Search Results (1,185)

Liquid calcium aluminate cement (LCAC) is an innovative material technology with significant potential for varied applications in civil engineering. However, despite its promising results, a significant gap remains in the direct application of LCAC as a concrete binder. The primary catalysts for LCAC are sodium hydroxide (NaOH) and potassium hydroxide (KOH). Therefore, it is crucial to investigate the effects of sodium and potassium ions on alkali–aggregate reactions in concrete structures. This study evaluated the durability of liquid calcium aluminate cement concrete catalyzed using four different concentrations of NaOH (0.5%, 1.0%, 1.5%, and 2.0%) as experimental variables, incorporating a control group of traditional concrete with a water–cement ratio of 0.64. The findings indicate that NaOH catalysis in the concrete significantly trigger alkali–aggregate reactions, leading to volume expansion. Furthermore, it increased chloride ion penetration and porosity in the concrete. These effects were more notable with the increase in NaOH concentration. The results suggested that NaOH catalysis can enhance certain chemical reactions within the concrete matrix; however, its concentration must be carefully controlled to mitigate adverse effects. The NaOH dosage should be limited to 0.5% to ensure optimal durability of the concrete. This study emphasizes the crucial importance of precisely balancing catalyst concentration to maintain the long-term durability and performance of liquid calcium aluminate cement concrete in structural applications. Full article

Soil salinization poses a significant constraint to agricultural productivity. However, certain plant growth-promoting bacteria (PGPB) can mitigate salinity stress and enhance crop performance. In this study, a bacterial isolate, R-18, isolated from saline-alkali soil in Ningxia, China, was identified as Enterobacter bugandensis based on 16S rRNA gene sequencing. The isolate was characterized for its morphological, biochemical, and plant growth-promoting traits and was evaluated for its potential to alleviate NaCl-induced stress in maize (Zea mays L.) under hydroponic conditions. Isolate R-18 exhibited halotolerance, surviving at NaCl concentrations ranging from 2.0% to 10.0%, and alkaliphilic adaptation, growing at pH 8.0–11.0. Biochemical assays confirmed it as a Gram-negative bacterium, displaying positive reactions in the Voges–Proskauer (V–P) tests, catalase activity, citrate utilization, fluorescent pigment production, starch hydrolysis, gelatin liquefaction, and ammonia production, while testing negative for the methyl red and cellulose hydrolysis. Notably, isolate R-18 demonstrated multiple plant growth-promoting attributes, including nitrogen fixation, phosphate and potassium solubilization, ACC deaminase activity, and indole-3-acetic acid (IAA) biosynthesis. Under 100 mM NaCl stress, inoculation with isolate R-18 significantly enhanced maize growth, increasing plant height, stem dry weight, root fresh weight, and root dry weight by 20.64%, 47.06%, 34.52%, and 31.25%, respectively. Furthermore, isolate R-18 improved ion homeostasis by elevating the K⁺/Na⁺ ratio in maize tissues. Physiological analyses revealed increased chlorophyll and proline content, alongside reduced malondialdehyde (MDA) levels, indicating mitigated oxidative damage. Antioxidant enzyme activity was modulated, with decreased superoxide dismutase (SOD) and peroxidase (POD) activities but increased catalase (CAT) activity. These findings demonstrated that Enterobacter bugandensis R-18 effectively alleviated NaCl-induced growth inhibition in maize by enhancing osmotic adjustment, reducing oxidative stress, and improving ion balance. Full article

