Study of acidified ignitable liquid residues in fire debris by solid‐phase microextraction with gas chromatography and mass spectrometry

The detection and identification of ignitable liquid residues in fire debris can be meaningful in fire investigations. However, background pyrolysis products and weathering hinder the identification and classification steps. In addition to those processes, the acidification of the ignitable liquids before the combustion process could make those tasks even more difficult. Nevertheless, there are no systematic studies assessing the extraction, analysis, and composition of acidified ignitable liquid residues obtained from fire debris. In this work, a method for the study of acidified ignitable liquid residues in fire debris by solid‐phase microextraction with gas chromatography and mass spectrometry is proposed. This methodology has been evaluated, first with simulated solutions (gasoline/sulfuric acid mixtures set on fire under controlled conditions), and then with analysis of samples from real fire debris obtained from 18 chemical ignition Molotov cocktails made with sulfuric acid and three different ignitable liquids (two types of gasoline and diesel fuel). In addition, the extensive modifications observed in chromatograms of acidified ignitable liquid residues regarding neat and weathered samples were studied. These alterations were produced by the combustion and acidification processes. As a consequence, tert‐butylated compounds are proposed as diagnostic indicators for the identification of acidified gasoline in fire debris, even in strongly weathered samples.     

DNA based multi-copper ions assembly using combined pyrazole and salen ligandosides

The DNA structure is an ideal building block for the construction of functional nano-objects. In this direction, metal coordinating base pairs (ligandosides) are an appealing tool for the future specific functionalization of such nano-objects. We present here a study, in which we combine the metal ion coordinating pyrazole ligandoside with the interstrand crosslinking salen ligandoside system. We show that both ligandosides, when combined, are able to create stable multi-copper ion complexing DNA double helix structures in a cooperative fashion.     

A New Porphyrin for the Preparation of Functionalized Water-Soluble Gold Nanoparticles with Low Intrinsic Toxicity

A potential new photosensitizer based on a dissymmetric porphyrin derivative bearing a thiol group was synthesized. 5-[4-(11-Mercaptoundecyloxy)-phenyl-10,15,20-triphenylporphyrin (PR-SH) was used to functionalize gold nanoparticles in order to obtain a potential drug delivery system. Water-soluble multifunctional gold nanoparticles GNP-PR/PEG were prepared using the Brust–Schiffrin methodology, by immobilization of both a thiolated polyethylene glycol (PEG) and the porphyrin thiol compound (PR-SH). The nanoparticles were fully characterized by transmission electron microscopy and ¹H nuclear magnetic resonance spectroscopy, UV/Vis absorption spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the ability of GNP-PR/PEGs to induce singlet oxygen production was analyzed to demonstrate the activity of the photosensitizer. Cytotoxicity experiments showed the nanoparticles are nontoxic. Finally, cellular uptake experiments demonstrated that the functionalized gold nanoparticles are internalized. Therefore, this colloid can be considered to be a novel nanosystem that could potentially be suitable as an intracellular drug delivery system of photosensitizers for photodynamic therapy.     

Automorphisms of the mapping class group of a nonorientable surface

Let an class="InlineEquation" id="IEq1">\(\mathcal {X}_S\)an> denote the class of spaces homeomorphic to two closed orientable surfaces of genus greater than one identified to each other along an essential simple closed curve in each surface. Let an class="InlineEquation" id="IEq2">\(\mathcal {C}_S\)an> denote the set of fundamental groups of spaces in an class="InlineEquation" id="IEq3">\(\mathcal {X}_S\)an>. In this paper, we characterize the abstract commensurability classes within an class="InlineEquation" id="IEq4">\(\mathcal {C}_S\)an> in terms of the ratio of the Euler characteristic of the surfaces identified and the topological type of the curves identified. We prove that all groups in an class="InlineEquation" id="IEq5">\(\mathcal {C}_S\)an> are quasi-isometric by exhibiting a bilipschitz map between the universal covers of two spaces in an class="InlineEquation" id="IEq6">\(\mathcal {X}_S\)an>. In particular, we prove that the universal covers of any two such spaces may be realized as isomorphic cell complexes with finitely many isometry types of hyperbolic polygons as cells. We analyze the abstract commensurability classes within an class="InlineEquation" id="IEq7">\(\mathcal {C}_S\)an>: we characterize which classes contain a maximal element within an class="InlineEquation" id="IEq8">\(\mathcal {C}_S\)an>; we prove each abstract commensurability class contains a right-angled Coxeter group; and, we construct a common CAT(0) cubical model geometry for each abstract commensurability class.