Engineering of Cysteine Residues Leads to Improved Production of a Human Dipeptidase Enzyme in <Emphasis Type="Italic">E. coli</Emphasis>

Low yields, poor folding efficiencies and improper disulfide bridge formation limit large-scale production of cysteine-rich proteins in Escherichia coli. Human renal dipeptidase (MDP), the only human β-lactamase known to date, is a homodimeric enzyme, which contains six cysteine residues per monomer. It hydrolyses penem and carbapenem β-lactam antibiotics and can cleave dipeptides containing amino acids in both d- and l-configurations. In this study, MDP accumulated in inactive form in high molecular weight, disulfide-linked aggregates when produced in the E. coli periplasm. Mutagenesis of Cys361 that mediates dimer formation and Cys93 that is unpaired in the native MDP led to production of soluble recombinant enzyme, with no change in activity compared with the wild-type enzyme. The removal of unpaired or structurally inessential cysteine residues in this manner may allow functional production of many multiply disulfide-linked recombinant proteins in E. coli.     

Observation of B0 meson decay to a 1 +/(1260)pi /+

We present a measurement of the branching fraction of the decay B(0)-->a1 (+/)(1260)pi(/+) with a1 (+/)(1260)-->pi(/+)pi(+/)pi(+/). The data sample corresponds to 218 x 10(6) BB[over ] pairs produced in e+e- annihilation through the Upsilon(4S) resonance. We measure the branching fraction Beta(B(0)-->a1(+/)(1260)pi(/+))Beta(a1(+/)(1260)-->pi(/+)pi(+/)pi(+/)) = (16.6+/1.9+/1.5) x 10(-6), where the first error quoted is statistical and the second is systematic.     

Measurement of the spin of the omega(-) hyperon

A measurement of the spin of the Omega(-) hyperon produced through the exclusive process Xi(c)(0)-->Omega(-)K(+) is presented using a total integrated luminosity of 116 fb(-1) recorded with the BABAR detector at the e(+)e(-) asymmetric-energy B factory at SLAC. Under the assumption that the Xi(c)(0) has spin 1/2, the angular distribution of the Lambda from Omega(-)-->LambdaK(-) decay is inconsistent with all half-integer Omega(-) spin values other than 3/2. Lower statistics data for the process Omega(c)(0)-->Omega(-)pi(+) from a 230 fb(-1) sample are also found to be consistent with Omega(-) spin 3/2. If the Xi(c)(0) spin were 3/2, an Omega(-) spin of 5/2 could not be excluded.     

Detection of pedestrians in far-infrared automotive night vision using region-growing and clothing distortion compensation

We present a night-time pedestrian detection system based on automotive infrared video processing. Far-infrared or thermal night vision is a technology well suited for automatic detection of pedestrians at night as they generally appear warmer than the background. However, the appearance of a pedestrian in IR video can vary dramatically depending on the physical properties of the clothing they wear, the time spent adjusting to the outside environment, and the ambient temperature. We highlight the difficulties of detection in low temperatures (below 8 °C) when pedestrians typically wear highly insulating clothing, which can lead to distortion of the IR signature of the pedestrian. A pre-processing step is presented, which compensates for this clothing-based distortion using vertically-biased morphological closing. Potential pedestrians (Regions of Interest) are then segmented using feature-based region-growing with high intensity seeds. Histogram of Oriented Gradients (HOG) features are extracted from candidates and utilised for Support Vector Machine classification. Positively classified targets are tracked between frames using a Kalman filter, adding robustness and increasing performance. The proposed system adapts not just to variations between images or video frames, but to variations in appearance between different pedestrians in the same image or frame. Results indicate improved performance compared to previous HOG–SVM automotive IR pedestrian detection systems, which utilised stereo IR cameras.     

Coupling tabulated chemistry with Large Eddy Simulation of turbulent reactive flows

A new modeling strategy is developed to introduce tabulated chemistry methods in the LES of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when the subgrid scale turbulence vanishes. The filtered flame structure is mapped by 1D filtered laminar premixed flames. Closure of the filtered progress variable and the energy balance equations are carefully addressed. The methodology is applied to 1D and 2D filtered laminar flames. These computations show the capability of the model to recover the laminar flame speed and the correct chemical structure when the flame wrinkling is completely resolved. The model is then extended to turbulent combustion regimes by introducing subgrid scale wrinkling effects on the flame front propagation. Finally, the LES of a 3D turbulent premixed flame is performed. To cite this article: R. Vicquelin et al., C. R. Mecanique 337 (2009).     

