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The importance of individual nutrients for microbial strain robustness and coexistence in habitats containing different members of the same species is not well understood. To address this for Lactiplantibacillus plantarum in food fermentations, we performed comparative genomics and examined the nutritive requirements and competitive fitness for L. plantarum strains B1.1 and B1.3 isolated from a single sample of teff injera fermentation batter. Compared to B1.1 and other L. plantarum strains, B1.3 has a smaller genome, limited biosynthetic capacities, and large mobilome. Despite these differences, B1.3 was equally competitive with B1.1 in a suspension of teff flour. In commercially sourced, nutrient-replete MRS (cMRS) medium, strain B1.3 reached 3-fold-higher numbers than B1.1 within 2 days of passage. Because B1.3 growth and competitive fitness were poor in mMRS medium (here called mMRS), a modified MRS medium lacking beef extract, we used mMRS to identify nutrients needed for robust B1.3 growth. No improvement was observed when mMRS was supplemented with nucleotides, amino acids, vitamins, or monovalent metals. Remarkably, the addition of divalent metal salts increased the growth rate and cell yields of B1.3 in mMRS. Metal requirements were confirmed by inductively coupled plasma mass spectrometry, showing that total B1.3 intracellular metal concentrations were significantly (up to 2.7-fold) reduced compared to B1.1. Supplemental CaCl2 conferred the greatest effect, resulting in equal growth between B1.1 and B1.3 over five successive passages in mMRS. Moreover, calcium supplementation reversed a B1.3 strain-specific, stationary-phase, flocculation phenotype. These findings show how L. plantarum calcium requirements affect competitive fitness at the strain level. IMPORTANCE Ecological theory states that the struggle for existence is stronger between closely related species. Contrary to this assertion, fermented foods frequently sustain conspecific individuals, in spite of their high levels of phylogenetic relatedness. Therefore, we investigated two isolates of Lactiplantibacillus plantarum, B1.1 and B1.3, randomly selected from a single batch of teff injera batter. These strains spanned the known genomic and phenotypic range of the L. plantarum species, and in laboratory culture medium used for strain screening, B1.3 exhibited poor growth and was outcompeted by the more robust strain B1.1. Nonetheless, B1.1 and B1.3 were equally competitive in teff flour. This result shows how L. plantarum has adapted for coexistence in that environment. The capacity for the single macronutrient calcium to restore B1.3 competitive fitness in laboratory culture medium suggests that L. plantarum intraspecies diversity found in food systems is fine-tuned to nutrient requirements at the strain level.

Recently, lipid nanoparticles (LNPs) have been extensively investigated as non-viral carriers of nucleic acid vaccines due to their high transport efficiency, safety, and straightforward production and scalability. However, the molecular mechanism underlying the interactions between nucleic acids and phospholipid bilayers within LNPs remains elusive. In this study, we employed the all-atom molecular dynamics simulation to investigate the interactions between single-stranded nucleic acids and a phospholipid bilayer. Our findings revealed that hydrophilic bases, specifically G in single-stranded RNA (ssRNA) and single-stranded DNA (ssDNA), displayed a higher propensity to form hydrogen bonds with phospholipid head groups. Notably, ssRNA exhibited stronger binding energy than ssDNA. Furthermore, divalent ions, particularly Ca2+, facilitated the binding of ssRNA to phospholipids due to their higher binding energy and lower dissociation rate from phospholipids. Overall, our study provides valuable insights into the molecular mechanisms underlying nucleic acid-phospholipid interactions, with potential implications for the nucleic acids in biotherapies, particularly in the context of lipid carriers. [ABSTRACT FROM AUTHOR]

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Monocyclic nitrogen-rich 3-(aminomethyl)-4,5-diamine-1,2,4-triazole (1) and fused cyclic 3,7-diamine-6-(aminomethyl)-[1,2,4] triazolo [4,3-b] [1,2,4] triazole (9) were synthesized through the convenient cyclization reaction from the readily available reactant. Their energetic salts with high nitrogen content were proved to be rare examples of divalent monocyclic/fused cyclic cationic salts according to the single crystal analyses. The structure of intermediate B was also identified and verified by its trivalent cation crystal 17.5H2O indirectly. Energetic compounds 2e8 and 10e17 were fully characterized by NMR spectroscopy, infrared spectroscopy, differential scanning calorimetry, elemental analysis. These energetic salts exhibit good thermal stability with decomposition temperatures ranged from 182 °C to 245 °C. The sensitivity of compounds 2, 6, 10 and 14 is similar or superior to that of RDX while the others were much more insensitive to mechanical stimulate. Furthermore, detonation velocity of 10 (8843 m/s) surpass that of RDX (D = 8795 m/s). Considering the high gas production volume (-808 L/kg) of 2, 4, 10 and 12, constant-volume combustion experiments were conduct to evaluate their gas production capacities specifically. These compounds possess much higher maximum gas-production pressures (Pmax: 7.88e10.08 MPa) than the commonly used reagent guanidine nitrate (GN: Pmax = 4.20 MPa), which indicate their strong gas production capacity. [ABSTRACT FROM AUTHOR]

