Influence de la longue mémoire sur le comportement asymptotique d'estimateurs fonctionnelsInfluence of long memory on the asymptotic behaviour of functional estimators

This Note gives asymptotic results for kernel estimators of several functionals (density, failure rate and distribution functions) of a long-memory process. The results are presented in such a way as to highlight the influence of the long dependence on the rates of convergence. To cite this article: G. Estevez-Perez, P. Vieu, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 271–274.     

Effects of processing on the structure of zein/oleic Acid films investigated by x-ray diffraction

Zein films plasticized with oleic acid were formed by solution casting, by the stretching of moldable resins, and by blown film extrusion. The effects of the forming process on film structure were investigated by X-ray diffraction. Wide-angle X-ray scattering (WAXS) patterns showed d-spacings at 4.5 and 10 A, which were attributed to the zein alpha-helix backbone and inter-helix packing, respectively. The 4.5 A d-spacing remained stable under processing while the 10 A d-spacing varied with processing treatment. Small-angle X-ray scattering (SAXS) detected a long-range periodicity for the formed films but not for unprocessed zein, which suggests that the forming process-promoted film structure development is possibly aided by oleic acid. The SAXS d-spacing varied among the samples (130-238 A) according to zein origin and film-forming method. X-ray scattering data suggest that the zein molecular structure resists processing but the zein supramolecular arrangements in the formed films are dependent on processing methods. Structural model for a zein molecular aggregate (based on Matsushima et al.10). Rectangular prisms of individual zein molecules are hexagonally aligned parallel to each other.     

A Protein‐Resistant Matrix for Electrochemical Based Recognition Assays

In this work, two well known polymers, carboxymethyl dextran and poly(ethyleneglycol), are used for easily producing a platform for electrochemical affinity assays, avoiding nonspecific adsorption of proteins. In this way, modified electrode surfaces able to bind a recognition agent are constructed through simple and reliable reactions.     

First- and second-order multivariate calibration applied to biological samples: determination of anti-inflammatories in serum and urine

First- and second-order multivariate calibration of fluorescence data have been compared as regards the determination of anti-inflammatories and metabolites in the biological fluids serum and urine. The simultaneous resolution of naproxen-salicylic acid mixtures in serum and naproxen-salicylic acid-salicyluric acid mixtures in urine was accomplished and employed for a discussion of the relative advantages of the applied chemometric tools. The analysis of second-order fluorescence excitation-emission matrices was performed using iteratively reweighted generalized rank annihilation method (IRGRAM), parallel factor analysis (PARAFAC), and self-weighted alternating trilinear decomposition (SWATLD). The results were compared with first-order fluorescence emission data analyzed with partial least-squares regression (PLS). In all cases, the performance of the methods was improved through the formation of inclusion complexes of the analytes with beta-cyclodextrin. The concentration ranges in which the analytes could be determined were as follows: naproxen, 0-250 ng mL(-1) in serum and 0-200 ng mL(-1) in urine; salicylic acid, 0-500 ng mL(-1) in serum and 0-300 ng mL(-1) in urine, and salicyluric acid, 0-300 ng mL(-1) in urine.     

The crystal structure of eudesma-4(15),7(11)-dien-8α, 12-olide: a sesquiterpene lactone fromTrattinickia rhoifolia Willd

The title compound, formula C₁₅H₂₀O₂, is orthorhombic, P2₁2₁2₁ witha=8.747(2),b=12.025(3),c=12.554(3)Å,Z=4, andD _m =1.32(2)g/ml. The structural analysis shows that the compound corresponds to eudesma-4(15),7(11)-dien-8,12-olide, a sesquiterpene lactone previously isolated fromAster umbellatus but whose crystal structure was unknown.     

