Abstract
We use the spectral energy distribution fitting code
Prospector
to reconstruct the nonparametric star formation history (SFH) of massive (
log
M
*
>
10.3
) star-forming galaxies (SFGs) and ...quiescent galaxies (QGs) at redshift
z
obs
∼ 2 to investigate the joint evolution of star formation activity and structural properties. Compared to extended SFGs, compact SFGs are more likely to have experienced multiple star formation episodes, with the fractional mass formed during the older (≥1 Gyr) episode being larger, suggesting that high-redshift SFGs assembled their central regions earlier and then kept growing in central mass as they become more compact. The SFH of compact QGs does not significantly differ from the average for this category, and shows an early burst followed by a gradual decline of the star formation rate. The SFH of extended QGs, however, is similar to that of post-starburst galaxies, and their morphology is also frequently disturbed. Knowledge of the SFH also enables us to empirically reconstruct the structural evolution of individual galaxies. While the progenitor effect is clearly observed and accounted for in our analysis, it alone is insufficient to explain the observed structural evolution. We show that, as they evolve from star-forming phase to quiescence, galaxies grow massive dense stellar cores. Quenching begins at the center and then propagates outward to the rest of the structure. We discuss possible physical scenarios for the observed evolution and find that our empirical constraints are in good quantitative agreement with the model predictions from dissipative accretion of gas to the center followed by massive starbursts before final quiescence (wet compaction).
The modifier of road materials from agricultural waste (AW) as raw material has been widely noticed. Considering the environmental impact of AW treatment and the National policy on the promotion of ...resource reuse, the feasibility of four AW (namely, bamboo powder, rape straw, corn cob, and wheat straw) for styrene butadiene styrene (SBS) asphalt modification is studied from the properties and mechanism perspectives. Through properties evaluation tests (such as the dynamic shear rheometer, multiple stress creep recovery, and rotating thin film oven test), the influence of four AW and different mixing amounts on the properties of SBS modified asphalt pavement is analyzed from the aspects of high-temperature deformation resistance and anti-aging properties. The results reveal that the four AW can improve the SBS asphalt's high-temperature deformation resistance and anti-aging properties, among which rape straw has the most significant improvement effect. In addition, through the fourier transform infrared spectroscopy test, the microscopic mechanism of the AW/SBS composite modified asphalt binder is revealed from the functional groups. The analysis shows that the AW is physically mixed with the SBS asphalt binder, which inhibits the growth of sulfoxide groups and the cracking of the SBS modifier during aging.
Plant pathogenic bacteria of the genus Xanthomonas possess transcription activator-like effectors (TALEs) that activate transcription of disease susceptibility genes in the host, inducing a state of ...disease. Here we report that some isolates of the rice pathogen Xanthomonas oryzae use truncated versions of TALEs (which we term interfering TALEs, or iTALEs) to overcome disease resistance. In comparison with typical TALEs, iTALEs lack a transcription activation domain but retain nuclear localization motifs and are expressed from genes that were previously considered pseudogenes. We show that the rice gene Xa1, encoding a nucleotide-binding leucine-rich repeat protein, confers resistance against X. oryzae isolates by recognizing multiple TALEs. However, the iTALEs present in many isolates interfere with the otherwise broad-spectrum resistance conferred by Xa1. Our findings illustrate how bacterial effectors that trigger disease resistance in the host can evolve to interfere with the resistance process and, thus, promote disease.
Rice Routes of Countering Xanthomonas oryzae Ji, Zhiyuan; Wang, Chunlian; Zhao, Kaijun
International journal of molecular sciences,
10/2018, Volume:
19, Issue:
10
Journal Article
Peer reviewed
Open access
Bacterial blight (BB) and bacterial leaf streak (BLS), caused by
pv.
and
pv.
, respectively, are two devastating diseases in rice planting areas worldwide. It has been proven that adoption of rice ...resistance is the most effective, economic, and environment-friendly strategy to avoid yield loss caused by BB and BLS. As a model system for plant-pathogen interaction, the rice-
pathosystem has been intensively investigated in the past decade. Abundant studies have shown that the resistance and susceptibility of rice to
is determined by molecular interactions between rice genes or their products and various pathogen effectors. In this review, we briefly overviewed the literature regarding the diverse interactions, focusing on recent advances in uncovering mechanisms of rice resistance and
virulence. Our analysis and discussions will not only be helpful for getting a better understanding of coevolution of the rice innate immunity and
virulence, but it will also provide new insights for application of plant
genes in crop breeding.
Abstract
The origins of Lyman continuum (LyC) photons responsible for the reionization of the universe are as of yet unknown and highly contested. Detecting LyC photons from the Epoch of Reionization ...is not possible due to absorption by the intergalactic medium, which has prompted the development of several indirect diagnostics to infer the rate at which galaxies contribute LyC photons to reionize the universe by studying lower-redshift analogs. We present the Low-redshift Lyman Continuum Survey (LzLCS) comprising measurements made with the Hubble Space Telescope Cosmic Origins Spectrograph for a
z
= 0.2–0.4 sample of 66 galaxies. After careful processing of the far-UV spectra, we obtain a total of 35 Lyman continuum emitters (LCEs) detected with 97.725% confidence, nearly tripling the number of known local LCEs. We estimate escape fractions from the detected LyC flux and upper limits on the undetected LyC flux, finding a range of LyC escape fractions up to 50%. Of the 35 LzLCS LCEs, 12 have LyC escape fractions greater than 5%, more than doubling the number of known local LCEs with cosmologically relevant LyC escape.
