-insoluble complexes with alginic acids. It was determined that when soaking dried S. japonica in water, the relative content of alginic acid increases, while the HC of kelp also increases. It has been established that HC equal to 20-26 corresponds to a significant removal of extractive biologically active substances (BAS) from S. japonica. At HC 14-16, up to 50% of biologically active substances remain in the tissues of algae, giving taste to kelp algae and their biological value. It has been shown that with the content of biologically active substances in algae up to 50% of the initial value, a real opportunity is created to obtain food, therapeutic and prophylactic products from dried S. japonica.

Zr4+ and glutaraldehyde cross-linked polyethyleneimine functionalized chitosan composite: Synthesis, characterization, Cr(VI) adsorption performance, mechanism and regeneration

In order to improve the stability, electrostatic interaction and ion exchange ability of chitosan for Cr (VI) removal, it is an effective strategy to introduce polyvalent metal ions and polymers into chitosan molecular chain through crosslinking. In this paper, Zr4+ and glutaraldehyde crosslinked polyethyleneimine functionalized chitosan (CGPZ) composite was successfully synthesized and characterized by XRD, SEM, FTIR, BET, and XPS. The results showed that polyethyleneimine was successfully grafted onto chitosan by Schiff base reaction, while the appearance of ZrO and ZrN bonds verified the successful preparation of CGPZ. The monolayer maximum adsorption capacity of Cr(VI) by CGPZ was 593.72 mg g−1 at 298 K and t = 210 min. The removal efficiency of 100 mg L−1 Cr(VI) reached 95.7 %. The thermodynamic, isotherm and kinetic results show that the adsorption process of Cr (VI) by CGPZ is a spontaneous endothermic process controlled by entropy, which accords with Freundlich model and pseudo-second-order kinetic model. The regeneration experiments show that both HCl and NaOH can effectively desorb Cr(III) and Cr(VI) from the adsorbent surface, and the adsorbent has good acid-base resistance and regeneration performance. The removal of Cr(VI) mainly involves electrostatic attraction, ion exchange, reduction and complexation. CGPZ can synergistically adsorb Cr(VI) by electrostatic interaction of -NH2/-C=N and ion exchange of Cl− ion in the center of Zr, then reduce Cr(VI) to Cr(III) (45.4 % at pH = 2.0) by the -OH group on its surface, and chelate Cr(III) through COO- and -NH- groups.

Metformin mitigates radiation toxicity exerting antioxidant and genoprotective properties.

The antidiabetic drug metformin (MF) exhibits redox-modulating effects in various pathologies associated with oxidative stress and mitigates ionizing radiation-induced toxicity, but the underlying mechanisms remain to be elucidated. Thus, we studied some radiomitigatory effects of MF and explored the possible mechanisms behind them. Highly sensitive luminescence methods and non-competitive enzyme-linked immunosorbent assay (ELISA) were used in in vitro studies, and in vivo the damage to bone marrow cells and its repair were assessed by the micronucleus test. In a solution, MF at concentrations exceeding 0.1µM effectively intercepts •OH upon X-ray-irradiation, but does not react directly with H2O2. MF accelerates the decomposition of H2O2 catalyzed by copper ions. MF does not affect the radiation-induced formation of H2O2 in the solution of bovine gamma-globulin (BGG), but has a modulating effect on the generation of H2O2 in the solution of bovine serum albumin (BSA). MF at 0.05-1mM decreases the radiation-induced formation of 8-oxoguanine in a DNA solution depending on the concentration of MF with a maximum at 0.25mM. MF at doses of 3mg/kg body weight (bw) and 30mg/kg bw administered to mice after irradiation, but not before irradiation, reduces the frequency of micronucleus formation in polychromatophilic erythrocytes of mouse red bone marrow. Our work has shown that the radiomitigatory properties of MF are mediated by antioxidant mechanisms of action, possibly including its ability to chelate polyvalent metal ions.

Temperature-triggered smart milk-derived hydrogel with programmable adhesion for versatile skin-attached iontronics

Despite the current advances in adhesives, it is still a huge challenge to develop a programmable adhesion material for wearable and skin-attached devices. Herein, a skin temperature-triggered smart adhesive hydrogel is developed by one-sidedly infiltrating polyvalent metal ions into the UCST-typed thermosensitive copolymers comprising milk-derived sodium caseinate (SC). The resulting hydrogel presents asymmetric and tunable adhesion, which is capable of the repeated, on-demand detachments by a mild skin temperature trigger. Meanwhile, the hydrogel also shows the programmable turbidity-switching ability because of adjustable phase transformation, and outstanding antimicrobial properties (killing rate: >99.0%). Besides, the hydrogel can sensitively perceive external strain (GF: 37.59, response time: 169 ms) and temperature (TCR: –4.03%/℃) variation by electrical signals. Thanks to these excellent features, the hydrogel can be applied to versatile wearable iontronics to precisely monitor various human motions, physiological signals and thermal distributions in real time. Therefore, our study establishes a novel and effective route for the rational design and fabrication of intelligent skin-attached materials.

