An investigation into the conversion of specific carbon atoms in oleic acid and methyl oleate to particulate matter in a diesel engine and tube reactor

The paper is concerned with particulate formation from the fuels oleic acid and methyl oleate. In particular the paper reports, quantitatively, the propensity of individual carbon atoms in these two molecules in being converted to particulate. The conversion of individual carbon atoms to particulate was traced by 'labelling' individual carbon atoms in those two fuel molecules with isotopic carbon-13 (C) and then measuring how many of the labelled atoms was found in the particulate. This allowed the measuring of the conversion rates of individual fuel carbon atoms to particulate. In the case of oleic acid, three carbon atoms were selected as being particularly relevant to particulate formation, and C labelled. One of the carbon atoms was double bonded to the oxygen atom on the carboxylic acid group; and the other two were part of the oleic acid molecule alkyl chain and double bonded to each other. In the case of the methyl oleate, one carbon atom was C labelled. This was the carbon atom that was double bonded to one of the oxygen atoms of the ester group. Experimental results are presented for particulate matter (PM) formed in a laminar flow tube reactor, and also in a direct injection compression ignition engine. The tube reactor has been used for the pyrolysis of oleic acid and methyl oleate at 1300 °C, under oxygen-free conditions and at air-fuel equivalence ratios (λ) of 0.1, and 0.2. Samples of PM were also collected from the compression ignition engine at an intermediate engine load. Isotope ratio mass spectrometry (IRMS) has been used to determine the relative abundance of C in the initial fuel and in the resulting PM. Significant differences in the relative conversion rates of individual carbon atoms are reported; a negligible contribution to PM from the carbon atom directly bonded to two oxygen atoms was found in both the engine and reactor. The labelling technique used in this paper requires low quantities of C labelled molecules to enrich otherwise unlabelled oleic acid; enrichment is at volumetric concentrations typically less than 0.7% (v/v). In addition, emissions data from the engine and tube reactor, including unburned hydrocarbons, CO, CO, NO, and PM size and number distributions measured by differential mobility spectrometer, are also presented

Quantification of the Fraction of Particulate Matter Derived from a Range of C-13-Labeled Fuels Blended into Heptane, Studied in a Diesel Engine and Tube Reactor

This paper presents the results of an experimental study that was carried out to determine the conversion rates to particulate matter (PM) of several liquid fuel hydrocarbon molecules and specific carbon atoms within those molecules. The fuels investigated (ethanol, n-propanol, i-propanol, acetone, and toluene) were blended in binary mixtures with n-heptane to a level of 10 mol percent. The contribution of the additive molecules to PM was quantified using a carbon-13 (13C) labeling experiment, in which the fuel of interest was enriched with 13C to serve as an atomic tracer. Measurement of the 13C/12C in the fuel and in the resulting PM was carried out using isotope ratio mass spectrometry. The fuel binary mixtures were tested under pyrolysis conditions in a tube reactor and also combusted in a direct injection compression ignition engine. In the tube reactor, samples were generated under oxygen-free pyrolysis conditions and at a temperature of 1300 °C, while the engine experiments were carried out at an intermediate load. Both in the tube reactor and in the engine it was found that, dependent on the fuel molecular structure, there were significant differences in the overall conversion rates to PM of the fuel molecules and of the “submolecular” carbon atoms. A separate experiment was also carried out in the compression ignition engine, with n-heptane as fuel, in order to determine the contribution of the engine lubrication oil to exhaust PM; the results showed that a significant portion (∼60%) of the total particulate was derived from the lubrication oil

Stabilization and control system power sensitivity study

Stabilization and control system sensitivity to power-off failure rate studied by simulated missions using block power switchin

Gazelle seasonal mobility in the Jordanian steppe: The use of dental isotopes and microwear as environmental markers, applied to Epipalaeolithic Kharaneh IV

The Early/Middle Epipalaeolithic aggregation site of Kharaneh IV in the east Jordan steppe is one of the largest of the period, showing repeated use, high degrees of site investment, and relatively prolonged periods of occupation. Hunters relied heavily on the single prey species, Gazella subgutturosa. This paper reports on isotopic analyses of gazelle teeth, drawn from the Kharaneh IV assemblage, to explore the seasonal and spatial distribution of gazelle in life and examine models of long-distance seasonal gazelle migrations. Dental microwear analysis is also employed to assess hunting seasons. Results from sequential isotope analyses of 11 Epipalaeolithic gazelle molars show that, with one exception, gazelle did not move seasonally from the limestone steppe onto other geologies, nor did they seasonally relocate to areas with different climate regimes. Rather, seasonal herd mobility seems to have been local, meaning animals would have been available in the vicinity of Kharaneh IV year-round. Results from 19 microwear analyses show some gazelle to have died in spring when grass graze was available, whilst others had been browsing around their time of death, indicating non-spring hunting. Microwear evidence thus suggests gazelle were hunted in more than one restricted season. The implications of these new datasets for hunter-gatherer use of the steppe, and potential hunting methods, is highlighted

Writing and Reading antiferromagnetic Mn2_2Au: N\'eel spin-orbit torques and large anisotropic magnetoresistance

