Oil spills in the subarctic marine environment off the coast of Labrador, Canada, are increasingly likely due to potential oil production and increases in ship traffic in the region. To understand ...the microbiome response and how nutrient biostimulation promotes biodegradation of oil spills in this cold marine setting, marine sediment microcosms amended with diesel or crude oil were incubated at
temperature (4°C) for several weeks. Sequencing of 16S rRNA genes following these spill simulations revealed decreased microbial diversity and enrichment of putative hydrocarbonoclastic bacteria that differed depending on the petroleum product. Metagenomic sequencing revealed that the genus
harbors previously unrecognized capabilities for alkane biodegradation, which were also observed in
. Genomic and amplicon sequencing together suggest that
and
degraded alkanes from diesel, while
and the novel PGZG01 lineage contributed to crude oil alkane biodegradation. Greater losses in PAHs from crude oil than from diesel were consistent with
,
D, and
genomes exhibiting aromatic hydrocarbon biodegradation potential. Biostimulation with nitrogen and phosphorus (4.67 mM NH
Cl and 1.47 mM KH
PO
) was effective at enhancing
-alkane and PAH degradation following low-concentration (0.1% vol/vol) diesel and crude oil amendments, while at higher concentrations (1% vol/vol) only
-alkanes in diesel were consumed, suggesting toxicity induced by compounds in unrefined crude oil. Biostimulation allowed for a more rapid shift in the microbial community in response to petroleum amendments, more than doubling the rates of CO
increase during the first few weeks of incubation.
Increases in transportation of diesel and crude oil in the Labrador Sea will pose a significant threat to remote benthic and shoreline environments, where coastal communities and wildlife are particularly vulnerable to oil spill contaminants. Whereas marine microbiology has not been incorporated into environmental assessments in the Labrador Sea, there is a growing demand for microbial biodiversity evaluations given the pronounced impact of climate change in this region. Benthic microbial communities are important to consider given that a fraction of spilled oil typically sinks such that its biodegradation occurs at the seafloor, where novel taxa with previously unrecognized potential to degrade hydrocarbons were discovered in this work. Understanding how cold-adapted microbiomes catalyze hydrocarbon degradation at low
temperature is crucial in the Labrador Sea, which remains relatively cold throughout the year.
This paper addresses the problem of the optimal design of batch plants with imprecise demands in product amounts. The design of such plants necessarily involves the way that equipment may be ...utilized, which means that plant scheduling and production must form an integral part of the design problem. This work relies on a previous study, which proposed an alternative treatment of the imprecision (demands) by introducing fuzzy concepts, embedded in a multi-objective Genetic Algorithm (GA) that takes into account simultaneously maximization of the net present value (
NPV) and two other performance criteria, i.e. the production delay/advance and a flexibility criterion. The results showed that an additional interpretation step might be necessary to help the managers choosing among the non-dominated solutions provided by the GA. The analytic hierarchy process (AHP) is a strategy commonly used in Operations Research for the solution of this kind of multicriteria decision problems, allowing the apprehension of manager subjective judgments. The major aim of this study is thus to propose a software integrating the AHP theory for the analysis of the GA Pareto-optimal solutions, as an alternative decision-support tool for the batch plant design problem solution.
The transformation of tropical forests to agricultural systems modifies the diversity of species. Species respond differentially to disturbance depending on how they interact with their environment; ...therefore, the diversity of species that results following the transformation of a tropical forest could depend on the type of agricultural system that is established and the traits and functions of the species that make up the native communities. In this study, the effect of establishing two agricultural systems on an assemblage of tropical forest lizards was evaluated. To do so, the functional diversity and species diversity of lizards in tropical forest, a lime crop, and a coconut crop in southeastern Mexico were analyzed. The results showed that both the functional diversity and the diversity of species decreased when the tropical forest was transformed into either of these agricultural systems. However, this decrease differs in magnitude depending on the type of crop, since in the lime crop (less heterogeneous) there was a greater reduction in species richness, of functional groups, and of the members of the functional groups than in the coconut crop (more heterogeneous). The agricultural systems studied are not capable of maintaining the diversity of native species or the functional diversity of tropical forest lizards. Therefore, in landscapes modified by humans, it is essential to maintain fragments of native forest between agricultural plots to conserve those species highly susceptible to tropical forest transformation, as well as assemblages of species with a wide variety of functional traits.
