Proposal of an FTIR Methodology to Monitor Oxidation Level in Used Engine Oils: Effects of Thermal Degradation and Fuel Dilution

This article describes a procedure, based on ASTM standards D7214 and E2412, that has been defined to improve quantification of oil oxidation in used engine oils. Taking into account typical problems that can be found in this type of sample, including thermal oxidation and fuel dilution, Fourier transform infrared (FTIR) spectra were analyzed also considering the effect of the oil formulation. Two zones were considered inside the typical wave number range for quantification of oxidation, where those problems can be detected and assessed more easily: zone A between 1725 and 1650 cm-1, where the main oxidation products, such as aldehydes, carboxylic acids, and ketones, occur due to thermal degradation of the oil; and zone B between 1770 and 1725 cm-1, where esters due to potential biodiesel dilution problems are detected. Copyright © Society of Tribologists and Lubrication Engineers.The authors are grateful for Spanish Grant TRA2008-06508 (GLAUTO) from the Ministerio de Ciencia e Innovacion-Direccion General de Investigacion for supporting this work.Macian Martinez, V.; Tormos, B.; Gomez Estrada, YA.; Salavert Fernández, JM. (2012). Proposal of an FTIR Methodology to Monitor Oxidation Level in Used Engine Oils: Effects of Thermal Degradation and Fuel Dilution. Tribology Transactions. 55(6):872-882. https://doi.org/10.1080/10402004.2012.721921S87288255

The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes

The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events

Evaluation of natural and tracer fluorescent emission methods for droplet size measurements in a diesel spray

