Addition Of Sodium Ions Research Articles

TPE-embedded butterfly bis-crown ether with controllable conformation and supramolecular chiroptical property

Understanding how subtle structural differences between macrocyclic conformational isomers impact their properties and separation has garnered increasing attention in the field of supramolecular synthetic chemistry. In this work, a series of tetraphenylene (TPE)-embedded butterfly bis-crown ether macrocycles (BCE[n], n = 4–7), comprising two crown ether side rings and a TPE core, are synthesized through intramolecular McMurry coupling. Unexpectedly, the presence of flexible oligoethylene chains with varying lengths are found to influence molecular conformation via multiple intramolecular interactions, resulting in the formation of two stabilized conformers with specific semi-rigid symmetric/asymmetric structures (sym-BCE[n] and asym-BCE[n], n = 5, 6). Moreover, it is noteworthy that neither symmetric nor asymmetric conformers are present in the more rigid BCE[4] or the more flexible BCE[7]. Interestingly, these conformers display distinct fluorescence properties and host-guest binding abilities, and only sym-BCE[5] can serve as a host for chiral polymer binding, resulting in the formation of chiral supramolecular assemblies through host-guest interaction induced chirality. Moreover, both circular dichroism and circularly polarized luminescence signals of the obtained assemblies can be switched off by the addition of sodium ion, suggesting potential applications in the field of dynamic chiral materials.

Effect of Sodium Ion Addition on Copper Selenide/Chitosan Film Towards Electrical and Shielding Efficiency Improvement

The operation of electronic devices can be disrupted by unwanted electromagnetic signals, affecting its operation. Deploying electromagnetic shielding is a viable solution to minimize the impact of electromagnetic interference (EMI). The conventional methods of electromagnetic shielding use metal gaskets to safeguard sensitive electronic components, which have drawbacks of cost and weight. Hence, electromagnetic shielding polymer can be an alternative to replace metal gaskets. This work investigates the effect of sodium ion (Na) addition to copper selenide/chitosan (CuSe/Ch) film for electromagnetic shielding applications. The shielding polymers were produced using solution casting methods, while the CuSe was synthesized using the chemical coprecipitation method. Impedance spectroscopy and two port waveguide methods were used to characterize the prepared polymer's electrical properties and shielding efficiency. The results indicate that Na incorporation in the CuSe/Ch film resulted in a 47 % decrease in bulk resistivity and increased DC conductivity from 6.07 × 10-6 S/cm to 3.69 × 10˗5 S/cm. The AC conductivity of films containing Na demonstrates a similar level of conductivity at lower frequencies, followed by a sharp increase at higher frequencies, indicating a more substantial influence of Na at higher frequencies. Higher absorption shielding efficiency (SEA) and lower reflection shielding efficiency (SER) were achieved by introducing Na into the CuSe chitosan film. The Na/CuSe/Ch film shows higher total shielding efficiency at an average of 20 dB, equivalent to 99 % of the EM power shield.

Metal ion cofactors modulate integral enzyme activity by varying differential membrane curvature stress.

Metal ions are well-known cofactors of protein function and stability. In the case of the integral membrane enzyme OmpLA (outer membrane phospholipase A) the active dimer is stabilized by calcium ions. We studied the lipid hydrolysis kinetics of OmpLA in charge-neutral and charged membranes with symmetric or asymmetric transbilayer lipid distributions. In charge-neutral membranes, OmpLA was more active in symmetric bilayers due to the lower differential curvature stress between membrane leaflets. Strikingly, this behavior was completely reversed in charged bilayers. Measurements revealed intrinsic molecular shape changes in the charged lipids upon addition of calcium. This effectively reduces the differential curvature stress in charged asymmetric membranes leading to increased protein activity. This conclusion is further supported by similar effects observed upon the addition of sodium ions, which also alter the shape of the lipids, but do not specifically interact with the protein. Additional lipid-protein interactions likely contribute to this phenomenon. Our findings demonstrate that ion cofactors not only interact directly with membrane proteins but also modulate protein activity indirectly by altering the effective molecular shape of charged lipid species.

