Identifying potential external forcings on dryland aridity at various timescales and clarifying underlying mechanisms can advance our knowledge of dryland climate behaviors. To address this issue, we ...examine the past 21 ka using a set of transient simulations driven by realistic climatic forcings, as well as multiple types of proxies. The simulations suggest the evolution of dryland aridity and dominant forcings vary over time and region. On average, global drylands feature two-phase aridification at the orbital scale: the first phase occurs before the Holocene and is dominated by ice sheet melting and rising greenhouse gas (GHG) concentrations, followed by the second phase driven by the summer insolation decrease over northern high latitudes after the early Holocene; different from the wetness during the orbital-scale glacial period, millennium-scale cold events forced by meltwater discharges correspond to desiccation, punctuating the long-term trend during the last deglaciation. In addition, the average aridity changes for drylands are larger than those for global landmasses under all forcings except GHG concentrations. Spatially, the dominant external forcings and aridity responses to the same forcing vary regionally, mainly related to the latitude and hemisphere. Further diagnosis indicates the manners to affect aridity, namely through altering precipitation or evaporative capacity, vary by forcing. The aforementioned evolution of the simulated aridity matches well with the proxies in most dryland zones. This study provides a scenario of time-varying responses of dryland aridity to external forcings over the last 21 ka and may shed light on the future changes.
•Dryland aridity over the past 21 ka is examined using simulations and proxies.•It is consistent across simulated aridity index, runoff, and soil moisture.•Dominant external forcings on dryland aridity have varied with time and region.•Aridity changes over dryland are larger than those over the global land.•Simulations match well with proxies.
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•A catalyst with tunable CuOx species distribution was prepared.•The optimal CuAl-LDO/carbon nanotubes catalyst for NH3-SCR was determined.•A synergistic mechanism of Cu2O/CuO ...denitration was proposed.•An effective way to improve the denitration performance of CuOx species was confirmed.
Cu-based catalysts have drawn much attention in ammonia-selective catalytic reduction (NH3-SCR) of NOx because of their outstanding low-temperature denitration (de-NOx) potential. Although satisfactory SCR performance was obtained with support from the catalytic activity of CuOx species in recent studies, the effect of the valence distribution of CuOx species on NH3-SCR reaction is still ambiguous, and elaborate exploration is necessary. Here, a series of CuAl-layered double oxide/carbon nanotubes-x (CuAl-LDO/CNTs-x) nanocatalysts with a tunable valence distribution of highly dispersed CuOx species was constructed from the topotactic transformation of CuAl-layered double hydroxide (CuAl-LDH) precursor and a controllable carbothermal reduction reaction. Multiple characterization techniques, including XRD, NH3-TPD, H2-TPR, NOx-TPD, XPS, in situ DRIFTS, and HR-TEM, were employed to elucidate the inherent relationship between the chemical properties and catalytic activity of the as-prepared catalysts. The obtained CuAl-LDO/CNTs-2 catalyst exhibited optimum catalytic performance, with NOx conversion exceeding 90% in the temperature range 180–305 °C. Such high catalytic efficiency can be attributed to the appropriate valence distribution of CuOx species, which can significantly improve the redox capacity and surface acidity of the catalysts, thereby promoting the adsorption and activation of the reactants. Combined with further theoretical calculation, a synergistic catalytic mechanism of Cu2O/CuO in the NH3-SCR reaction is tentatively proposed. Notably, the CuO active center can function as the dominant adsorption site of NO and NH3 to promote the formation of NO+ active species and the dehydrogenation activation of NH3. The Cu2O active center can act as the adsorption site for O, promoting the formation of active oxygen species O−. Consequently, the synergistic effect between Cu2O and CuO can lead to the rapid formation of reactive intermediates, proceeding via the Langmuir–Hinshelwood (reaction between adsorbed NH3 and adsorbed NOx) or Eley–Rideal (reaction between adsorbed NH3 and gaseous NO) mechanism reaction routes to complete the catalytic cycle. This work provides a fundamental understanding on Cu2O/CuO synergistic catalysis of NH3-SCR, which is propitious for the rational design and optimization of Cu-based oxide de-NOx catalysts.
