Development, uncertainty estimation and application of a LC-MS/MS method for simultaneous determination of acrylamide and 4hydroxy2,5-dimethyl-3(2H)-furanone in baby food.

Acrylamide, a heatgenerated food contaminant, has been associated with neurotoxic effects in humans and was classified under group 2A as a probable human carcinogen by the International Agency Research on Cancer (IARC) [1]. Additionally, hydroxy2,5dimethyl3(2H)furanone (DMHF), a furanic compound, has demonstrated genotoxic effects in vitro as also in vivo [2]. In this study, a new accurate liquid chromatographytandem mass spectrometry method was developed for simultaneous analysis of acrylamide and DMHF in baby food. To the best of our knowledge, this is the first study on DMHF in baby foods as well as pioneer in acrylamide monitoring in baby foods from Brazil. For this, a sample preparation method was optimized, which involves acetonitrile-based extraction, followed by dispersive solidphase extraction (dSPE) using primary and secondary amine sorbent (PSA) and then, a final cleanup of extract by solid phase extraction (SPE). An ACQUITY ultraperformance liquid chromatography (UPLC) system interfaced to a Quattro Premier XE triple quadrupole mass spectrometer with electrospray ionization (ESI) source (WATERS) was employed for analysis. The chromatographic separation was achieved on a C8 column (150 mm x 2.1 mm i.d., 5?m particle size) at 30ºC with a flow rate of 0.2 ml/min, and the injection volume was 20 ?l. The mobile phases consisted of MilliQ water (A) and acetonitrile (B), both containing 0.01% of formic acid, and the elution gradient employed was as follows: 0 min, 5% B? 5 min, 50% B? 5.1 min, 100% B? 6?10 min 5% B, resulting in a total run time of 10 min. Data acquisition was carried out in selective reaction monitoring (SRM) mode employing ESI in positive mode, whose conditions were: capillary voltage 3 KV? temperatures of source at 120°C and desolvation at 400°C and gas flow 500 L/h. The collision energy and cone voltage were 10 and 25 V. The m/z 55 and 44 (acrylamide) and m/z 101 and 83 (DMHF) were used respectively for quantitative and confirmative purposes. As a great result, the optimized sample preparation method provided sufficient removal of potential analytical interfering commonly present in fruitbased matrices, the amino acid valine, without affecting the sensitivity, trueness and precision of the method. Limits of detection (LOD) and quantification (LOQ) of 10 and 20 ?g/kg were obtained for both analytes. Linearity in solventonly and matrixmatched calibration curves was achieved in the range between 10 and 300 ?g/kg, with determination coefficients higher than 0.99. Matrix effects, calculated from slopes obtained for solvent and matrixmatched calibrations, were observed for acrylamide (?45%) and DMHF(?11%). Recoveries between 75 and 115% were obtained for the two studied compounds from blank baby foods spiked at 20 (LOQ), 100 and 200 ?g/kg. Precision, under repeatability and withinlaboratory reproducibility conditions, was verified with RSD values < 20%. In addition, by using data obtained from inhouse validation, was possible to estimate the expanded measurement uncertainty for the levels of acrylamide and DMHF detected in the samples, whose values were lower than 25%. The applicability of proposed analytical method was evaluated by analyzing 20 baby food samples available in Brazilian markets

Theta dependence of the vacuum energy in the SU(3) gauge theory from the lattice

We report on a precise computation of the topological charge distribution in the SU(3) Yang--Mills theory. It is carried out on the lattice with high statistics Monte Carlo simulations by employing the definition of the topological charge suggested by Neuberger's fermions. We observe significant deviations from a Gaussian distribution. Our results disfavour the theta behaviour of the vacuum energy predicted by instanton models, while they are compatible with the expectation from the large Nc expansion.Comment: Plain latex, 4 pages, 2 figure

Summary of the SUSY Working Group of the 1999 Les Houches Workshop

The results obtained by the Working Group on Supersymmetry at the 1999 Les Houches Workshop on Collider Physics are summarized. Separate chapters treat "general" supersymmetry, R-parity violation, gauge mediated supersymmetry breaking, and anomaly mediated supersymmetry breaking.Comment: LaTeX, 110 pages with numerous .ps and .eps files. proc.tex is main tex fil

Remarks on the forces generated by two-neutrino exchange

A brief up-to-date review of the long range forces generated by two neutrino exchange is presented. The potential due to exchange of a massive neutrino-antineutrino pair between particles carrying weak charge might be larger than expected if the neutrinos have not only masses but also magnetic moments close to the present experimental bounds. It still remains too small to be observable.Comment: 10 pages, 3 figures. One figure added. Accepted for publication in EPJ