Unveiling the gemcitabine drug complexation with cucurbit[n]urils (n = 6–8): a computational analysis

In this work, we have investigated the complex formation capability of gemcitabine drug with host cucurbit[n]urils, Q[n] (n = 6, 7, and 8) using density functional theory (DFT). The DFT studies demonstrate that the most stable configuration is a fully encapsulated complex. In the encapsulated gemcitabine@Q[6] and gemcitabine@Q[7] complexes, the gemcitabine amino -NH2 and the alcoholic groups bond with the carbonyl units of Q[n]. The addition of sodium ions leads to the partial exclusion of the gemcitabine molecule and the sodium atoms lie close to the carbonyl portal of Q[7]. Thermodynamic parameters computed for the complexation process exhibit high negative Gibbs free energy change, implying that the encapsulation process is spontaneous and is an enthalpy-driven process. Frontier molecular orbitals are located mainly on the gemcitabine uracil ring, before and after encapsulation, indicating that the encapsulation occurs by pure physical adsorption. Quantitative molecular electrostatic potentials demonstrate a shift in electron density during the complex formation and are more pronounced in gemcitabine@Q[7]. Atoms-in-molecule (AIM) topological analysis illustrate that these complexes are stabilized by various non-covalent interactions including hydrogen bonding (HBs) and C···F interactions. The reduced density gradient (RDG) graph exhibits the presence of strong HBs and weak van der Waals interactions and the presence of steric repulsion. The isosurface non-covalent interactions (NCI) diagram shows predominant steric interaction in the gemcitabine@Q[6] complex. The NCI isosurface for gemcitabine encapsulated complexes with Q[7] and Q[8] host displays that the green patches are uniformly distributed in all directions. Finally, EDA results demonstrate Pauling’s repulsive energy is predominant in gemcitabine@Q[6] complex, while the orbital and dispersion energies stabilize the gemcitabine@Q[7] complex.

Photoluminescence study of reddish orange emitting Eu3+ activated LaPO4 Nanoparticles via hydrothermal method

Lanthanum phosphate (LaPO4) belongs to the family of rare earth phosphates characterized as a fluorescence material. Europium ion is known for its orange –red fluorescence. In order to include orange –red fluorescence for pure white light generation we are doping LaPO4 with Eu3+. The crystalline planes are identified from the XRD pattern show that the particles have monoclinic structure with pure LaPO4. The addition of sodium ions to the LaPO4: Eu3+ sample it is found that the luminescence property gets increased. It is also found that reversal of the emission spectrum intensity takes place for the sodium doped sample which indicates that Eu3+ ions are located in a highly symmetric environment.

Improved thermoluminescence response of terbium doped magnesium orthosilicate by co-doping with sodium ions

Magnesium orthosilicate doped with terbium (Mg2SiO4:Tb) has been reported as the most efficient thermoluminescence dosimeter material. The results of this paper indicate that further sensitivity improvements of this material are achievable by co-doping with Na+ ions. The main peak of the thermoluminescence is enhanced three times with the addition of sodium ions. The optimized concentration of Na+ is 11 mol% which is much higher than the expectation for the role of a trace element dopant. The results suggest that the addition of sodium ions may not only remove the charge unbalance problem and enhance the emission intensity, but also play an important role in defining and stabilizing the defect structures.

Efficient Mass Spectrometric Dissection of Glycans via Gold Nanoparticle-Assisted in-Source Cation Adduction Dissociation.

Structural identification of glycans is important but remains challenging, for which tandem mass spectrometry has evolved as an indispensable tool. However, it requires additional complex hardware and extra time for ion extraction. Herein, we report a straightforward approach called gold nanoparticles (AuNPs)-assisted in-source cation adduction dissociation (isCAD) for efficient mass spectrometry (MS) dissection of glycans. Although AuNPs have been employed as an inorganic matrix for MALDI MS, this is the first report of AuNP-induced fragmentation. In this approach, AuNPs were employed as an energy absorber for laser ionization as well as a trigger for fragmentation, while residual or deliberately added sodium ions acted as a cationizing agent. The addition of sodium ions induced intensive fragmentation, but the addition of protons suppressed the fragmentation, allowing for facile tuning of the degree of fragmentation. In addition, it was found that larger oligosaccharides and glycans were much easier to fragment as compared with their smaller counterparts, and the use of high-concentration AuNPs effectively suppressed the degree of fragmentation and thereby provided abundant molecular ions. Without any extra hardware and ion extraction, this approach provides a straightforward, cost-efficient and tunable fragmentation for efficient MS dissection of saccharides, including monosaccharides, oligosaccharides, and glycans. Thus, it opens new access to efficient MS dissection of glycans.

Experimental study of the effects of soil pH and ionic species on the electro-osmotic consolidation of kaolin.

