745 research outputs found
Predicting the Reactions of CS2 with Group IV and Group VI Transition Metal Oxides
Building onto a recent serious of ab initio studies of various acid-gas reactions with metal oxide sorbents, electronic structure methods are being used to study the addition of CSâ to Group IV (MOâ)â and Group VI (MOâ)â (n = 1, 2, 3) nanoclusters, beginning with the MOâ and MOâ monomers according to a âbottom-upâ approach. The preliminary density functional theory (DFT) calculations in this study provide structures and vibrational frequency thermodynamic corrections for later expanding upon by way of single point correlated molecular-orbital theory (MO) calculations, mainly CCSD(T) and MP2 to study the structures and energies which could arise from Lewis acid-base addition (physisorption) and formation of COSâÂČâ» (chemisorption) of CSâ to these clusters will be predicted. For future work, these CSâ ligand binding energies (LBE) will be compared to established COâ results in the literature and to any known experimental and computational values for the interactions of CSâ with bulk metal oxides. These LBEs will then be analyzed for any correlation to any known trends in the metal oxide Lewis acidity, metal oxide redox chemistry, and acid gas basicity to establish useful thermodynamic benchmarks for the practicality of Group IV and Group VI transition metal oxides for the sequestration and conversion of CSâ. The results of this work and beyond could also have serious implications for the sequestration of CSâ from high-sulfur areas of the arctic permafrost and could provide valuable mechanistic insights into the possible reactions and products of metal oxide degradation during the Claus Process.https://scholarworks.moreheadstate.edu/celebration_posters_2023/1062/thumbnail.jp
Coming unmoored: Disproportionate increases in obesity prevalence among young, disadvantaged white women
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109980/1/oby20913.pd
Collision-induced C_60 rovibrational relaxation probed by state-resolved nonlinear spectroscopy
Quantum state-resolved spectroscopy was recently achieved for C60 molecules
when cooled by buffer gas collisions and probed with a midinfrared frequency
comb. This rovibrational quantum state resolution for the largest molecule on
record is facilitated by the remarkable symmetry and rigidity of C60, which
also present new opportunities and challenges to explore energy transfer
between quantum states in this many-atom system. Here we combine state-specific
optical pumping, buffer gas collisions, and ultrasensitive intracavity
nonlinear spectroscopy to initiate and probe the rotation-vibration energy
transfer and relaxation. This approach provides the first detailed
characterization of C60 collisional energy transfer for a variety of collision
partners, and determines the rotational and vibrational inelastic collision
cross sections. These results compare well with our theoretical modeling of the
collisions, and establish a route towards quantum state control of a new class
of unprecedentedly large molecules
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Accurate forest projections require long-term wood decay experiments because plant trait effects change through time.
Whether global change will drive changing forests from net carbon (C) sinks to sources relates to how quickly deadwood decomposes. Because complete wood mineralization takes years, most experiments focus on how traits, environments and decomposer communities interact as wood decay begins. Few experiments last long enough to test whether drivers change with decay rates through time, with unknown consequences for scaling short-term results up to long-term forest ecosystem projections. Using a 7 year experiment that captured complete mineralization among 21 temperate tree species, we demonstrate that trait effects fade with advancing decay. However, wood density and vessel diameter, which may influence permeability, control how decay rates change through time. Denser wood loses mass more slowly at first but more quickly with advancing decay, which resolves ambiguity about the after-life consequences of this key plant functional trait by demonstrating that its effect on decay depends on experiment duration and sampling frequency. Only long-term data and a time-varying model yielded accurate predictions of both mass loss in a concurrent experiment and naturally recruited deadwood structure in a 32-year-old forest plot. Given the importance of forests in the carbon cycle, and the pivotal role for wood decay, accurate ecosystem projections are critical and they require experiments that go beyond enumerating potential mechanisms by identifying the temporal scale for their effects
Comparative genomics of Steinernema reveals deeply conserved gene regulatory networks
Background:
Parasitism is a major ecological niche for a variety of nematodes. Multiple nematode lineages have specialized as pathogens, including deadly parasites of insects that are used in biological control. We have sequenced and analyzed the draft genomes and transcriptomes of the entomopathogenic nematode Steinernema carpocapsae and four congeners (S. scapterisci, S. monticolum, S. feltiae, and S. glaseri).
Results:
We used these genomes to establish phylogenetic relationships, explore gene conservation across species, and identify genes uniquely expanded in insect parasites. Protein domain analysis in Steinernema revealed a striking expansion of numerous putative parasitism genes, including certain protease and protease inhibitor families, as well as fatty acid- and retinol-binding proteins. Stage-specific gene expression of some of these expanded families further supports the notion that they are involved in insect parasitism by Steinernema. We show that sets of novel conserved non-coding regulatory motifs are associated with orthologous genes in Steinernema and Caenorhabditis.