In this work, graphite anodes and lithium iron phosphate (LFP) cathodes are used to examine the effects of sodium hexafluorophosphate (NaPF₆) and potassium hexafluorophosphate (KPF₆) electrolyte additives on the formation of the solid electrolyte interphase and the performance of lithium-ion batteries in both half-cell and full-cell designs. The objective is to assess whether these additives may increase cycle performance, decrease irreversible capacity loss, and improve interfacial stability. Compared to the control electrolyte (1.22 M Lithium hexafluorophosphate (LiPF₆)), cells with NaPF₆ and KPF₆ additives produced less SEI products, which decreased irreversible capacity loss and enhanced initial coulombic efficiency. Following the formation of the solid electrolyte interphase, the specific capacity of the control cell was 607 mA·h/g, with 177 mA·h/g irreversible capacity loss. In contrast, irreversible capacity loss was reduced by 38.98% and 37.85% in cells containing KPF₆ and NaPF₆ additives, respectively. In full cell cycling, a considerable improvement in capacity retention was achieved by adding NaPF₆ and KPF₆. The electrolyte, including NaPF₆, maintained 67.39% greater capacity than the LiPF₆ baseline after 20 cycles, whereas the electrolyte with KPF₆ demonstrated a 30.43% improvement, indicating the positive impacts of these additions. X-ray photoelectron spectroscopy verified that sodium (Na⁺) and potassium (K⁺) ions were present in the SEI of samples containing NaPF₆ and KPF₆. While K⁺ did not intercalate in LFP, cyclic voltammetry confirmed that Na⁺ intercalated into LFP with negligible impact on the energy storage of full cells. These findings demonstrate that NaPF₆ and KPF₆ are suitable additions for enhancing lithium-ion battery performance in the popular artificial graphite/LFP system. Full article

Ant venoms are rich sources of bioactive molecules, including peptide toxins with potent and selective activity on ion channels, which makes them valuable for pharmacological research and therapeutic development. Voltage-dependent potassium (Kv) channels, critical for regulating cellular excitability or cell cycle progression control, are targeted by a diverse array of venom-derived peptides. This study focuses on MYRTX_A4-Tb11a, a peptide from Tetramorium bicarinatum venom, which was previously shown to have a strong paralytic effect on dipteran species without cytotoxicity on insect cells. In the present study, we show that Tb11a exhibited no or low cytotoxicity toward mammalian cells either, even at high concentrations, while electrophysiological studies revealed a blockade of hKv1.3 activity. Additionally, Ta11a, an analog of Tb11a from the ant Tetramorium africanum, demonstrated similar Kv1.3 inhibitory properties. Structural analysis supports that the peptide acts on Kv1.3 channels through the functional dyad Y21-K25 and that the disulfide bridge is essential for biological activity, as reduction seems to disrupt the peptide conformation and impair the dyad. These findings highlight the importance of three-dimensional structure in channel modulation and establish Tb11a and Ta11a as promising Kv1.3 inhibitors. Future research should investigate their selectivity across additional ion channels and employ structure-function studies to further enhance their pharmacological potential. Full article

Background: Crystalline glucosamine sulfate (cGS) claims to be a stabilized form of glucosamine sulfate with a defined crystalline structure intended to enhance chemical stability. It is proposed to offer pharmacokinetic advantages over regular glucosamine sulfate (rGS) which is stabilized with potassium or sodium chloride. However, comparative human bioavailability data are limited. Since both forms dissociate in gastric fluid into constituent ions, the impact of cGS formulation on absorption remains uncertain. This pilot study aimed to compare the bioavailability of cGS and rGS using a randomized, double-blind, crossover design. Methods: Ten healthy adults received a single 1500 mg oral dose of either cGS or rGS with a 7-day washout between interventions. Capillary blood samples were collected over 24 h. Glucosamine and its metabolite concentrations were quantified by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS), and pharmacokinetic parameters—including maximum concentration (C_max), time to reach C_max (T_max), and area under the curve (AUC)—were calculated. Results: Mean AUC_0–24, C_max, T_max, and T_½ values for glucosamine and glucosamine-6-sulfate (GlcN-6-S) were comparable between cGS and rGS. Although the AUC_0–24 for glucosamine was modestly higher with rGS (18,300 ng·h/mL) than with cGS (12,900 ng·h/mL), the difference was not statistically significant (p = 0.136). GlcN-6-S exposure was also similar between formulations (rGS: 50,700 ng·h/mL; cGS: 50,600 ng·h/mL), with a geometric mean ratio of 1.39, a delayed T_max (6–8 h) and longer half-life, consistent with its role as a downstream metabolite. N-acetylglucosamine levels remained stable, indicating potential homeostatic regulation. Conclusions: This pilot study found no significant pharmacokinetic advantage of cGS over rGS. These preliminary findings challenge claims of cGS’ pharmacokinetic superiority, although the small sample size limits definitive conclusions. Larger, adequately powered studies are needed to confirm these results. Full article

