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171.
A new CE method was developed for the identification and quantitation of inorganic cations in post‐blast residues. The simultaneous analysis in 20 min total runtime of eight cations in post‐blast residues (ammonium, potassium, monomethylammonium, calcium, sodium, magnesium, strontium), plus lithium cation as the internal reference, was carried out with a BGE involving a non‐CMR (carcinogenic, mutagenic, and harmful to reproduction) chromophore (guanidinium cation) and a double‐layer modified capillary (hexadimethrine bromide/polyvinylsulfonate). A study of UV detection conditions using guanidinium ion as the probe led us to set the analysis and reference wavelengths and their associated bandwidths as well as the probe concentration fixed at 15 mM. The successive multiple ionic‐polymer layer approach limited the cation adsorption on capillary wall and improved the EOF stability. These caused a significant improvement in method repeatability. Intermediate precisions were 2.4% for corrected areas and 1.3% for normalized migration times. Limits of detection close to 1 mg/L for all cations were obtained. The matrix effects were studied with chemometric approach for different matrices representative of those collected after explosion. Tests with blank matrix extracts of soil, cloth, and with simulated matrix extract containing 800 mg/L Ca2+ and 500 mg/L Fe2+ were carried out and no significant matrix effects were observed. Finally, analyses of real residues collected after cash dispenser and homemade firework explosions demonstrate excellent correlation between the CE results and those obtained with the ion chromatography method used routinely. 相似文献
172.
Hosseinidoust Z Van de Ven TG Tufenkji N 《Langmuir : the ACS journal of surfaces and colloids》2011,27(9):5472-5480
The rise of antibiotic-resistant bacteria has directed substantial attention toward the use of bacteriophages as a means to control bacterial populations. It has been proposed that bacteriophages can be applied as a coating on surfaces in healthcare settings or on indwelling medical devices to create an antimicrobial surface. In this study, antimicrobial model surfaces functionalized with five different types of bacteriophage were prepared and characterized with X-ray photoelectron spectroscopy and atomic force microscopy. The bacterial capture efficiency of these functionalized surfaces was studied for two common bacteria, Escherichia coli and Salmonella typhimurium. Binding of the phages to a solid surface affected their biofunctionality as expressed by the capture efficiency and rate of host membrane disruption. Moreover, the size and shape of the bacteriophage and positioning of its specific binding proteins significantly affected its bacterial capture capability in the immobilized state. Symmetric bacteriophages were found to be a better choice for antibacterial surfaces compared to more asymmetric tailed bacteriophages. Immobilized phages were found to disrupt the membranes of attached bacteria and are thus proposed as a candidate for antimicrobial surfaces. 相似文献
173.
Canioni R Marchal-Roch C Leclerc-Laronze N Haouas M Taulèlle F Marrot J Paul S Lamonier C Paul JF Loridant S Millet JM Cadot E 《Chemical communications (Cambridge, England)》2011,47(22):6413-6415
{Mo(132)} Keplerate anion reacts with tellurites to give a soluble precursor to produce in hydrothermal conditions single-phase M1 MoVTeO light-alkanes oxidation catalyst. Characterization of this Te-containing intermediate by single-crystal X-ray diffraction, (125)Te NMR, UV-visible and redox titration reveals a molybdotellurite anion as a crown-capped Keggin derivative. 相似文献
174.
Lamoureux N Mercier X Pauwels JF Desgroux P 《The journal of physical chemistry. A》2011,115(21):5346-5353
NCO is a short-lived species involved in NO(x) formation. It has never been quantitatively measured in flame conditions. In the present study, laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) were combined to measure NCO radical concentrations in premixed low-pressure flames (p = 5.3 kPa). NCO LIF excitation spectrum and absorption spectrum (using CRDS) measured in a stoichiometric CH(4)/O(2)/N(2)O/N(2) flame were found in good agreement with a simulated spectrum using PGOPHER program that was used to calculate the high-temperature absorption cross section of NCO in the A(2)Σ(+)-X(2)Π transition around 440.479 nm. The relative NCO-LIF profiles were measured in stoichiometric CH(4)/O(2)/N(2)O/N(2) flames where the ratio N(2)O/O(2) was progressively decreased from 0.50 to 0.01 and in rich CH(4)/O(2)/N(2) premixed flames. Then, the LIF profiles were converted into NCO mole fraction profiles from the absorption measurements using CRDS in a N(2)O-doped flame. 相似文献
175.
176.
Dr. Louisa J. Esdaile Dr. Llew Rintoul Mean See Goh Khalissa Merahi Dr. Nathalie Parizel Dr. R. Mark Wellard Dr. Sylvie Choua Prof. Dennis P. Arnold 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3430-3446
We report the synthesis and characterisation of new examples of meso‐hydroxynickel(II) porphyrins with 5,15‐diphenyl and 10‐phenyl‐5,15‐diphenyl/diaryl substitution. The OH group was introduced by using carbonate or hydroxide as nucleophile by using palladium/phosphine catalysis. The NiPor?OHs exist in solution in equilibrium with the corresponding oxy radicals NiPor?O.. The 15‐phenyl group stabilises the radicals, so that the 1H NMR spectra of {NiPor?OH} are extremely broad due to chemical exchange with the paramagnetic species. The radical concentration for the diphenylporphyrin analogue is only 1 %, and its NMR line‐broadening was able to be studied by variable‐temperature NMR spectroscopy. The EPR signals of NiPor?O. are consistent with somewhat delocalised porphyrinyloxy radicals, and the spin distributions calculated by using density functional theory match the EPR and NMR spectroscopic observations. Nickel(II) meso‐hydroxy‐10,20‐diphenylporphyrin was oxidatively coupled to a dioxo‐terminated porphodimethene dyad, the strongly red‐shifted electronic spectrum of which was successfully modelled by using time‐dependent DFT calculations. 相似文献
177.
