A Comparison Study of Soot Precursor and Aggregate Property Between Algae-Based Aviation Biofuel and Aviation Kerosene RP-3 in Laminar Flame

Algae-based aviation biofuel shows the potential to reduce soot emission in flight. A comparison study of soot precursor and aggregate property between algae-based biofuel and aviation kerosene RP-3 in laminar flame was conducted to investigate the reason of biofuel’s less soot formation. The soot precursors were determined by the fringe lengths of soot particles. At a typical dimensionless height DH = 0.50 of both flames, the geometric mean fringe lengths of biofuel and RP-3 are measured to be 0.67 and 0.73 nm, respectively, approximating to the size of five-ringed (A5) and seven-ringed (A7) poly-aromatic hydrocarbon, respectively. An A5 growth mechanism was then added to biofuel surrogate mechanisms for soot formation simulation. Since the carbon number component of biofuel is wide and difficult for comprehensive mechanism development, two surrogate mechanisms were developed. One is based on the C8–C16 n-alkane that covers biofuel’s main components, and the other one is based on biofuel’s average carbon number to simplify the mechanism. Meanwhile, an A7 growth mechanism was added to a popular RP-3 mechanism. The soot formation simulation with the combination mechanisms for both fuels provides a better agreement with the measured primary particle diameter and suggests that the reason for less soot production by biofuel is its less soot precursor production that weakens soot nucleation and growth. Lastly, the soot fractal dimension of biofuel is smaller than that of RP-3, indicating that biofuel has a looser soot aggregate.

Why scaling up uncertain predictions to higher levels of organisation will underestimate change

Uncertainty is an irreducible part of predictive science, causing us to over- or underestimate the magnitude of change that a system of interest will face. In a reductionist approach, we may use predictions at the level of individual system components (e.g. species biomass), and combine them to generate predictions for system-level properties (e.g. ecosystem function). Here we show that this process of scaling up uncertain predictions to higher levels of organization has a surprising consequence: it will systematically underestimate the magnitude of system-level change, an effect whose significance grows with the system’s dimensionality. This stems from a geometrical observation: in high dimensions there are more ways to be more different, than ways to be more similar. This general remark applies to any complex system. Here we will focus on ecosystems thus, on ecosystem-level predictions generated from the combination of predictions at the species-level. In this setting, the ecosystem’s dimensionality is a measure of its diversity. We explain why dimensional effects do not play out when predicting change of a single linear aggregate property (e.g. total biomass), yet are revealed when predicting change of non-linear properties (e.g. absolute biomass change, stability or diversity), and when several properties are considered at once to describe the ecosystem, as in multi-functional ecology. Our findings highlight and describe the counter-intuitive effects of scaling up uncertain predictions, effects that will occur in any field of science where a reductionist approach is used to generate predictions.

Trait-based approach to bacterial growth efficiency

Bacterial growth efficiency (BGE) is the proportion of assimilated carbon that is converted into biomass and reflects the balance between growth and energetic demands. Often measured as an aggregate property of the community, BGE is highly variable within and across ecosystems. To understand this variation, we first identified how species identity and resource type affect BGE using 20 bacterial isolates belonging to the phylum Proteobacteria that were enriched from north temperate lakes. Using a trait-based approach that incorporated genomic and phenotypic information, we characterized the metabolism of each isolate and tested for predicted trade-offs between growth rate and efficiency. A substantial amount of variation in BGE could be explained at both broad (i.e., order, 20 %) and fine (i.e., strain, 58 %) taxonomic levels. While resource type was a relatively weak predictor across species, it explained > 60 % of the variation in BGE within a given species. Furthermore, a metabolic trade-off (between maximum growth rate and efficiency) and genomic features revealed that BGE is a predictable metabolic feature. Our study suggests that genomic and phylogenetic information may help predict aggregate microbial community functions like BGE and the fate of carbon in ecosystems.Originality and SignificanceBacterial growth efficiency (BGE) is an important yet notoriously variable measure of metabolism that has proven difficult to predict. To better understand how assimilated carbon is allocated, we explored growth efficiency across a collection of bacteria strains using a trait-based approach. Specifically, we measured respiration and biomass formation rates for populations grown in minimal media containing one of three carbon resources. In addition, we collected a suite of physiological traits to describe each strain, and we sequenced the genome of each organism. Our results suggest that species identity and resource type may contribute to growth efficiency when measured as an aggregate property of a natural community. In addition, we identified genomic pathways that are associated with elevated BGE. The findings have implications for integrating microbial metabolism from the cellular to ecosystem scale.

Impact of Highways on Property Values: Case Study of Superstition Freeway Corridor

The effects of freeway development on land use and property values were examined. A case study was prepared for the Superstition Freeway (US-60) corridor in Mesa and Gilbert, Arizona. Among the findings were the following observations. First, access benefits are transferred from highway users to nonusers through changes in property values. Freeway construction may have an adverse impact on some properties, but in the aggregate, property values tend to increase with freeway development. Second, freeways do not affect all properties' values in the same way. Proximity to the freeway was observed to have a negative effect on the value of detached single-family homes in the US-60 corridor but a positive effect on multifamily residential developments (e.g., condominiums) and most commercial properties. Finally, the most important factor in determining negative impact on property values appears to be the level of traffic on any major roads in the proximate area, which implies that regional traffic growth is more significant than the presence of a freeway per se.

Possible problems with high PSV aggregate of the gritstone trade group

This paper considers the methods of assessment of high PSV greywacke aggregate from the Longford Down Massif. It reviews current specification requirements concluding that PSV is regarded as the most important surfacing aggregate property in the UK. Using a set of data, PSV is correlated with other test properties including AIV, TFV, MSSV, AAV and MDE. Despite poor correlations, the data shows general trends between properties indicating that PSV is achieved at the expense of other test properties.

The Relative Wealth of the Parties as a Factor in Tortious Liability

In its desire to reduce the loss and expense involved in the occurrence of accidents, organized society is likely to consider various factors determining the nature of the rules (whether legal or other) that will guide it in its decision. These factors may includemoralfault (in the accepted meaning of the term),economicfault or the relative wealth of the parties involved in causing the loss.The purpose of this article is to examine the third factor, ie‥ relative wealth. By “relative wealth of the parties” we mean the quantity of property of monetary value in the hands of each of the parties relative to the aggregate property of the other parties and to the property of each. The parties in question are not necessarily those physically involved in causing the damage but those persons or groups which the rules for allocation of loss regard as potential bearers of the loss.