The final publication is available at Springer via http://dx.doi.org/10.1007/s12239-012-0070-zSpray sizing that records fluorescent emission and scattered light has been widely applied to spray diagnostics over the last two decades. Different experimental strategies have been developed, but comparing the different solutions offered has remained of interest to experimentalists. In this work, a comparison of two fluorescence strategies for measuring droplet size in the liquid phase of a last-generation DI diesel spray is conducted. The natural fluorescent emission of a commercial diesel fuel and the fluorescence emitted by a tracer (Rhodamine B) are compared using theoretical and experimental approaches. The LIF/Mie ratio commonly called Planar Droplet Sizing (PDS) technique is applied in two different ways to elucidate the possible advantages of using a fluorescent dopant. The sprays were injected under non-evaporative conditions into a constant pressure vessel that simulates densities present at the moment of injection in currently used passenger car diesel engines. Characterization of the signal properties was performed by measuring the absorption coefficient, fluorescence emission spectrum, quantum yield and lifetime of both configurations. The scattered light and fluorescence intensities were calculated to verify the dependencies of the droplet surface and volume. When applying the two techniques to quantify droplet size in dense diesel sprays, the results show that signal weakness and lack of control over the properties of natural fluorescence produce distortion in the shape of the spray and cause measurements to be unreliable. © 2012 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.This research has been funded in the frame of the project PROFUEL reference TRA2011-26293 from Ministerio de Ciencia e Innovacion. The injectors are part of the ECN international project.Pastor Soriano, JV.; Payri, R.; Salavert Fernandez, J.; Manin, J. (2012). Evaluation of natural and tracer fluorescent emission methods for droplet size measurements in a diesel spray. International Journal of Automotive Technology. 13(5):713-724. https://doi.org/10.1007/s12239-012-0070-zS713724135Albrecht, H. E., Damaschke, N., Borys, M. and Tropea, C. (2003). Laser Doppler and Phase Doppler Measurement Techniques. Springer. Berlin.Barnes, M. D., Whitten, W. B. and Ramsey, J. M. (1994). Enhanced fluorescence yields through cavity quantumelectrodynamic effects in microdroplets. J. Optical Society of America B 11,7, 1297–1304.Benajes, J., Molina, S., Novella, R., Amorim, R., Ben Hadj Hamouda, H. and Hardy, J. (2010). Comparison of two injection systems in an HSDI diesel engine using split injection and different injector nozzles. Int. J. Automotive Technology 11,2, 139–146.Charalampous, G. and Hardalupas, Y. (2011). Method to reduce errors of droplet sizing based on the ratio of fluorescent and scattered light intensities (laser-induced fluorescence/Mie technique). Applied Optics, 50, 3622–3637.Chen, G., Mazumder, M., Chang, R. K., Swindal, J. C. and Acker, W. P. (1996). Laser diagnostics for droplet characterization: Application of morphology dependent resonances. Progress in Energy and Combustion Science 22,2, 163–188.Desantes, J. M., Payri, R., Garcia, J. M. and Salvador, F. J. (2007). A contribution to the understanding of isothermal diesel spray dynamics. Fuel 86,7–8, 1093–1101.Domann, R. and Hardalupas, Y. A. (2000). Study of parameters that influence the accuracy of the planar droplet sizing (PDS) technique. Part. Part. Syst. Charact. 3–11.Domann, R. and Hardalupas, Y. A. (2001). Spatial distribution of fluorescence within large doplets and its dependence on dye concentration. Applied Optics 40,21, 3586–3597.Domann, R. and Hardalupas, Y. A. (2002). Quantitative measurement of planar droplet sauter mean diameter in sprays using planar droplet sizing. 