The application of an electric field on soil mass induces both electro-osmotic flow and electro-migration, which has been used for the dewatering of soft soils and remediation of contaminated soils. The physical and chemical properties of soft soils are influenced by the soil pH as well as ionic species and their concentrations, which subsequently influence the dewatering and remediation efficiency. In the present study, one-dimensional column experiments were conducted to investigate the influence of soil pH and ionic species on the electro-osmotic consolidation process of kaolin. The initial drainage rate, total volume of the discharged water and the voltage loss near the anode increased with the increase in the initial soil pH. After electro-osmosis, the water content was lower near the anode and higher near the cathode for sample with higher initial soil pH. The addition of copper ions reduced the dewatering efficiency while the addition of sodium ions increased the drainage rate and total volume of discharged water. Moreover, the precipitation of copper ions increased the voltage loss near the cathode.

Enhanced cycleability and dendrite-free lithium deposition by addition of sodium ion in electrolyte for lithium metal batteries

The effects of adding sodium (Na) ion into lithium (Li) ion containing organic electrolyte on the cycle behaviors of Li deposition–stripping on Li22Sn5 substrate are investigated. The functions and mechanism of Na+ addition to the electrolyte are evaluated through scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, element mapping, energy dispersive spectrometer, electrochemical impedance spectroscopy, and cyclic voltammetry analyses. The results show that Li–Na co–deposition and co–stripping processes occur during cycles. Utilizing Li–Na co–deposition/stripping reactions to replace the reactions of single Li in organic electrolyte is an effective way to inhibit Li dendrite growth and improve the cycling performance of Li anode in Li metal batteries.

NaCl-Dependent Ordering and Dynamic Mechanical Response in Nanoconfined Water.

Understanding the dynamics of water under nanoscale confinement is important for biology, geology, tribology, and nanotechnology. In many naturally occurring situations, ions are present in water at various concentrations. Here we report on how the addition of sodium ions alters the squeeze-out behavior of water nanoconfined between a mica surface and silicon oxide tip. We find that Na+ ions enhance molecular ordering and lead to longer mechanical relaxation times. We also observed a critical ion concentration, above which the confined water switches from a viscous to an elastic (solid-like) response at very slow, quasistatic compression speeds.

Top Seeded Solution Growth, Structural and Vibrational Analyses of K1−x Na x Gd(WO4)2 (0.0 ≤ x ≤ 0.2) Single Crystals

Laser host single crystals of K1−xNaxGd(WO4)2 (0.0 ≤ x ≤ 0.2) have been grown by high temperature top seeded solution with low viscus K2WO4 as flux. The powder x-ray diffraction pattern of the synthesised charge confirmed the crystalline quality and possible incorporation of sodium in the KGd(WO4)2 (KGW) matrix. Estimated lattice parameters of the grown crystals revealed that there were no anomalous structural changes due to the incorporation of sodium in the KGW matrix. The change in structural phase transition and its thermal stability due to addition of sodium ions have been studied through differential thermal analysis. The homogeneous distribution of sodium and other metal ions in the matrix were qualitatively studied from energy-dispersive x-ray spectroscopy measurements. The Raman and Fourier transform infrared spectroscopy analyses have shown the influence of vibrational changes due to the incorporation of sodium ions in KGW. The optical absorption studies have shown the broad absorption band in the near-ultra violet region corresponding to the W6+ to O2− charge transfer band. These results suggest that incorporation of sodium in a KGW matrix appear to have modulated the physical properties of the grown crystals.

Influence of sodium addition on taurine adduct formation generated in acetic acid/acetate salt buffer applied in LC–MS/MS analysis

To investigate the influence of sodium ion addition on analyte adduct formation generated in acetic acid/acetate salt buffer appropriate infusion experiments of a 1 and 10 μg/mL taurine solution prepared both in methanol with a 1 mmol L−1/10 mmol L−1 CH3COONH4/CH3COOH buffer and with a 1 mmol L−1/10 mmol L−1 CH3COONa/CH3COOH buffer were performed. The results achieved revealed that sodium ion concentration has a relevant influence on taurine adduct formation in the negative electrospray ionisation mode since depending on conditions applied different analyte adducts are favored. Sodium ions which originate from the glassware/chemicals make an effective detection of taurine dimer adducts possible, but taurine adducts with sodium acetate are not formed effectively. On the other side sodium ion addition enables an effective taurine adduct formation with sodium acetate, but taurine dimer based adducts can be observed only at higher analyte concentrations.