Developing environmental purification techniques for water resources is important for realising a sustainable society. Inorganic ion-exchanger is one of the research themes in technological development, particularly titania nanotubes (TNTs), which have been studied for the removal of cationic heavy metals and radionuclides. Although many studies have reported the adsorption properties of TNTs, the sorption behaviour and state of intercalated cations in the structure are still unclear. In this study, the sorption properties of Co2+, Ni2+, Zn2+, and Sr2+ on TNTs were investigated using the equilibrium isotherms, kinetics and detailed analysis of residues under simple batch conditions. The sorption isotherms of cations on TNTs were fitted with the Langmuir model, and the maximum sorption amount (Qmax) was in the order of Sr2+ (1.13 mmol/g) > Zn2+ (0.99 mmol/g) > Co2+ (0.85 mmol/g) > Ni2+ (0.78 mmol/g). The sorption kinetics data fitted well with pseudo second-order model. The X-ray analysis indicated that the Sr2+ sorption on TNTs resulted from the ion-exchange and formation of carbonate compounds. In contrast, the Co2+, Ni2+, and Zn2+ ions were estimated to be incorporated in an ionic state in the TNT interlayer by ion-exchange with Na+ and H+ via chelation with surface hydroxyl groups on TNTs. These results indicate that the crystallographic properties of TNTs, ionic size, and chemical property of the target cation, and reactivity with carbonic acid are important factors to consider in the design of water purification systems using TNTs.

Achieving the removal of pharmaceuticals and personal care products (PPCPs) while selectively rejecting divalent cations like Ca2⁺ and Mg2⁺ without compromising water productivity and recovery remains a challenge for existing commercial nanofiltration (NF) membranes used in drinking water treatment. These challenges stem from the limited pore size and insufficient negatively charged surface density of conventional NF membrane. This study employed a polydopamine-coated nanofibrous membrane, uniformly embedded with in-situ grown ZnO nanoparticles, as a porous support layer. In the interfacial polymerization process, the fabricated substrate regulated the diffusion of aqueous monomers, thereby optimizing the polyamide layer on composite NF membrane with thinner thickness, stronger surface density, crumple structure and appropriate pore size. This resulting membrane demonstrated excellent PPCP rejection while maintaining high permeability to essential minerals. Under optimal conditions, the designed membrane achieved an impressive water flux at about 21 L m⁻2 h⁻1 bar⁻1 and showed significant selectivity for PPCP and divalent cation, with diclofenac sodium rejection exceeding 90 % and Ca2⁺ rejection of below 20 %. The incorporation of ZnO nanoparticles enlarged the active filtration surface and created additional water pathways, resulting in a water permeation rate that was double that of a pristine NF membrane, without compromising PPCP/divalent cation selectivity. This work provides valuable insights and important correlations for developing NF membranes aimed at enhancing water production while preserving selectivity for PPCP/divalent cation. [Display omitted] • Uniformly embedded ZnO nanoparticles induce a crumpled PA structure. • PDA incorporation enhances the bonding interface between PA layer and nanofibers. • The hydrophilic integration of PDA and ZnO/PVDF nanofibers boosts permeability. • The developed NF membrane exhibits high selectivity for PPCP and divalent cation. [ABSTRACT FROM AUTHOR]

Jurkat, an immortalized cell line derived from human leukemic T lymphocytes, has been employed as an excellent surrogate model of human primary T-cells for the advancement of T-cell biology and their applications in medicine. However, presumably due to its T-cell origin, Jurkat cells are very difficult to transfect. Thus, for the genetic modification of Jurkat cells, expensive and time-consuming viral vectors are normally required. Despite many previous efforts, non-viral vectors have not yet overcome the hurdles of low transfection efficiency and/or high toxicity in transfection of Jurkat cells. Here, we report that a simple addition of calcium ions (Ca2+) into culture media at optimal concentrations can enhance the efficiency of the polyplex-mediated transfection using poly(ethylene imine) (PEI) by up to 12-fold when compared to the polyplex-only control. We show that calcium enhances the association between polyplex and Jurkat, which is at least partially responsible for the increase in transmembrane delivery of polyplex and consequential enhancement in expression of transgene. Other cations, Mg2+ or Na+ did not show similar enhancement. Interestingly, addition of Ca2+ was rather detrimental for the transfection of lipoplex on Jurkat cells. Observation of significant enhancement in the transfection of non-viral vectors with a simple and physiologically relevant reagent like Ca2+ in the engineering of hard-to-transfect cells such as Jurkat warrants further investigation on similar strategies.

