scholarly journals Spectroscopic Signatures of the Dynamical Hydrophobic Solvation Shell Formation

2019 ◽  
Vol 123 (9) ◽  
pp. 2106-2113
Author(s):  
Henning Kirchberg ◽  
Peter Nalbach ◽  
Christian Bressler ◽  
Michael Thorwart
Keyword(s):  
Solvation Shell ◽  
Shell Formation ◽  
Spectroscopic Signatures ◽  
Hydrophobic Solvation

scholarly journals Hydrophobicity with atomic resolution: Steady-state and ultrafast X-ray absorption and molecular dynamics studies

2012 ◽  
Vol 85 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Thomas J. Penfold ◽  
Christopher J. Milne ◽  
Ivano Tavernelli ◽  
Majed Chergui
Keyword(s):  
Molecular Dynamics ◽  
Md Simulations ◽  
Solvation Shell ◽  
Water Molecules ◽  
Time Resolved ◽  
X Ray ◽  
Bond Network ◽  
Hydrophobic Solvation ◽  
X Ray Absorption ◽  
Small Anisotropy

Static and time-resolved X-ray absorption spectroscopy (XAS) is used to probe the solvent shell structure around iodide and iodine. In particular, we characterize the changes observed upon electron abstraction of aqueous iodide, which reflects the transition from hydrophilic to hydrophobic solvation after impulsive electron abstraction from iodide. The static spectrum of aqueous iodide, which is analyzed using quantum mechanical/molecular mechanics (QM/MM) molecular dynamics (MD) simulations, indicates that the hydrogens of the closest water molecules point toward the iodide, as expected for hydrophilic solvation. In addition, these simulations demonstrate a small anisotropy in the solvent shell. Following electron abstraction, most of the water molecules move away from iodine, while one comes closer to form a complex with it that survives for 3–4 ps. This lifetime is governed by the reorganization of the main solvation shell, basically the time it takes for the water molecules to reform a hydrogen bond network in the hydrophobic solvation shell.

The Effect of Exogenous Fluoride on the Calcium PUMP, Ciliary Activity, and Shell Formation of the Fingernail Clam, Musculium Transversum

1982 ◽  
Vol 40 ◽  
pp. 58-59
Author(s):  
Anthony Paparo ◽  
Judy A. Murphy ◽  
Robert Dean
Keyword(s):  
Mississippi River ◽  
Calcium Pump ◽  
Bottom Fauna ◽  
Ciliary Activity ◽  
Shell Formation ◽  
Middle Reach ◽  
Shell Matrix ◽  
Fingernail Clams ◽  
Ca Carbonate

In the mid-1950's, fingernail clams virtually disappeared from a 100-mile section of the IL River, a tributary of the Mississippi River, due to unknown causes. A survey of the bottom fauna of the IL River in 1979, revealed that the clams were still absent from the middle reach of the River, where they had been abundant prior to the die-off in the 1950's. Some factor(s) in the River currently prevent the clams from recolonizing areas where they were formerly abundant. Recently, clams exposed to fluoride developed abnormal grooves in the shell matrix. Fluorides are known to be protoplasmic poisons removing essential body calcium by precipitation. Since the shell consists primarily of Ca carbonate, this investigation examines the possible role of fluoride on shell formation and the poisoning of the Ca pump which can directly inhibit lateral ciliary activity on the gill.

Silicon Substitution for Calcium in the Shell of the Fingernail Clam, Musculium Transversum Studied By X-Ray Analysis

1980 ◽  
Vol 38 ◽  
pp. 560-561
Author(s):  
Judith A. Murphy ◽  
Anthony Paparo ◽  
Richard Sparks
Keyword(s):  
Carbonic Anhydrase ◽  
River Water ◽  
Food Chains ◽  
Well Water ◽  
Shell Formation ◽  
X Ray ◽  
Molluscan Shell ◽  
Fingernail Clams

Fingernail clams (Muscu1ium transversum) are dominant bottom-dwelling animals in some waters of the midwest U.S. These organisms are key links in food chains leading from nutrients in water and mud to fish and ducks which are utilized by man. In the mid-1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R. Some factor(s) in the river and/or sediment currently prevent clams from recolonizing areas where they were formerly abundant. Recently, clams developed shell deformities and died without reproducing. The greatest mortality and highest incidence of shell deformities appeared in test chambers containing the highest proportion of river water to well water. The molluscan shell consists of CaCO3, and the tissue concerned in its secretion is the mantle. The source of the carbonate is probably from metabolic CO2 and the maintenance of ionized Ca concentration in the mantle is controlled by carbonic anhydrase. The Ca is stored in extracellular concentric spherical granules(0.6-5.5μm) which represent a large amount of inertCa in the mantle. The purpose of this investigation was to examine the role of raw river water and well water on shell formation in the fingernail clam.

