Identification and determination of inorganic anions in real extracts from pre- and post-blast residues by capillary electrophoresis

Fast, selective, and sensitive analysis of inorganic anions is compulsory for the identification of explosives in post-blast or environmental samples. For the last twenty years, capillary electrophoresis (CE) has become a valuable alternative to ion chromatography (IC) for the analysis of inorganic-based explosives because of its low running costs and its simplicity of use. This article focuses on the development and validation of a CE method for the simultaneous analysis of 10 anions (chloride, nitrite, nitrate, thiosulphate, perchlorate, chlorate, thiocyanate, carbonate, sulphate, and phosphate) which can be found in post-blast residues, plus for the first time azide anion, possibly present in the composition of detonators, and the internal standard (formate) in 20 min total runtime. Intermediate precisions were 2.11% for normalized areas and 0.72% for normalized migration times. Limits of detection close to 0.5 ppm for all anions were obtained with the use of preconcentration techniques, thanks to a fast and simple sample preparation allowing the analysis of a large variety of matrices with the developed generic CE method. The matrix effects were statistically studied for the first time in the explosive field for different matrices, containing interfering anions and cations, sometimes at high levels. In fact, no significant matrix effect occurred (tests with blank matrix extracts of soil, cloth, glass, plastic, paper, cotton, and metal). Finally, analyses of real post-blast residues and real detonator extracts were performed. The CE results were compared with those obtained with the IC method used routinely and showed excellent correlation.     

Multifunctional,water‐soluble,C60‐pendant maleic anhydride copolymer

Starting from the synthesis of a new methanofullerene derivative bearing an alcohol group, we report on the preparation of a water‐soluble, fullerene‐pendant copolymer. This multifunctional, C₆₀‐pendant maleic anhydride copolymer was characterized by conductometric titration, Fourier transform infrared and ultraviolet spectroscopy, thermogravimetric analysis, and cyclic voltammetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5814–5822, 2005     

Influence of high‐conductivity buffer composition on field‐enhanced sample injection coupled to sweeping in CE

The aim of this work was to clarify the mechanism taking place in field‐enhanced sample injection coupled to sweeping and micellar EKC (FESI‐Sweep‐MEKC), with the utilization of two acidic high‐conductivity buffers (HCBs), phosphoric acid or sodium phosphate buffer, in view of maximizing sensitivity enhancements. Using cationic model compounds in acidic media, a chemometric approach and simulations with SIMUL5 were implemented. Experimental design first enabled to identify the significant factors and their potential interactions. Simulation demonstrates the formation of moving boundaries during sample injection, which originate at the initial sample/HCB and HCB/buffer discontinuities and gradually change the compositions of HCB and BGE. With sodium phosphate buffer, the HCB conductivity increased during the injection, leading to a more efficient preconcentration by staking (about 1.6 times) than with phosphoric acid alone, for which conductivity decreased during injection. For the same injection time at constant voltage, however, a lower amount of analytes was injected with sodium phosphate buffer than with phosphoric acid. Consequently sensitivity enhancements were lower for the whole FESI‐Sweep‐MEKC process. This is why, in order to maximize sensitivity enhancements, it is proposed to work with sodium phosphate buffer as HCB and to use constant current during sample injection.     

Traceability of absorbed dose in photon radiation therapy: from primary standard to patient treatment

The relevant standard quantity for radiation therapy is the absorbed dose to water. This quantity refers to the amount of energy locally absorbed in a small volume of water divided by the mass of this volume. The aim of this paper is to present a short overview on the establishment of traceability to national standards of absorbed doses delivered to patients in radiation therapy. The approach used at LNE-LNHB, the French national metrology laboratory for ionizing radiation, to determine the reference value of absorbed dose to water is presented and the chain of traceability from the reference value to the treatment of the patient is described.     

Evidence for equilibration of hot nuclei

The production cross sections of⁷Li in its ground and first excited states have been measured at 14°, 120°, 150°, for the 742 MeV²⁰Ne+⁶⁰Ni reaction. Hauser-Feshbach calculations show that the backward angle data are consistent with an emission temperature greater than 6 MeV. This is in agreement with the values extracted from the slope of the energy spectra and indicates that the emitting source is equilibrated.     

The level structure of 56Fe

High-spin states in ⁵⁶Fe have been investigated in three reactions, ⁵⁰Cr(¹²C, α2p), ⁵⁴Fe(α, 2p), ⁵⁶Fe(α, α). The level scheme, the spin and parity assignments and lifetime measurements of these states were obtained through in-beam γ-ray spectroscopy techniques. Calculations were performed in the frame of the shell model with a relatively small configuration space and in the aligned scheme model: the experimental results can be interpreted as due to the interplay between three converging sequences of states of different shapes.     

Etude Stéréochimique par RMN 1H de Tetrahydropyrannes β-Chlorés α-Substitués

The ¹H NMR study of 2-alkyl-3-chlorotetrahydropyrans, obtained by reaction of Grignard reagents with a mixture of cis/trans-2,3-dichlorotetrahydropyrans, shows cis/trans configuration of two isomers in which the alkyl substituents are exclusively in the equatorial position. 3-Chloro-2-phenyltetrahydropyran exists in trans (eq-eq) configuration only. The ¹H NMR study of cis/trans 2-alkoxy (or aryloxy)-3-chlorotetrahydropyrans, obtained by reaction of alcohols or phenol with 2,3-dichlorotetrahydropyrans, shows the axial position of the alkoxy (or aryloxy) substituent.     

Lifetimes and decays of energy levels in 60Ni

The Doppler shift attenuation technique was used to investigate the lifetimes of 33 states of ⁶⁰Ni up to 5.6 MeV of excitation; 18 were measured for the first time. Gamma rays from the ⁶⁰Ni(p,p′ψ) reaction were observed in coincidence with protons by two Ge(Li) detectors at 40° and 130° lab. We find a new doublet (3.381–3.393 MeV) and give several previously unknown ψ-ray branching ratios; the lifetimes allow one to attribute some spins or parities or to reject other assignments. In order to complement the existing information on ⁶⁰Ni, we have studied the proton configuration by the ⁵⁹Co(³He,dψ) reaction. The results are different from those expected from simple 1p-1h states of the proton core; many of the levels observed are multiplets decaying by cascades.     

Photomechanical actuation and manipulation of the electronic properties of linear pi-conjugated systems

A photodynamic molecular architecture has been synthesized by covalent fixation of a photoisomerizable azobenzene group at two fixed points of a conformationally flexible pi-conjugated quaterthiophene chain. The crystallographic structure shows that the two systems lie in parallel planes with a short interplane distance. Theoretical modelization and experimental analysis by 1H NMR and cyclic voltammetry unequivocally show that trans to cis photoisomerization of the azobenzene group induces dimensional and conformational changes in the underlying pi-conjugated system. These geometrical changes produce, in turn, an increase of the HOMO level and a narrowing of the HOMO-LUMO gap, thus providing a first example of photomechanical control of the electronic properties of the pi-conjugated system.     

Formal Asymmetric (4+1) Annulation Reaction between Sulfur Ylides and 1,3‐Dienes

A highly enantioselective synthesis of functionalized cyclopentanoids by a formal asymmetric (4+1) annulation strategy was developed. The methodology consists of a stereoselective cyclopropanation reaction between chiral sulfur ylides and 1,3‐dienes followed by a, in situ, stereospecific MgI₂‐catalyzed rearrangement of vinylcyclopropanes. This method is distinguished by a remarkable compatibility with functional groups and a high stereocontrol.