Substitution of ionic either anion or cation in a controlled amount into carbonated hydroxyapatite (CHA) structure is one of the efficient and safest ways in enhancing the properties of the materials. However, most of the works studied only focused on the physical and mechanical properties of single ionic substitution. For the first time, the influence of simultaneous ternary substitutions of divalent cations into porous CHA scaffolds on the physicochemical, mechanical, degradative, and in vitro biological properties is investigated in the present study. Three different compositions of porous scaffolds with binary and ternary divalent cations, namely, pure CHA (S11), CoSr CHA (S21), and MgCoSr CHA (S31) were fabricated using a polyurethane (PU) foam replication technique. Despite a small amount of Mg2+, Co2+, and Sr2+ being added, these divalent cations had successfully substituted into the Ca2+ site and remained as single-phase B-type CHA. The produced scaffolds demonstrated open, interconnected, and uniform pores. Interestingly, simultaneous ternary divalent cation substitution into CHA structure had successfully enhanced the compressive strength of the sintered scaffolds and also promoted better cell attachment and activities than the binary doped- and pure CHA scaffolds. It is important to note that choosing the right divalent cation can be the determining factor in tuning the physicochemical, mechanical, and biological properties of CHA scaffolds. [ABSTRACT FROM AUTHOR]

Welan is a branched polymer in the gellan family of polysaccharides. It has good compatibility with divalent calcium ions with a potential use in cementing applications. It is also been utilized as an anti-washout material for underwater concrete placement. Herein, influence of divalent cations Ca2+, Ni2+, Mg2+, Zn2+ and Sr2+ on the gelling and thermal properties of welan have been investigated. The viscoelastic properties reveal strong gelation behavior that are stable up to 80 °C. Among all the five cations Ni2+, Ca2+, Zn2+ and Sr2+ are suited well, compared to Mg2+ ions, to promote favorable interactions among the welan chains leading to stronger junction zones and elastic moduli. The melting peak and enthalpy are dependent on the nature and size of the divalent cation. The outcome is deemed to aid to expand the welan utility in food and non-food applications.

Divalent ion-conducting solid electrolytes with NASICON-type three-dimensional network structures (MxHf1−x)4/(4−2x)Nb(PO4)3 (M = Ni, Mg, Ca, Sr) were successfully developed by introducing M2+ cations into HfNb(PO4)3 solids. The presence of high-valence cations such as Hf4+, Nb5+, and P5+ in the structures effectively reduced the electrostatic interaction between the conducting M2+ cations and the surrounding oxide anions, enabling the M2+ cations to migrate smoothly in the rigid crystal lattice. The relationship between the cation conductivity in NASICON-type solids and the ionic radius of the migrating divalent cation species was also clarified by taking into account the relative sizes of the conduction pathways in the structures.

Surfactant losses by adsorption to rock surfaces make surfactant-based enhanced oil recovery economically less feasible. We investigated polyacrylate (PA) as a sacrificial agent in the reduction of anionic surfactant adsorption with focus on calcite surfaces by using quartz crystal microbalance with dissipation monitoring. It was found that the adsorption of the anionic surfactant alcohol alkoxy sulfate (AAS) followed a Langmuir adsorption isotherm, and the adsorbed amount reached saturation above its critical micellar concentration. Adsorption of PA was a much slower process compared to AAS adsorption. Increasing the calcium ion concentration also increased the amount of AAS adsorbed as well as the mass increase rate of PA adsorption. Experimental results combined with density functional theory calculations indicated that calcium cation bridging was important for anionic surfactant AAS and PA adsorption to calcite surfaces. To effectively reduce the amount of surfactant adsorption, it was needed to preflush with PA, rather than by a simultaneous injection. Preflushing with 30 ppm of PA gave a reduction of AAS adsorption of 30% under high salinity (HS, 31,800 ppm) conditions, compared to 8% reduction under low salinity (LS, 3180 ppm) conditions. In the absence of PA, the amount of adsorbed AAS was reduced by already 50% upon changing from HS to LS conditions. Lower calcium ion concentrations, as under LS conditions, contributed to this observation. On different mineral surfaces, PA reduced the AAS adsorption in the order of alumina > calcite > silica. These results offer important insights into mitigating surfactant adsorption using PA polyelectrolyte as sacrificial agent and contribute to improved flooding strategies with reduced surfactant loss. [ABSTRACT FROM AUTHOR]