GSH-depleting and H2O2-self-supplying hybrid nanozymes for intensive catalytic antibacterial therapy by photothermal-augmented co-catalysis

Nanozyme-based chemodynamic therapy (CDT) has shown tremendous potential in the treatment of bacterial infections. However, the CDT antibacterial efficacy is severely limited by the catalytic activity of nanozymes or the infection microenvironments such as insufficient hydrogen peroxide (H2O2) and overexpressed glutathione (GSH). Herein, a versatile hybrid nanozyme (MoS2/CuO2) is rationally constructed by simply decorating ultrasmall CuO2 nanodots onto lamellar MoS2 platelets of hydrangea-like MoS2 nanocarrier via a covalent Cu-S bond. The MoS2/CuO2 nanozyme exhibits the peroxidase-mimic activity for catalytically converting H2O2 produced by acid-triggered decomposition of the decorated CuO2 into hydroxyl radical (•OH). Meanwhile, the MoS2/CuO2 can consume GSH overexpressed in the infection sites via redox reaction mediated by polyvalent transition metal ions (Cu2+ and Mo6+) for enhanced CDT. More importantly, MoS2 support can promote the conversion of Cu2+ to Cu+ by a co-catalytic reaction based on the Mo4+/Mo6+ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS2/CuO2 nanozymes possesses a desirable catalytic property, as well as a remarkably improved antibacterial efficiency both in vitro and in vivo. Taken together, this study proposes a synergetic multiple enhancement strategy to successfully construct the versatile hybrid nanozymes for intensive in vivo PTT/CDT dual-mode anti-infective therapy. Statement of significanceChemodynamic therapy (CDT) has shown great potentialities in the treatment of bacterial infections, while its therapeutic efficiency is severely limited by the infection microenvironments such as insufficient hydrogen peroxide (H2O2) and overexpressed glutathione (GSH). Here, we rationally construct a hybrid nanozyme (MoS2/CuO2) with peroxidase-like activity that can enhance CDT by regulating local microenvironments, that is, simultaneously self-supplying H2O2 and consuming GSH. Importantly, MoS2 support can promote the conversion of Cu2+ to Cu+ by the Mo4+/Mo6+ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS2/CuO2 shows desirable PTT/CDT dual-mode antibacterial efficacy both in vitro and in vivo. This study proposes a versatile hybrid nanozyme with multiple enhancement effects for intensive in vivo anti-infective therapy.

Cooperative Cationic and Anionic Redox Reactions in Ultrathin Polyvalent Metal Selenide Nanoribbons for High-Performance Electrochemical Magnesium-Ion Storage.

Rechargeable magnesium batteries (RMBs) are considered as potential energy storage devices due to their high volumetric specific capacity, good safety, as well as source abundance. Despite extensive efforts devoted to constructing an efficient magnesium battery system, the sluggish Mg2+ diffusion in conventional cathode materials often leads to slow rate kinetics, low capacity, and poor cycling lifespan. Although transition metal selenides with soft anion frameworks have attracted extensive attention, their Mg2+ storage mechanism still needs to be clarified. Herein, we demonstrate that the ultrathin CoSe2 nanoribbons can be used as a robust cathode material for RMBs and reveal a novel Mg2+ storage mechanism based on cooperative cationic (Co) and anionic (Se) redox processes via systematic ex-situ characterizations. Compared to other metal selenide cathodes based on conversion reactions of solely metal cations, the cooperative cationic-anionic redox reactions of the CoSe2 cathode contribute to obtaining an enhanced specific capacity and boosted electrochemical kinetics. Moreover, on one hand, the ultrathin nanoribbon structure enables effective contact between the electrode material and electrolyte and on the other hand significantly reduces the length and time consumption of Mg2+ diffusion, leading to dominated surface-driven capacitance-controlled Mg2+ storage behavior and rapid Mg2+ storage kinetics. As a result, the ultrathin CoSe2 nanoribbon cathode exhibits a reversible discharge capacity of ∼130 mAh g-1 at 100 mA g-1, good rate capability (116 mAh g-1 at 300 mA g-1), and long cyclability over 600 cycles. This finding confirms the development potentiality of polyvalent metal selenide cathode materials based on a cooperative cationic-anionic redox mechanism for the construction of next-generation multivalent secondary batteries.

New 2-thiazol-5-yl-benzimidazoles: synthesis and determining of their potential as chemosensor reagents for polyvalent metal ions