The mechanism by which voltage-gated ion channels open and close has been the subject of intensive investigation for decades. For a large class of potassium channels and related sodium channels, the consensus has been that the gating current preceding the main ionic current is a large movement of positively charged segments of protein from voltage-sensing domains that are mechanically connected to the gate through linker sections of the protein, thus opening and closing the gate. We have pointed out that this mechanism is based on evidence that has alternate interpretations in which protons move. Very little literature considers the role of water and protons in gating, although water must be present, and there is evidence that protons can move in related channels. It is known that water has properties in confined spaces and at the surface of proteins different from those in bulk water. In addition, there is the possibility of quantum properties that are associated with mobile protons and the hydrogen bonds that must be present in the pore; these are likely to be of major importance in gating. In this review, we consider the evidence that indicates a central role for water and the mobility of protons, as well as alternate ways to interpret the evidence of the standard model in which a segment of protein moves. We discuss evidence that includes the importance of quantum effects and hydrogen bonding in confined spaces. K⁺ must be partially dehydrated as it passes the gate, and a possible mechanism for this is considered; added protons could prevent this mechanism from operating, thus closing the channel. The implications of certain mutations have been unclear, and we offer consistent interpretations for some that are of particular interest. Evidence for proton transport in response to voltage change includes a similarity in sequence to the H_v1 channel; this appears to be conserved in a number of K⁺ channels. We also consider evidence for a switch in -OH side chain orientation in certain key serines and threonines. Full article

To address the issue of excessive chemical fertilizer use in agricultural production, this study conducted a pot experiment with four treatments: CK (no fertilization), T1 (the application of potassium magnesium sulfate fertilizer), T2 (the application of slow-release fertilizer equal to T1), and T3 (the application of slow-release fertilizer with the same fertility as T1). The effects of these treatments on garlic seedling yield, growth quality, chlorophyll content, photosynthetic characteristics, and the soil environment were investigated to evaluate the feasibility of replacing conventional fertilizers with slow-release formulations. The results showed that compared with CK, all three fertilized treatments (T1, T2, and T3) significantly increased the plant heights and stem diameters of the garlic sprouts (p < 0.05). Plant height increased by 14.85%, 17.81%, and 27.75%, while stem diameter increased by 9.36%, 8.83%, and 13.96%, respectively. Additionally, the chlorophyll content increased by 4.34%, 7.22%, and 8.05% across T1, T2, and T3, respectively. Among the treatments, T3 exhibited the best overall growth performance. Compared with those in the CK group, the contents of soluble sugars, soluble proteins, free amino acids, vitamin C, and allicin increased by 64.74%, 112.17%, 126.82%, 36.15%, and 45.43%, respectively. Furthermore, soil organic matter, available potassium, magnesium, and phosphorus increased by 109.02%, 886.25%, 91.65%, and 103.14%, respectively. The principal component analysis indicated that soil pH and exchangeable magnesium were representative indicators reflecting the differences in the soil’s chemical properties under different fertilization treatments. Compared with the CK group, the metal contents in the T1 group slightly increased, while those in T2 and T3 generally decreased, suggesting that the application of slow-release fertilizer exerts a certain remediation effect on soils contaminated with heavy metals. This may be attributed to the chemical precipitation and ion exchange capacities of phosphogypsum, as well as the high adsorption and cation exchange capacity of bentonite, which help reduce the leaching of soil metal ions. In summary, slow-release fertilizers not only promote garlic sprout growth but also enhance soil quality by regulating its chemical properties. Full article