Conclusions:
We have identified a set of expanded gene families that are likely to be involved in parasitism. We have also identified a set of non-coding motifs associated with groups of orthologous genes in Steinernema and Caenorhabditis involved in neurogenesis and embryonic development that are likely part of conserved proteinâDNA relationships shared between these two genera
A Knockout of the Tsg101 Gene Leads to Decreased Expression of ErbB Receptor Tyrosine Kinases and Induction of Autophagy Prior to Cell Death
The Tumor Susceptibility Gene 101 (Tsg101) encodes a multi-domain protein that mediates a variety of molecular and biological processes including the trafficking and lysosomal degradation of cell surface receptors. Conventional and conditional knockout models have demonstrated an essential requirement of this gene for cell cycle progression and cell viability, but the consequences of a complete ablation of Tsg101 on intracellular processes have not been examined to date. In this study, we employed mouse embryonic fibroblasts that carry two Tsg101 conditional knockout alleles to investigate the expression of ErbB receptor tyrosine kinases as well as stress-induced intracellular processes that are known to be associated with a defect in growth and cell survival. The conditional deletion of the Tsg101 gene in this well-controlled experimental model resulted in a significant reduction in the steady-state levels of the EGFR and ErbB2 but a stress-induced elevation in the phosphorylation of mitogen activated protein (MAP) kinases independent of growth factor stimulation. As part of an integrated stress response, Tsg101-deficient cells exhibited extensive remodeling of actin filaments and greatly enlarged lysosomes that were enriched with the autophagy-related protein LC3. The increase in the transcriptional activation and expression of LC3 and its association with Lamp1-positive lysosomes in a PI3K-dependent manner suggest that Tsg101 knockout cells utilize autophagy as a survival mechanism prior to their ultimate death. Collectively, this study shows that a knockout of the Tsg101 gene causes complex intracellular changes associated with stress response and cell death. These multifaceted alterations need to be recognized as they have an impact on defining particular functions for Tsg101 in processes such as signal transduction and lysosomal/endosomal trafficking
MINDS. Abundant water and varying C/O across the disk of Sz 98 as seen by JWST/MIRI
MIRI/MRS on board the JWST allows us to probe the inner regions of
protoplanetary disks. Here we examine the disk around the classical T Tauri
star Sz 98, which has an unusually large dust disk in the millimetre with a
compact core. We focus on the HO emission through both its ro-vibrational
and pure rotational emission. Furthermore, we compare our chemical findings
with those obtained for the outer disk from Atacama Large
Millimeter/submillimeter Array (ALMA) observations. In order to model the
molecular features in the spectrum, the continuum was subtracted and LTE slab
models were fitted. The spectrum was divided into different wavelength regions
corresponding to HO lines of different excitation conditions, and the slab
model fits were performed individually per region. We confidently detect CO,
HO, OH, CO, and HCN in the emitting layers. The isotopologue
HO is not detected. Additionally, no other organics, including
CH, are detected. This indicates that the C/O ratio could be
substantially below unity, in contrast with the outer disk. The HO emission
traces a large radial disk surface region, as evidenced by the gradually
changing excitation temperatures and emitting radii. The OH and CO emission
are relatively weak. It is likely that HO is not significantly
photodissociated; either due to self-shielding against the stellar irradiation,
or UV-shielding from small dust particles. The relative emitting strength of
the different identified molecular features point towards UV-shielding of
HO in the inner disk of Sz 98, with a thin layer of OH on top. The majority
of the organic molecules are either hidden below the dust continuum, or not
present. In general, the inferred composition points to a sub-solar C/O ratio
(<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in
the gas in the outer disk found with ALMA.Comment: Submitted to A&A on May 25 2023. 18 pages, 11 figure
MINDS. The detection of CO with JWST-MIRI indicates abundant CO in a protoplanetary disk
We present JWST-MIRI MRS spectra of the protoplanetary disk around the
low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey (MINDS) GTO
program. Emission from CO, CO, HO, HCN,
CH, and OH is identified with CO being detected for
the first time in a protoplanetary disk. We characterize the chemical and
physical conditions in the inner few au of the GW Lup disk using these
molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high
signal-to-noise data is essential to identify these species and determine their
column densities and temperatures. The -branches of these molecules,
including those of hot-bands, are particularly sensitive to temperature and
column density. We find that the CO emission in the GW Lup disk is
coming from optically thick emission at a temperature of 400 K.