First Results from Commissioning of the Phin Photo Injector for CTF3

Installation of the new photo-injector for the CTF3 drive beam (PHIN) has been completed on a stand-alone test bench. The photo-injector operates with a 2.5 cell RF gun at 3 GHz, using a Cs2Te photocathode illuminated by a UV laser beam. The test bench is equipped with transverse beam diagnostic as well as a 90-degree spectrometer. A grid of 100 micrometer wide slits can be inserted for emittance measurements. The laser used to trigger the photo-emission process is a Nd:YLF system consisting of an oscillator and a preamplifier operating at 1.5 GHz and two powerful amplifier stages. The infrared radiation produced is frequency quadrupled in two stages to obtain the UV. A Pockels cell allows adjusting the length of the pulse train between 50 nanoseconds and 50 microseconds. The nominal train length for CTF3 is 1.272 microseconds (1908 bunches). The first electron beam in PHIN was produced in November 2008. In this paper, results concerning the operation of the laser system and measurements performed to characterize the electron beam are presented

Problems in Lattice Gauge Fixing

We review many topics and results about numeric gauge fixing in lattice QCD.Comment: 47 pages, 16 eps figures. Review article sent to IJMP

A major genetic locus controlling natural Plasmodium falciparum infection is shared by East and West African Anopheles gambiae

Background: Genetic linkage mapping identified a region of chromosome 2L in the Anopheles gambiae genome that exerts major control over natural infection by Plasmodium falciparum. This 2L Plasmodium-resistance interval was mapped in mosquitoes from a natural population in Mali, West Africa, and controls the numbers of P. falciparum oocysts that develop on the vector midgut. An important question is whether genetic variation with respect to Plasmodium-resistance exists across Africa, and if so whether the same or multiple geographically distinct resistance mechanisms are responsible for the trait. Methods: To identify P falciparum resistance loci in pedigrees generated and infected in Kenya, East Africa, 28 microsatellite loci were typed across the mosquito genome. Genetic linkage mapping was used to detect significant linkage between genotype and numbers of midgut oocysts surviving to 7–8 days post-infection. Results: A major malaria-control locus was identified on chromosome 2L in East African mosquitoes, in the same apparent position originally identified from the West African population. Presence of this resistance locus explains 75% of parasite free mosquitoes. The Kenyan resistance locus is named EA_Pfin1 (East Africa_ Plasmodium falciparum Infection Intensity). Conclusion: Detection of a malaria-control locus at the same chromosomal location in both East and West African mosquitoes indicates that, to the level of genetic resolution of the analysis, the same mechanism of Plasmodium-resistance, or a mechanism controlled by the same genomic region, is found across Africa, and thus probably operates in A. gambiae throughout its entire range

Multijoule scaling of laser-induced condensation in air

Using 100 TW laser pulses, we demonstrate that laser-induced nanometric particle generation in air increases much faster than the beam-averaged incident intensity. This increase is due to a contribution from the photon bath, which adds up with the previously identified one from the filaments and becomes dominant above 550 GW/cm2. It appears related to ozone formation via multiphotondissociation of the oxygen molecules and demonstrates the critical need for further increasing the laser energy in view of macroscopic effects in laser-induced condensation

Experimental Studies of Temporal Electron Beam Shaping at the DUV-FEL Accelerator

The photoinjectors for future short wavelength high brightness accelerator driven light sources need to produce an electron beam with ultra-low emittance. At the DUVFEL facility at BNL, we studied the effect of longitudinally shaping the photocathode laser pulses on the electron beam dynamics. We report on measurements of the longitudinal phase space distributions and the time-resolved transverse beam parameters for both a Gaussian and a flat-top temporal laser pulse profile

Effects of deletion of the Streptococcus pneumoniae lipoprotein diacylglyceryl transferase gene lgt on ABC transporter function and on growth in vivo

Lipoproteins are an important class of surface associated proteins that have diverse roles and frequently are involved in the virulence of bacterial pathogens. As prolipoproteins are attached to the cell membrane by a single enzyme, prolipoprotein diacylglyceryl transferase (Lgt), deletion of the corresponding gene potentially allows the characterisation of the overall importance of lipoproteins for specific bacterial functions. We have used a Δlgt mutant strain of Streptococcus pneumoniae to investigate the effects of loss of lipoprotein attachment on cation acquisition, growth in media containing specific carbon sources, and virulence in different infection models. Immunoblots of triton X-114 extracts, flow cytometry and immuno-fluorescence microscopy confirmed the Δlgt mutant had markedly reduced lipoprotein expression on the cell surface. The Δlgt mutant had reduced growth in cation depleted medium, increased sensitivity to oxidative stress, reduced zinc uptake, and reduced intracellular levels of several cations. Doubling time of the Δlgt mutant was also increased slightly when grown in medium with glucose, raffinose and maltotriose as sole carbon sources. These multiple defects in cation and sugar ABC transporter function for the Δlgt mutant were associated with only slightly delayed growth in complete medium. However the Δlgt mutant had significantly reduced growth in blood or bronchoalveolar lavage fluid and a marked impairment in virulence in mouse models of nasopharyngeal colonisation, sepsis and pneumonia. These data suggest that for S. pneumoniae loss of surface localisation of lipoproteins has widespread effects on ABC transporter functions that collectively prevent the Δlgt mutant from establishing invasive infection