Biological agent inactivation in a flowing air stream by photocatalysis

The first decontamination of a flowing air stream polluted by bacteria, via room temperature non-germicidal UV photocatalysis on titania, leads to a simple and 99.1-99.8% efficient process.     

Characterisation of middle-distillates by comprehensive two-dimensional gas chromatography (GC x GC): A powerful alternative for performing various standard analysis of middle-distillates

The detailed characterisation of middle distillates is essential for a better understanding of reactions involved in refining process. Owing to higher resolution power and enhanced sensitivity, comprehensive two-dimensional gas chromatography (GC x GC) is a powerful tool for improving characterisation of petroleum samples. The aim of this paper is to compare GC x GC and various ASTM methods -- gas chromatography (GC), liquid chromatography (LC) and mass spectrometry (MS) -- for group type separation and detailed hydrocarbon analysis. Best features of GC x GC are demonstrated and compared to these techniques in terms of cost, time consumption and accuracy. In particular, a new approach of simulated distillation (SimDis-GC x GC) is proposed: compared to the standard method ASTM D2887 it gives unequal information for better understanding of conversion process.     

Neutron scattering study on dynamics of water molecules in MCM-41. 2. Determination of translational diffusion coefficient

Quasielastic neutron scattering (QENS) spectra of water-filled MCM-41 samples (pore diameters: 21.4 and 28.4 Angstrom) were measured over the temperature range 238-298 K and the momentum transfer range 0.31-0.99 A(-1) to investigate the dynamics of confined water molecules. The spectra, which consist mainly of contributions from the translational diffusion of water molecules, were analyzed by using the Lorentzian and the stretched exponential functions. Comparison of the fits indicated that the latter analysis is more reliable than the former one. The fraction of immobile water molecules located in the vicinity of the pore walls, which give an elastic component, was found to be 0.044-0.061 in both pores. The stretch exponent beta was determined as 0.66-0.80. It was shown that the translational diffusion of water molecules in the pores is decelerated by confinement and that the deceleration becomes marked with a decrease in pore size. The ratios of the translational diffusion coefficient D(T) of confined water to that of bulk water at room temperature were within a range of 0.47-0.63.     

Direct structural identification of polysaccharides from red algae by FTIR microspectrometry II: Identification of the constituents ofGracilaria verrucosa

The use of the infrared microspectrometry analytical technique as a new tool for the identification of the polysaccharides contained in the red algaeGracilaria verrucosa has demonstrated that in addition to agar spectra, features of the other coexisting constituents can also be obtained. Indeed, the infrared spectra recorded previously, all exhibit two important bands at about 1645 and 1530cm^–1. These two bands were not present in the infrared spectra of the extracted agars and they are expected to be due to the amide I and amide II protein vibrations. In order to confirm this supposition, we have applied some enzymatic treatments, firstly on the whole algae and secondly on the ground algae (the algae has been previously depigmented and then dehydrated). Agarase, xylanase and cellulase were successively carried out on the algae. The last resulting spectrum, i.e. the spectrum obtained from the fraction which has undergone the three treatments, has been identified to be characteristic of proteins. This spectrum contained, both the amide I and II vibrations and in addition, weak absorption at 1230 cm^–1 due probably to the amide III, was observed. Additional weak bands in the 1400–1300 cm^–1 due to the different skeletal modes of the proteins were also present in this spectrum.The infrared spectra also revealed that the use of the enzymatic treatments on the ground algae is more efficient than when it is carried out on the whole algae.     

Chiral 3-aminopyrrolidines as a rigid diamino scaffold for organocatalysis and organometallic chemistry

Over 20 new and easily prepared diamines were screened for the asymmetric Morita–Baylis–Hillman reaction. Chiral non-racemic 3-(N,N-dimethylamino)-1-methylpyrrolidine was found to promote efficiently the reaction of methyl vinyl ketone and substituted benzaldehydes. Enantiomeric excesses up to 73% were reached with electron-deficient benzaldehyde derivatives. After a simple deprotonation, one of these diamines was transformed into a chiral mixed aggregate for the enantioselective synthesis of (R)-1-o-tolylethanol with 76% ee.     

