Search Results (380)

Heating at 95 °C or boiling E. coli HT115 (DE3) cells is often used to extract heterologous dsRNA or kill bacteria, although these temperatures cause dsRNA denaturation and destruction. In this study, we examined the risk of degradation of dsRNA fragments of AT-rich genes at high temperature. The expression of dsRNA fragments of AT-rich genes encoding DNA replication enzymes from the microsporidia Vairimorpha ceranae and Nosema bombycis in E. coli HT115 (DE3) was accompanied by heating the bacteria at 95 °C for 30 min. In contrast to four control fragments with normal GC content, the AT-rich dsRNAs of microsporidia were destroyed by this treatment. The in vitro synthesis and heating of the studied dsRNAs showed the degradation of both microsporidia and control fragments. The thermal degradation of in vitro-synthesized control dsRNA with a normal GC content of 47.6% was prevented by the addition of 2 × YT media, NaCl, or low concentrations of MgSO₄. This demonstrates the important role of mono- and divalent cations in stabilizing heated fragments and helps explain the preservation of their integrity and RNAi-initiating activity despite the treatment of bacteria at temperatures that denature dsRNA. Feeding Colorado potato beetle larvae with the same in vitro-synthesized dsRNA containing fragments of three Leptinotarsa decemlineata genes showed that their thermal destruction was accompanied by a decrease in pest-suppressing activity. No dsRNA degradation was observed at 80 °C or after E. coli sonication, and these treatments, as well as increasing cation content, may help to avoid the degradation of heat-sensitive dsRNA. Full article

Selenium nanoparticles (SeNPs) show great potential for sustainable agriculture, but their green synthesis and practical application still need further optimization. This study established a green synthesis method for SeNPs using lyophilized rose (Rosa rugosa Thunb.) powder as both a reducing and stabilizing agent to reduce sodium selenite (Na₂SeO₃), key parameters, including template concentration, Na₂SeO₃/VC ratio, and reaction temperature were systematically optimized. This process yielded stable, spherical SeNPs with optimal properties, exhibiting a diameter of 90 nm and a zeta potential of −35 mV. Structural characterization confirmed that selenium forms chelation complexes through carboxyl and hydroxyl oxygen-binding sites. The SeNPs exhibited exceptional stability (retained 426 days at 25 °C) and pH tolerance (pH 4–10), though divalent cations (Ca²⁺) triggered aggregation. In agricultural application tests, 5 mg/L SeNPs increased tomato plant biomass by 84% and antioxidant capacity by 152% compared to controls, and the biosynthesis pathways of salicylic acid and jasmonic acid were upregulated. Moreover, the SeNPs exhibited strong concentration-dependent antifungal activity against several major pathogens. Among these pathogens, tomato gray mold (Botrytis cinerea) was the most sensitive, as evidenced by its low EC₅₀ (4.86 mg/L) and sustained high inhibition rates, which remained substantial even at 1 mg/L and reached 94% at 10 mg/L. These findings highlight SeNPs as a friendly alternative for minimizing agrochemical use in sustainable agriculture. Full article

Temperature is a key factor in regulating interfacial behaviors and enhancing oil recovery during low-salinity water flooding in tight sandstone reservoirs. This study systematically investigates the synergistic mechanisms of temperature and salinity on ion exchange, wettability alteration, interfacial tension, and crude oil desorption. The experimental results show that elevated temperature significantly strengthens the oil–water–rock interactions induced by low-salinity water, thereby improving oil recovery. At 70 °C, the release of divalent cations such as Ca²⁺ and Mg²⁺ from the rock surface is notably enhanced. Simultaneously, the increase in interfacial electrostatic repulsion is evidenced by a shift in the rock–brine zeta potential from −3.14 mV to −6.26 mV. This promotes the desorption of polar components, such as asphaltenes, from the rock surface, leading to a significant change in wettability. The wettability alteration index increases to 0.4647, indicating a strong water-wet condition. Additionally, the reduction in oil–water interfacial zeta potential and the enhancement in interfacial viscoelasticity contribute to a further decrease in interfacial tension. Under conditions of 0.6 PW salinity and 70 °C, non-isothermal core flooding experiments demonstrate that rock–fluid interactions are the dominant mechanism responsible for enhanced oil recovery. By applying a staged injection strategy, where 0.6 PW is followed by 0.4 PW, the oil recovery reaches 34.89%, which is significantly higher than that achieved with high-salinity water flooding. This study provides critical mechanistic insights and optimized injection strategies for the development of high-temperature tight sandstone reservoirs using low-temperature waterflooding. Full article