Limit of stokesian settling concentration characterizes sludge settling velocity

Flocculent settling (stokesian) is predominant within ideally operating clarifiers, and the shift to ‘slower’ hindered settling (non-stokesian) causes both failure and poor effluent quality. Therefore, a new metric for settling characteristics was developed and classified as Limit of Stokesian Settling (LOSS). The technique consisted of determining the total suspended solids (TSS) concentration at which mixed liquor settling characteristics transition from stokesian to non-stokesian settling. An image analytical technique was developed with the aid of MATLAB® to identify this transition. The MATLAB tool analyzed RGB images from video, and identified the presence of an interface by a dramatic shift in the Red indices. LOSS data for Secondary activated-sludge systems were analyzed for a period of 60 days at the Blue Plains Advanced Wastewater Treatment Plant. LOSS for secondary systems typically occurred between 600 and 700 mg TSS/L but reached 1000 mg TSS/L for a good settling secondary sludge and 500 mg TSS/L for a poor settling secondary sludge, settling quality was based on hindered settling rates. In addition, LOSS was collected for granular systems seeded with cyclone underflow from Strass Wastewater Treatment Plant, it was observed that LOSS was higher for granular systems ranging from 1600 to 5500 mg TSS/L for low and high levels of granulation, respectively. The monovalent to divalent cation ratio (M/D) was increased with the addition of sodium ions to deteriorate settling properties. Samples adjusted with higher M/D consistently had 100 mg TSS/L (15%) decrease in LOSS from the control. LOSS numbers collected experimentally were validated with the Takacs et al. (1991) settling model. When compared to flux curves with small changes in sludge matrix, LOSS was proven to be faster at characterizing hindered settling velocity and was less erratic. This is the first time a measurement method has been developed to characterize the transition from stokesian to non-stokesian settling. Additionally, this is the first step in developing new metrics to predict clarifier failure, and determine effluent quality through the development of flocculent settling metrics.

Titania-functionalized graphene oxide for an efficient adsorptive removal of phosphate ions

Titania-functionalized graphene oxide (T-F GO), synthesized by a sol–gel process, was used as a highly efficient material to remove phosphate ions from the simulated wastewater. X-ray diffraction spectra, Fourier transform infrared spectra and scanning electron micrographs of T-F GO confirmed that titania particles were successfully grown on graphene oxide (GO) surface. The phosphate ion adsorption capacities of GO, titania and T-F GO as a function of the contact time and the pH were investigated by a UV–visible spectrophotometer. Results showed that T-F GO could absorb phosphate ions better than titania and GO could. This indicated the synergistic effect between titania and GO in the phosphate ion adsorption. The pH increment lowered the absorption capacities due to increasing the repulsion between phosphate anions and the charges on the T-F GO surface, whereas the addition of sodium ions increased the adsorption capacities. Also, phosphate ions were absorbed by specific sites of T-F GO and formed a monolayer on its surface. Finally, the maximum adsorption capacity of T-F GO was 33.11 mg/g at pH 6, much higher than those of GO and titania. Therefore, T-F GO could be a promising material to remove phosphate ions from wastewater in the future.

Chromatin compaction under mixed salt conditions: opposite effects of sodium and potassium ions on nucleosome array folding.

It is well known that chromatin structure is highly sensitive to the ionic environment. However, the combined effects of a physiologically relevant mixed ionic environment of K+, Mg2+ and Na+, which are the main cations of the cell cytoplasm, has not been systematically investigated. We studied folding and self-association (aggregation) of recombinant 12-mer nucleosome arrays with 177 bp DNA repeat length in solutions of mixtures of K+ and Mg2+ or Na+ and Mg2+. In the presence of Mg2+, the addition of sodium ions promotes folding of array into 30-nm fibres, whereas in mixtures of K+ and Mg2+, potassium ions abrogate folding. We found that self-association of nucleosome arrays in mixed salt solutions is synergistically promoted by Mg2+ and monovalent ions, with sodium being slightly more efficient than potassium in amplifying the self-association. The results highlight the importance of a mixed ionic environment for the compaction of chromatin under physiological conditions and demonstrate the complicated nature of the various factors that determine and regulate chromatin compaction in vivo.

Spontaneous helical folding of bis(Ni-salphen) complexes in solution and in the solid state: spectroscopic tracking of the unfolding process induced by Na+ ions

Four kinds of bis(Ni-salphen) complexes containing a 2-methylenepropane-1,3-diyl linker were synthesised and characterised. Crystal structural analysis revealed that one of the complexes folded into a helical structure, in which two Ni atoms were at a distance of 3.2 Å from each other. NMR measurements suggested that a similar folded state was maintained in solution, and the energy barrier for refolding through an unfolded state was 47 kJ mol(-1). The folded complex also exhibited a significant bathochromic shift in its UV-Vis absorption structure. Addition of sodium ions caused unfolding of the complexes, and the corresponding spectra were attributed to a virtually isolated state. DFT calculations reproduced well the energy barrier and folding-induced bathochromic shift.

