Colorado State University

About: Colorado State University is a education organization based out in Fort Collins, Colorado, United States. It is known for research contribution in the topics: Population & Radar. The organization has 31430 authors who have published 69040 publications receiving 2724463 citations. The organization is also known as: CSU & Colorado Agricultural College.

Biodegradation kinetics of benzene, toluene, and phenol as single and mixed substrates for Pseudomonas putida F1

Abstract: Although microbial growth on substrate mixtures is commonly encountered in bioremediation, wastewater treatment, and fermentation, mathematical modeling of mixed substrate kinetics has been limited. We report the kinetics of Pseudomonas putida F1 growing on benzene, toluene, phenol, and their mixtures, and compare mathematical models to describe these results. The three aromatics are each able to act as carbon and energy sources for this strain. Biodegradation rates were measured in batch cultivations following a protocol that eliminated mass transfer limitations for the volatile substrates and considered the culture history of the inoculum and the initial substrate to inoculum mass ratio. Toluene and benzene were better growth substrates than phenol, resulting in faster growth and higher yield coefficients. In the concentration ranges tested, toluene and benzene biodegradation kinetics were well described by the Monod model. The Monod model was also used to characterize phenol biodegradation by P. putida F1, although a small degree of substrate inhibition was noted. In mixture experiments, the rate of consumption of one substrate was found to be affected by the presence of the others, although the degree of influence varied widely. The substrates are catabolized by the same enzymatic pathway, but purely competitive enzyme kinetics did not capture the substrate interactions well. Toluene significantly inhibited the biodegradation rate of both of the other substrates, and benzene slowed the consumption of phenol (but not of toluene). Phenol had little effect on the biodegradation of either toluene or benzene. Of the models tested, a sum kinetics with interaction parameters (SKIP) model provided the best description of the paired substrate results. This model, with parameters determined from one- and two-substrate experiments, provided an excellent prediction of the biodegradation kinetics for the three-component mixture.

New kagome prototype materials: Discovery of KV3Sb5,RbV3Sb5, and CsV3Sb5

Abstract: In this work, we present our discovery and characterization of a new kagome prototype structure, ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$. We also present the discovery of the isostructural compounds ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ and ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$. All materials exhibit a structurally perfect two-dimensional kagome net of vanadium. Density-functional theory calculations indicate that the materials are metallic, with the Fermi level in close proximity to several Dirac points. Powder and single-crystal syntheses are presented, with postsynthetic treatments shown to deintercalate potassium from single crystals of ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$. Considering the proximity to Dirac points, deintercalation provides a convenient means to tune the Fermi level. Magnetization measurements indicate that ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$ exhibits behavior consistent with a the Curie-Weiss model at high temperatures, although the effective moment is low $(0.22{\ensuremath{\mu}}_{\text{B}}$ per vanadium ion). An anomaly is observed in both magnetization and heat capacity measurements at 80 K, below which the moment is largely quenched. Elastic neutron scattering measurements find no obvious evidence of long-range or short-range magnetic ordering below 80 K. The possibility of an orbital-ordering event is considered. Single-crystal resistivity measurements show the effect of deintercalation on the electron transport and allow estimation of the Kadowaki-Woods ratio in ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$. We find that $A/{\ensuremath{\gamma}}^{2}\ensuremath{\sim}61\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{Ohm}$ cm ${\mathrm{mol}}_{\text{FU}}^{2}\phantom{\rule{4pt}{0ex}}{\mathrm{K}}^{2}\phantom{\rule{4pt}{0ex}}{\mathrm{J}}^{\ensuremath{-}2}$, suggesting that correlated electron transport may be possible. ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$ and its cogeners ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ and ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ represent a new family of kagome metals, and our results demonstrate that they deserve further study as potential model systems.

Autophagy protects against active tuberculosis by suppressing bacterial burden and inflammation

Abstract: Autophagy is a cell biological pathway affecting immune responses In vitro, autophagy acts as a cell-autonomous defense against Mycobacterium tuberculosis, but its role in vivo is unknown Here we show that autophagy plays a dual role against tuberculosis: antibacterial and anti-inflammatory M tuberculosis infection of Atg5(fl/fl) LysM-Cre(+) mice relative to autophagy-proficient littermates resulted in increased bacillary burden and excessive pulmonary inflammation characterized by neutrophil infiltration and IL-17 response with increased IL-1α levels Macrophages from uninfected Atg5(fl/fl) LysM-Cre(+) mice displayed a cell-autonomous IL-1α hypersecretion phenotype, whereas T cells showed propensity toward IL-17 polarization during nonspecific activation or upon restimulation with mycobacterial antigens Thus, autophagy acts in vivo by suppressing both M tuberculosis growth and damaging inflammation

Mitigating Climate Change in US Cities: Opportunities and obstacles

Abstract: This study examines opportunities for and obstacles to the mitigation of climate change in US cities using the example of the Cities for Climate Protection (CCP) campaign sponsored by the International Council for Local Environmental Initiatives. The CCP experience suggests a number of ways in which municipal governments can control greenhouse gas (GHG) emissions but also highlights several obstacles that make it difficult for local officials to do so. First, climate change is generally framed as a global issue. The CCP experience suggests that climate change is most likely to be reframed as a local issue when the preferred policy response (controlling GHG emissions) can be linked to issues (e.g. air quality) already on the local agenda. Secondly, even when local governments recognise that they should do something to control GHG emissions, institutional barriers make it difficult for municipalities to move from political rhetoric to policy action. Finally, it is questionable whether local initiatives can ...