Large-conductance, voltage- and calcium-activated potassium (BK) channels are crucial regulators of cellular excitability, influenced by various signaling molecules, including heme. The BK channel contains a heme-sensitive motif located at the sequence ⁶¹²CKACH⁶¹⁶, which is a conserved heme regulatory motif (HRM) found in the cytochrome c protein family. This motif is situated within a linker region of approximately 120 residues that connect the RCK1 and RCK2 domains, and it also includes terminal α-helices similar to those found in cytochrome c family proteins. However, much of this region has yet to be structurally defined. We conducted a sequence alignment of the BK linker region with mitochondrial cytochrome c and cytochrome c domains from various hemoproteins to better understand this functionally significant region. In addition to the HRM motif, we discovered that important structural and functional elements of cytochrome c proteins are conserved in the BK RCK1-RCK2 linker. Firstly, the part of the BK region that is resolved in available atomic structures shows similarities in secondary structural elements with cytochrome c domain proteins. Secondly, the Met80 residue in cytochrome c domains, which acts as the second axial ligand to the heme iron, aligns with the BK channel. Beyond its role in electron shuttling, cytochrome c domains exhibit various catalytic properties, including peroxidase activity—specifically, the oxidation of suitable substrates using peroxides. Our findings reveal that the linker region endows human BK channels with peroxidase activity, showing an apparent H₂O₂ affinity approximately 40-fold greater than that of mitochondrial cytochrome c under baseline conditions. This peroxidase activity was reduced when substitutions were made at ⁶¹²CKACH⁶¹⁶ and other relevant sites. These results indicate that the BK channel possesses a novel module similar to the cytochrome c domains of hemoproteins, which may give rise to unique physiological functions for these widespread ion channels. Full article

Brugada syndrome is a rare inherited heart disease characterized by ventricular arrhythmias and characteristic ST segment elevation, which increases the risk of sudden death. Studies have shown that the pathogenesis of this disease involves a variety of gene mutations, including abnormal functions of sodium, calcium, and potassium ion channels, resulting in cardiac electrophysiological disorders. These variants affect excitability and conduction of cardiomyocytes, thereby increasing the susceptibility to ventricular arrhythmias and sudden death. However, many genetic variants remain of uncertain significance or are insufficiently characterized, necessitating further investigation. This review summarizes the genetic variants associated with Brugada syndrome and discusses their potential implications for improving diagnosis and therapeutic approaches. Full article

Based on an integrated analysis, this study summarized the current status of soil quality in Yantai apple orchards, developed a multivariate regulation model for key soil physicochemical properties, and proposed optimized fertilization strategies to improve soil quality in the region. The study analyzed the physicochemical properties of the topsoil (0–30 cm) in 19 representative apple orchards across Yantai, including indicators like pH, organic matter (OM), major nutrient ions, and salinity indicators, using standardized measurements and multivariate statistical methods, including descriptive statistics analysis, frequency distribution analysis, canonical correlation analysis, stepwise regression equation analysis, and regression fit model analysis. The results demonstrated that in apple orchards across the Yantai region, reductions in pH were significantly mitigated under the combined increased OM and exchangeable calcium (Ca). Exchangeable potassium (EK) rose in response to the joint elevation of OM and available nitrogen (AN), and AN was also positively influenced by EK, while OM also exhibited a promotive effect on Olsen phosphorus (OP). Furthermore, Ca increased with higher pH. AN and EK jointly contributed to the increases in electrical conductivity (EC) and chloride ions (Cl), while elevated exchangeable sodium (Na) and soluble salts (SS) were primarily driven by EK. Accordingly, enhancing organic and calcium source fertilizers is recommended to boost OM and Ca levels, reduce acidification, and maintain EC within optimal limits. By primarily reducing potassium’s application, followed by nitrogen and phosphorus source fertilizers, the supply of macronutrients can be optimized, and the accumulation of Na, Cl, and SS can be controlled. Collectively, the combined analysis of soil quality status and the multivariate regulation model clarified the optimized fertilization strategies, thereby establishing a solid theoretical and practical foundation for recognizing the necessity of soil testing and formula fertilization, the urgency of improving soil quality, and the scientific rationale for nutrient input management in Yantai apple orchards. Full article

