Forensic Discrimination of Smokeless Powders Using Carbon and Nitrogen Isotope Ratios.

Improvised explosive devices pose a threat to the public by way of terrorism and criminal activities. In the United States a commonly used low explosive in improvised explosive devices is smokeless powder (SP), due to its ease of access. Traditionally, forensic examinations are often sufficient in determining the physical and chemical characteristics of SPs. However, these exams are limited in differentiating or associating SPs when comparing two materials which are physically and/or chemically consistent. Stable isotope analysis of carbon and nitrogen has been used for explosives to further forensic chemical comparisons and aid in sample differentiation. In this manuscript we explore the utility of stable isotope analysis of SPs to differentiate manufacturer and geographic origin. Both bulk isotope analysis and component isotope analysis of carbon and nitrogen via an extraction method using dichloromethane were evaluated to compare the overall isotope signature of individual SPs. Through the combination of bulk and component isotope measurements of SPs, we were able to identify geographic relationships; however, the manufacturer origins were not as clearly discriminated. This technique demonstrates a potential improvement to traditional forensic examinations of smokeless powder by adding additional information when explosives are chemically and/or physically consistent.

Halide ions complex and deprotonate dipicolinamides and isophthalamides: assessment by mass spectrometry and UV-visible spectroscopy.

The F(-), Cl(-), and Br(-) binding selectivity of bis(p-nitroanilide)s of dipicolinic and isophthalic acids was studied by using competitive electrospray mass spectrometry and UV-Visible spectroscopy. Both hosts prefer binding Cl(-) over either F(-) or Br(-). Host deprotonation was observed to some extent in all experiments in which the host was exposed to halide ions. When F(-) was present, host deprotonation was often the major process, whereas little deprotonation was observed by Cl(-) or Br(-), which preferred complexation. A solution of either host changed color when mixed with a F(-), H(2)PO(4)(-), di- or triphenylacetate solution.

Dianilides of dipicolinic acid function as synthetic chloride channels.

We report that N(2),N(6)-bis(4-nitrophenyl)pyridine-2,6-dicarboxamide, which is related to known isophthalic acid dianilides, transports Cl(-) ions through phospholipid bilayer membranes and shows clear evidence of channel activity.

Self-assembled, cogged hexameric nanotubes formed from pyrogallol[4]arenes with a unique branched side chain.

A branched side chain pyrogallol[4]arene self-assembles into a previously-unreported cogged hydrogen-bonded nanotube structure in the solid state and self-assembles at the air-water interface on the Langmuir trough.

Synthetic, biologically active amphiphilic peptides.

Amphiphilic peptides typically consist of a peptide portion that may be 5-25 (or more) amino acids in length. The hydrophobic portion may be a single fatty acid residue, but can also be more elaborate. The main focus of this article lies on the family of synthetic anion binders (SATs) of the general structure (R(1))(2)N-COCH(2)OCH(2)CO-(Aaa)(n)-OR(3). The most-common R(1) group is the octadecyl (C(18)H(37)) group. The most studied peptide sequence in this family is (Gly)(3)-Pro-(Gly)(3), although different sequences (and longer and shorter peptides) have been prepared as well. The C-terminal ester residue providing the most effective anion release from liposomes is heptyl (C(7)H(15)), although many others have been examined. The compound (C(18)H(37))(2)N-COCH(2)OCH(2)CO-(Gly)(3)-Pro-(Gly)(3)-OBn (Bn=benzyl) was found to mediate Cl(-) transport in mouse epithelial cells.

HETEROCYCLIC AMIDE HYDRAPHILE SYNTHETIC CATION TRANSPORTERS.

A family of hydraphile ionophores has been prepared in which various approximately CH(2)N approximately to approximately CON approximately replacements have been made to assess the effect on Na(+) transport through phospholipid bilayers. When the central relay (see graphical abstract) was a third macrocycle, symmetrical carbonyl for methylene replacements enhanced activity, but the presence of four or six amide residues diminished transport. When a pair of amides was incorporated into compounds having a 4,4'-bipiperidyl central relay, both significant increases and decreases were observed depending upon the amide positions. The presence of amides alters both the donor group type and strength and the conformation of the structural unit in which it occurs. These changes are shown to depend on the liposomes in which the Na(+) release studies were conducted. These changes are shown to affect the toxicity of the hydraphiles to E. coli.