Rapid Screening and Estimation of Binding Constants for Interactions of Fe3+ with Two Metalloproteins, Apotransferrin and Transferrin, Using Affinity Mode of Capillary Electrophoresis

The interaction behavior of Fe3+ with transferrin and apotransferrin (iron-free form) was investigated in this study using affinity capillary electrophoresis. Change in the mass and charge of protein upon binding to the metal ion in the capillary tube led to variation in its migration time and was used to measure the noncovalent binding interactions by fast screening method. Acetanilide was used as the electroosmotic flow (EOF) marker to avoid possible errors due to the change in EOF during the experiment. The binding results were calculated from the mobility ratios of protein (Ri) and EOF marker (Rf) using the formula (Ri − Rf)/Rf or ∆R/Rf. For more comprehensive understanding, the kinetics of the interaction was studied and binding constants were calculated. Results showed that the Fe3+ displayed insignificant interaction with both proteins at lower metal ion concentrations (5–25 μmol/mL). However, transferrin exhibited significant interactions with the metal ion at 50 and 100 μmol/mL (ΔR/Rf = 0.0114 and 0.0201, resp.) concentrations and apotransferrin showed strong binding interactions (ΔR/Rf = −0.0254 and 0.0205, resp.) at relatively higher Fe3+ concentrations of 100 and 250 μmol/mL. The binding constants of 18.968 mmol−1 and −13.603 mmol−1 were recorded for Fe3+ interaction with transferrin and apotransferrin, respectively, showing significant interactions. Different binding patterns of Fe3+ with both proteins might be attributed to the fact that the iron-binding sites in transferrin have already been occupied, which was not the case in apotransferrin. The present study may be used as a reference for the investigation of protein-metal ion, drug-protein, drug-metal ion, and enzyme-metal ion interactions and may be helpful to provide preliminary insight into the new metal-based drug development.

Evaluating the impact of doping concentration on the performance of in-band pumped thulium-doped fiber amplifiers

This study is to investigate the impact of thulium concentration on the performance of in-band pumped thulium-doped silica fiber amplifiers with considering ion–ion interactions. Due to the fluorescence quenching in silica glass, the fluorescence lifetimes are required to compute at every Tm concentration. The theoretical model of fluorescence decay curves at in-band pumped thulium-doped silica fiber is used to determine the fluorescence lifetimes of the 3F4 and 3H4 levels. The calculated lifetimes of the commercially available thulium-doped silica fiber are 650 µs for 3F4 level and 14 µs for 3H4 level and these results are consentient well with the experimental reported results. The theoretical evaluating of the amplifier performance shows that the gain amplifier reduces with concentration increase because of the impact of both fluorescence quenching and the reverse cross-relaxation process. Thus, in contrast to pumping wavelength at 790 nm, there are negative effects of the high doping concentration of Tm ions on the amplifier performance at the in-band pumping scheme.

Formation and Transformation Trends of Metal Carbonates With Cation Ratio and Ion Interaction in Post-treatment Process of Desalination Brine

BackgroundTo address the negative effects of desalination plants, CO2 emissions, and discharge of desalination brine, we studied the carbon capture utilization (CCU) process based on metal carbonation via the reuse of desalination brine. In this study, we converted CO2 and simulated desalination brine into metal carbonate using monoethanolamine as an aqueous absorbent. The produced metal carbonate varied according to the cation component of the simulated desalination brine. We focused on ion interactions in the aqueous system, occurred by cation ratio, and other phenomena caused by the interactions.ResultsWe determined that the common ion effect, which occurred owing to the ion interactions of the system, was the main reason for the various carbonation trends. Ionic atmospheres that were changed by the ionic components significantly affected the trends. The high salinity of the desalination brine also affected the metal carbonation. We further deduced that the variation in the results was derived from interactions between the abovementioned effects. And we also found that Na+, which was overlooked in former studies about polymorph transformation, also affects polymorph transformation.ConclusionsAll the phenomena in the metal carbonation interrupt desalination brine post-treatment because of their unpredictability. However, we suggest ambient estimation of its cation components, which would help future studies and demonstrate desalination brine post-treatment.

Prediction of the Osmotic/activity Coefficients of Alkali Hydroxide Electrolytes

<div><div><div><p>The osmotic/activity coefficients are one of the most fundamental and important properties of electrolyte solutions. There is currently no reliable means of predicting them from first principles without relying on extensive fitting to experimental measure- ments. The alkali hydroxide aqueous electrolytes are a particularly important class of solutions due to the crucial role they play in a vast range of applications. Here, for the first time we predict the osmotic/activity coefficients of these solutions without any fitting using a previously developed continuum solvent model of ion–ion interactions with no modifications. The feasibility of making these predictions with first princi- ples molecular simulation is also assessed. This demonstrates the reliability of this continuum solvent model and provides a plausible pathway to the fast and accurate prediction of these important properties for a wide range of electrolyte solutions.</p></div></div></div>

3-D TCAD Monte Carlo Device Simulator: State-of-the-art FinFET Simulation

This work presents a comprehensive description of an in-house 3D Monte Carlo device simulator for physical mod-eling of FinFETs. The simulator was developed to consider var-iability effects properly and to be able to study deeply scaled devices operating in the ballistic and quasi-ballistic regimes. The impact of random dopants and trapped charges in the die-lectric is considered by treating electron-electron and electron-ion interactions in real-space. Metal gate granularity is in-cluded through the gate work function variation. The capability to evaluate these effects in nanometer 3D devices makes the pre-sented simulator unique, thus advancing the state-of-the-art. The phonon scattering mechanisms, used to model the transport of electrons in pure silicon material system, were validated by comparing simulated drift velocities with available experi-mental data. The proper behavior of the device simulator is dis-played in a series of studies of the electric potential in the device, the electron density, the carrier's energy and velocity, and the Id-Vg and Id-Vd curves.