•Diesel injector body operating with high-pressure gasoline.•Custom designed injector nozzles with canonical internal geometry.•Higher injector temperatures increase mass flow rate under all ...conditions.•Momentum coefficients are proportional to cavitation number, indicating cavitation.•Nozzle geometry had strongest effect on spray development after spray break-up time.
High fuel injection pressure (>500 bar) in direct injection gasoline engines is an important means to reduce particulate emissions. While decades of fuel spray research has dramatically advanced the understanding high-pressure diesel fuel sprays, few studies focus on high-pressure gasoline sprays. The objective of this work was to quantify the effects of different injector nozzle geometries on important high-pressure gasoline spray characteristics including injection mass flow rate, momentum flux, and spray imaging at evaporative and non-evaporative conditions. Three categories of nozzle internal geometry were evaluated: inlet rounding; converging-, diverging-, and straight-cylindrical internal flow passages; and different nozzle outlet diameters. Reference grade gasoline was used at injection pressures of 600, 900, 1200, and 1500 bar at chamber pressures from 1 to 30 bar and chamber temperatures from 293 to 800 K. Two fuel injector temperatures of 293 K and 363 K were studied. The mass and momentum measurements were used to quantify differences in injector geometry as well as to evaluate for effects of cavitation. The visualization data were analyzed to determine spray penetration and spray angle development for a broad range of operating and state conditions. The results showed internal flow significantly impacts injector performance, where nozzles with inlet rounding resulted in 20% higher mass flow rate compared with straight cylindrical nozzles. Higher fuel injector temperatures also increased mass flow rate by up to 5%. Spray momentum coefficients showed a linear relationship with cavitation number indicating all nozzles were cavitating at all conditions tested. Trends in fuel spray penetration and spray angle development were similar to those observed previously for diesel sprays, which was unexpected given the significant differences in thermal-physical properties of the fuels. Chamber pressure had the strongest influence on penetration distance, and the momentum measurements were good indicators of the injector geometry with the highest penetration distance.
Abstract
Warm absorber spectra contain bound-bound and bound-free absorption features seen in the X-ray and UV spectra from many active galactic nuclei. The widths and centroid energies of these ...features indicate they occur in outflowing gas, and the outflow can affect the gas within the host galaxy. Thus, the warm absorber mass and energy budgets are of great interest. Estimates for these properties depend on models that connect the observed strengths of the absorption features with the density, composition, and ionization state of the absorbing gas. Such models assume that the ionization and heating of the gas come primarily from the strong continuum near the central black hole. They also assume that the various heating, cooling, ionization, and recombination processes are in a time-steady balance. This assumption may not be valid, owing to the intrinsic time variability of the illuminating continuum or other factors that change the cloud environment. This paper presents models for warm absorbers that follow the time dependence of the ionization, temperature, and radiation field in warm absorber gas clouds in response to a changing continuum illumination. We show that the effects of time variability are important over a range of parameter values, that time-dependent models differ from equilibrium models in meaningful ways, and that these effects should be included in models that derive properties of warm absorber outflows.
We present a domain decomposition (DD) framework for the analysis of impenetrable structures; it allows for the electric field integral equation (EFIE) and combined field integral equation (CFIE), ...and for open, closed, and open-closed structures. The DD results in an effective preconditioner for large and complex problems exploiting iterative solution and fast factorizations. The DD employs specialized transmission conditions among the domains, and the use of discontinuous Galerkin (DG) allows conformal as well as nonconformal discretizations of domain boundaries; the nonconformal nature of the decomposition gives considerable flexibility in the meshing. The strategy is highly parallelizable, as all the operations involving the subdomains can be performed in parallel. The proposed scheme is implementation independent and can be easily merged with existing electromagnetic codes.