The competition transport of sodium ions and protons in the cytoplasmic access channel of the Na+,K+-ATPase

The changes in capacitance and conductance of lipid bilayer membranes have been studied with adsorbed membrane fragments containing Na+,K+-ATPase. These changes have been initiated by fast release of protons from a bound form (“caged H+”) induced by an UV flash. The changes of the capacitance in the presence of Na+,K+-ATPase were affected by the frequency of the applied voltage, pH and the concentration of sodium ions. Addition of sodium ions altered the changes of capacitance caused by a pH jump in the medium due to caged H+ photolysis, and the magnitude and sign of this effect depended on the initial pH. These results are explained by competitive binding of sodium ions and protons to the ion-binding sites of the Na+,K+-ATPase at its cytoplasmic side. The pH at which the sign of the sodium ion effect changed allows the evaluation of the pK of the proton binding site, which is about 7.6.

Effect of heavy-metal ions on dynamic characteristics of collagen molecules in solutions

Effect of heavy (Pb2+, Cs+) and light (Na+) metal ions on the molecular-dynamic characteristics of type-I collagen in aqueous solution was studied using the method of dynamic light scattering. It was found that the dependence of the translational diffusion coefficient Dt from pH solutions has a nonlinear form with a pronounced extremum close to the isoelectric point of the protein (pI 6.0). For pure aqueous solution of protein there is a maximum of Dt in isoelectric point. For collagen solutions with the addition of heavy-metal salts the minimum of Dt was observed near the isoelectric point. This fenomenon is connected with the formation of protein nanoclusters in solution. With concentration of heavy metal ions increasing translational diffusion coefficient Dt decreases, which shows on increasing of aggregation effect. The addition of sodium ions in aqueous solution of collagen containing heavy metal ions sharp decreasing of the translational diffusion of molecules is observed. That can be connected with the rise of scattering particles masses.

Guest Inclusion in Cucurbiturils Studied by ESR and DFT: The Case of Nitroxide Radicals and Spin Adducts of DMPO and MNP

We present an ESR and DFT study of the interaction of cucurbiturils CB[6], CB[7], and CB[8] with di-tert-butyl nitroxide ((CH(3))(3)C)(2)NO (DTBN) and with spin adducts of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2-methyl-2-nitrosopropane (MNP). The primary goal was to understand the structural parameters that determine the inclusion mechanism in the CBs using DTBN, a nitroxide with great sensitivity to the local environment. In addition, we focused on the interactions with CBs of the spin adducts DMPO/OH and MNP/CH(2)COOH generated in aqueous CH(3)COOH. A range of interactions between DTBN and CBs was identified for pH 3.2, 7, and 10. No complexation of DTBN with CB[6] was deduced in this pH range. The interaction between DTBN and CB[7] is evident at all pH values: "in" and "out" nitroxides, with (14)N hyperfine splitting, a(N), values of 15.5 and 17.1 G, respectively, were detected by ESR. Interaction of DTBN with CB[8] was also detected for all pH values, and the only species had a(N) = 16.4 G, a result that can be rationalized by an "in" nitroxide in a less hydrophobic environment compared to CB[7]. Computational studies indicated that the DTBN complex with CB[7] is thermodynamically favored compared to that in CB[8]; the orientations of the NO group are parallel to the CB[7] plane and perpendicular to the CB[8] plane (pointing toward the annulus). Addition of sodium ions led to the ESR detection of a three-component complex between CB[7], DTBN, and the cations; the ternary complex was not detected for CB[8]. The DMPO/OH spin adduct was stabilized in the presence of CB[7], but the effect on a(N) was negligible, indicating that the N-O group is located outside the CB cavity. Computational studies indicated more favorable energetics of complexation for DMPO/OH in CB[7] compared to DTBN. An increase of a(N) was detected in the presence of CB[7] for the MNP/CH(2)COOH adduct generated in CH(3)COOH, a result that was assigned to the generation of the three-component radical between the spin adduct, sodium cations, and CB[7].

Synthesis and extension/contraction motion of spiroborate-based double-stranded helicates consisting of substituted oligophenol strands

A new class of ortho- and meta-substituted tetraphenols at the terminal phenyl residues with a biphenylene unit in the middle were synthesized and the effect of the substitution position on the spiroborate-based double-stranded helicate formation with sodium borohydride was investigated. The ortho-substitution considerably hampered the spiroborate formation between the terminal biphenol units and the boron atoms, whereas the meta-substituted oligomers formed a double-stranded helicate bridged by spiroborate groups accommodating a sodium cation in the center, which displayed an extension and contraction motion triggered by the removal and addition of sodium ions in solution.