Key points: An UHPLC method to measure picomole amounts of magnesium has been developed.The method is sensitive, specific, accurate and reproducible.The method is suitable for quantifying magnesium transport across intact epithelia. Magnesium is involved in many biological processes. Extracellular magnesium homeostasis mainly depends on the renal handling of magnesium, the study of which requires measurement of low concentrations of magnesium in renal tubular fluid. We developed an ultra‐high‐performance liquid chromatography method to measure millimolar concentrations of magnesium in nanolitre samples. Within‐assay and between‐assay coefficients of variation were lower than 5% and 6.6%, respectively. Measurement of magnesium concentration was linear (r2 = 0.9998) over the range 0–4 mmol/l. Absolute bias ranged from −0.03 to 0.05 mmol/l. The lower limit of quantification was 0.2 mmol/l. Recovery was 97.5–100.3%. No significant interference with calcium, another divalent cation present in the same samples, was detected. The method was successfully applied to quantify transepithelial magnesium transport by medullary and cortical thick ascending limbs during ex vivo microperfusion experiments. In conclusion, ultra‐high‐performance liquid chromatography is suitable for measurement of picomole amounts of magnesium in renal tubular fluid. The method allows detailed studies of transepithelial magnesium transport across native epithelium. Key points: An UHPLC method to measure picomole amounts of magnesium has been developed.The method is sensitive, specific, accurate and reproducible.The method is suitable for quantifying magnesium transport across intact epithelia. [ABSTRACT FROM AUTHOR]

Jurkat, an immortalized cell line derived from human leukemic T lymphocytes, has been employed as an excellent surrogate model of human primary T-cells for the advancement of T-cell biology and their applications in medicine. However, presumably due to its T-cell origin, Jurkat cells are very difficult to transfect. Thus, for the genetic modification of Jurkat cells, expensive and time-consuming viral vectors are normally required. Despite many previous efforts, non-viral vectors have not yet overcome the hurdles of low transfection efficiency and/or high toxicity in transfection of Jurkat cells. Here, we report that a simple addition of calcium ions (Ca2+) into culture media at optimal concentrations can enhance the efficiency of the polyplex-mediated transfection using poly(ethylene imine) (PEI) by up to 12-fold when compared to the polyplex-only control. We show that calcium enhances the association between polyplex and Jurkat, which is at least partially responsible for the increase in transmembrane delivery of polyplex and consequential enhancement in expression of transgene. Other cations, Mg2+ or Na+ did not show similar enhancement. Interestingly, addition of Ca2+ was rather detrimental for the transfection of lipoplex on Jurkat cells. Observation of significant enhancement in the transfection of non-viral vectors with a simple and physiologically relevant reagent like Ca2+ in the engineering of hard-to-transfect cells such as Jurkat warrants further investigation on similar strategies. [ABSTRACT FROM AUTHOR]

Integrases of different retroviruses assemble as functional complexes with varying multimers of the protein. Retroviral integrases require a divalent metal cation to perform one-step transesterification catalysis. Tetrameric prototype foamy virus (PFV) intasomes assembled from purified integrase and viral DNA oligonucleotides were characterized for their activity in the presence of different cations. While most retroviral integrases are inactive in calcium, PFV intasomes appear to be uniquely capable of catalysis in calcium. The PFV intasomes also contrast with other retroviral integrases by displaying an inverse correlation of activity with increasing manganese beginning at relatively low concentrations. The intasomes were found to be significantly more active in the presence of chloride co-ions compared to acetate. While HIV-1 integrase appears to commit to a target DNA within 20 s, PFV intasomes do not commit to target DNA during their reaction lifetime. Together, these data highlight the unique biochemical activities of PFV integrase compared to other retroviral integrases.

Divalent ion-conducting solid electrolytes with NASICON-type three-dimensional network structures (MxHf1−x)4/(4−2x)Nb(PO4)3 (M = Ni, Mg, Ca, Sr) were successfully developed by introducing M2+ cations into HfNb(PO4)3 solids. The presence of high-valence cations such as Hf4+, Nb5+, and P5+ in the structures effectively reduced the electrostatic interaction between the conducting M2+ cations and the surrounding oxide anions, enabling the M2+ cations to migrate smoothly in the rigid crystal lattice. The relationship between the cation conductivity in NASICON-type solids and the ionic radius of the migrating divalent cation species was also clarified by taking into account the relative sizes of the conduction pathways in the structures. [ABSTRACT FROM AUTHOR]

