Differentiation of two main ammunition brands in Chile by Regularized Discriminant Analysis (RDA) of metals in gunshot residues

Conventionally, chemical patterns of gunshot residues (GSR) can be used for identification of a suspect involved in criminal fire arm incidents. Furthermore, metals composition in GSR is well related with the ammunition brand. In Chile the two main ammunition brands used are FAMAE and CBC. Metals, such as Pb, Ba, Sb, Cu, Zn and Ca are common elements detected in both brands. This work describes the application of both conventional and chemometric analysis of data (Regularized Discriminant Analysis, RDA) for differentiation of ammunition brands according to the metal patterns of GSR collected from shooter individuals. Real samples of GSR were collected from hands (dorsal region) of both shooters and non-shooters. Metals were analyzed using the techniques Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES). By means of conventional plotting techniques for differentiation, such as binary and ternary plots, differences between the two brands are observed although without quantitative certainty. For the first time, applying chemometric analysis, such as regularized discriminant analysis (RDA), the investigated ammunition brands can be classified and differentiated correctly with 100% certainty.     

Preparation of modified peptides: direct conversion of α-amino acids into β-amino aldehydes

A direct method for the transformation of α-amino acids into β-amino aldehydes was developed, and applied to the modification of the C-terminal residue of peptides. The method takes place in good yields and under mild conditions. The application of this methodology to the preparation of small peptides with γ-amino alcohol units, which are precursors of analogues of peptaibol antibiotics, is also described.     

Affinity of An(VI) for N4-Tetradentate Donor Ligands: Complexation of the Actinyl(VI) Ions with N4-Tetradentate Ligands

In this report the affinity of four N₄-tetradentate ligands that incorporate the 2-methylpyridyl functionality with hexavalent actinides $(\mathrm{AnO}_{2}^{2+})$ has been investigated in methanol solution. The ligands studied include N,N??-bis(2-methylpyridyl)diaminoethane (BPMDAE), N,N??-bis(2-methylpyridyl)-1,3-diaminopropane (BPMDAP), N,N??-bis(2-pyridylmethyl)piperazine (BPMPIP), and trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC). Conditional stability constants describing the strength of the interaction were determined by UV?Cvisible spectrophotometry. The log₁₀ K ₁₀₁ values for both U(VI) and Pu(VI) are comparable and show the same trend of stability with ligand structure. Dinuclear complexes are also indicated as being important. The log₁₀ K ₂₀₁ values for Pu(VI) complexation with the N₄-ligands are identical for the four ligands (within experimental error), indicating that the structure of the ligand backbone has little effect on the stability of the (PuO₂)₂L²⁺ complex. The exception to this trend is the behavior of N,N??-bis(2-pyridylmethyl)piperazine (BPMPIP) with Pu(VI). This ligand displays a tendency to reduce Pu(VI) within the experimental time frame of 45 minutes. BPMPIP is the only ligand tested that contains tertiary amines in the ligand backbone. The decomposition of BPMPIP by Pu(VI) suggests a susceptibility of tertiary amines to oxidative degradation.     

Multistep conformational interconversion mechanism of cyclododecane. A simple and fast analysis using potential energy curves

An ab initio and Density Functional Theory (DFT) study of the conformational properties of cyclododecane was carried out. The energetically preferred equilibrium structures, their relative stability, and some of the transition state (TS) structures involved in the conformational interconversion pathways were analyzed from RHF/6‐31G(d), B3LYP/6‐31G(d,p) and B3LYP/6311++G(d,p) calculations. Aug‐cc‐pVDZ//B3LYP/6311++G(d,p) single point calculations predict that the multistep conformational interconversion mechanism requires 11.07 kcal/mol, which is in agreement with the available experimental data. These results allow us to form a concise idea about the internal intricacies of the preferred forms of cyclododecane, describing the conformations as well as the conformational interconversion processes in the conformational potential energy hypersurface. Our results indicated that performing an exhaustive analysis of the potential energy curves connecting the most representative conformations is a valid alternate tool to determine the principal conformational interconversion paths for cyclododecane. This methodology represents a satisfactory first approximation for the conformational analysis of medium‐ and large‐size flexible cyclic compounds. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