11th Int. Symp. Application of Laser Techniques to Fluid Mechanics, Lisbon, Portugal.Eckbreth, A. C. (1988). Laser Diagnostics for Combustion Species and Temperature. Abacus. Cambridge. Mass.Greenhalgh, D. A. (1999). Planar measurements of fuel vapour, liquid fuel, liquid droplet size and soot. Planar Optical Measurement Methods for Gas Turbine Components, 1–7.Im, K., Lin, K., Lai, M. and Chon, M. (2011). Breakup modeling of a liquid jet in cross flow. Int. J. Automotive Technology 12,4, 489–496.Jermy, M. C. and Greenhalgh, D. A. (2000). Planar dropsizing by elastic and fluorescence scattering in sprays too dense for phase doppler measurement. Appl. Phys. B, 71, 703–710.Kim, Y., Kim, K. and Lee, K. (2011). Effect of a 2-stage injection strategy on the combustion and flame characteristics in a PCCI engine. Int. J. Automotive Technology 12,5, 639–644.Ko, F. H., Weng, L. Y., Ko, C. J. and Chu, T. C. (2006). Characterization of imprinting polymeric temperature variation with fluorescent Rhodamine B molecule. Microelectronic Engineering, 83, 864–868.Lakowicz, J. R. (2006). Principles of Fluorescence Spectroscopy. 3rd Edn. Springer.Lee, S. H., Teong, J., Lee, J. T., Ryou, H. S. and Hong, K. (2005). Investigation on spray characteristics under ultrahigh injection pressure conditions. Int. J. Automotive Technology 6,2, 125–131.Lee, B., Song, J., Chang, Y. and Jeon, C. (2010). Effect of the number of fuel injector holes on characteristics of combustion and emissions in a diesel engine. Int. J. Automotive Technology 11,6, 783–791.LeGal, P., Farrugia, N. and Greenhalgh, D. A. (1999). Laser sheet dropsizing of dense sprays. Optics and Laser Techn., 31, 75–83.Lockett, R. D., Richter, J. and Greenhalgh, D. A. (1998). The characterisation of a diesel spray using combined laser induced fluorescence and laser sheet dropsizing. Conf. Lasers and Electro-Optics Europe.Magde, D., Rojas, G. E. and Seybold, P. (1999). Solvent dependence of the fluorescence lifetimes of xanthene dyes. Photochem. Photobiol., 70, 737.Naber, J. and Siebers, D. (1996). Effects of gas density and vaporization on penetration and dispersion of diesel sprays. SAE Paper No. 960034.Pastor, J. V., López, J. J., Juliá, J. E. and Benajes, J. V. (2002). Planar laser-induced fluorescence fuel concentration measurements in isothermal diesel sprays. Opt. Express 10,7, 309–323.Pastor, J. V., Payri, R., Araneo, L. and Manin, J. (2009). Correction method for droplet sizing by laser-induced fluorescence in a controlled test situation. Optical Engineering 48,1, 013601.Payri, R., Garcia, J. M., Salvador, F. J. and Gimeno, J. (2005a). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84, 551–561.Payri, R., Salvador, F. J., Gimeno, J. and Soare, V. (2005b). Determination of diesel sprays characteristics in real engine in-cylinder air density and pressure conditions. J. Mech. Sci. Technol., 19, 2040–2052.Payri, R., Tormos, B., Salvador, F. J. and Araneo, L. (2008). Spray droplet velocity characterization for convergent nozzles with three different diameters. Fuel 87,15, 3176–3182.Payri, F., Pastor, J., Payri, R. and Manin, J. (2011). Determination of the optical depth of a DI diesel spray. J. Mech. Sci. Technol., 25, 209–219.Potz, D., Chirst, W. and Dittus, B. (2000). Diesel nozzle: The determining interface between injection system and combustion chamber. Conf. Thermo and Fluid-dynamic Processes in Diesel Engines, Valencia, Spain.Ramírez, A. I., Som, S., Aggarwal, S. K., Kastengren, A. L., El-Hannouny, E. M., Longman, D. E. and Powell, C. F. (2009). Quantitative X-ray measurements of highpressure fuel sprays from a production heavy duty diesel injector. Experiments in Fluids 47,1, 119–134.Schulz, C. and Sick, V. (2005). Tracer-LIF diagnostics: quantitative measurement of fuel concentration, temperature and fuel/air ratio in practical combustion systems. Progress in Energy and Combustion Science, 31, 75–121.Sjoback, R. and Nygren, J. and Kubista, M. (1998). Characterization of fluorescein—oligonucleotide conjugates and measurement of local electrostatic potential. Biopolymers, 46, 445–453.Soare, V. (2007). Phase Doppler Measurement in Diesel Dense Sprays: Optimisation of Measurements and Study of the Orifice Geometry Influence Over the Spray at Microscopic Level. Ph.D. Dissertion. E.T.S. Ingenieros Industriales. Universidad Politécnica de Valencia. Spain.Williams, A. T. R., Winfield, S. A. and Miller, J. N. (1983). Relative fluorescence quantum yields using a computer controlled luminescence spectrometer. Analyst., 108, 1067.Yeh, C. N., Kosaka, H. and Kamimoto, T. A. (1993). Fluorescence/scattering imaging technique for instantaneous 2-D measurements of particle size distribution in a transient spray. 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Revisiting and modelling the woodland farming system of the early Neolithic Linear Pottery Culture (LBK), 5600–4900 B.C