Diarrheagenic E. coli (DEC) strains are one of the most important etiology factors causing diarrhea in children worldwide, especially in developing countries. DEC strains have characteristic ...virulence factors; however, other supplemental virulence genes (SVG) may contribute to the development of diarrhea in children. Therefore, this study aimed to determine the prevalence of DEC in children with diarrhea in southwestern Mexico and to associate childhood symptoms, SVG, and pathotypes with diarrhea-causing DEC strains. DEC strains were isolated from 230 children with diarrhea aged 0-60 months from the state of Oaxaca, southwestern Mexico; clinical data were collected, and PCR was used to identify SVG and pathotypes. Antibiotic resistance profiling was performed on DEC strains. 63% of samples were DEC positive, single or combined infections (two (21%) or three strains (1.3%)) of aEPEC (51%), EAEC (10.2%), tEPEC (5.4%), DAEC (4.8%), ETEC (4.1%), EIEC (1.4%), or EHEC (0.7%) were found. Children aged ≤ 12 and 49-60 months and symptoms (e.g., fever and blood) were associated with DEC strains. SVG related to colonization (nleB-EHEC), cytotoxicity (sat-DAEC and espC-tEPEC), and proteolysis (pic-aEPEC) were associated with DECs strains. E. coli phylogroup A was the most frequent, and some pathotypes (aEPEC-A, DAEC-B), and SVG (espC-B2, and sat-D) were associated with the phylogroups. Over 79% of the DEC strains were resistant to antibiotics, and 40% were MDR and XDR, respectively. In conclusion aEPEC was the most prevalent pathotype in children with diarrhea in this region. SVG related to colonization, cytotoxicity, and proteolysis were associated with diarrhea-producing DEC strains, which may play an essential role in the development of diarrhea in children in southwestern Mexico.
•SARS-CoV-2 RNA was detected in the wastewater of three hospitals.•Abundance of SARS-CoV-2 correlated with increasing burden of active-COVID-19 cases.•Hospital SARS-CoV-2 outbreaks were distinguished ...from community acquired cases.•Wastewater surveillance is useful for COVID-19 monitoring in high-risk facilities.
SARS-CoV-2 has been detected in wastewater and its abundance correlated with community COVID-19 cases, hospitalizations and deaths. We sought to use wastewater-based detection of SARS-CoV-2 to assess the epidemiology of SARS-CoV-2 in hospitals. Between August and December 2020, twice-weekly wastewater samples from three tertiary-care hospitals (totaling > 2100 dedicated inpatient beds) were collected. Hospital-1 and Hospital-2 could be captured with a single sampling point whereas Hospital-3 required three separate monitoring sites. Wastewater samples were concentrated and cleaned using the 4S-silica column method and assessed for SARS-CoV-2 gene-targets (N1, N2 and E) and controls using RT-qPCR. Wastewater SARS-CoV-2 as measured by quantification cycle (Cq), genome copies and genomes normalized to the fecal biomarker PMMoV were compared to the total daily number of patients hospitalized with active COVID-19, confirmed cases of hospital-acquired infection, and the occurrence of unit-specific outbreaks. Of 165 wastewater samples collected, 159 (96%) were assayable. The N1-gene from SARS-CoV-2 was detected in 64.1% of samples, N2 in 49.7% and E in 10%. N1 and N2 in wastewater increased over time both in terms of the amount of detectable virus and the proportion of samples that were positive, consistent with increasing hospitalizations at those sites with single monitoring points (Pearson's r = 0.679, P < 0.0001, Pearson's r = 0.799, P < 0.0001, respectively). Despite increasing hospitalizations through the study period, nosocomial-acquired cases of COVID-19 (Pearson's r = 0.389, P < 0.001) and unit-specific outbreaks were discernable with significant increases in detectable SARS-CoV-2 N1-RNA (median 112 copies/ml) versus outbreak-free periods (0 copies/ml; P < 0.0001). Wastewater-based monitoring of SARS-CoV-2 represents a promising tool for SARS-CoV-2 passive surveillance and case identification, containment, and mitigation in acute- care medical facilities.
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Many pathways for hydrocarbon degradation have been discovered, yet there are no dedicated tools to identify and predict the hydrocarbon degradation potential of microbial genomes and metagenomes. ...Here we present the Calgary approach to ANnoTating HYDrocarbon degradation genes (CANT-HYD), a database of 37 HMMs of marker genes involved in anaerobic and aerobic degradation pathways of aliphatic and aromatic hydrocarbons. Using this database, we identify understudied or overlooked hydrocarbon degradation potential in many phyla. We also demonstrate its application in analyzing high-throughput sequence data by predicting hydrocarbon utilization in large metagenomic datasets from diverse environments. CANT-HYD is available at https://github.com/dgittins/CANT-HYD-HydrocarbonBiodegradation.
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