Abstract Quantum-mechanical calculations using density functional theory were employed to calculate the incorporation energies of divalent cations (e.g., Mg2+, Ca2+, Sr2+, and Ba2+) in uranium dioxide (UO 2). Divalent cations are known to incorporate into the uranium dioxide system, albeit the incorporation mechanism remains unclear. In this work, three charge-balancing mechanisms were evaluated to achieve a net neutral system, including the substitution of (1) a divalent cation for a tetravalent uranium atom and oxygen atom; (2) two divalent cations for a tetravalent uranium atom; and (3) a divalent cation for a tetravalent uranium atom and associated oxidation of two additional tetravalent uranium atoms. Multiple incorporation scenarios were considered for each charge-balancing mechanism to determine the lowest energy case. For the energetically favorable incorporation mechanisms, Sr2+ incorporation is favored over Mg2+, Ca2+, and Ba2+ incorporation by 0.11 eV–0.97 eV. The coupled substitution of two divalent cations for one uranium cation is unfavorable. The mechanism where the substitution of a divalent cation for a U4+ atom is accompanied with the oxidation of two U4+ to U5+ (e.g. , ΔE incorp (Sr2+) = −3.63 eV), is the most favorable incorporation mechanism compared to the other mechanisms investigated in this paper. In general, the most favorable case is where the oxidized uranium atoms are located at a first nearest neighbor distance (3.914 Å) from the substituted divalent cation and are minimally separated (U5+-U5+ distance = 3.936 Å). Graphical abstract Image 1 Highlights • Divalent cations incorporate in V U '''' in UO 2 requiring charge balancing mechanisms. • Energetically favorable charge balanced mechanisms include an V O ⋅ ⋅ or U U ⋅ . • Most favorable incorporation mechanism occurs with U U ⋅ . • The change in volume corresponds to the size of atomic radii of dopant. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • SMA polymers SZ300110 and SMA2000 are comparable for protein solubilisation, yield, purity and thermostability. • Sensitivity of SMALPs to Mg2+ is similar for different membrane proteins. • The sensitivity to Mg2+ is independent of the concentration of SMALPs. • SMALPs are even more sensitive to larger divalent cations. Abstract Amphipathic co-polymers such as styrene-maleic acid (SMA) have gained popularity over the last few years due to their ability and ease of use in solubilising and purifying membrane proteins in comparison to conventional methods of extraction such as detergents. SMA2000 is widely used for membrane protein studies and is considered as the optimal polymer for this technique. In this study a side-by-side comparison of SMA2000 with the polymer SZ30010 was carried out as both these polymers have similar styrene:maleic acid ratios and average molecular weights. Ability to solubilise, purify and stabilise membrane proteins was tested using three structurally different membrane proteins. Our results show that both polymers can be used to extract membrane proteins at a comparable efficiency to conventional detergent dodecylmaltoside (DDM). SZ30010 was found to give a similar protein yield and, SMALP disc size as SMA2000, and both polymers offered an increased purity and increased thermostability compared to DDM. Further investigation was conducted to investigate SMALP sensitivity to divalent cations. It was found that the sensitivity is polymer specific and not dependent on the protein encapsulated. Neither is it affected by the concentration of SMALPs. Larger divalent cations such as Co2+ and Zn2+ resulted in an increased sensitivity. [ABSTRACT FROM AUTHOR]

Abstract A simultaneous high rejection of trace organic compounds (TrOCs) and low rejection of divalent cations (Ca2+/Mg2+) would be desirable for nanofiltration (NF) applied for drinking water treatment. The target was however not attainable by using the currently available commercial NF membranes. In this study, 3,5-diaminobenzoic acid (BA) was used as an additional diamine monomer besides piperazine (PIP) to prepare novel thin film composite NF membranes via interfacial polymerization with trimesoyl chloride (TMC). A series of NF membranes were prepared by varying BA to PIP concentration ratios in order to obtain a proper membrane pore size and a sufficiently high negative surface charge density. Membrane characterizations and performance tests showed that the incorporation of BA could increase the pore size, enhance the negative surface charge and change the structural properties of the membrane, which in turn affected the membrane water permeability and separation performance. The optimal membrane prepared with a BA/PIP ratio of 50%:50% exhibited a low rejection of CaCl 2 (25.8%) and MgCl 2 (32.0%) in single salt solutions at 10 mmol/L and a moderate rejection of Ca2+/Mg2+ ions (<60%) in a real tap water, while maintaining a reasonably high water permeability and an effective removal (>80%) for six out of eight selected pharmaceuticals (PhACs). The ATR-FTIR spectra and XPS analysis showed that BA could interfere the polymerization between PIP and TMC in forming the membrane active layer while the cross-linking degree between BA and TMC was relatively low. This implied that the proposed treatment target could also be achieved by using some other acidic diamines with similar functionalities of BA. Graphical abstract fx1 Highlights • 3,5-diaminobenzoic acid (BA) in addition to PIP was used to prepare novel NF membranes. • Addition of BA increased membrane pore size and negative surface charge density. • The optimal membrane exhibited low rejection of Ca2+/Mg2+ and high rejection of TrOCs. • The role of BA in affecting PA layer structure and properties was elucidated. [ABSTRACT FROM AUTHOR]

The bacterial flagellar motor is a reversible rotary molecular nanomachine, which couples ion flux across the cytoplasmic membrane to torque generation. It comprises a rotor and multiple stator complexes, and each stator complex functions as an ion channel and determines the ion specificity of the motor. Although coupling ions for the motor rotation were presumed to be only monovalent cations, such as H+ and Na+, the stator complex MotA1/MotB1 of Paenibacillus sp. TCA20 (MotA1TCA/MotB1TCA) was reported to use divalent cations as coupling ions, such as Ca2+ and Mg2+. In this study, we initially aimed to measure the motor torque generated by MotA1TCA/MotB1TCA under the control of divalent cation motive force; however, we identified that the coupling ion of MotA1TCAMotB1TCA is very likely to be a monovalent ion. We engineered a series of functional chimeric stator proteins between MotB1TCA and Escherichia coli MotB. E. coli ΔmotAB cells expressing MotA1TCA and the chimeric MotB presented significant motility in the absence of divalent cations. Moreover, we confirmed that MotA1TCA/MotB1TCA in Bacillus subtilis ΔmotABΔmotPS cells generates torque without divalent cations. Based on two independent experimental results, we conclude that the MotA1TCA/MotB1TCA complex directly converts the energy released from monovalent cation flux to motor rotation.