P2X receptors are a family of ATP-gated ion channels widely distributed in various tissues, especially in neuronal cells and hematopoietic cells. ATP activates P2X receptors, causing the opening of an ionic channel with preferential permeability to the passage of mono- and divalent cations. High concentrations of ATP stimulate the P2X7 subtype through prolonged activation, which opens pores and causes inflammation, proalgesic effects, and cell death. Peptides, including antimicrobials (antimicrobial peptides), are present in several organisms, such as amphibians, mammals, fish, arachnids, and plants, where they act as the first line of defense. Thus, these peptides have the capacity to eliminate a wide spectrum of microorganisms, such as bacteria, fungi, and some viruses. In general, the mechanism of action of antimicrobial peptides involves interactions with the lipid bilayer of the cell membrane, which can lead to an increase in the internal liquid content of liposomes. However, many peptides can act on ion channels, such as those of the P2X family, especially the P2X7 receptor. We investigated the action of peptides that directly modulate P2X7 receptors, such as beta-amyloid, LL-37/hCap18, Pep19-2.5, rCRAMP, ADESG, and polymyxin B. Additionally, we evaluated peptides that modulate the activity of P2X family receptor subtypes. In this review, we intend to describe the relationships between peptides with distinct characteristics and how they modulate the functionality of P2X receptors. Full article

This study aims to elucidate the geochemical reactions between CO₂-saturated water and rocks in CO₂-enhanced geothermal system (CO₂-EGS) reservoirs by focusing on andesite found in island arc regions, such as Japan. Laboratory flow tests of CO₂-saturated water (3 wt.% CO₂) and rocks (particle size: 0.14–1 mm) were conducted under varying temperature (150–250 °C) and flow rate (0.3 and 1.0 mL/min) conditions using a flow-through reactor. Elevated temperatures enhanced the dissolution of silicate minerals, reflected by increased Na⁺, K⁺, Ca²⁺, and Si concentrations, whereas those of Fe²⁺ and Al³⁺ remained low, suggesting secondary mineral precipitation. The dissolution process was dominant at 150 °C. Al-bearing minerals, such as gibbsite and boehmite, as well as clay minerals, including beidellite and kaolinite, were predominant at higher temperatures (200–250 °C). Carbonate minerals were not observed, attributable to low pH and limited availability of divalent cations. Flow rate substantially influenced Si dissolution rates, with lower flow rates promoting longer residence times and higher Si dissolution rates. These results indicate that the test conditions simulate the environment around the injection well, where the fluid is acidic and dissolution is the main reaction in the rock. Although a small amount of secondary minerals precipitated and the Si dissolution rates were of the same order of magnitude as those for labradorite, it may be considered that andesite has less impact on permeability variations than basalt near the injection well in CO₂-EGS reservoirs. Full article

The Long Interspersed Element-1 (L1) retrotransposon is an ancient genetic parasite that comprises a significant part of the human genome. ORF2p is a multifunctional enzyme with endonuclease (EN) and reverse transcriptase (RT) activities that mediate target-primed reverse transcription of RNA into DNA. Structural studies of LINE-1 ORF2p consistently show a single Mg²⁺ cation in the reverse transcriptase active site, conflicting with the common DNA polymerase mechanism which involves two divalent cations. We explored a reaction pathway of the DNA elongation based on the recent high-resolution ternary complex structure of the ORF2p. The combined quantum and molecular mechanics approach at the QM (PBE0-D3/6-31G**)/MM (CHARMM) level is employed for biased umbrella sampling molecular dynamics simulations followed by umbrella integration utilized to obtain the free energy profile. The nucleotidyl transfer reaction proceeds in a single step with a free energy barrier of 15.1 ± 0.8 kcal/mol, and 7.8 ± 1.2 kcal/mol product stabilization relative to reagents. Concerted nucleophilic attack by DNA O3′ and proton transfer to Asp703 occur without a second catalytic metal ion. Estimated rate constant ∼60 s⁻¹ aligns with RT kinetics, while analysis of the Laplacian of the electron density along the cleaving P-O bond identifies a dissociative mechanism. Full article