Thiabendazole and its analogues are widely used and reasonably well studied in terms of their biological activity, while their potential as chemosensory compounds with optical detection and sensitivity to metal ions remains unexplored. On the other hand, the introduction of a thiazole ring into the heteroaromatic system of benzimidazole significantly expands the directions of practical application of benzimidazole derivatives. Thus, one of the important structural features of the benzimidazole-thiazole system is the presence of a chelate cavity. It is a potential center of complexation with metal ions, which, with their bright fluorescence, create additional opportunities for their use as luminescent probes and chemosensors. Considering the affinity of the sulfur atom for polyvalent heavy metals, sensors based on these compounds can be used in medically and environmentally oriented analysis of toxic metal compounds. In this publication, we focus on the synthesis of various 2- and 4-substituted 2-thiazol-5-yl-benzimidazoles, as well as the determination of their spectral-fluorescence properties. Therefore, we started from 2,4-dihalogen 5-formyl thiazoles, the methods of synthesis of which are well known. Their modification in 2nd position we have described in previous works. To obtain the target products, the Weidenhagen method was chosen, which consists in the reaction of o-phenylenediamine with an aromatic or aliphatic aldehyde under oxidation conditions. For creating such conditions copper acetate was used. The possibility of coordination of metal ions by the obtained compounds was established using electronic absorption and fluorescence spectroscopy. It was found that these compounds selectively form complexes with Cd2+ and Mg2+ ions. Our qualitative studies allow us to make conclusion that the benzimidazole-thiazole fragment is a promising coordination site for metal ions, which can be used in the design of fluorescent probes for the determination of Cd2+ and Mg2+ ions.

Metal-coordination and surface adhesion-assisted molding enabled strong, water-resistant carboxymethyl cellulose films

Developing renewable and biodegradable materials derived from cellulose is an attractive strategy to replace petroleum-derived plastics. In this study, metal ions (Cu2+, Fe3+, and Al3+) were added as a green binder into carboxymethyl cellulose (CMC) films to improve their mechanical properties and water resistance capacity. The tensile strengths of CMCAl3+ films were 133 MPa and 99 MPa at 43 % and 97 % humidity, respectively, which were comparable to or greater than those of the majority of commercially available plastics. Additionally, we proposed an interfacial adhesion-assisted molding strategy for forming cellulose-based films, avoiding film wrinkles and unevenness during drying and metal-coordination formation. The resultant films exhibited high transparency, excellent mechanical properties, water resistance capacity, ultraviolet light (UV) shielding, and antibacterial activity. In summary, the biodegradable, eco-friendly, excellent application performance, and adaptability of CMCMn+ (Mn+: polyvalent metal ions) films open new prospects as a viable alternative to non-biodegradable plastics.

Efficient Removal of Polyvalent Metal Ions (Eu(III) and Th(IV)) from Aqueous Solutions by Polyurea-Crosslinked Alginate Aerogels.

The removal of polyvalent metal ions Eu(III) and Th(IV) from aqueous solutions using polyurea-crosslinked calcium alginate (X-alginate) aerogels has been investigated by batch-type experiments under ambient conditions and pH 3. The material presents relatively high sorption capacity for Eu(III) (550 g kg−1) and Th(IV) (211 g kg−1). The lower sorption capacity for Th(IV) compared to Eu(III) is attributed to the net charge of the dominant species in solution under the given experimental conditions, which is Eu3+ for Eu(III), and Th(OH)22+ and Th(OH)3+ for Th(IV). Generally, the sorption is an endothermic and entropy-driven process, and it follows the Langmuir isotherm model. According to the FTIR spectra, sorption occurs via formation of inner-sphere complexes between the surface functional groups and the f-metal cationic species. The presence of europium and thorium in the adsorbent material was confirmed and quantified with EDS analysis. To the best of our knowledge, this is the first report of an aerogel material used as an adsorbent for Eu(III). Compared to other materials used for the sorption of the specific ions, which are mostly carbon-based, X-alginate aerogels show by far the highest sorption capacity. Regarding Th(IV) uptake, X-alginate aerogels show the highest capacity per volume (27.9 g L−1) among the aerogels reported in the literature. Both Eu(III) and Th(IV) could be recovered from the beads by 65% and 70%, respectively. Furthermore, Th(VI) could also be quantitatively removed from wastewater, while Eu(III) could be removed by 20%. The above, along with their stability in aqueous environments, make X-alginate aerogels attractive candidates for water treatment and metal recovery applications.

Viscoelastic systems for well construction

One of the most important factors ensuring the required quality of well cementing is the use of effective flushing fluids (spacers). Among these fluids are viscoelastic systems (VES), which provide the best displacement of the drilling fluid during the cementing process.
 The article discusses the mechanism of polymerization of viscoelastic systems when using polyacrylamide cross-linked with polyvalent metal cations and the prospects for using these systems for oil and gas wells cementing. Models of the viscoelastic systems flow and their differences due to the presence of normal stresses in viscoelastic systems are shown in this article. The substantiation of the component composition of viscoelastic systems and their main properties, ensuring their efficiency as flushing fluids are given. The article also provides a description of the scientific instruments that were used during the research.
 It has been experimentally confirmed that it is necessary to use additives with the highest oxidation state when choosing a polyvalent cation as a "cross-linker" for viscoelastic systems. This will help to increase the rate of strength characteristics development. The most adequate ratios of components have been experimentally substantiated and the best solids-carrying capacity of a viscoelastic flushing fluid in comparison with other types has been proven. This eliminates the possibility of cement slurry flowing down in the annular space after the completion of the cementing process.
 The special installations proved the best degree of wellbore cleaning in vugular formation zones with a laminar flow regime. In order to minimize the negative effect of polymer films from viscoelastic systems on the adhesion of the cement stone to the casing strings it is recommended to inject a portion of the liquid containing the polymer destructor after a portion of the viscoelastic fluid.