Leadership training to improve adenoma detection rate in screening colonoscopy: A randomised trial

Objective Suboptimal adenoma detection rate (ADR) at colonoscopy is associated with increased risk of interval colorectal cancer. It is uncertain how ADR might be improved. We compared t

Mid-infrared PS and LIF detection of CH4 and C2H 6 in cold flows and flames at atmospheric pressure

Mid-infrared polarization spectroscopy (IRPS) and laser-induced fluorescence (IRLIF) have been applied for detection of methane and ethane in atmospheric pressure cold flows and flames. Lines belonging to the asymmetric C-H stretching vibration bands v3 and v7 for methane and ethane, respectively, were probed with a tunable infrared laser beam at about 3.4 μm, which was obtained from difference frequency generation in a LiNbO3 crystal pumped by a dye-laser beam and a Nd:YAG fundamental laser beam. The dependence of IRPS and IRLIF signal of CH4 on different buffer gases, including He, Ar, N2, and CO2 was investigated. Simultaneous measurements of IRPS and IRLIF signals allowed a direct comparison of the two techniques, and IRPS was found to be superior in detection sensitivity and background discrimination. IRPS excitation scans of a methane and ethane mixture diluted in Ar were also performed in a jet at ambient pressure and temperature. Lines in the spectrum belonging to methane and ethane were fully recognized and assigned. From the ethane lines in the IRPS excitation spectrum, a detection limit of 50 ppm was conservatively estimated, and this indicates that IRPS is a promising sensitive technique for hydrocarbon identification and detection. Finally, CH4 IRPS detection in a CH4/H2/air premixed flat flame was demonstrated, with spatially resolved IRPS CH4 measurements along different heights in the flame

Mid-infrared PS and LIF detection of CH4 and C2H6 in cold flows and flames at atmospheric pressure

Mid-IR polarization spectroscopy (IRPS) and laser-induced fluorescence were applied for detection of CH4 and ethane in 1 atm cold flows and flames. The dependence of IRPS and IRLIF signal of CH4 on different buffer gases, including He, Ar, N2, and CO2 were studied. Simultaneous measurements of IRPS and IRLIF signals allowed a direct comparison of the two techniques. IRPS was superior in detection sensitivity and background discrimination. IRPS excitation scans of a CH4 and ethane mixture diluted in argon were also carried out in a jet at ambient pressure and temperature. Lines in the spectrum belonging to CH4 and ethane were fully recognized and assigned. From the ethane lines in the IRPS excitation spectrum, a detection limit of 50 ppm was conservatively estimated, indicating that IRPS is a promising sensitive technique for hydrocarbon identification and detection. CH4 IRPS detection in a CH4/H2/air premixed flat flame was demonstrated, with spatially resolved IRPS CH4 measurements along different heights in the flame. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004)

Mid-infrared polarization spectroscopy of polyatomic molecules: Detection of nascent CO2 and H2O in atmospheric pressure flames

We report the application of mid-infrared polarization spectroscopy (IRPS) for detection of nascent CO2 and H2O in atmospheric pressure flames. The recorded IRPS spectra demonstrated both the quantitative nature of the method and the suppression of strong infrared emission from flames. In spite of the high line-density of the hot polyatomic ro-vibrational spectrum, lines belonging to different CO2 and H2O hot bands were recognized in the chosen spectral region, which ensures the species-selective application of IRPS.Z.S. Li, M. Rupinski, J. Zetterberg, Z.T. Alwahabi and M. Aldénhttp://www.elsevier.com/wps/find/journaldescription.cws_home/505707/description#descriptio

Mid-IR polarization spectroscopy applied for detection of methane at atmospheric pressure

Methane was studied with mid-infrared polarization spectroscopy (PS) in an atmospheric gas jet. Detection limit was investigated and laser induced fluorescence and PS spectra for the P, Q, and R branch are presented

Strategies for formaldehyde detection in flames and engines using a single-mode Nd : YAG/OPO laser system

Technical developments for the detection of formaldehyde using laser-induced fluorescence were presented. A technique for simultaneous detection of formaldehyde and OH using one laser system was presented. The combined formaldehyde and OH technique was applied in laboratory flames and a small spark-ignition engine. The iodine measurement was performed in a cell using the second harmonic of the single-mode Nd:YAG laser and used for wavelength calibration of the laser. Spectral studies of the fluorescence emission indicated that both the peaks as well as the continuous part originated from formaldehyde. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004)

Comparative functional genomics of mammalian DNA methyltransferases

DNA methylation involves biochemical modification of DNA by addition of methyl groups onto CpG dinucleotides, and this epigenetic mechanism regulates gene expression in disease and development. Mammalian DNA methyltransferases, DNMT (DNMT1, DNMT3A and DNMT3B), together with the accessory protein DNMT3L establish specific DNA methylation patterns in the genome during gametogenesis, embryogenesis and somatic tissue development. The present study addresses the structural and functional conservation of the DNMT in humans, mice and cattle and the patterns of mRNA abundance of the different enzymes during embryogenesis to improve understanding of epigenetic regulation in early development. The findings showed a high degree of structural and functional conservation among the human, mouse, and bovine DNMT. The results also showed similar patterns of transcript abundance for all of the proteins at different stages of early embryo development. Remarkably, all of the DNMT with an important role in DNA methylation (DNMT1, DNMT3A, DNMT3B, and DNMT3L) show a greater degree of structural similarity between human and bovine than that between human and mouse. These results have important implications for the selection of an appropriate model for study of DNA methylation during early development in humans. © 2010, Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved

Strategies for formaldehyde engines using a single-mode detection in flames and Nd : YAG/OPO laser system

This paper presents technical developments for the detection of formaldehyde (CH2O) using laser-induced fluorescence. The easily accessible third harmonic of the Nd:YAG laser at 355 nm was used for excitation of formaldehyde. In order to investigate potential background fluorescence, e.g., from large molecules such as polyaromatic hydrocarbons, special attention was paid to investigating the possibility of scanning the wavelength of a single-mode Nd:YAG laser under the gain profile, similar to 3 cm(-1), on and off resonance. Furthermore, a technique for simultaneous detection of formaldehyde and 011 using one laser system is presented. The single-mode Nd:YAG laser at 355 nm in combination with an optical parametric oscillator (OPO) laser tuned to 283 nm was used for simultaneous two-dimensional imaging of both species using one charge-coupled device (CCD) detector equipped with a dual filter image separator. The techniques are demonstrated with measurements in laboratory flames and the combined measurements are also demonstrated in an engine