Dr. Gaëlle Charron Dr. Elena Malkin Dr. Guillaume Rogez Dr. Luke J. Batchelor Dr. Sandra Mazerat Dr. Régis Guillot Dr. Nathalie Guihéry Dr. Anne‐Laure Barra Dr. Talal Mallah Dr. Hélène Bolvin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16850-16862
By using complementary experimental techniques and first‐principles theoretical calculations, magnetic anisotropy in a series of five hexacoordinated nickel(II) complexes possessing a symmetry close to C2v, has been investigated. Four complexes have the general formula [Ni(bpy)X2]n+ (bpy=2,2′‐bipyridine; X2=bpy ( 1 ), (NCS?)2 ( 2 ), C2O42? ( 3 ), NO3? ( 4 )). In the fifth complex, [Ni(HIM2‐py)2(NO3)]+ ( 5 ; HIM2‐py=2‐(2‐pyridyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazolyl‐1‐hydroxy), which was reported previously, the two bpy bidentate ligands were replaced by HIM2‐py. Analysis of the high‐field, high‐frequency electronic paramagnetic resonance (HF‐HFEPR) spectra and magnetization data leads to the determination of the spin Hamiltonian parameters. The D parameter, corresponding to the axial magnetic anisotropy, was negative (Ising type) for the five compounds and ranged from ?1 to ?10 cm?1. First‐principles SO‐CASPT2 calculations have been performed to estimate these parameters and rationalize the experimental values. From calculations, the easy axis of magnetization is in two different directions for complexes 2 and 3 , on one hand, and 4 and 5 , on the other hand. A new method is proposed to calculate the g tensor for systems with S=1. The spin Hamiltonian parameters (D (axial), E (rhombic), and gi) are rationalized in terms of ordering of the 3 d orbitals. According to this orbital model, it can be shown that 1) the large magnetic anisotropy of 4 and 5 arises from splitting of the eg‐like orbitals and is due to the difference in the σ‐donor strength of NO3? and bpy or HIM2‐py, whereas the difference in anisotropy between the two compounds is due to splitting of the t2g‐like orbitals; and 2) the anisotropy of complexes 1 – 3 arises from the small splitting of the t2g‐like orbitals. The direction of the anisotropy axis can be rationalized by the proposed orbital model. 相似文献
178.
A stepwise approach to the formation of heterometallic discrete complexes and infinite architectures
Baudron SA Hosseini MW Kyritsakas N Kurmoo M 《Dalton transactions (Cambridge, England : 2003)》2007,(11):1129-1139
A strategy for the controlled construction of heterobimetallic discrete complexes and 1-D coordination networks is presented. The organic ligand based on the methanedithiolate group and the 4,5-diazafluorene moiety behaving as primary and secondary coordination poles respectively leads to the formation of a series of discrete metal complexes with various geometries via binding through the dithiolate site. The observed coordination geometries range from square-planar for Ni(ii) and Pd(ii) to distorted tetrahedral for Zn(ii) and Hg(ii). The square-planar Pd(ii) complex affords a discrete bimetallic trinuclear complex when treated with a capped Ni(ii) center. All three Ni(ii), Pd(ii) and Hg(ii) discrete complexes have been also shown to behave as metallatectons leading to the generation of infinite networks in the presence of bridging cations such as sodium. 相似文献
179.
Werner Seebacher Marcel Kaiser Reto Brun Robert Saf Robert Weis 《Monatshefte für Chemie / Chemical Monthly》2007,138(7):709-714
Summary. We synthesized several 4-aminobicyclo[2.2.2] octan-2-ols and 4-amino-2-azabicyclo[3.2.2]nonanes from epimerized 4-amino-bicyclo[2.2.2]octan-2-ones.
The new compounds were tested for their activity against Trypanosoma b. rhodesiense, the causative organism of East African sleeping sickness, and Plasmodium falciparum K
1, a multiresistant protozoan parasite which causes Malaria tropica. The results are compared to the activities of their formerly
synthesized stereoisomers and structure–activity relationships are discussed. 相似文献
180.
Determination of polydimethylsiloxane-air partition coefficients using headspace sorptive extraction
Polydimethylsiloxane-air partition coefficients (K(PDMS-A)) were determined using direct headspace analysis and headspace sorptive extraction (HSSE) with polydimethylsiloxane-coated (PDMS) stir bars. The partition coefficients were investigated for three compounds, p-dichlorobenzene (PDCB), naphthalene and camphor, all of which sublimate at room temperature and find use as moth repellents. In order to determine the K(PDMS-A) values of these compounds, the air concentration and the concentration present on PDMS, both at equilibrium, were measured. The results indicate that PDMS-air partition coefficients are proportional to octanol-air partition coefficients. Thus, the latter could be used to estimate the extraction efficiency of PDMS for these compounds in air. Alternatively, octanol-air partition coefficients for organic compounds could be estimated from the PDMS-air partition coefficient values. As expected, the PDMS-air (or octanol-air) partition coefficient increased with decreasing temperature. Importantly, the partition coefficients determined at saturated vapor pressures were lower than the values determined at lower analyte concentrations, with the differences being greater for compounds with larger partition coefficients. Consequently, caution should be exercised when applying K(PDMS-A) values determined at high analyte concentrations to measurements at lower concentrations, especially when the partition coefficients are large. 相似文献