How to Prove Dynamical Localization

Let H be a self-adjoint operator on l ²(Z ^d ) or L ²(R ^d ) with pure point spectrum on some interval I. We establish general necessary and sufficient conditions for dynamical localization for a given vector and on the interval of energies I. The sufficient conditions we obtain improve the existing ones such as SULE or WULE and can be useful in applications. Received: 16 November 2000 / Accepted: 14 February 2001     

Two-Dimensional Brownian Random Interlacements

Potential Analysis - We introduce the model of two-dimensional continuous random interlacements, which is constructed using the Brownian trajectories conditioned on not hitting a fixed set...     

Synthesis and Crystal Structure of [Fe(Cp)2]3(Bi2Cl9)·thf

Single crystals of [Fe(Cp)₂]₃(Bi₂Cl₉)·thf were obtained from a thf solution containing ferrocene and BiCl₃. The structure shows disorder at room temperature which disappears upon cooling, coupled with a decrease in symmetry. The title compound crystallizes in the orthorhombic space group P2₁2₁2₁ [a = 1698.64(2), b = 2318.69(3), c = 1085.66(2) pm] with three ferrocenium ions, one nonachlorodibismutate ion and one molecule of thf in the asymmetric unit.     

Asymptotically sharp uniform estimates in a scalar spectral stiff problemEstimations asymptotiques uniformes pour le spectre d'un problème scalaire raide

Estimates of convergence rates for rescaled eigenvalues of the stiff Neumann problem for the Laplacian are obtained. The bounds are expressed in terms of the stiffness ratio and properties of the limit spectrum both for low and middle frequency ranges. To cite this article: M. Lobo et al., C. R. Mecanique 331 (2003).     

Cosmic-ray muon search at Mt. Blanc Laboratory

Summary In this paper the main scientific activities, over 20 years, of our group at Mt. Blanc Laboratory are described on the basis of three experiments: SCE (Spark Chamber Experiment), NUSEX (Nucleon Stability Experiment) and LSD (Liquid Scintillation Detector). A first noteworthy step to the muon physics deep underground has been done by SCE in the 70's, while at the present time a very important impact is given by NUSEX and LSD experiments, now fully running, playing a heavy role both on the elementary particle and astrophysics research. The results of these experiments are discussed focusing expecially on the physics of muons of atmospheric origin and of those locally originated at Mt. Blanc Laboratory, 5000 m w.e. deep underground.

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Riassunto Si descrivono le principali attività scientifiche svolte dal nostro gruppo del Mt. Bianco durante 20 anni, relative a tre esperimenti: SCE (Spark Chamber Experiment), NUSEX (Nucleon Stability Experiment) e LSD (Liquid Scintillator Detector). Un primo e significativo contributo alla fisica dei muoni sottoterra è stato dato dall'esperimento SCE negli anni settanta, mentre un notevole apporto alla ricerca nel campo della fisica delle particelle elementari e astrofisica, con un ruolo di prim'ordine, viene dato dagli attuali esperimenti in funzione NUSEX e LSD. I risultati di questi esperimenti sono discussi focalizzando soprattutto la fisica dei muoni di origine atmosferica e quelli prodotti localmente nel laboratorio del Mt. Bianco a 5000 m. w.e. sottoterra.

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Резюме В этой статье описываются основные направления научной деятельности нашей группы в лаборатории Монблан за 20-летний период работы. Изложение основано на 3-х экспериментах: SCE (эксперимент с искровыми камерами), NUSEX (эксперимент по определению стабильности нулкона) и LSD (детектор на жидком сцинтнлляторе). Первый существенный шаг в изучении мюонов на больших глубинах под землей мы сделали в эксперименте SCE в 70-х годах. Дальнейшее значительное продвижение связано с полностью работающими сейчас установками NUSEX и LSD, которые играют важную роль как в исследованиях элементарных частиц, так и в астрофизике. Обсуждаются результаты этих экспериментов, причем основное внимание уделено изучению мюонов атмосферного и локального происхождения на глубине 5000 мв.э. под Монбланом.