The thermal runaway (TR) of NCM811 Lithium-ion battery (LIB) triggered by nail penetration was tested under three cases of full depth@100%SOC, half depth@100%SOC, and full depth@50%SOC, respectively. ...The internal temperature of the battery was measured by the built-in thermocouple, the fire behavior in four stages during TR was recorded by high-speed photography, the flame intensity was quantified by image processing method, and the internal structure of the battery was studied after TR. The results show that the effect of SOC on thermal runaway is more significant than that of penetration depth. In the case of full depth@100%SOC and full depth@50%SOC, the internal peak temperature is 887.3 °C and 483.2 °C, the maximum temperature difference between the internal and surface is 256.3 °C and 92.9 °C, the maximum jet angle is 72.0° and 47.9°, the jet area duty ratio is 41.2% and 17.8%, and the mass loss is 41.7 g and 18.6 g. For different cathode materials, the thermal runaway of NCM811 LIB is more serious than that of NCM532 LIB. For different trigger modes, the thermal runaway of NCM811 LIB triggered by nail penetration is more serious than that triggered by external overheating.
The goal of this paper is to analyze the aging behavior and the mechanism evolution of nano-Al2O3 (NA)-reinforced styrene-butadiene-styrene (SBS) asphalt under different thermal-oxidative aging ...conditions. First, NA/SBS-modified asphalt and SBS-modified asphalt with different aging levels were prepared. Second, the viscosity and high temperature rheological performance of the specimens were tested and the property-related aging indexes were calculated and compared. Third, a Fourier transform infrared (FTIR) test of the specimen was conducted and the chemical group-related aging indexes were calculated and analyzed. Fourth, gel permeation chromatography (GPC) was used to analyze the molecular weight of the specimens under different aging levels. Then, an atomic force microscope (AFM) was adopted to analyze the microsurface morphology of different specimens. Finally, correlation analysis between property-related indexes and chemical group indexes was conducted. The results show that NA can enhance the thermal-oxidative aging resistance of SBS asphalt. NA can inhibit the increase in sulfoxide groups and the degradation of the SBS polymer with the increase in aging. NA can slow down the formation of large molecule during the aging process. The degree of change in both the bee structures and micromorphological roughness of NA/SBS asphalt is lower than that of SBS asphalt under different aging levels.
Plant Executor Genes Ji, Zhiyuan; Guo, Wei; Chen, Xifeng ...
International journal of molecular sciences,
01/2022, Volume:
23, Issue:
3
Journal Article
Peer reviewed
Open access
Executor (
) genes comprise a new type of plant resistance (
) genes, identified from host-
interactions. The
-secreted transcription activation-like effectors (TALEs) usually function as major ...virulence factors, which activate the expression of the so-called "susceptibility" (
) genes for disease development. This activation is achieved via the binding of the TALEs to the effector-binding element (EBE) in the
gene promoter. However, host plants have evolved EBEs in the promoters of some otherwise silent
genes, whose expression directly causes a host cell death that is characterized by a hypersensitive response (HR). Such
genes are called
genes because they trap the pathogen TALEs in order to activate expression, and the resulting HR prevents pathogen growth and disease development. Currently, deploying
gene resistance is becoming a major component in disease resistance breeding, especially for rice bacterial blight resistance. Currently, the biochemical mechanisms, or the working pathways of the E proteins, are still fuzzy. There is no significant nucleotide sequence homology among
genes, although E proteins share some structural motifs that are probably associated with the signal transduction in the effector-triggered immunity. Here, we summarize the current knowledge regarding TALE-type avirulence proteins,
gene activation, the E protein structural traits, and the classification of
genes, in order to sharpen our understanding of the plant
genes.
Abstract
We present a study of spatially resolved star formation histories (SFHs) for 60
z
∼ 2.3 main-sequence, star-forming galaxies selected from the MOSDEF spectroscopic survey in the GOODS-N ...field, with median stellar mass
log
(
M
⋆
/
M
⊙
)
= 9.75 and spanning the range
8.6
<
log
(
M
⋆
/
M
⊙
)
<
11.5
. Photometry is decomposed into a central and an outer spatial component using observed
z
F850LP
−
H
F160W
colors. The
Prospector
code is used to model spectral energy distributions for the center, outskirt, and integrated galaxy using Hubble Space Telescope/ACS and WFC3, Spitzer/IRAC, and ground-based photometry, with additional constraints on gas-phase metallicity and spectroscopic redshift from MOSDEF spectroscopy. For the low-resolution bands, spatially resolved photometry is determined with an iterative approach. The reconstructed SFHs indicate that the majority of galaxies with
log
(
M
⋆
/
M
⊙
)
<
10.5
are observed while their central regions undergo relatively recent (<100 Myr) bursts of star formation, whereas the outskirts have a smooth, quasi-steady SFH that gently increases toward the redshift of observation. The enhanced star formation activity of the central parts is broadly consistent with the idea that it is produced by highly dissipative gas compaction and accretion. The wide range of central densities and sizes observed in the sample suggests that, for the selected galaxies, such a process has started but is still far from being completed. The implication would be that selecting star-forming galaxies at cosmic noon frequently includes systems in an “evolved” evolutionary phase where the centers have recently started a burst of star formation activity that will likely initiate inside-out quenching in the next several hundred million years.
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