Non-conventional water sources (saline and brackish water) are viable options for crop cultivation. Current salt-tolerance research largely focuses on Na⁺ and Cl⁻, while other ions in these waters remain ill-understood. Synthetic seawater was a representative of saline and brackish water in a Design of Experiments (DoE) treatment design used to evaluate the effects of factors [synthetic seawater (0, 15, 30, or 45%, v/v, Instant Ocean^®), total inorganic nitrogen (0, 14, or 28 mM; 1 NH₄⁺:8 NO₃⁻ ratio), potassium (0, 9, or 21 mM), calcium (0, 2, or 5 mM), silicon (0, 0.03, or 0.09 mM) and zinc (0, 0.05, or 2 mM)] on seedlings for two varieties of Brassica juncea [‘Carolina Broadleaf’ (CB) and ‘Florida Broadleaf’ (FB)] using a hydroponic assay. In 30–45% synthetic seawater, 0.09 mM of silicon or 2 mM of calcium alleviated salt stress. In FB, 0.04–0.06 mM of silicon was optimal for the production of new leaves. The CB variety showed greater production of new leaves with 0.09 mM of silicon and 28 mM of potassium. Potassium and calcium are components of seawater, and a sodium chloride assay would not account for their interactions without a multivariate approach to evaluate salt tolerance. The seedling assay identified factors and established criteria for larger-scale harvest experiments. Full article

Redox regulation is crucial for the cardiac action potential, coordinating the sodium-driven depolarization, calcium-mediated plateau formation, and potassium-dependent repolarization processes required for proper heart function. Under physiological conditions, low-level reactive oxygen species (ROS), generated by mitochondria and membrane oxidases, adjust ion channel function and support excitation–contraction coupling. However, when ROS accumulate, they modify a variety of important channel proteins in cardiomyocytes, which commonly results in reducing potassium currents, enhancing sodium and calcium influx, and enhancing intracellular calcium release. These redox-driven alterations disrupt the cardiac rhythm, promote after-depolarizations, impair contractile force, and accelerate the development of heart diseases. Experimental models demonstrate that oxidizing agents reduce repolarizing currents, whereas reducing systems restore normal channel activity. Similarly, oxidative modifications of calcium-handling proteins amplify sarcoplasmic reticulum release and diastolic calcium leak. Understanding the precise redox-dependent modifications of cardiac ion channels would guide new possibilities for targeted therapies aimed at restoring electrophysiological homeostasis under oxidative stress, potentially alleviating myocardial infarction and cardiovascular dysfunction. Full article

As a renewable alternative to fossil fuels, the industrial production of biodiesel urgently requires the development of efficient and recyclable solid base catalysts. In this study, the physicochemical properties and catalytic performance differences between MgO/Na₂CO₃ and MgO/K₂CO₃ catalysts were systematically compared using soybean oil as the raw material. By regulating the calcination temperature (500–700 °C), alcohol-to-oil ratio (3:1–24:1), and metal carbonate loading (10–50%), combined with N₂ adsorption–desorption, CO₂-TPD, XRD, SEM-EDS, and cycling experiments, the regulatory mechanisms of the ionic radius differences between sodium and potassium on the catalyst structure and performance were revealed. The results showed that MgO/Na₂CO₃-600 °C achieved a FAME yield of 97.5% under optimal conditions, which was 1.7% higher than MgO/K₂CO₃-600 °C (95.8%); this was attributed to its higher specific surface area (148.6 m²/g vs. 126.3 m²/g), homogeneous mesoporous structure, and strong basic site density. In addition, the cycle stability of MgO/K₂CO₃ was significantly lower, retaining only 65.2% of the yield after five cycles, while that of MgO/Na₂CO₃ was 88.2%. This stability difference stems from the disparity in their solubility in the reaction system. K₂CO₃ has a higher solubility in methanol (3.25 g/100 g at 60 °C compared to 1.15 g/100 g for Na₂CO₃), which is also reflected in the ion leaching rate (27.7% for K⁺ versus 18.9% for Na⁺). This study confirms that Na⁺ incorporation into the MgO lattice can optimize the distribution of active sites. Although K⁺ surface enrichment can enhance structural stability, the higher leaching rate leads to a rapid decline in catalyst activity, providing a theoretical basis for balancing catalyst activity and durability in sustainable biodiesel production. Full article