Surfactin, which is an anionic bio-surfactant, can be effective for enhanced oil recovery because it decreases interfacial tension between oil and water. However, it forms precipitation by binding with divalent cations. This study examined the countermeasure to prevent surfactin from forming precipitation for applying it to enhanced oil recovery. Alcohols, chelating agents, a cationic surfactant and an ion capturing substance were selected as the candidates for inhibiting surfactin from forming precipitation. Citric acid and trisodium citrate were selected as promising candidates through the measurements of turbidity of the mixture of the candidate, surfactin and calcium ions. Those chemicals also had a function as a co-surfactant for surfactin. However, the permeability of the Berea sandstone core into which the solution containing surfactin and trisodium citrate was injected was decreased significantly, whereas citric acid could be injected into the core without significant permeability reduction. Citric acid was therefore selected as the best inhibitor and subjected to the core flooding experiments. High enhancement of oil recovery of 9.4% (vs. original oil in place (OOIP)) was obtained and pressure drop was not increased during the injection of surfactin and citric acid. Those results suggest that citric acid has a dual role as the binding inhibitor and co-surfactant for surfactin.

Abstract Transglutaminase 2 (TGase2) kinase has emerged as an important regulator of apoptosis as well as chromatin structure and function; however, details about the pathophysiological functions of TGase2 kinase have been limited because of the lack of a suitable activity assay for systematic investigation of TGase2 kinase regulation in a high-throughput manner. Thus, we developed a novel on-chip TGase2 kinase activity assay using a cysteine-modified insulin-like growth factor-binding protein-3-derived peptide (CMI peptide) on an array platform. This peptide array-based activity assay was reproducible, with a detection limit of 2.127 μg/ml. We successfully applied this assay to investigate the effects of thiol-reactive compounds and divalent cations on TGase2 kinase by determining the half maximal inhibitory concentrations (IC 50). Thiol-reactive compounds inhibited TGase2 kinase activity in a concentration-dependent manner, with IC 50 values ranging from 0.125 to 5.550 mM. Divalent metal cations also showed a concentration-dependent inhibition, with IC 50 values ranging from 0.005 to 1.937 mM; however, Ca2+ had no effect on TGase2 kinase activity. Thus, this novel kinase activity assay using the CMI peptide array described here is suitable for systematic investigation of TGase2 kinase regulation and may be useful for investigating the roles of TGase2 kinase in pathogenesis of kinase-mediated diseases. Graphical abstract Image 1 Highlights • We developed a novel on-chip transglutaminase 2 (TGase2) kinase activity assay using a cysteine-modified insulin-like growth factor-binding protein-3-derived peptide on an array platform. • TGase2 kinase activity was determined by selective detection of the phosphorylated CMI peptide using well-type amine arrays. • We successfully used this assay to investigate regulation of TGase2 kinase activity by thiol-reactive compounds and divalent metal ions. • Thus, this novel kinase activity assay using the CMI peptide array is suitable for systematic investigation of TGase2 kinase regulation. • And may be useful for investigating the roles of TGase2 kinase in pathogenesis of kinase-mediated diseases. [ABSTRACT FROM AUTHOR]

Retroviruses have two essential activities: reverse transcription and integration. The viral protein integrase (IN) covalently joins the viral cDNA genome to the host DNA. Prototype foamy virus (PFV) IN has become a model of retroviral intasome structure. However, this retroviral IN has not been well-characterized biochemically. Here we compare PFV IN to previously reported HIV-1 IN activities and discover significant differences. PFV IN is able to utilize the divalent cation calcium during strand transfer while HIV-1 IN is not. HIV-1 IN was shown to completely commit to a target DNA within 1 min, while PFV IN is not fully committed after 60 min. These results suggest that PFV IN is more promiscuous compared to HIV-1 IN in terms of divalent cation and target commitment. [ABSTRACT FROM AUTHOR]

