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21.
Multivariate statistical analysis has been applied to time series measurements of aerosol elemental composition from PIXE
analysis of filter samples, and principal components have been resolved that represent distinct particle types in an external
mixture in the atmosphere. In this study, it is argued that a combination of chemical and statistical analyses of the data
may be more powerful in determining chemical species in atmospheric aerosols than studies that employ mainly direct chemical
analysis of chemical species in unresolved mixtures of aerosol particle samples. Sulfur is generally associated with mineral
dust elements. It is reasoned that the association may represent sulfuric acid coatings on particles that can lead to mineral
dissolution and solubilization of significant amounts of aluminum, iron, and other metals.
Upon wet or dry deposition to the surface, the fluxes of these metals in biologically-available form may be sufficient to
affect primary productivity in the world ocean and cause ecological damage in lakes. As a consequence, the fluxes of biogenic
trace gases to the atmosphere may be changed, possibly leading to changes in the tropospheric concentration of ozone. The
inputs to lakes of soluble aluminum, which is toxic to fish, may be partly by deposition directly from the atmosphere, thus
not limited to leaching of soils by acid deposition. Human inhalation of soluble aluminum and other solulilized mineral metals
may account, in part, for the observed geographic pattern of deaths attributed to chronic obstructive pulmonary disease (COPD)
that show high rates in cities of the Western US and the southeast region, but low in most of the midwest and northeast. 相似文献
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Marta Royo Vicente Chulvi Elena Mulet Laura Ruiz-Pastor 《Journal of Industrial Ecology》2023,27(2):562-586
One of the approaches followed by the circular economy (CE) to achieve sustainability through design is product life extension. Extending the life of products to make them useful for as long as possible is a means to reduce waste production and materials consumption, as well as the related impacts. For designers, conceptualizing products in a way that allows them to be used for longer is a challenge, and assessing how well they extend their lifespan can be helpful when it comes to choosing the best proposal. In this paper, 70 tools and methods related to eco-design and circular economy are studied to determine how many of them consider parameters related to life extension and which can be applied in the early stages of design. The results of the analysis show that most of the existing tools and methods are applicable to developed products, and only a few of them take into account parameters related to extending the useful life. Of the 70 tools and methods, only 14 include some parameter related to life extension and are applicable to concepts. CE toolkit, Eco-design PILOT, CE Designer, Circularity Assessment tool, Circularity Potential Indicator and Circular Design Tools take into consideration eight or more parameters to assess life extension in concepts. This will help designers select the most appropriate and will indicate the need for more complete tools to consider useful life extension in the early stages of design and thus enhance the selection of more sustainable products. 相似文献
25.
During mate choice, receivers often assess the magnitude (duration, size, etc.) of signals that vary along a continuum and reflect variation in signaller quality. It is generally assumed that receivers assess this variation linearly, meaning each difference in signalling trait between signallers results in a commensurate change in receiver response. However, increasing evidence shows receivers can respond to signals non-linearly, for example through Weber's Law of proportional processing, where discrimination between stimuli is based on proportional, rather than absolute, differences in magnitude. We quantified mate preferences of female green swordtail fish, Xiphophorus hellerii, for pairs of males differing in body size. Preferences for larger males were better predicted by the proportional difference between males (proportional processing) than the absolute difference (linear processing). This demonstration of proportional processing of a visual signal implies that receiver perception may be an important mechanism selecting against the evolution of ever-larger signalling traits. 相似文献
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Continuous culture experiments with identical experimental designs were run with a mixed microbial community of activated sludge origin and an axenic bacterial culture derived from it. Each culture received 2-chlorophenol (2-CP) at a concentration of 160 mg/L as COD and L-lysine at a concentration of 65 mg/L as COD. A factorial experimental design was employed with dilution rate and media composition as the two controlled variables. Three dilution rates were studied: 0.015, 0.0325, and 0.05 h–1. Media composition was changed by adding four biogenic compounds (butyric acid, thymine, glutamic acid and lactose) in equal COD proportions at total concentrations of 0, 34, 225, and 1462 mg/L as COD. The measured variables were the effluent concentrations of 2-CP as measured by the 4-aminoantipyrene test and lysine as measured by the o-diacetylbenzene procedure. The results suggest that community structure and substrate composition play important roles in the response of a microbial community to mixed substrates. The addition of more biogenic substrates to the axenic culture had a deleterious effect on the removal of both lysine and 2-CP, although the effect was much larger on lysine removal. In contrast, additional substrates had a positive effect on the removal of 2-CP by the mixed community and much less of a negative effect on the removal of lysine. The dilution rate at which the cultures were growing had relatively little impact on the responses to the additional substrates.Abbreviations COD
chemical oxygen demand
- 2-CP
2-chlorophenol
- DOC
dissolved organic carbon
- MDL
method detection limit
- SS
suspended solids 相似文献
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The selectins are a family of proteins that mediate leukocytetethering and rolling along the vascular endothelium. E-, P-,and L-selectin recognize various derivatives of the Lewisa andLewisx trisaccharides. The distribution of negative chargeson the Lewisa and Lewisx oligosaccharides appears to be an importantfactor in their binding by the selectins. Previous work exploringthis electrostatic dependence found that a series of syntheticanionic trisaccharides, 3'-sulfo, 3'-phospho, 6'-sulfo, and3',6'-disulfo Lewisa. (Glc), exhibited differing selectin inhibitoryefficacies. To explore the possibility that these differencesarise from conformational differences between the sugars, thesolution structures of these trisaccharides were determinedusing NMR and molecular dynamics simulations. Interproton distancesand interglycosidic torsion angles were determined at 37°Cusing NOESY buildup curves and 1D LRJ experiments, respectively.Data from both experiments agreed well with predictions madefrom 2000 picosecond unrestrained molecular dynamics simulations.We found that 3'-sulfation did not alter the core Lewisa conformation,a finding that reaffirms the results of previous study. In addition,we found that sulfation at the 6' position also leaves the trisaccharideconformation unperturbed. This is significant because the proximityof the 6'-sulfate group to the fucose ring might have alteredthe canonical Lewisa structure. The disulfate exhibited greaterflexibility than the other derivatives in dynamics simulations,but not so much as to affect NOE and heteronuclear couplingconstant measurements. Taken together, our findings supportthe use of Lewisa as a template onto which charged groups maybe added without significantly altering the trisaccharide'sstructure. oligosaccharides molecular dynamics simulations NMR sulfated Lewisa phosphorylated Lewisa 相似文献