119 research outputs found
Efficient Syntheses of Biobased Terephthalic Acid, p-Toluic Acid, and p-Methylacetophenone via One-Pot Catalytic Aerobic Oxidation of Monoterpene Derived Bio-p-cymene.
An efficient elevated-pressure catalytic oxidative process (2.5 mol % Co(NO3)2, 2.5 mol % MnBr2, air (30 bar), 125 °C, acetic acid, 6 h) has been developed to oxidize p-cymene into crystalline white terephthalic acid (TA) in ∼70% yield. Use of this mixed Co2+/Mn2+ catalytic system is key to obtaining high 70% yields of TA at relatively low reaction temperatures (125 °C) in short reaction times (6 h), which is likely to be due to the synergistic action of bromine and nitrate radicals in the oxidative process. Recycling studies have demonstrated that the mixed metal catalysts present in recovered mother liquors could be recycled three times in successive p-cymene oxidation reactions with no loss in catalytic activity or TA yield. Partial oxidation of p-cymene to give p-methylacetophenone (p-MA) in 55-60% yield can be achieved using a mixed CoBr2/Mn(OAc)2 catalytic system under 1 atm air for 24 h, while use of Co(NO3)2/MnBr2 under 1 atm O2 for 24 h gave p-toluic acid in 55-60% yield. Therefore, access to these simple catalytic aerobic conditions enables multiple biorenewable bulk terpene feedstocks (e.g., crude sulfate turpentine, turpentine, cineole, and limonene) to be converted into synthetically useful bio-p-MA, bio-p-toluic acid, and bio-TA (and hence bio-polyethylene terephthalate) as part of a terpene based biorefinery
Mapping Cosmic Dawn and Reionization: Challenges and Synergies
Cosmic dawn and the Epoch of Reionization (EoR) are among the least explored
observational eras in cosmology: a time at which the first galaxies and
supermassive black holes formed and reionized the cold, neutral Universe of the
post-recombination era. With current instruments, only a handful of the
brightest galaxies and quasars from that time are detectable as individual
objects, due to their extreme distances. Fortunately, a multitude of
multi-wavelength intensity mapping measurements, ranging from the redshifted 21
cm background in the radio to the unresolved X-ray background, contain a
plethora of synergistic information about this elusive era. The coming decade
will likely see direct detections of inhomogenous reionization with CMB and 21
cm observations, and a slew of other probes covering overlapping areas and
complementary physical processes will provide crucial additional information
and cross-validation. To maximize scientific discovery and return on
investment, coordinated survey planning and joint data analysis should be a
high priority, closely coupled to computational models and theoretical
predictions.Comment: 5 pages, 1 figure, submitted to the Astro2020 Decadal Survey Science
White Paper cal
Separating the effects of early and later life adiposity on colorectal cancer risk:a Mendelian randomization study
BACKGROUND: Observational studies have linked childhood obesity with elevated risk of colorectal cancer; however, it is unclear if this association is causal or independent from the effects of obesity in adulthood on colorectal cancer risk. METHODS: We conducted Mendelian randomization (MR) analyses to investigate potential causal relationships between self-perceived body size (thinner, plumper, or about average) in early life (age 10) and measured body mass index in adulthood (mean age 56.5) with risk of colorectal cancer. The total and independent effects of body size exposures were estimated using univariable and multivariable MR, respectively. Summary data were obtained from a genome-wide association study of 453,169 participants in UK Biobank for body size and from a genome-wide association study meta-analysis of three colorectal cancer consortia of 125,478 participants. RESULTS: Genetically predicted early life body size was estimated to increase odds of colorectal cancer (odds ratio [OR] per category change: 1.12, 95% confidence interval [CI]: 0.98–1.27), with stronger results for colon cancer (OR: 1.16, 95% CI: 1.00–1.35), and distal colon cancer (OR: 1.25, 95% CI: 1.04–1.51). After accounting for adult body size using multivariable MR, effect estimates for early life body size were attenuated towards the null for colorectal cancer (OR: 0.97, 95% CI: 0.77–1.22) and colon cancer (OR: 0.97, 95% CI: 0.76–1.25), while the estimate for distal colon cancer was of similar magnitude but more imprecise (OR: 1.27, 95% CI: 0.90–1.77). Genetically predicted adult life body size was estimated to increase odds of colorectal (OR: 1.27, 95% CI: 1.03, 1.57), colon (OR: 1.32, 95% CI: 1.05, 1.67), and proximal colon (OR: 1.57, 95% CI: 1.21, 2.05). CONCLUSIONS: Our findings suggest that the positive association between early life body size and colorectal cancer risk is likely due to large body size retainment into adulthood. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-022-02702-9
Single cell spatial analysis reveals inflammatory foci of immature neutrophil and CD8 T cells in COVID-19 lungs
Single cell spatial interrogation of the immune-structural interactions in COVID −19 lungs is challenging, mainly because of the marked cellular infiltrate and architecturally distorted microstructure. To address this, we develop a suite of mathematical tools to search for statistically significant co-locations amongst immune and structural cells identified using 37-plex imaging mass cytometry. This unbiased method reveals a cellular map interleaved with an inflammatory network of immature neutrophils, cytotoxic CD8 T cells, megakaryocytes and monocytes co-located with regenerating alveolar progenitors and endothelium. Of note, a highly active cluster of immature neutrophils and CD8 T cells, is found spatially linked with alveolar progenitor cells, and temporally with the diffuse alveolar damage stage. These findings offer further insights into how immune cells interact in the lungs of severe COVID-19 disease. We provide our pipeline [Spatial Omics Oxford Pipeline (SpOOx)] and visual-analytical tool, Multi-Dimensional Viewer (MDV) software, as a resource for spatial analysis
Mitigating Internal Instrument Coupling for 21 cm Cosmology. II. A Method Demonstration with the Hydrogen Epoch of Reionization Array
We present a study of internal reflection and cross-coupling systematics in Phase I of the Hydrogen Epoch of Reionization Array (HERA). In a companion paper, we outlined the mathematical formalism for such systematics and presented algorithms for modeling and removing them from the data. In this work, we apply these techniques to data from HERA's first observing season as a method demonstration. The data show evidence for systematics that, without removal, would hinder a detection of the 21 cm power spectrum for the targeted Epoch of Reionization (EoR) line-of-sight modes in the range 0.2 h −1 Mpc−1 < < 0.5 h −1 Mpc−1. In particular, we find evidence for nonnegligible amounts of spectral structure in the raw autocorrelations that overlaps with the EoR window and is suggestive of complex instrumental effects. Through systematic modeling on a single night of data, we find we can recover these modes in the power spectrum down to the integrated noise floor, achieving a dynamic range in the EoR window of 106 in power (mK2 units) with respect to the bright galactic foreground signal. Future work with deeper integrations will help determine whether these systematics can continue to be mitigated down to EoR levels. For future observing seasons, HERA will have upgraded analog and digital hardware to better control these systematics in the field
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