To assess the relationship between metal ion-mediated microstructures and the macro-performance, Cu- and Zn-doped α-Fe 2 O 3 nanoparticles were prepared via a solvothermal method. The morphologies of the as-synthesized nanoparticles were investigated by scanning electron microscopy and transmission electron microscopy. The results revealed that the sizes and morphologies could be regulated by doping with divalent cations. The structures of the as-synthesized nanoparticles were characterized by X-ray diffraction and Raman spectroscopy, indicating that Cu 2+ and Zn 2+ ions had diffused into the lattice of α-Fe 2 O 3 matrix. The magnetization behaviors of these nanoparticles were measured to analyze the effect of doping on α-Fe 2 O 3 . Furthermore, the catalytic activities of Cu- and Zn-doped α-Fe 2 O 3 nanoparticles demonstrated that the high-temperature decomposition temperature of ammonium perchlorate could be lowered by 115 °C and 107 °C, respectively, compared to that of ammonium perchlorate without catalyst. The enhanced catalytic activity could be attributed to the defect structure induced by doping with divalent cations. [ABSTRACT FROM AUTHOR]

Summary: Aquaporin (AQP) channels in the major intrinsic protein (MIP) family are known to facilitate transmembrane water fluxes in prokaryotes and eukaryotes. Some classes of AQPs also conduct ions, glycerol, urea, CO2, nitric oxide, and other small solutes. Ion channel activity has been demonstrated for mammalian AQPs 0, 1, 6, Drosophila Big Brain (BIB), soybean nodulin 26, and rockcress AtPIP2;1. More classes are likely to be discovered. Newly identified blockers are providing essential tools for establishing physiological roles of some of the AQP dual water and ion channels. For example, the arylsulfonamide AqB011 which selectively blocks the central ion pore of mammalian AQP1 has been shown to impair migration of HT29 colon cancer cells. Traditional herbal medicines are sources of selective AQP1 inhibitors that also slow cancer cell migration. The finding that plant AtPIP2;1 expressed in root epidermal cells mediates an ion conductance regulated by calcium and protons provided insight into molecular mechanisms of environmental stress responses. Expression of lens MIP (AQP0) is essential for maintaining the structure, integrity and transparency of the lens, and Drosophila BIB contributes to neurogenic signalling pathways to control the developmental fate of fly neuroblast cells; however, the ion channel roles remain to be defined for MIP and BIB. A broader portfolio of pharmacological agents is needed to investigate diverse AQP ion channel functions in situ. Understanding the dual water and ion channel roles of AQPs could inform the development of novel agents for rational interventions in diverse challenges from agriculture to human health. [ABSTRACT FROM AUTHOR]

Fate and transport of engineered nanoscale titanium dioxide (nTiO 2 ) have received much attention during the past decade. The aggregation and stability of nTiO 2 in water with complicated components, however, have not been fully examined. The objective of this paper is to determine the individual and synergistic effect of cation valence, humic acid, and clay colloids on nTiO 2 stability and aggregation, and elucidate the related mechanisms. We conducted systematic laboratory experiments to determine nTiO 2 stability and aggregation in NaCl and MgCl 2 solutions, both in the absence and presence of humic acid and illite colloids. Results showed that Mg 2+ , in comparison to Na + , could make the zeta potential of nTiO 2 more positive, and shift the point of zero charge of nTiO 2 (pH pzc,TiO2 ) towards higher pH. We also found that nTiO 2 are destabilized by illite colloids at pH < pH pzc,TiO2 through formation of illite-nTiO 2 hetero-aggregates, but are not interfered by illite colloids at higher pH. HA was found to make nTiO 2 stable via electrostatic and steric effects, both in the absence and presence of illite colloids. Calculated interaction energy based on DLVO theory revealed that instability of the nTiO 2 suspensions is mainly caused by primary minima, and that secondary minima normally do not destabilize the suspension, even though they are found to promote aggregation. [ABSTRACT FROM AUTHOR]

Although long thought to simply be a source of synaptic noise, spontaneous, action potential-independent release of neurotransmitter from presynaptic terminals has multiple roles in synaptic function. We explored whether and to what extent the two predominantly proposed mechanisms for explaining spontaneous release, stochastic activation of voltage-gated Ca2+ channels (VGCCs) or activation of Ca2+-sensing receptors (CaSRs) by extracellular Ca2+, played a role in the sensitivity of spontaneous release to the level of extracellular Ca2+ concentration at excitatory synapses at CA1 pyramidal cells of the adult male mouse hippocampus. Blocking VGCCs with Cd2+ had no effect on spontaneous release, ruling out stochastic activation of VGCCs. Although divalent cation agonists of CaSRs, Co2+ and Mg2+, dramatically enhanced miniature excitatory postsynaptic current (mEPSC) frequency, potent positive and negative allosteric modulators of CaSRs had no effect. Moreover, immunoblot analysis of hippocampal lysates failed to detect CaSR expression, ruling out the CaSR. Instead, the increase in mEPSC frequency induced by Co2+ and Mg2+ was mimicked by lowering postsynaptic Ca2+ levels with BAPTA. Together, our results suggest that a reduction in intracellular Ca2+ may trigger a homeostatic-like compensatory response that upregulates spontaneous transmission at excitatory synapses onto CA1 pyramidal cells in the adult hippocampus. NEW & NOTEWORTHY We show that the predominant theories for explaining the regulation of spontaneous, action potential-independent synaptic release do not explain the sensitivity of this type of synaptic transmission to external Ca2+ concentration at excitatory synapses onto hippocampal CA1 pyramidal cells. In addition, our data indicate that intracellular Ca2+ levels in CA1 pyramidal cells regulate spontaneous release, suggesting that excitatory synapses onto CA1 pyramidal cells may express a novel, rapid form of homeostatic plasticity. [ABSTRACT FROM AUTHOR]

