79,102 research outputs found

    Holographic analysis of thin films

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    Technique for monitoring deposition of films on surfaces, in place on a real-time basis, reads both the thickness and the uniformity of the deposited film. Holograms are produced from both reflected and transmitted light on one plate

    Quick-change absorption column

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    Column has end caps held in place by springs; prefilled packs of absorbent can be exchanged quickly. Both ends of metal or plastic body tube of size which can hold adequate amount of absorbent are machined to provide seat for perforated plate and groove for its spring retainer ring

    Mercury accumulation in fishes from tropical aquatic ecosystems in the Niger Delta, Nigeria

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    Fishes are important biomarkers of trace elements in aquatic ecosystems, and are used to evaluate the status of water pollution by mercury in tropical aquatic ecosystems in Nigeria. Common fishes, Chrysichthys nigrodigitatus,Brycinus nurse, Hemichromis fasciatus, Lutianus ava, Oreochromis nilotica, Pomadasys jubelini, Stellifer stellifer and Tilapia guineensis were analysed for Hg accumulation using the cold vapour atomic absorption spectrophotometry technique. The results showed that Hg concentration in P. jubelini was relatively the highest, with a mean concentration of 0.063 ± 0.03 mg kg–1. Other concentration values were 0.044 ± 0.031 mg kg–1 for O. nilotica, 0.026 ± 0.013 mg kg–1 for B. nurse, 0.034 ± 0.034 mg kg–1 for H. fasciatus, 0.023 ± 0.020 mg kg–1 for C. nigrodigitatus and 0.33 ± 0.016 mg kg–1 for L. ava. Concentrations of Hg accumulated by the fishes were low and within internationally accepted limit, not likely to cause mercury poisoning. Because of the high Hg accumulating potential of P. jubelini, it is recommended as a biomarker for assessment of Hg toxicity in a tropical aquatic environment

    Light-Quark FLIC Fermion Simulations of the 1−+1^{-+} Exotic Meson

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    We investigate the mass of the 1−+1^{-+} exotic meson, created with hybrid interpolating fields. Access to light quark masses approaching 25 MeV is facilitated by the use of the Fat-Link Irrelevant Clover (FLIC) fermion action, and large (203×4020^3 \times 40) lattices. Our results indicate that the 1−+1^{-+} exotic exhibits significant curvature close to the chiral limit, and yield a 1−+1^{-+} mass in agreement with the π1(1600)\pi_1 (1600) candidate and exclusive of the π1(1400)\pi_1 (1400).Comment: 6 pages, 1 table, 2 figures, talk given at Lattice '05. Removed unccessary figure

    Start-to-end modelling of a mode-locked optical klystron free electron laser amplifier

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    A free electron laser (FEL) in a mode-locked optical klystron (MLOK) configuration is modelled using start-to-end simulations that simulate realistic electron beam acceleration and transport before input into a full three-dimensional FEL simulation code. These simulations demonstrate that the MLOK scheme is compatible with the present generation of radiofrequency accelerator designs. A train of few-optical cycle pulses is predicted with peak powers similar to those of the equivalent conventional FEL amplifier. The role of electron beam energy modulation in these results is explained and the limitations of some simulation codes discussed. It is shown how seeding the FEL interaction using a High Harmonic seed laser can improve the coherence properties of the output

    Hot Electron Capture Dissociation Distinguishes Leucine from Isoleucine in a Novel Hemoglobin Variant, Hb Askew, ÎČ54(D5)Val→Ile

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    Population migration has led to the global dispersion of human hemoglobinopathies and has precipitated a need for their identification. An effective mass spectrometry-based procedure involves analysis of the intact α- and ÎČ-globin chains to determine their mass, followed by location of the variant amino acid residue by direct analysis of the enzymatically digested chains and low-energy collision induced dissociation of the variant peptide. Using this procedure, a variant was identified as either ÎČ54Val→Leu or ÎČ54Val→Ile, since the amino acids leucine and isoleucine cannot be distinguished using low-energy collisions. Here, we describe how hot electron capture dissociation on a Fourier transform-ion cyclotron resonance mass spectrometer was used to distinguish isoleucine from leucine and identify the mutation as ÎČ54(D5)Val→Ile. This is a novel variant, and we have named it Hb Askew
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