Understanding surface charge behavior is essential for improving ion separation during lithium brine treatment. This paper investigates the performance of a three-compartment electrodialysis system designed for the selective removal of divalent cations (Mg²⁺ and Ca²⁺). The relationship between zeta potential and the recovery of Li⁺, Na⁺, and K⁺ is analyzed. Zeta potential measurements at various pH values showed that Mg(OH)₂ particles maintained a positive charge. The system facilitated the precipitation of Mg(OH)₂ and Ca(OH)₂ via electrochemically generated OH⁻ ions. The specific electrical energy consumption was evaluated for each operating condition. The results showed that the zeta potential of the precipitates was affected by both the current density and temperature. This influenced lithium losses due to brine entrapment within the precipitated solids. At 600 A/m² and 50 °C, more than 99% of Mg²⁺ and Ca²⁺ were removed, and more than 90% of lithium was recovered, with a specific electric energy consumption of 2.58 kWh per kilogram of Li recovered. The system also generates HCl as a valuable by-product, which improves the sustainability of the process. This study provides a new framework for improving the energy efficiency of lithium purification from brines and lithium recovery. Full article

The rational design of functional and sustainable polymers is central to addressing global environmental challenges. In this context, unmodified lignin derived from Sarkanda grass (Tripidium bengalense), an abundant agro-industrial lignocellulosic byproduct, was systematically investigated as a natural polymeric adsorbent for the remediation of aqueous media contaminated with heavy metals. The study evaluates lignin’s behavior toward nine metal(loid) ions: arsenic, cadmium, chromium, cobalt, copper, iron, nickel, lead, and zinc. Adsorption performance was systematically investigated under static batch conditions, optimizing key parameters, with equilibrium and kinetic data modeled using established isotherms and rate equations. Surface characterization and seed germination bioassays provided supporting evidence. Unmodified Sarkanda grass lignin demonstrated effective adsorption, exhibiting a clear preference for Cu(II) followed by other divalent cations, with lower capacities for As(III) and Cr(VI). Adsorption kinetics consistently followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism. Thermodynamic studies revealed spontaneous and endothermic processes. Bioassays confirmed significant reduction in aqueous toxicity and strong metal sequestration. This work positions unmodified Sarkanda grass lignin as a bio-based, low-cost polymer platform for emerging water treatment technologies, contributing to circular bioeconomy goals and highlighting the potential of natural polymers in sustainable materials design. Full article

We hypothesized that compounds containing ether linkages within their backbone structures, when exposed to hydroxyl radicals (•OH), can generate ultra-weak photon emission (UPE) as a result of the formation of triplet excited carbonyl species (³R=O*). To evaluate this hypothesis, we investigated the UPE of four compounds, each at a final concentration of 185.2 µmol/L: EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid), a potent chelator of divalent cations, and three crown ethers—12-crown-4, 15-crown-5, and 18-crown-6—containing two, four, five, and six ether bonds, respectively. •OH was generated using a modified Fenton reagent—92.6 µmol/L Fe²⁺ and 2.6 mmol/L H₂O₂. The highest UPE was recorded for the Fe²⁺–EGTA–H₂O₂ (2863 ± 158 RLU; relative light units), followed by 18-crown-6, 15-crown-5, and 12-crown-4 (1161 ± 78, 615± 86, and 579 ± 109 RLU, respectively; p < 0.05), corresponding to the number of ether groups present. Controls lacking either H₂O₂ or Fe²⁺ exhibited no significant light emission compared to the buffer medium. These findings support the hypothesis that ether bonds, when oxidatively attacked by •OH, undergo chemical transformations resulting in the formation of ³R=O* species, the decay of which is associated with UPE. In crown ethers exposed to Fe²⁺-H₂O₂, the intensity of UPE was correlated with the number of ether bonds in their structure. Full article