Measurement of the branching fractions of exclusive _B-->D(*)(pi)l-_nu l decays in events with a fully reconstructed B meson

We report a measurement of the branching fractions for _B-->D(*)(pi)l- _nu(l) decays based on 341.1 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II e+ e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- -->D(0)l-_nu(l)=(2.33+/-0.09(stat)+/-0.09(syst)%, B(B- -->D(*0)l-_nu(l)=(5.83+/-0.15(stat) +/-0.30(syst) %, B(_B(0)-->D+l-_nu(l)=(2.21+/-0.11(stat) +/-0.12(syst)%, B(_B(0)-->D(*)l-_nu(l)=(5.49+/-0.16(stat)+/-0.25(syst)%, B(B- -->D+pi-l-_nu(l)=(0.42+/-0.06(stat)+/-0.03(syst)%, B(B- -->D(*)+pi-l-_nu(l)=(0.59+/-0.05(stat)+/-0.04(syst)%, B(_B(0)-->D(0)pi+l-_nu(l)=(0.43+/-0.08(stat)+/-0.03(syst)%, and B(_B(0)-->D(*0)pi+l-_nu(l)=(0.48+/-0.08(stat)+/-0.04(syst)%.     

Preparation techniques alter the mineral and organic fractions of fish otoliths: insights using Raman micro-spectrometry

The high spatial resolution analysis of the mineral and organic composition of otoliths using Raman micro-spectrometry involves rigorous protocols for sample preparation previously established for microchemistry and trace elements analyses. These protocols often include otolith embedding in chemically neutral resin (i.e., resins which do not contain, in detectable concentration, elements usually sought in the otoliths). Such embedding may however induce organic contamination. In this paper, Raman micro-spectrometry reveals the presence of organic contamination onto the surface obtained from the use of epoxy resin, specifically Araldite. This contamination level varies depending on otolith structures. Core and checks, known as structural discontinuities, exhibit the most important level of contaminations. Our results suggest that otolith embedding with resin affects the organic matrix of the otolith, probably through an infiltration of the resin in the crystalline structure. The interpretation of chemical otolith signatures, especially Raman otolith signatures, and stable isotope analyses should then be revised in light of these results. In this respect, we propose a method for the correction of Raman otolith signatures for contamination effects.     

Comparative molecular field analysis of CCK-A antagonists using field-fit as an alignment technique. A convenient guide to design new CCK-A ligands

Summary Comparative molecular field analysis (CoMFA) has been used as a three-dimensional quantitative structure-activity relationship (QSAR) method to correlate the affinities of several antagonists towards CCK-A receptors with their steric and electrostatic fields. In this publication, we describe, for the first time, a field-fit operation as an alignment technique. These results could serve as a guide for the design of new non-peptide antagonists.     

Low-potential cyclometalated osmium(II) mediators of glucose oxidase

The osma(II)cycles [Os(phpy)(LL)(2)]PF(6) (LL = 1,10-phen (3a) and 4,4'-Me(2)-2,2'-bpy (3b)) are made from [(eta(6)-C(6)H(6))Os(micro-Cl)Cl](2) (1) either via transmetalation using the [Hg(phpy)(2)] organomercurial in MeOH or via the sp(2)-C-H bond cleavage of 2-phenylpyridine (phpyH) in MeCN to afford [(eta(6)-C(6)H(6))Os(phpy)Cl] or [(eta(6)-C(6)H(6))Os(phpy)(MeCN)]PF(6), respectively. The latter two react cleanly with LL to give 3a and 3b, the M(II/III) redox potentials of which equal 30 and -100 mV (vs Ag/AgCl), respectively. The electrochemically made Os(III) species oxidize rapidly reduced glucose oxidase. The second-order rate constant equals 1.1 x 10(7) M(-)(1) s(-)(1) for 3a at 25 degrees C, pH 7.