Is UV laser ablation a suitable tool for geochemical analysis of organic rich source materials?

Abstract not available

GFIT2: an experimental algorithm for vertical profile retrieval from near-IR spectra

An algorithm for retrieval of vertical profiles from ground-based spectra in the near IR is described and tested. Known as GFIT2, the algorithm is primarily intended for CO₂, and is used exclusively for CO₂ in this paper. Retrieval of CO₂ vertical profiles from ground-based spectra is theoretically possible, would be very beneficial for carbon cycle studies and the validation of satellite measurements, and has been the focus of much research in recent years. GFIT2 is tested by application both to synthetic spectra and to measurements at two Total Carbon Column Observing Network (TCCON) sites. We demonstrate that there are approximately 3° of freedom for the CO2 profile, and the algorithm performs as expected on synthetic spectra. We show that the accuracy of retrievals of CO₂ from measurements in the 1.61μ (6220 cm⁻¹) spectral band is limited by small uncertainties in calculation of the atmospheric spectrum. We investigate several techniques to minimize the effect of these uncertainties in calculation of the spectrum. These techniques are somewhat effective but to date have not been demonstrated to produce CO₂ profile retrievals with sufficient precision for applications to carbon dynamics. We finish by discussing ongoing research which may allow CO₂ profile retrievals with sufficient accuracy to significantly improve the scientific value of the measurements from that achieved with column retrievals

Potential of short wavelength laser ablation of organic materials

Although the literature contains several articles on UV laser ablation of synthetic polymers [1] and human tissue for surgical applications, to our knowledge there is no published record on organic geochemical applications for UV laser pyrolysis–gas chromatography–mass spectrometry (LA-GC-MS). In this study we have demonstrated the use of a 213 nm UV laser beam for ablating kerogens and organic rich rocks to liberate and analyse hydrocarbon signatures and compared the results against IR laser pyrolysis and traditional Py-GC-MS. It is possible to equate laser wavelength to electron volts where 1064 nm (IR) = 1.2 eV and 213 nm (UV) = 5.8 eV. Most chemical bonds have an energy between 2-4 eV and C-C bonds are ~3.6 eV. Organic materials can absorb radiation from a UV laser and chemical bonds can be cleaved cleanly by complex photochemical pathways by a single photon [2]. Ablation occurs with almost no heating of the sample and hence the term laser ablation instead of pyrolysis. Visible or IR lasers have insufficient energy to break bonds with a single photon this results in the heating of sample by the absobtion of energy into the vibrational modes of the molecule which can then result in pyrolysis. A solvent-extracted kerogen consisting mainly of higher plant material (Brownie Butte, Montanna, ~ 70 Ma) was used for initial experiments. A number of other samples have also been analysed. Laser ablation work was performed off-line in a static helium cell followed by solvent extraction of the laser cell. Separate analysis of the same samples using a more traditional flash pyrolysis approach was performed with a CDS pyroprobe and IR laser pyrolysis [3] for comparative purposes. As can be seen in Fig 1 UV laser ablation is able to liberate relatively high molecular weight fragments with no alkenes or other pyrolysis artefacts detected. SEM images of ablation pits indicate there is no obvious thermal alteration of the sample. The results of the pyrolysis techniques (on-line and IR laser pyrolysis) are similar and display a number of artefacts related to the pyrolysis process. Laser ablation of a number of samples has also shown that the distributions of biomarkers are comparable with the solvent extracts. Product yields although not quantified appear to be much higher than traditional pyrolysis technique

Microarray karyotyping of commercial wine yeast strains reveals shared, as well as unique, genomic signatures

BACKGROUND: Genetic differences between yeast strains used in wine-making may account for some of the variation seen in their fermentation properties and may also produce differing sensory characteristics in the final wine product itself. To investigate this, we have determined genomic differences among several Saccharomyces cerevisiae wine strains by using a "microarray karyotyping" (also known as "array-CGH" or "aCGH") technique. RESULTS: We have studied four commonly used commercial wine yeast strains, assaying three independent isolates from each strain. All four wine strains showed common differences with respect to the laboratory S. cerevisiae strain S288C, some of which may be specific to commercial wine yeasts. We observed very little intra-strain variation; i.e., the genomic karyotypes of different commercial isolates of the same strain looked very similar, although an exception to this was seen among the Montrachet isolates. A moderate amount of inter-strain genomic variation between the four wine strains was observed, mostly in the form of depletions or amplifications of single genes; these differences allowed unique identification of each strain. Many of the inter-strain differences appear to be in transporter genes, especially hexose transporters (HXT genes), metal ion sensors/transporters (CUP1, ZRT1, ENA genes), members of the major facilitator superfamily, and in genes involved in drug response (PDR3, SNQ1, QDR1, RDS1, AYT1, YAR068W). We therefore used halo assays to investigate the response of these strains to three different fungicidal drugs (cycloheximide, clotrimazole, sulfomethuron methyl). Strains with fewer copies of the CUP1 loci showed hypersensitivity to sulfomethuron methyl. CONCLUSION: Microarray karyotyping is a useful tool for analyzing the genome structures of wine yeasts. Despite only small to moderate variations in gene copy numbers between different wine yeast strains and within different isolates of a given strain, there was enough variation to allow unique identification of strains; additionally, some of the variation correlated with drug sensitivity. The relatively small number of differences seen by microarray karyotyping between the strains suggests that the differences in fermentative and organoleptic properties ascribed to these different strains may arise from a small number of genetic changes, making it possible to test whether the observed differences do indeed confer different sensory properties in the finished wine

Safety and/or Hazard Near Miss Reporting in an International Energy Company

This paper presents the preliminary progress of an industry driven programme to improve the data monitoring of safety/hazard near miss reporting from front line staff of a branch of a multinational energy supply company in Ireland. The paper discusses the main factors that emerged as possible causes for underreporting and the course of action selected for addressing them. The initiative, which is only in operation for 4 months has already led to an increase in reporting of “near misses” by a factor of nine. Furthermore, the level and detail of the reports is far greater than had previously being received