Fibrosis represents a pivotal pathological process in numerous diseases, characterized by excessive deposition of extracellular matrix (ECM) that disrupts normal tissue architecture and function. In the heart, cardiac fibrosis significantly impairs both structural integrity and functional capacity, contributing to the progression of heart failure. Central to this process are cardiac fibroblasts (CFs), which, upon activation, differentiate into contractile myofibroblasts, driving pathological ECM accumulation. Transforming growth factor-beta (TGFβ) is a well-established regulator of fibroblast activation; however, the precise molecular mechanisms, particularly the involvement of ion channels, remain poorly understood. Emerging evidence highlights the regulatory role of ion channels, including calcium-activated potassium (K_Ca) channels, in fibroblast activation. This study elucidates the role of ion channels and investigates the mechanism by which Yoda1, an agonist of the mechanosensitive ion channel Piezo1, modulates TGFβ-induced fibroblast activation. Using NIH/3T3 fibroblasts, we demonstrated that TGFβ-induced activation is regulated by tetraethylammonium (TEA)-sensitive potassium channels, but not by specific K⁺ channel subtypes such as BK, SK, or IK channels. Intriguingly, Yoda1 was found to inhibit TGFβ-induced fibroblast activation through a Piezo1-independent mechanism. Transcriptomic analysis revealed that Yoda1 modulates fibroblast activation by altering gene expression pathways associated with fibrotic processes. Bromodomain-containing protein 4 (BRD4) was identified as a critical mediator of Yoda1’s effects, as pharmacological inhibition of BRD4 with JQ1 or ZL0454 suppressed TGFβ-induced expression of the fibroblast activation marker Periostin (Postn). Conversely, BRD4 overexpression attenuated the inhibitory effects of Yoda1 in both mouse and rat CFs. These results provide novel insights into the pharmacological modulation of TGFβ-induced cardiac fibroblast activation and highlight promising therapeutic targets for the treatment of fibrosis-related cardiac pathologies. Full article

This study presents a sustainable approach for synthesizing high-performance activated carbon from Spirulina Alga through hydrothermal carbonization followed by chemical activation using potassium hydroxide. The resulting activated carbon exhibited a high Brunauer–Emmett–Teller (BET) surface area of 1747 m²/g and a total pore volume of 1.147 cm³/g, with micropore volume accounting for 0.4 cm³/g. Characterization using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS), and gas adsorption analyses confirmed the presence of hierarchical micro- and mesoporosity as well as favorable surface functional groups. The synthesized carbon was used to fabricate electrodes for membrane capacitive deionization (MCDI) along with cation and anion-selective membranes, which were then tested with saline water (500–5000 ppm) and synthetic hard water (898 ppm of total salts). The salt adsorption capacity (SAC) reached 25 (batch) to 40 (continuous) mg/g, while rapid adsorption rates with average salt adsorption rates (ASARs) values exceeding 10 (batch) to 30 (continuous) mg·g⁻¹·min⁻¹ during early stages were obtained. Batch MCDI experiments demonstrated a higher SAC compared to continuous operation, with non-monotonic trends in SAC observed as a function of feed concentration. Ion adsorption kinetics were influenced by ion valency, membrane selectivity, and pore structure. The specific energy consumption (SEC) was calculated as 8–21 kJ/mol for batch and 0.1–0.5 kJ/mol for continuous process. These performance metrics are on par with or surpass those reported in the recent literature for similar single-electrode CDI configurations. The results demonstrate the viability of using Alga-derived carbon as an efficient and eco-friendly electrode material for water desalination technologies. Full article