Zeolite N is a synthetic zeolite of the EDI framework family from the more than 200 known zeolite types. Previous experimental laboratory and field data show that zeolite N has a high capacity for exchange of ions. Computational modelling and simulation techniques are effective tools that help explain the atomic-scale behaviour of zeolites under different processing conditions and allow comparison with experiment. In this study, the ion exchange behaviour of synthetic zeolite N in an aqueous environment is investigated by molecular dynamics simulations. The exchange mechanism of K+ extra-framework cations with alkaline and alkaline-earth cations NH4+, Li+, Na+, Rb+, Cs+, Mg2+ and Ca2+ is explored in different crystallographic directions inside the zeolite N structure. Moreover, the effect of different framework partial charges on MD simulation results obtained from different DFT calculations are examined. The results show that the diffusion and exchange of cations in zeolite N are affected by shape and size of channels controlling the ion exchange flow as well as the nature of cation, ionic size and charge density.

Prior to 2008, all previously studied conventional bacterial flagellar motors appeared to utilize either H or Na as coupling ions. Membrane-embedded stator complexes support conversion of energy using transmembrane electrochemical ion gradients. The main H-coupled stators, known as MotAB, differ from Na-coupled stators, PomAB of marine bacteria, and MotPS of alkaliphilic Bacillus. However, in 2008, a MotAB-type flagellar motor of alkaliphilic Bacillus clausii KSM-K16 was revealed as an exception with the first dual-function motor. This bacterium was identified as the first bacterium with a single stator-rotor that can utilize both H and Na for ion-coupling at different pH ranges. Subsequently, another exception, a MotPS-type flagellar motor of alkaliphilic Bacillus alcalophilus AV1934, was reported to utilize Na plus K and Rb as coupling ions for flagellar rotation. In addition, the alkaline-tolerant bacterium Paenibacillus sp. TCA20, which can utilize divalent cations such as Ca, Mg, and Sr, was recently isolated from a hot spring in Japan, which contains a high Ca concentration. These findings show that bacterial flagellar motors isolated from unique environments utilize unexpected coupling ions. This suggests that bacteria that grow in different extreme environments adapt to local conditions and evolve their motility machinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dually charged membranes were prepared by loading UiO-66-(NH 2) 2 into polyamide layer. • The amino-rich nanochannels could be regulated by ligand replacement strategy. • Satisfactory rejection for both CaCl 2 and Na 2 SO 4 could achieved with high permeance. • UiO-66-(NH 2) 2 played a crucial role in the enhanced rejection of divalent cations. • Migration energy barrier across UiO-66-(NH 2) 2 was an order of magnitude higher. Traditional polyamide nanofiltration membranes suffer from permeability-selectivity trade-off limitation and unsatisfactory rejection for divalent cations. Herein, a novel dually charged membrane was constructed by incorporating positively charged UiO-66-(NH 2) 2 into the negatively charged polyamide layer. Thanks to the customizable nanochannels of metal-organic frameworks, the amino-rich nanochannels of UiO-66-(NH 2) 2 could be fabricated through a ligand replacement strategy. UiO-66-(NH 2) 2 played a crucial role in the enhanced rejection of divalent cations, meanwhile negatively charged polyamide surface guaranteed the efficient Na 2 SO 4 rejection. Satisfactory rejections of CaCl 2 (96.07 %) and Na 2 SO 4 (90.62 %) were achieved simultaneously by optimal TFN-D5. Meanwhile, TFN-D5 owned the greatly-improved water permeance of 19.44 LMH/bar, which was about 1.5 times better than that of the TFC-control. Calculations based on density functional theory further confirmed UiO-66-(NH 2) 2 rejected Ca2+ efficiently since the migration energy barrier across UiO-66-(NH 2) 2 was an order of magnitude higher than that of UiO-66-NH 2 and UiO-66. Moreover, the desirable rejections were beyond 94 % towards many divalent cation salts including MgCl 2 , NiCl 2 , PbCl 2 , MnCl 2 , CdCl 2 and ZnCl 2. Thus, this work provided an efficient way to realize the synergistic removal of both divalent cations and anions. [ABSTRACT FROM AUTHOR]