CO is optically thinner and based on a lower temperature of
325 K, may be tracing deeper into the disk and/or a larger emitting
radius than CO. The derived /
ratio is orders of magnitude higher than previously derived for GW Lup and
other targets based on \textit{Spitzer}-IRS data. This high column density
ratio may be due to an inner cavity with a radius in between the HO and
CO snowlines and/or an overall lower disk temperature. This paper
demonstrates the unique ability of JWST to probe inner disk structures and
chemistry through weak, previously unseen molecular features.Comment: 15 pages, 10 figures. Accepted to ApJ
The MDT-15 Subunit of Mediator Interacts with Dietary Restriction to Modulate Longevity and Fluoranthene Toxicity in Caenorhabditis elegans
Dietary restriction (DR), the limitation of calorie intake while maintaining proper nutrition, has been found to extend life span and delay the onset of age-associated disease in a wide range of species. Previous studies have suggested that DR can reduce the lethality of environmental toxins. To further examine the role of DR in toxin response, we measured life spans of the nematode Caenorhabditis elegans treated with the mutagenic polyaromatic hydrocarbon, fluoranthene (FLA). FLA is a direct byproduct of combustion, and is one of U.S. Environmental Protection Agency's sixteen priority environmental toxins. Treatment with 5 ”g/ml FLA shortened the life spans of ad libitum fed nematodes, and DR resulted in increased sensitivity to FLA. To determine the role of detoxifying enzymes in the toxicity of FLA, we tested nematodes with mutations in the gene encoding the MDT-15 subunit of mediator, a transcriptional coactivator that regulates genes involved in fatty acid metabolism and detoxification. Mutation of mdt-15 increased the life span of FLA treated animals compared to wild-type animals with no difference observed between DR and ad libitum fed mdt-15 animals. We also examined mutants with altered insulin-IGF-1-like signaling (IIS), which is known to modulate life span and stress resistance in C. elegans independently of DR. Mutation of the genes coding for the insulin-like receptor DAF-2 or the FOXO-family transcription factor DAF16 did not alter the animals' susceptibility to FLA compared to wild type. Taken together, our results suggest that certain compounds have increased toxicity when combined with a DR regimen through increased metabolic activation. This increased metabolic activation appears to be mediated through the MDT-15 transcription factor and is independent of the IIS pathway
Correction for Johansson et al., An open challenge to advance probabilistic forecasting for dengue epidemics.
Correction for âAn open challenge to advance probabilistic forecasting for dengue epidemics,â by Michael A. Johansson, Karyn M. Apfeldorf, Scott Dobson, Jason Devita, Anna L. Buczak, Benjamin Baugher, Linda J. Moniz, Thomas Bagley, Steven M. Babin, Erhan Guven, Teresa K. Yamana, Jeffrey Shaman, Terry Moschou, Nick Lothian, Aaron Lane, Grant Osborne, Gao Jiang, Logan C. Brooks, David C. Farrow, Sangwon Hyun, Ryan J. Tibshirani, Roni Rosenfeld, Justin Lessler, Nicholas G. Reich, Derek A. T. Cummings, Stephen A. Lauer, Sean M. Moore, Hannah E. Clapham, Rachel Lowe, Trevor C. Bailey, Markel GarcĂa-DĂez, Marilia SĂĄ Carvalho, Xavier RodĂł, Tridip Sardar, Richard Paul, Evan L. Ray, Krzysztof Sakrejda, Alexandria C. Brown, Xi Meng, Osonde Osoba, Raffaele Vardavas, David Manheim, Melinda Moore, Dhananjai M. Rao, Travis C. Porco, Sarah Ackley, Fengchen Liu, Lee Worden, Matteo Convertino, Yang Liu, Abraham Reddy, Eloy Ortiz, Jorge Rivero, Humberto Brito, Alicia Juarrero, Leah R. Johnson, Robert B. Gramacy, Jeremy M. Cohen, Erin A. Mordecai, Courtney C. Murdock, Jason R. Rohr, Sadie J. Ryan, Anna M. Stewart-Ibarra, Daniel P. Weikel, Antarpreet Jutla, Rakibul Khan, Marissa Poultney, Rita R. Colwell, Brenda Rivera-GarcĂa, Christopher M. Barker, Jesse E. Bell, Matthew Biggerstaff, David Swerdlow, Luis Mier-y-Teran-Romero, Brett M. Forshey, Juli Trtanj, Jason Asher, Matt Clay, Harold S. Margolis, Andrew M. Hebbeler, Dylan George, and Jean-Paul Chretien, which was first published November 11, 2019; 10.1073/pnas.1909865116. The authors note that the affiliation for Xavier RodĂł should instead appear as Catalan Institution for Research and Advanced Studies (ICREA) and Climate and Health Program, Barcelona Institute for Global Health (ISGlobal). The corrected author and affiliation lines appear below. The online version has been corrected
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