Antiferromagnets are magnetically ordered materials which exhibit no net moment and thus are insensitive to magnetic fields. Antiferromagnetic spintronics aims to take advantage of this insensitivity for enhanced stability, while at the same time active manipulation up to the natural THz dynamic speeds of antiferromagnets is possible, thus combining exceptional storage density and ultra-fast switching. However, the active manipulation and read-out of the N\'eel vector (staggered moment) orientation is challenging. Recent predictions have opened up a path based on a new spin-orbit torque, which couples directly to the N\'eel order parameter. This N\'eel spin-orbit torque was first experimentally demonstrated in a pioneering work using semimetallic CuMnAs. Here we demonstrate for Mn$_2$Au, a good conductor with a high ordering temperature suitable for applications, reliable and reproducible switching using current pulses and readout by magnetoresistance measurements. The symmetry of the torques agrees with theoretical predictions and a large read-out magnetoresistance effect of more than $\simeq 6$~$\%$ is reproduced by ab initio transport calculations.Comment: 5 pages, 4 figure

Stability of Organic Carbon Components in Shale: Implications for Carbon Cycle

Stability and mobility of organic matter in shale is significant from the perspective of carbon cycle. Shale can only be an effective sink provided that the organic carbon present is stable and immobile from the host sites and, not released easily during geological processes such as low pressure-temperature burial diagenesis and higher pressure-temperature subduction. To examine this, three Jurassic shale samples of known mineralogy and total organic carbon content, with dominantly continental source of organic matter, belonging to the Haynesville-Bossier Formation were combusted by incremental heating from temperature of 200 to 1400◦C. The samples were analyzed for their carbon and nitrogen release profiles, bulk δ 13C composition and C/N atomic ratio, based on which, at least four organic carbon components are identified associated with different minerals such as clay, carbonate, and silicate. They have different stability depending on their host sites and occurrences relative to the mineral phases and consequently, released at different temperature during combustion. The components identified are denoted as, C-1 (organic carbon occurring as free accumulates at the edge or mouth of pore spaces), C-2 (associated with clay minerals, adsorbed or as organomineral nanocomposites; with carbonate minerals, biomineralized and/or occluded), C-3(a) (occurring with silicate minerals, biomineralized and/or occluded) and C-3(b) (graphitized carbon). They show an increasing stability and decreasing mobility from C-1 to C-3(b). Based on the stability of the different OC components, shale is clearly an efficient sink for the long term C cycle as, except for C-1 which forms a very small fraction of the total and is released at temperature of ∼200◦C, OC can be efficiently locked in shale surviving conditions of burial diagenesis and, subduction at fore arc regions in absence of infiltrating fluids. Under low fluid flux, C-3(b) can be efficiently retained as a refractory phase in the mantle when subducted. It is evident that the association and interaction of the organic matter with the different minerals play an important role in its retention in the shale

Late glacial palaeoclimate investigations at King Arthur’s Cave and Sun Hole Cave.

King Arthur’s Cave (Wye Valley) and Sun Hole Cave (Cheddar Gorge) currently provide the earliest dates for a human presence in the British Isles after the Last Glacial Maximum. The earliest phase of activity at these sites has been dated to c. 15.2 to 14.6 thousand years cal. BP, which spans the onset of the Late Glacial Interstadial, a major global climate transition characterised by rapidly warming temperatures. Here we present stable isotope data from horse (Equus ferus) teeth found in the zooarchaeological assemblages at the sites. We also report two new radiocarbon dates on specimens from King Arthur’s Cave. The Equus tooth enamel provides a record of climatic conditions during the animals’ tooth formation. Evidence of human modification of the teeth (cut marks and fractures) chronologically tie these palaeoclimatic records to the earliest post-LGM archaeology at the two sites, thus informing on the climatic and environmental context under which human activity in these areas took place. Results indicate that people were present at the two sites during a period of climatic warming, with temperatures perhaps only marginally colder than present day conditions. However, suboptimal environmental conditions are suggested and may indicate changing vegetation dynamics within the local landscape

Conceptual mechanization studies for a horizon definition spacecraft electrical power subsystem

Solar cell-battery electrical power subsystem for horizon definition spacecraf

QTL mapping of carrot resistance to leaf blight with connected populations: stability across years and consequences for breeding

Combining biparental and multiparental connected population analyses was useful for the identification of 11 QTLs in two new genetic backgrounds of carrot resistance to Alternaria dauci and for breeding recommendations. Leaf blight due to the fungus Alternaria dauci is the major carrot foliar disease worldwide. Some resistance QTLs have been previously identified in one population, but the evaluation of additional genetic backgrounds with higher level of resistance would give opportunities for breeders to combine them by pyramiding. For this purpose, two segregating populations were evaluated twice across 4 years in the same environment (1) to compare the efficiency of the single vs. the connected populations approach for characterizing the new sources of carrot resistance to Alternaria dauci; (2) to evaluate the stability of QTLs over the years; and (3) to give recommendations to breeders for marker-assisted selection. Single and connected analyses were complementary; their combination allowed the detection of 11 QTLs. Connected analyses allowed the identification of common and specific QTLs among the two populations and the most favorable allele at each QTL. Important contrasts between allelic effects were observed with four and five most favorable alleles coming from the two resistant parental lines, whereas two other favorable alleles came from the susceptible parental line. While four QTLs were consistent across years, seven were detected within a single year. The heritabilities for both populations PC2 and PC3 were high (75 and 78 %, respectively), suggesting that the resistance of carrot to A. dauci was little affected by these environmental conditions, but the instability of QTL over years may be due to changing environmental conditions. The complementarity between these parental lines in terms of interesting allelic combinations is also discussed