Solution chemistry effects on the solvation shell of metal ions

2020 ◽  
Author(s):  
Xiangwen Wang ◽  
Dimitrios Toroz ◽  
Seonmyeong Kim ◽  
Simon Clegg ◽  
Gun-Sik Park ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pure Water ◽  
Solvation Shell ◽  
Solution Chemistry ◽  
Chemical Characteristics ◽  
Velocity Autocorrelation Function ◽  
Ionic Solvation ◽  
General Terms ◽  
Alkaline Earth Metal Ions ◽  
Wide Range

<div> <p>As natural aqueous solutions are far from being pure water, being rich in ions, the properties of solvated ions are of relevance for a wide range of systems, including biological and geochemical environments. We conducted ab initio and classical MD simulations of the alkaline earth metal ions Mg<sup>2+</sup> and Ca<sup>2+</sup> and of the alkali metal ions Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup> and Cs<sup>+</sup> in pure water and electrolyte solutions containing the counterions Cl<sup>–</sup> and SO<sub>4</sub><sup>2–</sup>. Through a detailed analysis of these simulations, this study reports on the effect of solution chemistry (composition and concentration of the solution) to the ion–water structural properties and interaction strength, and to the dynamics, hydrogen bond network, and low-frequency dynamics of the ionic solvation shell. Except for the ion–water radial distribution function, which is weakly dependent on the counter-ions and concentrations, we found that all other properties can be significantly influenced by the chemical characteristics of the solution. Calculation of the velocity autocorrelation function of magnesium ions, for example, shows that chlorine ions located in the second coordination shell of Mg<sup>2+</sup> weaken the Mg(H<sub>2</sub>O)<sub>6</sub><sup>2+</sup> hydration ‘cage’ of the cation. The result reported in this study suggest that ionic solvation shell can be significantly influenced by the interactions between other ions present in solution ions, especially those of opposite charge. In more general terms, the chemical characteristics of the solution, including the balance between ion-solvent and ion-ion interactions, could result in significant differences in behavior and function of the ionic solvation shell.</p> </div>

Synthesis of mussel-inspired polydopamine-gallium nanoparticles for biomedical applications

Nanomedicine ◽  
2021 ◽  
Author(s):  
Jean Valdir Uchôa Teixeira ◽  
Fátima Raquel Azevedo Maia ◽  
Mariana Carvalho ◽  
Rui Reis ◽  
Joaquim Miguel Oliveira ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Biomedical Applications ◽  
Adipose Derived Stem Cells ◽  
Cell Analysis ◽  
Shell Formation ◽  
X Ray ◽  
Alkali Medium ◽  
Reproducible Method ◽  
Gallium Nanoparticles

Aim: To established a simple, controlled and reproducible method to synthesize gallium (Ga)-coated polydopamine (PDA) nanoparticles (NPs). Materials & methods: PDA NPs were synthesized in alkali medium with posterior Ga shell formation due to ion chelation on the NP surface. Results: The obtained results with energy-dispersive x-ray spectroscopy confirmed the incorporation of Ga on the PDA NP surface. The cytotoxicity of Ga-coated PDA NPs was evaluated in vitro at different concentrations in contact with human adipose-derived stem cells. Further cell analysis also demonstrated the benefit of Ga-coated PDA NPs, which increased the cell proliferation rate compared with noncoated PDA NPs. Conclusion: This study indicated that Ga could work as an appropriate shell for PDA NPs, inducing cell proliferation at the analyzed concentrations.

scholarly journals The Three Pillars of Natural Product Dereplication. Alkaloids from the Bulbs of Urceolina peruviana (C. Presl) J.F. Macbr. as a Preliminary Test Case

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 637
Author(s):  
Mariacaterina Lianza ◽  
Ritchy Leroy ◽  
Carine Machado Rodrigues ◽  
Nicolas Borie ◽  
Charlotte Sayagh ◽  
...  
Keyword(s):  
Natural Product ◽  
Spectroscopic Data ◽  
Preliminary Test ◽  
Rapid Identification ◽  
Molecular Structures ◽  
Data Sources ◽  
Test Case ◽  
The Andes ◽  
Spectroscopic Signatures ◽  
Product Chemistry

The role and importance of the identification of natural products are discussed in the perspective of the study of secondary metabolites. The rapid identification of already reported compounds, or structural dereplication, is recognized as a key element in natural product chemistry. The biological taxonomy of metabolite producing organisms, the knowledge of metabolite molecular structures, and the availability of metabolite spectroscopic signatures are considered as the three pillars of structural dereplication. The role and the construction of databases is illustrated by references to the KNApSAcK, UNPD, CSEARCH, and COCONUT databases, and by the importance of calculated taxonomic and spectroscopic data as substitutes for missing or lost original ones. Two NMR-based tools, the PNMRNP database that derives from UNPD, and KnapsackSearch, a database generator that provides taxonomically focused libraries of compounds, are proposed to the community of natural product chemists. The study of the alkaloids from Urceolina peruviana, a plant from the Andes used in traditional medicine for antibacterial and anticancer actions, has given the opportunity to test different approaches to dereplication, favoring the use of publicly available data sources.

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