RESUMO
The trio elements found in Gunshot Residue (GSR) are considered the key elements that are characteristic of GSR. To date, most forensic laboratories have mainly concentrated on employing carbon stubs analyzed by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) to find IGSR on the hands and clothing of a person. A little elevated from the normal practice, this work is focused on the evaluation of compositional and morphological variations of GSR collected from muzzle end, trajectory, and target obtained by firing the ammunition of choice (9×19 mm Indian ammunition). Even though there may be variations in IGSR compositions within various locations of a weapon, this hasn't been investigated or documented up to this point. To ascertain whether it is possible to identify any variation in GSR particles gathered from these three different locations, the objective of this study is to investigate the structural characteristics and elemental composition of GSR to identify the distinctive parameters that allow for comparison and to establish the composition of the primer. The study also focuses on assessing any possible surface modification that may occur to GSR upon striking the target and establishing a correlation between GSR particles and propellant powder. The collected GSR samples were analyzed using a digital microscope, SEM/EDS, and EDXRF. It was discovered that the primer type showed a strong correlation to the elemental composition and morphology of GSR. By analyzing the GSR particles collected from the various sites as mentioned above, it was possible to identify the primer mixture used in the ammunition and its diversity in elemental concentration. The obtained GSR samples were not spherical but showed an elongated structure and possessed a diameter ranging from 695.4 µm-1.640 mm, 536.2 µm-1.412 mm, and 775.8 µm-1.772 mm respectively. However, the morphology and the size distribution of the particles collected from all three different points showed slight deviation as moving from ME towards TG. The obtained results could identify the primer mixture and diversity in its elemental concentration. The morphology and size distribution of GSR collected from three different points showed deviations.
RESUMO
While the antitumor activity of P(4+) is relatively well understood, the binding mechanism and thermodynamics for formation of (P(4+)·DNA) complexes remain in question. The thermodynamic parameters (Ka, ΔG, ΔH, and -TΔS) for formation of DNA complexes of the ruthenium dimer, [(phen)2Ru(tatpp)Ru(phen)2](4+) (abbreviated as P(4+)), where phen is 1,10-phenanthroline and tatpp is 9,11,20,22-tetraazatetrapyrido[3,2-a:2',3'-c:3â³,2â³-1:2â´,3â´-n]-pentacene, were determined using isothermal titration calorimetry. Calorimetric and spectroscopic titration experiments were performed in which P(4+) was added to three duplex DNAs of different lengths. We determined that P(4+) binds to duplex DNA at 298 K with modest affinity (Ka ≈ 3.8 × 10(5) M(-1), ΔG ≈ -7.6 kcal/mol), that the enthalpy change is unfavorable (ΔH ≈ +2.1 kcal/mol), and that complex formation is driven by a large favorable change in entropy (-TΔS ≈ -9.7 kcal/mol). These thermodynamic values were found to be approximately independent of the length of the DNA, and the stoichiometry of the (P(4+)·DNA) complexes was determined to be 1 P(4+)/2 DNA bp, at least for the two shorter DNAs. On the basis of the thermodynamic parameters, and the binding stoichiometry (verified in ESI-MS experiments), we conclude that P(4+) is intercalating between two adjacent DNA base pairs and that the neighbor sites on either side of the bound ligand are excluded from binding additional P(4+).