This study focuses on the exchange of mono- and divalent metal cations in FAU-type zeolite and their behavior in gas-phase CO₂ adsorption measurements and liquid-phase methylene blue (MB) adsorption in the absence of oxidizing agents under dark conditions. Firstly, zeolites exchanged with different cations were characterized by several techniques, such as XRD, SEM, XRF, XPS, and N₂ adsorption–desorption, to reveal the impact of the cations on the zeolite texture and structure. The adsorption studies revealed a positive effect of cation exchange on the adsorption capacity of the zeolite, particularly for silver-loaded FAU zeolite. In liquid-phase experiments, Ag-Y zeolite also demonstrated the highest MB removal, with a value of 79 mg/g. Kinetic studies highlighted that Ag-Y could reach the MB adsorption equilibrium within 1 h, with its highest rate of adsorption occurring during the first 5 min. In gas-phase adsorption studies, the highest CO₂ adsorption capacity was also achieved over Ag-Y, yielding 10.4 µmol/m² of CO₂ captured. Full article

Increasing water scarcity in arid regions has prompted the mining industry to develop strategies to maximize water recovery and reuse, especially in tailings treatment processes. In this context, the present investigation evaluated the effects of sodium polyacrylate (NaPA) on the compressibility and viscoelasticity of clayey tailings in the presence of hard water containing calcium and magnesium. To this end, clayey slurries were analyzed using rheological tests (rheograms and oscillatory viscoelasticity), zeta potential measurements, and compressibility tests using batch centrifugation. The yield stress was determined using the Herschel–Bulkley model, while the compressive yield stress (Py(Φ)) was calculated as a key indicator to characterize the degree of sediment consolidation. The results showed that NaPA, due to its anionic nature and high degree of ionization at pH 8, induces effective particle dispersion by increasing electrostatic repulsion and decreasing the interaction force between particles, which reduces both rheological parameters and compressive yield stress. For the 70/30 quartz/kaolin mixture, the yield stress decreased from 70.54 to 61.64 Pa in CaCl₂ and from 57.51 to 52.95 Pa in MgCl₂ in the presence of NaPA. It was also observed that suspensions in the presence of magnesium ions presented greater compressibility than those with calcium, attributable to the greater hydration radius of magnesium (10.8 Å), which favors less dense and more easily deformable network structures. Furthermore, a higher proportion of kaolin in the mixture resulted in higher yield stresses, a product of the clay’s laminar structure, colloidal size, and high surface area, both in the absence and presence of NaPA. Overall, the results show that incorporating NaPA significantly improves the compressibility and rheology of clayey tailings in hard water, offering a promising alternative for optimizing water recovery and improving tailings management efficiency in the context of water restrictions. Full article

Wastewater contains dyes originating from textile industries, and above a certain concentration, they can become dangerous due to their high toxicity. Divalent and trivalent metal coagulants, usually aluminum- or iron-based, have been studied worldwide. However, tetravalent coagulants, such as tin chloride, have not yet been extensively studied for application in wastewater treatment. Therefore, in this study, three types of coagulants were examined: SnCl₄, Cs, and a hybrid composite (CS@Sn) in two different mass ratios, abbreviated hereafter as CS@Sn_5% and CS@Sn_50%. The formation of the suggested CS@Sn hybrid coagulants was confirmed by applying SEM, XRD, and FTIR techniques. The results showed that the optimum conditions for RB5 removal was the addition of 20 mg Sn/L SnCl₄ (97.8%) and 50 mg Sn/L of CS@Sn_50% (64.8%) at pH 3.0. In addition, SnCl₄ was found to be an effective coagulant for all the examined anionic dyes, but it was not as effective for cationic dyes. Moreover, the coagulants were then tested in two mixed-dye solutions, both anionic dyes (RB5/RR120) and anionic/cationic (RB5/MV), resulting in a synergistic effect in the first one and a competitive effect in the secon. Finally, the proposed coagulants were successfully tested on real wastewater samples from an untreated textile dyeing industry. Therefore, the coagulants presented in this work for the removal of several dyes are also capable of being used for wastewater treatment. Full article