International audienceThis article presents the conception and the conceptual results of a modelling representation of the farming systems of the Linearbandkeramik Culture (LBK). Assuming that there were permanent fields (PF) then, we suggest four ways that support the sustainability of such a farming system over time: a generalized pollarding and coppicing of trees to increase the productivity of woodland areas for foddering more livestock, which itself can then provide more manure for the fields, a generalized use of pulses grown together with cereals during the same cropping season, thereby reducing the needs for manure. Along with assumptions limiting bias on village and family organizations, the conceptual model which we propose for human environment in the LBK aims to be sustainable for long periods and can thereby overcome doubts about the PFs hypothesis for the LBK farming system. Thanks to a reconstruction of the climate of western Europe and the consequent vegetation pattern and productivity arising from it, we propose a protocol of experiments and validation procedures for both testing the PFs hypothesis and defining its eco-geographical area

Bibliografía histórica sobre la Ciencia y la Técnica en España. 1997

Repertori de bibliografia històrica sobre la ciència i la tècnica a Espanya editada en 1994. //.Repertorio de bibliografía histórica sobre la ciencia y la técnica en España editada en 1994

The place of millet in food globalization during Late Prehistory as evidenced by new bioarchaeological data from the Caucasus

Two millets, Panicum miliaceum and Setaria italica, were domesticated in northern China, around 6000 BC. Although its oldest evidence is in Asia, possible independent domestication of these species in the Caucasus has often been proposed. To verify this hypothesis, a multiproxy research program (Orimil) was designed to detect the first evidence of millet in this region. It included a critical review of the occurrence of archaeological millet in the Caucasus, up to Antiquity; isotopic analyses of human and animal bones and charred grains; and radiocarbon dating of millet grains from archaeological contexts dated from the Early Bronze Age (3500–2500 BC) to the 1st Century BC. The results show that these two cereals were cultivated during the Middle Bronze Age (MBA), around 2000–1800 BC, especially Setaria italica which is the most ancient millet found in Georgia. Isotopic analyses also show a significant enrichment in 13C in human and animal tissues, indicating an increasing C4 plants consumption at the same period. More broadly, our results assert that millet was not present in the Caucasus in the Neolithic period. Its arrival in the region, based on existing data in Eurasia, was from the south, without excluding a possible local domestication of Setaria italica

Duration of Treatment for Pseudomonas aeruginosa Bacteremia : a Retrospective Study

Introduction: There is no consensus regarding optimal duration of antibiotic therapy for Pseudomonas aeruginosa bacteremia. We aimed to evaluate the impact of short antibiotic course. Methods: We present a retrospective multicenter study including patients with P. aeruginosa bacteremia during 2009-2015. We evaluated outcomes of patients treated with short (6-10 days) versus long (11-15 days) antibiotic courses. The primary outcome was a composite of 30-day mortality or bacteremia recurrence and/or persistence. Univariate and inverse probability treatment-weighted (IPTW) adjusted multivariate analysis for the primary outcome was performed. To avoid immortal time bias, the landmark method was used. Results: We included 657 patients; 273 received a short antibiotic course and 384 a long course. There was no significant difference in baseline characteristics of patients. The composite primary outcome occurred in 61/384 patients in the long-treatment group (16%) versus 32/273 in the short-treatment group (12%) (p = 0.131). Mortality accounted for 41/384 (11%) versus 25/273 (9%) of cases, respectively. Length of hospital stay was significantly shorter in the short group [median 13 days, interquartile range (IQR) 9-21 days, versus median 15 days, IQR 11-26 days, p = 0.002]. Ten patients in the long group discontinued antibiotic therapy owing to adverse events, compared with none in the short group. On univariate and multivariate analyses, duration of therapy was not associated with the primary outcome. Conclusions: In this retrospective study, 6-10 days of antibiotic course for P. aeruginosa bacteremia were as effective as longer courses in terms of survival and recurrence. Shorter therapy was associated with reduced length of stay and less drug discontinuation

Epidemiological trends of HIV/HCV coinfection in Spain, 2015-2019

Altres ajuts: Spanish AIDS Research Network; European Funding for Regional Development (FEDER).Objectives: We assessed the prevalence of anti-hepatitis C virus (HCV) antibodies and active HCV infection (HCV-RNA-positive) in people living with HIV (PLWH) in Spain in 2019 and compared the results with those of four similar studies performed during 2015-2018. Methods: The study was performed in 41 centres. Sample size was estimated for an accuracy of 1%. Patients were selected by random sampling with proportional allocation. Results: The reference population comprised 41 973 PLWH, and the sample size was 1325. HCV serostatus was known in 1316 PLWH (99.3%), of whom 376 (28.6%) were HCV antibody (Ab)-positive (78.7% were prior injection drug users); 29 were HCV-RNA-positive (2.2%). Of the 29 HCV-RNA-positive PLWH, infection was chronic in 24, it was acute/recent in one, and it was of unknown duration in four. Cirrhosis was present in 71 (5.4%) PLWH overall, three (10.3%) HCV-RNA-positive patients and 68 (23.4%) of those who cleared HCV after anti-HCV therapy (p = 0.04). The prevalence of anti-HCV antibodies decreased steadily from 37.7% in 2015 to 28.6% in 2019 (p < 0.001); the prevalence of active HCV infection decreased from 22.1% in 2015 to 2.2% in 2019 (p < 0.001). Uptake of anti-HCV treatment increased from 53.9% in 2015 to 95.0% in 2019 (p < 0.001). Conclusions: In Spain, the prevalence of active HCV infection among PLWH at the end of 2019 was 2.2%, i.e. 90.0% lower than in 2015. Increased exposure to DAAs was probably the main reason for this sharp reduction. Despite the high coverage of treatment with direct-acting antiviral agents, HCV-related cirrhosis remains significant in this population