Hasil untuk "Evolution"

D. Heggie

E. Uchupi

J. Coddington, H. W. Levi

S. Shettleworth

Ary A. Hoffmann, Juha Merilä

E. Herre, Nancy Knowlton, Nancy Knowlton et al.

W. Fitch

M. Anisimova, J. Bielawski, Ziheng Yang

N. Smith, A. Eyre-Walker

Ravi Kumar, Jasmine Novak, P. Raghavan et al.

G. M. Jenkins, A. Rambaut, O. Pybus et al.

M. O’Neill, C. Ryan

Natasha Noy, M. Klein

Bodie Breza, Matthew C. Nixon, Eliza M.-R. Kempton

The evolution and structure of sub-Neptunes may be strongly influenced by interactions between the outer gaseous envelope of the planet and a surface magma ocean. However, given the wide variety of permissible interior structures of these planets, it is unclear whether conditions at the envelope–mantle boundary will always permit a molten silicate layer or whether some sub-Neptunes might instead host a solid silicate surface. In this work, we use internal structure modeling to perform an extensive exploration of surface conditions within the sub-Neptune population across a range of bulk and atmospheric parameters. We find that a significant portion of the population may lack present-day magma oceans. In particular, planets with a high atmospheric mean molecular weight and large envelope mass fraction are likely to instead have a solid silicate surface, since the pressure at the envelope–mantle boundary is high enough that the silicates will be in solid postperovskite phase. This result is particularly relevant given recent inferences of high-mean molecular weight atmospheres from JWST observations of several sub-Neptunes. We apply this approach to a number of sub-Neptunes with existing or upcoming JWST observations and find that in almost all cases, a range of solutions exist that do not possess a present-day magma ocean. Our analysis provides critical context for interpreting sub-Neptunes and their atmospheres.

Christopher J. Miller, Byunghoon Lee, Jacob A. Barrett et al.

Recent reports show [FeFe] hydrogenase mimics are active for the electrochemical reduction of CO2 to formate (HCOO−). Herein, the electrochemical reduction of CO2 with the [FeFe] hydrogenase mimic [Fe2(μ‐pdt)(CO)6, 1, where pdt = propane‐1,3‐dithiolate] in acetonitrile is reported. In the presence of the weak acid, methanol (MeOH), 1 reduces CO2 to both CO (Faradaic Efficiency maximum [FEmax] of 16 ± 6%) and HCOO− (FEmax = 20%) and produces H2 (FEmax = 56 ± 4%). Without added MeOH, 1 reacts with adventitious water to form H2 (FEmax = 85 ± 1%), HCOO− (FEmax = 7.8%), and CO (FEmax = 7 ± 3%) with CO32− being detected by infrared spectroscopy.  Product formation is potential dependent: more negative potentials increases selectivity for HCOO− over CO. The first reduction of 1 forms a pdt‐bridged dimer, 2. However, the reduction of 2 at the potentials required for electrochemical CO2 reduction leads to two new species. Using density functional theory, and infrared spectroelectrochemistry (IR‐SEC), these structures are identified to be [Fe(CO)4]2− (3) and a trinuclear Fe3 species (4). While these species can reduce CO2 to CO and HCOO−, the predominant formation of H2 reveals kinetic issues in  CO2 reduction. The work offers to consider alternate competing mechanistic pathways and explains the lack of product selectivity when using hydrogen evolution reaction catalyst for CO2 reduction to HCOO−.

Ozone Subsystems

G. Bell

S. Shabalina, E. Koonin

H. Nijhout

Mary Kate Hollifield, Ching-Yi Chen, Eric Psota et al.

Abstract Background With the introduction of digital phenotyping and high-throughput data, traits that were previously difficult or impossible to measure directly have become easily accessible, offering the opportunity to enhance the efficiency and rate of genetic gain in animal production. It is of interest to assess how behavioral traits are indirectly related to the production traits during the performance testing period. The aim of this study was to assess the quality of behavior data extracted from day-wise video recordings and estimate the genetic parameters of behavior traits and their phenotypic and genetic correlations with production traits in pigs. Behavior was recorded for 70 days after on-test at about 10 weeks of age and ended at off-test for 2008 female purebred pigs, totaling 119,812 day-wise records. Behavior traits included time spent eating, drinking, laterally lying, sternally lying, sitting, standing, and meters of distance traveled. A quality control procedure was created for algorithm training and adjustment, standardizing recording hours, removing culled animals, and filtering unrealistic records. Results Production traits included average daily gain (ADG), back fat thickness (BF), and loin depth (LD). Single-trait linear models were used to estimate heritabilities of the behavior traits and two-trait linear models were used to estimate genetic correlations between behavior and production traits. The results indicated that all behavior traits are heritable, with heritability estimates ranging from 0.19 to 0.57, and showed low-to-moderate phenotypic and genetic correlations with production traits. Two-trait linear models were also used to compare traits at different intervals of the recording period. To analyze the redundancies in behavior data during the recording period, the averages of various recording time intervals for the behavior and production traits were compared. Overall, the average of the 55- to 68-day recording interval had the strongest phenotypic and genetic correlation estimates with the production traits. Conclusions Digital phenotyping is a new and low-cost method to record behavior phenotypes, but thorough data cleaning procedures are needed. Evaluating behavioral traits at different time intervals offers a deeper insight into their changes throughout the growth periods and their relationship with production traits, which may be recorded at a less frequent basis.