Analytical Study of Enrichment of Low Content Platinum in Natural Minerals by using Polymeric Sorbent

In order to enrich low content platinum (Pt), polystyrene-azo-thiazan-dithion-2.4(PSTDT) has been selected from several polymeric sorbents that able to create with it a chelate complex. We studied physical-chemical characteristics of sorbent and their complexes with platinum. Analytical parameters of condition for platinum concentration are determined. The platinum sorption process with sorbents having thiazan-dithion groups runs with detaching of two protons from FAG. In the complex these results allow to suggest the obvious, structure of chelate fragments. We define that in the optimal conditions for platinumsorption [H+], sorption all time and temperature. A new rapid and reliable method of concentration and derivation of quantitative of (Pt) natural minerals objects by polymeric FAG thiazan-dithion groups is proposed

Molecular Modeling of Acidic Treated PSTM-3T Polymer for Removal of Heavy Metal Ions by Experimental and Computational Studies

The synthesized poly[N,N′-bis(3-silsesquioxanilpropyl)-thiocarbamide] (PSTM-3T) was used and the surface morphology and microstructure of it were analyzed by scanning electron microscopy with energy dispersive spectrometer (SEM/EDS). The molecular structure change of the PSTM-3T polymer of the PSTM-3T after treatment by acidic solution with different pHs was revealed using FT-IR experiments and ab initio calculations with density functional theory method. The sorption efficiency of the heavy metal ions depends on the molecular structure change of PSTM-3T after treatment of different pH aqueous solutions. After the treatment of acidic solution (pH = 2) of PSTM-3T, the polymer formed the tautomer state to increase the sorption efficiency for chromate ion. For the increment of pH value for acidic solution, the PSTM-3T polymer was dissociated to increase the sorption efficiency for copper ion

Production cross sections of 68Ga and radioactive by-products in deuteron-induced reactions on natural zinc

Activation cross sections of the deuteron-induced reactions on natural zinc are studied for the production of the medical radionuclide 68Ga. The stacked foil activation method and the γ-ray spectrometry were used. Co-produced radionuclides 65,66,67Ga, 63,65,69mZn, 61Cu, and 58Co are also investigated to evaluate amounts of impurities for practical use of 68Ga. Physical yields of the radionuclides were deduced from the measured cross sections

Dynamic Structure and Orientation of Melittin Bound to Acidic Lipid Bilayers, As Revealed by Solid-State NMR and Molecular Dynamics Simulation

Melittin is a venom peptide that disrupts lipid bilayers at temperatures below the liquid-crystalline to gel phase transition temperature (<i>T</i>_c). Notably, the ability of melittin to disrupt acidic dimyristoylphosphatidylglycerol (DMPG) bilayers was weaker than its ability to disrupt neutral dimyristoylphosphatidylcholine bilayers. The structure and orientation of melittin bound to DMPG bilayers were revealed by analyzing the ¹³C chemical shift anisotropy of [1-¹³C]-labeled melittin obtained from solid-state ¹³C NMR spectra. ¹³C chemical shift anisotropy showed oscillatory shifts with the index number of residues. Analysis of the chemical shift oscillation properties indicated that melittin bound to a DMPG membrane adopts a bent α-helical structure with tilt angles for the N- and C-terminal helices of −32 and +30°, respectively. The transmembrane melittin in DMPG bilayers indicates that the peptide protrudes toward the C-terminal direction from the core region of the lipid bilayer to show a pseudotransmembrane bent α-helix. Molecular dynamics simulation was performed to characterize the structure and interaction of melittin with lipid molecules in DMPG bilayers. The simulation results indicate that basic amino acid residues in melittin interact strongly with lipid head groups to generate a pseudo-transmembrane alignment. The N-terminus is located within the lipid core region and disturbs the lower surface of the lipid bilayer

Dynamic Structure of Bombolitin II Bound to Lipid Bilayers as Revealed by Solid-state NMR and Molecular-Dynamics Simulation

Bombolitin II (BLT2) is one of the hemolytic heptadecapeptides originally isolated from the venom of a bumblebee. Structure and orientation of BLT2 bound to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membranes were determined by solid-state 31P and 13C NMR spectroscopy. 31P NMR spectra showed that BLT2-DPPC membranes were disrupted into small particles below the gel-to-liquid crystalline phase transition temperature (Tc) and fused to form a magnetically oriented vesicle system where the membrane surface is parallel to the magnetic fields above the Tc. 13C NMR spectra of site-specifically 13C-labeled BLT2 at the carbonyl carbons were observed and the chemical shift anisotropies were analyzed to determine the dynamic structure of BLT2 bound to the magnetically oriented vesicle system. It was revealed that the membrane-bound BLT2 adopted an α-helical structure, rotating around the membrane normal with the tilt angle of the helical axis at 33°. Interatomic distances obtained from rotational-echo double-resonance experiments further showed that BLT2 adopted a straight α-helical structure. Molecular dynamics simulation performed in the BLT2-DPPC membrane system showed that the BLT2 formed a straight α-helix and that the C-terminus was inserted into the membrane. The α-helical axis is tilted 30° to the membrane normal, which is almost the same as the value obtained from solid-state NMR. These results suggest that the membrane disruption induced by BLT2 is attributed to insertion of BLT2 into the lipid bilayers