Effect of ionic solutes on the hydrogen bond network dynamics of water: power spectral analysis of aqueous NaCl solutions

To understand the modifications of the hydrogen bond network of water by ionic solutes, power spectra as well as static distributions of the potential energies of tagged solvent molecules and solute ions have been computed from molecular dynamics simulations of aqueous NaCl solutions. The key power spectral features of interest are the presence of high-frequency peaks due to localized vibrational modes, the existence of a multiple time scale or 1/falpha frequency regime characteristic of networked liquids, and the frequency of crossover from 1/falpha type behavior to white noise. Hydrophilic solutes, such as the sodium cation and the chloride anion, are shown to mirror the multiple time scale behavior of the hydrogen bond network fluctuations, unlike hydrophobic solutes which display essentially white noise spectra. While the power spectra associated with tagged H2O molecules are not very sensitive to concentration in the intermediate frequency 1/falpha regime, the crossover to white noise is shifted to lower frequencies on going from pure solvent to aqueous alkali halide solutions. This suggests that new and relatively slow time scales enter the picture, possibly associated with processes such as migration of water molecules from the hydration shell to the bulk or conversion of contact ion pairs into solvent-separated ion pairs which translate into variations in equilibrium transport properties of salt solutions with concentration. For anions, cations, and solvent molecules, the trends in the alpha exponents of the multiple time scale region and the self-diffusivities are found to be strongly correlated.     

Synthesis and characterization of zinc benzoate complexes through combined solid and solution phase reactions

A combined solid and solution phase methodology for the synthesis of a series of mononuclear and polynuclear zinc benzoate complexes is described. The substituent on the aromatic ring and the effect of solvent on deciding the composition of the complexes is presented. From the 4-substituted benzoic acids 4-methylbenzoic acid (ptolH), 4-nitrobenzoic acid (pnitrobenH) and 4-chlorobenzoic acid (pchlorbenH), the mononuclear complexes [Zn(ptol)₂(H₂O)₂], [Zn(pnitroben)₂(H₂O)(DMSO)₂] and [Zn(pchlorben)₂py)₂] (where DMSO = dimethylsulfoxide, py = pyridine) have been synthesized and structurally characterised. Zinc complexes from the reaction of zinc sulfate heptahydrate with 3-methylbenzoic acid (mtolH) and 2-methylbenzoic acid (otolH), the dinuclear complexes [Zn₂(μ²-mtol)₄(py)₂], [Zn₂(μ²-otol)₄(py)₂], pentanuclear complex [Zn₅(μ²-mtol)₆(mtol)₂(μ³-OH)₂ (py)₂] and tetranuclear complex [Zn₄(μ²-otol)₆(μ⁴-O) (DMSO)₂], have been prepared by varying the reaction conditions and the complexes have been structurally characterized.     

The Shapley value as the maximizer of expected Nash welfare

We provide an alternative interpretation of the Shapley value in TU games as the unique maximizer of expected Nash welfare.     

γ-Resorcyclic Acid-Based AIEgens for Illuminating Endoplasmic Reticulum**

Endoplasmic reticulum (ER) has emerged as one of the interesting sub-cellular organelles due to its role in myriads of biological phenomena. Subsequently, visualization of the structure-function and dynamics of ER remained a major challenge to understand its involvement in different diseased states including cancer. To illuminate the ER, herein we have designed and synthesized γ-resorcyclic acid-based small molecules, which showed remarkable aggregation-induced emission (AIE) property in water. This AIE property was originated from the dual intramolecular H-bonding leading to the self-assembled 2D aggregation confirmed by pH- and temperature-dependent fluorescence quenching studies as well as scanning electron microscopy. These small molecules illuminated the sub-cellular ER in HeLa cervical cancer cells as well as non-cancerous RPE-1 human retinal epithelial cells within 1 h. These novel small molecules have the potential to light up ER chemical biology in diseased states.     

Uncovering giant nanowheels for magnesium ion–based batteries

The giant wheel-shaped Na₁₅{[Mo₁₅₄O₄₆₂H₁₄(H₂O)₇₀]_0.5[Mo₁₅₂O₄₅₇H₁₄(H₂O)₆₈]_0.5}·ca. 400 H₂O (Mo₁₅₄) is one of the fascinating clusters with the open host framework, which is designed by simple metal-oxygen fragment–linked coordination modes. The generation of structural vacancies (here referred to as defects), the substitution of ligands, and incorporation of heterometallic centers in Mo₁₅₄ could offer several attractive possibilities to achieve good electrochemical performance such as high specific capacity and stability in multivalent batteries. Herein, we have introduced electronically rich giant nanowheel Mo₁₅₄ as a potential cathode material in magnesium-rechargeable batteries (MRBs). The experimental evidence indicates that the Mo₁₅₄ wheels offer a reversible capacity of ～150 mAh g^?1 at 50 mA g^?1 in MRBs, which was retained to about 55 mAh g^?1 after a long cycling life (>500 cycles). Typically, the divalent alkali metals (Mg²⁺) suffer from diffusion and insertion reactions in host materials; however, the stable and high rate performance against cycling with good Coulombic efficiency was achieved for Mo₁₅₄ electrodes. Thus, the work demonstrates that the complex inorganic clusters are promising cathode materials in multivalent ion batteries.     

Upper Tail Large Deviations of Regular Subgraph Counts in Erdős-Rényi Graphs in the Full Localized Regime

For a -regular connected graph H the problem of determining the upper tail large deviation for the number of copies of H in , an Erdős-Rényi graph on n vertices with edge probability p, has generated significant interest. For and , where is the number of vertices in H, the upper tail large deviation event is believed to occur due to the presence of localized structures. In this regime the large deviation event that the number of copies of H in exceeds its expectation by a constant factor is predicted to hold at a speed , and the rate function is conjectured to be given by the solution of a mean-field variational problem. After a series of developments in recent years, covering progressively broader ranges of p, the upper tail large deviations for cliques of fixed size were proved by Harel, Mousset, and Samotij in the entire localized regime. This paper establishes the conjecture for all connected regular graphs in the whole localized regime. © 2021 Wiley Periodicals LLC.