Flow-through optical fiber sensor for automatic sulfide determination in waters by multisyringe flow injection analysis using solid-phase reflectometry

A software-controlled flow-through optical fiber diffuse reflectance sensor capitalized on the implementation of disk-based solid-phase pre-concentration schemes in a multisyringe flow injection analysis (MSFIA) set-up is proposed for the trace determination of sulfide in environmental waters and wastewaters. The fully automated flowing methodology is based on Fischer's coupling reaction of sulfide with N,N-dimethyl-p-phenylenediamine (DMPD) in the presence of Fe(iii) as oxidizing reagent in a 0.5 M HCl medium. The on-line generated methylene blue dye is subsequently delivered downstream to a dedicated optode cell furnished with an octadecyl-chemically modified (C(18)) disk, while continuously recording the diffuse reflectance spectrum of the pre-concentrated compound. A double regeneration protocol is finally executed to warrant minimum background noise and negligible baseline. Under the optimized chemical and hydrodynamic conditions, the optosensing MSFIA method features coefficients of variation better than 0.7%(n= 10) at 50 microg l(-1) concentration, a linear working range of 20-200 microg l(-1) sulfide, a 3sigma(blank) detection limit of 2.9 microg l(-1) sulfide and an injection throughput of 8 h(-1) for a pre-concentration sample volume of 2.9 ml. The interfacing of the robust and versatile multisyringe flow injection-based optode with a plug-in spectrophotometer furnished with a light emitting diode assures the miniaturization of the overall flow analyzer, which is, thus, readily adaptable to real-time monitoring schemes. The potential of the multisyringe flow method was assessed via the determination of sulfide traces in water samples of different complexity (namely, freshwater, seawater and wastewater).     

Metal-catalyzed anaerobic disproportionation of hydroxylamine. Role of diazene and nitroxyl intermediates in the formation of N2, N2O, NO+, and NH3

The catalytic disproportionation of NH(2)OH has been studied in anaerobic aqueous solution, pH 6-9.3, at 25.0 degrees C, with Na(3)[Fe(CN)(5)NH(3)].3H(2)O as a precursor of the catalyst, [Fe(II)(CN)(5)H(2)O](3)(-). The oxidation products are N(2), N(2)O, and NO(+) (bound in the nitroprusside ion, NP), and NH(3) is the reduction product. The yields of N(2)/N(2)O increase with pH and with the concentration of NH(2)OH. Fast regime conditions involve a chain process initiated by the NH(2) radical, generated upon coordination of NH(2)OH to [Fe(II)(CN)(5)H(2)O](3)(-). NH(3) and nitroxyl, HNO, are formed in this fast process, and HNO leads to the production of N(2), N(2)O, and NP. An intermediate absorbing at 440 nm is always observed, whose formation and decay depend on the medium conditions. It was identified by UV-vis, RR, and (15)NMR spectroscopies as the diazene-bound [Fe(II)(CN)(5)N(2)H(2)](3)(-) ion and is formed in a competitive process with the radical path, still under the fast regime. At high pH's or NH(2)OH concentrations, an inhibited regime is reached, with slow production of only N(2) and NH(3). The stable red diazene-bridged [(NC)(5)FeHN=NHFe(CN)(5)](6)(-) ion is formed at an advanced degree of NH(2)OH consumption.     

Metal-oxygen-metal arrays in lamellar hybrid materials: cobalt and manganese 4-cyclohexene-1,2-dicarboxylates

We have obtained three layered hybrid materials from the hydrothermal reaction of 4-cyclohexene-1,2-dicarboxylic acid with Co and Mn salts: Co(C(8)H(8)O(4))[1], Mn(H(2)O)(C(8)H(8)O(4))[2], and Mn(4)(H(2)O)(C(8)H(8)O(4))(4).0.3(H(2)O)[3]. The structures for all materials were solved by single-crystal XRD ([1]P1, a=4.805(2) A, b=6.650(3) A, c=12.960(6) A, alpha=98.285(7) degrees, beta=98.986(7) degrees, gamma=95.689(7) degrees, V= 401.6(3) A(3), R(1)= 0.0438; [2] P2(1)/c, a=11.151(2) A, b=11.330(2) A, c=7.6560(15) A, beta=108.813(3) degrees , V=915.6(3) A(3), R(1)=0.0412; [3] P1, a= 11.412(3) A, b=12.136(4) A, c=13.809(4) A, alpha=104.703(6) degrees, beta=103.207(6) degrees, gamma=92.468(5) degrees, V=1790.6(9) A(3), R(1)=0.1056). While all three structures are two-dimensional overall, the metal-oxygen-metal dimensionality within the layers varies from isolated metal atoms in the case of [1] to 1D ribbons of vertex sharing MnO(6) octahedra [2] and 2D arrays of edge- and vertex-sharing polyhedra in [3].     

