Osmolytic Co-Solute Perturbing the Surface Enhancement of Halide Ions

We have investigated the variation in the surface binding free energy with the choice of halide ion, F^–, Cl^–, Br^–, and I^–, in water–glycerol binary mixtures with varying glycerol concentrations using umbrella sampling with a polarizable force field. We have found that halide surface adsorption is significantly perturbed by glycerol. At no or low glycerol concentration, the surface preference follows the Hofmeister series (I^– > Br^– > Cl^– > F^–). However, at the highest concentration, Br^– is preferentially stabilized. Decomposition of the free energy indicates that the halide surface adsorption is dominated by enthalpy and, specifically, by the solvent–solvent polarization interaction. The differences in this interaction between the chaotropic halides are reduced by glycerol addition, which is in line with a recent measurement of the solvent excess enthalpy for the same systems studied here. Moreover, our calculations indicate that the effect of an osmolyte (glycerol) on surface ion concentrations parallels the known effect of osmolytes on protein folding

Anion Effects in the Scattering of CO₂ from the Room-Temperature Ionic Liquids [bmim][BF4] and [bmim][Tf2N]: Insights from Quantum Mechanics/Molecular Mechanics Trajectories

Quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations have been carried out to model the scattering of hyperthermal (15 kcal/mol) CO₂ on the surfaces of two common imidazolium based room-temperature ionic liquids (RTILs) [bmim]­[BF4] and [bmim]­[Tf2N]. Good agreement was achieved in comparison with experiment. The [bmim]­[BF4] surface is found to be more absorptive of CO₂ than [bmim]­[Tf2N], which leads to greater loss in translational energy and less rotational excitation of CO₂’s that scatter from [bmim]­[BF4]. These differences are found to result from a interplay of differences in the structure of the interface and the strength of interactions that depend on anion identity. Our results also suggest that CO₂ interacts strongly with ionic species on the RTIL surfaces due to the large induced dipole moments on CO₂ during the collisions. The inclusion of electronic polarization is critical in determining the final rotational excitation of CO₂ compared to results from an MM model with fixed charge

Plots of mean phase values in the left and right brains of WD and control groups.

<p>The plots show the mean phase value of bilateral gray matter nuclei in left (A) and right (B) brain of WD and control groups. The differences in phase values for all nuclei on both sides of the brain were significantly different between WD groups and normal controls (P<0.001), with the most substantial difference occurring in PUT.</p

Conventional MRI phase images of WD patients.

<p>Many patients showed hypointense areas on T1-weighted images(A) and hyperintense areas on T2-weighted images(B).</p

ROIs used for calculation of mean phase values.

<p>Phase images show the ROIs used for the measurement of the mean phase values in bilateral PUT (1, 2), GP (3, 4), HCN (5, 6), (A) SN (7, 8), and RN (9, 10) (B).</p

Phase images of WD groups and sex- and age-matched healthy controls.

<p>A, B: WD patients. C, D: Control patients. The signal intensity on phase images of gray matter nuclei in WD groups (A, B) was lower, and the outlines of gray matter nuclei were clearer than in control groups (C, D).</p

Diverse early diagenetic processes of ferromanganese nodules from the eastern Pacific Ocean: evidence from mineralogy and in-situ geochemistry

Ferromanganese nodules are a potential energy resource because of their high contents of economically interesting elements (i.e. Mn, Ni, Cu, and Zn). These are higher in diagenetic layers than in hydrogenetic layers. The study of the causes of elemental accumulation in the diagenetic layer is useful for the exploration metal-rich nodules. A diagenetic-dominant ferromanganese nodule, from the central Clarion–Clipperton Fracture Zone of the eastern Pacific Ocean was studied from core to rim. It was divided into four layers and seven sublayers, of the four typical diagenetic sublayers (L1, L2-1, L2-2, and L3-1). Differences were observed in these diagenetic sublayers. L1 presents the highest Mn/Fe ratio (54), the lowest Co content (2262 ppm), and a positive Ce anomaly. L2-1 exhibits high Co (3122 ppm) and Ba contents (4020 ppm), a positive Ce anomaly, and an obvious peak for 10 Å manganate minerals. L2-2 contains the lowest Ni+Cu contents (3.2 wt%), the highest Ba and Co contents (5110 ppm), and the strongest positive Ce anomaly. In L2-2, the δCe value can be positively correlated to the Mn/Fe ratio and a pronounced peak for 10 Å manganate minerals indicates that this layer has the highest mineral crystallinity. L3-1 shows the highest Ni+Cu contents (5.4 wt%), the lowest Ba (1247ppm), and Co (1725 ppm), a weakly positive Ce anomaly, and the poorest mineral crystallization. Diagenetic- and hydrogenetic-endmember mixing models reveal that hydrogenetic input contributes minimally to these chemical changes, whereas diagenetic input contributes greatly. The changes in diagenetic input may be caused by the changes in primary productivity brought about by movement of tectonic plates and the intense activity of the diagenetic pore fluid. The activity may provide a metal source for the diagenetic sublayer (anomalously high Co and Ce content) via the incorporation of metals released from dissolved buried nodules and micronodules under a suboxic or reducing environments.</p