41 research outputs found
An overview of the evolution of infrared spectroscopy applied to bacterial typing
The sustained emergence of new declared bacterial species makes typing a continuous challenge for microbiologists. Molecular biology techniques have a very significant role in the context of bacterial typing, but they are often very laborious, time consuming and eventually fail when dealing with very closely related species. Spectroscopic-based techniques appear in some situations as a viable alternative to molecular methods with advantages in terms of analysis time and cost. Infrared and mass spectrometry are among the most exploited techniques in this context: particularly, infrared spectroscopy emerged as a very promising method with multiple reported successful applications. This article presents a systematic review on infrared spectroscopy applications for bacterial typing, highlighting fundamental aspects of infrared spectroscopy, a detailed literature review (covering different taxonomic levels and bacterial species), advantages and limitations of the technique over molecular biology methods and a comparison with other competing spectroscopic techniques such as MALDI-TOF MS, Raman and intrinsic fluorescence. Infrared spectroscopy possesses a high potential for bacterial typing at distinct taxonomic levels and worthy of further developments and systematization. The development of databases appears fundamental towards the establishment of infrared spectroscopy as a viable method for bacterial typing.FCT -Fundação para a Ciência e a Tecnologia(PT2020 UID/QUI/50006/2013)info:eu-repo/semantics/publishedVersio
Galaxy bulges and their massive black holes: a review
With references to both key and oft-forgotten pioneering works, this article
starts by presenting a review into how we came to believe in the existence of
massive black holes at the centres of galaxies. It then presents the historical
development of the near-linear (black hole)-(host spheroid) mass relation,
before explaining why this has recently been dramatically revised. Past
disagreement over the slope of the (black hole)-(velocity dispersion) relation
is also explained, and the discovery of sub-structure within the (black
hole)-(velocity dispersion) diagram is discussed. As the search for the
fundamental connection between massive black holes and their host galaxies
continues, the competing array of additional black hole mass scaling relations
for samples of predominantly inactive galaxies are presented.Comment: Invited (15 Feb. 2014) review article (submitted 16 Nov. 2014). 590
references, 9 figures, 25 pages in emulateApJ format. To appear in "Galactic
Bulges", E. Laurikainen, R.F. Peletier, and D.A. Gadotti (eds.), Springer
Publishin
Effect of temperature on the rheological behavior of hydroxyl terminated polybutadiene propellant slurry
Effect of Pyrolysis Temperature on Adsorbent Properties of Carbon From Leather Buffing Dust and Sawdust
Mars outflow channels: A reappraisal of the estimation of water flow speeds from water depths, regional slopes and channel floor properties.
Methods used so far to assess the flow velocities of the water commonly assumed to be responsible for forming the major outflow channel systems on Mars have relied widely on various versions of the Manning equation. This has led to problems in allowing for the difference between the accelerations due to gravity on Mars and Earth and for the differences of scale between Martian floods and most river systems on Earth. We reanalyze the problem of estimating water flow velocities in Martian outflow channels using equations based on the Darcy-Weisbach friction factor instead of the Manning n factor. We give simplified formulae appropriate to Mars for the Darcy-Weisbach friction coefficient as a function of bedrock size distribution. For a given channel floor slope and water flood depth, similar mean flow velocities are implied for a wide range of values of the ratio of bed roughness to water depth relevant to Martian outflow channels. Using a recent rederivation of Manning's equation based on turbulence theory, we obtain a new value of 0.0545 s m−1/3 for the Manning n coefficient appropriate to Martian channels and show that previous analyses have generally overestimated (though in some cases underestimated) water flow velocities on Mars by a factor of order two. Combining the consequences of this flow velocity overestimate with likely overestimates of flow depth from assuming bank-full flow, we show that discharges may have been overestimated by a factor of up to 25, leading to corresponding overestimates of subsurface aquifer permeabilities, rates of filling of depressions with water, and grain sizes of sediments on channel floors. Despite the availability of an improved value for the Manning n coefficient for Mars, we strongly recommend that modified forms of the original version of the Manning equation should be replaced by the modern form or, preferably, by the Darcy-Weisbach equation in future work