The rapid development of the global energy industry has driven an escalating worldwide demand for lithium resources. As a major lithium source, salt lake brines contain abundant divalent ions that hinder efficient lithium extraction. Compared with conventional lithium recovery technologies, nanofiltration membranes emerge as an energy-efficient and environmentally friendly alternative. Over the past decade, interfacial polymerization has been widely adopted to fabricate nanofiltration membranes for lithium–magnesium separation, with studies confirming the superior performance of positively charged membranes in distinguishing monovalent and divalent cations. This review systematically summarizes recent advancements in positively charged nanofiltration membranes synthesized via interfacial polymerization for lithium–magnesium separation, categorizing the design strategies into five distinct approaches. The correlations between intrinsic membrane structural characteristics and separation performance are critically analyzed. Furthermore, current challenges and future research directions are discussed to provide new perspectives for developing high-performance positively charged composite nanofiltration membranes. This work aims to inspire innovative designs and accelerate the practical implementation of nanofiltration technology in lithium extraction from salt lake brines. Full article

Lead (Pb) is a pervasive neurotoxicant with well-documented detrimental effects on the central nervous system, particularly in vulnerable populations such as children. Despite historical recognition of its toxicity, Pb exposure remains a significant public health concern due to its environmental persistence, historical industrial use, and ongoing applications in modern technologies. This review focuses on the mechanisms by which Pb disrupts glutamatergic signaling, a critical pathway for learning, memory, and synaptic plasticity. Pb’s interference with glutamate receptors (ionotropic NMDA and AMPA, as well as metabotropic receptors), transporters (EAATs, VGLUTs, and SNATs), and metabolic pathways (glutamate–glutamine cycle, TCA cycle, and glutathione synthesis) are detailed. By mimicking divalent cations like Ca²⁺ and Zn²⁺, Pb²⁺ disrupts calcium homeostasis, exacerbates excitotoxicity, and induces oxidative stress, ultimately impairing neuronal communication and synaptic function. These molecular disruptions manifest cognitive deficits, behavioral abnormalities, and increased susceptibility to neurodevelopmental and neurodegenerative disorders. Understanding Pb’s impact on glutamatergic neurotransmission offers critical insights into its neurotoxic profile and highlights the importance of addressing its effects on neural function. Full article

Riboswitches regulate gene expression through intricate dynamic conformational transitions, with divalent cation Mg²⁺ and their ligands playing pivotal roles in this process. The dynamic structural mechanism by which the S-adenosyl-L-methionine (SAM) responsive SAM-VI riboswitch (riboSAM) regulates the downstream SAM synthase gene translation remains unclear. In this study, we employed position-selective labeling of RNA (PLOR) to incorporate Cy3-Cy5 into designated positions of riboSAM, applying single-molecule Förster resonance energy transfer (smFRET) method to track its conformational switches in response to Mg²⁺ and SAM. smFRET analysis revealed that in the absence of Mg²⁺ and ligand, riboSAM predominantly adopted a translation-activating apo conformation. Physiological concentrations of Mg²⁺ induced riboSAM to fold into dynamic transit-p and holo-p states, creating a transient and structurally pliable binding pocket for ligand binding. SAM binding locks the dynamic transit-p and holo-p states into their final stable transit and holo conformations through conformational selection, turning off downstream cis-gene expression and completing feedback regulation of cellular SAM concentration. The observed synergistic regulatory effect of Mg²⁺ ions and ligand on riboSAM’s conformational dynamics at single-molecule resolution provides new mechanistic insights into gene regulation by diverse riboswitch classes. Full article