2-Mercaptomethyl-thiazolidines use conserved aromatic–S interactions to achieve broad-range inhibition of metallo-β-lactamases

Infections caused by multidrug resistant (MDR) bacteria are a major public health threat. Carbapenems are among the most potent antimicrobial agents that are commercially available to treat MDR bacteria. Bacterial production of carbapenem-hydrolysing metallo-β-lactamases (MBLs) challenges their safety and efficacy, with subclass B1 MBLs hydrolysing almost all β-lactam antibiotics. MBL inhibitors would fulfil an urgent clinical need by prolonging the lifetime of these life-saving drugs. Here we report the synthesis and activity of a series of 2-mercaptomethyl-thiazolidines (MMTZs), designed to replicate MBL interactions with reaction intermediates or hydrolysis products. MMTZs are potent competitive inhibitors of B1 MBLs in vitro (e.g., K_i = 0.44 μM vs. NDM-1). Crystal structures of MMTZ complexes reveal similar binding patterns to the most clinically important B1 MBLs (NDM-1, VIM-2 and IMP-1), contrasting with previously studied thiol-based MBL inhibitors, such as bisthiazolidines (BTZs) or captopril stereoisomers, which exhibit lower, more variable potencies and multiple binding modes. MMTZ binding involves thiol coordination to the Zn(ii) site and extensive hydrophobic interactions, burying the inhibitor more deeply within the active site than d/l-captopril. Unexpectedly, MMTZ binding features a thioether–π interaction with a conserved active-site aromatic residue, consistent with their equipotent inhibition and similar binding to multiple MBLs. MMTZs penetrate multiple Enterobacterales, inhibit NDM-1 in situ, and restore carbapenem potency against clinical isolates expressing B1 MBLs. Based on their inhibitory profile and lack of eukaryotic cell toxicity, MMTZs represent a promising scaffold for MBL inhibitor development. These results also suggest sulphur–π interactions can be exploited for general ligand design in medicinal chemistry.

Metallo-β-lactamases (MBLs) are major culprits of resistance to carbapenems in bacteria. A series of thiazolidines are potent MBL inhibitors, restoring the activity of carbapenems. Metal binding and sulphur–π interactions are key to inhibition.     

Determination of mazindol in human oral fluid by high performance liquid chromatography–electrospray ionization mass spectrometry

Brazil is one of the countries most affected by abuse of stimulant medications by professional drivers, especially fenproporex, amfepramone and mazindol. Even though their sale is banned, they can be found in illegal markets, such as those located on the country's borders. The use of oral fluid to monitor drug levels has many advantages over plasma and urine because it is noninvasive, easier to collect and more difficult to adulterate. The aim of this study was to develop and validate a sensitive and specific method to quantify mazindol in human oral fluid by liquid chromatography–mass spectrometry (LC‐MS). The LC system consisted of an LC‐MS system operated in selected ion monitoring mode. The mobile phase was composed of water at pH 4.0, acetonitrile and methanol (60:15:25 v/v/v) at a flow rate of 1.0 mL/min and propranolol was used as internal standard. Total running time was 10 min. The lower limit of quantification was 0.2 ng/mL and the method exhibited good linearity within the 0.2–20 ng/mL range (r = 0.9987). A rapid, specific, sensitive, linear, precise and accurate method was developed for determination of mazindol in human oral fluid according to European Medicines Agency guidelines, and is suitable for monitoring mazindol levels in oral fluid of professional drivers. Copyright © 2014 John Wiley & Sons, Ltd.