Palladium-mediated arylation of 3-aminopiperidines and 3-aminopyrrolidines

This paper describes the palladium-catalyzed arylation of 1-substituted 3-aminopyrrolidines or piperidines. Palladium(0) (1-2 mol %) in conjunction with "Buchwald's ligand" [2-(dimethylamino)-2'-(dicyclohexylphosphine)biphenyl] was shown to be the catalyst of choice for the coupling with aryl bromides or chlorides. When bromobenzene was used, a strong temperature effect was noticed. Whereas no reaction occurred at 100 degrees C, yields higher than 85% were obtained at 130 degrees C for each substrate. Such an effect was not observed when diphosphines were used. Whereas Xantphos and, to a lesser extent BINAP, were moderately efficient in the coupling of all diamines, the palladium-mediated arylation in the presence of monophosphines was strongly dependent on the substrate. The results suggest the participation of both nitrogens of the aminoheterocycle in the reactive intermediate. This participation could also account for the highly selective arylation of the endocyclic nitrogen of unsubstituted 3-aminopyrrolidine or piperidine. Optimal conditions were found for the arylation using 2- or 4-substituted electron-poor or enriched aryl halides.     

Loading capacity of carrier ampholytes--based buffers in capillary electrophoresis

Narrow pH cuts of carrier ampholytes (CAs), originally designed for IEF, have been used as BGEs in CE. Their physicochemical properties, rather high buffering capacity and low conductivity, allow very efficient protein separations under high electric field strength. Due to their isoelectric properties, CA BGEs are expected to present a low ionic concentration and consequently a low loading capacity. In this study, we developed a simple method that allows the estimation of the loading capacity of a UV-absorbing BGE by CE. We first characterized in terms of loading capacity, classical ammediol-chromate UV-absorbing BGEs and a 10 mM histidine solution, a classical isoelectric buffer. Then, the loading capacity of four different CA-based BGEs has been assessed. Experimental results have shown that the CA-based buffers were presenting a rather high loading capacity, comparable to classical buffer ones and far higher than the one of the 10 mM histidine solution.     

VUV photoionization of acetamide studied by electron/ion coincidence spectroscopy in the 8-24 eV photon energy range

A VUV photoionization study of acetamide was carried out over the 8-24 eV photon energy range using synchrotron radiation and photoelectron/photoion coincidence (PEPICO) spectroscopy. Threshold photoelectron photoion coincidence (TPEPICO) measurements were also made. Photoion yield curves and branching ratios were measured for the parent ion and six fragment ions. The adiabatic ionization energy of acetamide was determined as I.E. (1²A′) = (9.71 ± 0.02) eV, in agreement with an earlier reported photoionization mass spectrometry (PIMS) value. The adiabatic energy of the first excited state of the ion, 1²A″, was determined to be ≈10.1 eV. Assignments of the fragment ions and the pathways of their formation by dissociative photoionization were made. The neutral species lost in the principal dissociative photoionization processes are CH₃, NH₂, NH₃, CO, HCCO and NH₂CO. Heats of formation are derived for all ions detected and are compared with literature values. Some astrophysical implications of these results are discussed.     

Reflected BSDEs and robust optimal stopping for dynamic risk measures with jumps

We study the optimal stopping problem for dynamic risk measures represented by Backward Stochastic Differential Equations (BSDEs) with jumps and its relation with reflected BSDEs (RBSDEs). The financial position is given by an RCLL adapted process. We first state some properties of RBSDEs with jumps when the obstacle process is RCLL only. We then prove that the value function of the optimal stopping problem is characterized as the solution of an RBSDE. The existence of optimal stopping times is obtained when the obstacle is left-upper semi-continuous along stopping times. Finally, we investigate robust optimal stopping problems related to the case with model ambiguity and their links with mixed control/optimal stopping game problems. We prove that, under some hypothesis, the value function is equal to the solution of an RBSDE. We then study the existence of saddle points when the obstacle is left-upper semi-continuous along stopping times.