This study examines changes in aridity levels during the mid-Holocene (approximately 6000 cal. yr ago) using multi-model simulations from the Paleoclimate Modelling Intercomparison Project Phase III. ...Overall, there is little difference in the total area of drylands from the preindustrial period; global drylands are 8% wetter than during the preindustrial period as measured by an aridity index; and 16% of preindustrial drylands convert to a wetter climate subtype, double the sum of zones that are replaced by a drier category. Considerable variations are present among regions with major contractions of each dryland subtype from northern Africa to South Asia and the main expansions of arid, semiarid, and dry subhumid climates in southern hemisphere continents. The difference in precipitation is the leading factor of the aforementioned changes. The second factor is the altered potential evapotranspiration as mainly induced by relative humidity, which contributes to additional aridity changes in a same direction as precipitation does. The collective effects of precipitation and relative humidity account for more than 80% of the dryland variations. In comparison, the simulated aridity change is in reasonable agreement with reconstructions, while there are model–data discrepancies for Australia and uncertainties across proxies for southern Africa.
This study investigates terrestrial moisture changes and associated mechanisms during the last glacial maximum (LGM; approximately 21,000 calendar years ago) using multi-model simulations from the ...Paleoclimate Modelling Intercomparison Project phase 3 (PMIP3). Considering that terrestrial moisture is not determined solely by precipitation, an aridity index (AI) is employed for measuring the terrestrial moisture by combining the effects of both precipitation and potential evapotranspiration (PET), where the latter represents atmospheric water demand and is greatly decreased mainly by the intense cooling during the LGM. Compared to the preindustrial period, the magnitude of global mean terrestrial moisture change is small, as the wetness brought by decreased PET counteracts the dryness induced by decreased precipitation. Regionally, the moisture changes depend on the different combinations of changes in precipitation and PET: (i) drying occurs where precipitation deceases and PET hardly changes, such as the northern tropical Americas and Southeast Asia; (ii) wetting is found in regions with precipitation increases and PET decreases (e.g., northwestern Africa and the central Andes), and their contributions are comparable; (iii) in particular, wetting can also occur in regions of decreased precipitation if a sufficient decrease in PET also occurs (i.e., southeastern North America and the northern and southern parts of eastern Asia), with the latter wetting effect reversing the former drying effect. The multi-model median field is consistent with available paleo-records in southern North America, the northern tropical Americas, the Andes, northwestern Africa, the southern Iberian Peninsula, southwestern Africa, the central part of eastern Asia, and Java but disagrees with proxies in Australia, central Brazil, southeastern Africa, the northern Iberian Peninsula, and the southern part of eastern Asia.
•We examine last glacial maximum (LGM) terrestrial moisture by results of nine models.•Both effects of precipitation and potential evapotranspiration are considered.•LGM moisture is little varied globally but notably varied regionally.•LGM global and regional moisture changes can be physically explained.•A model–data comparison is performed qualitatively.
Abstract
Spodoptera frugiperda
is a highly polyphagous pest worldwide with a wide host range that causes serious losses to many economically important crops. Recently, insect-microbe associations ...have become a hot spot in current entomology research, and the midgut microbiome of
S. frugiperda
has been investigated, while the effects of cruciferous vegetables remain unknown. In this study, the growth of
S. frugiperda
larvae fed on an artificial diet,
Brassica campestris
and
Brassica oleracea
for 7 days was analyzed. Besides, the microbial community and functional prediction analyses of the larval midguts of
S. frugiperda
fed with different diets were performed by high-throughput sequencing. Our results showed that
B. oleracea
inhibited the growth of
S. frugiperda
larvae. The larval midgut microbial community composition and structure were significantly affected by different diets. Linear discriminant analysis effect size (LEfSe) suggested 20 bacterial genera and 2 fungal genera contributed to different gut microbial community structures. The functional classification of the midgut microbiome analyzed by PICRUSt and FUNGuild showed that the most COG function categories of midgut bacterial function were changed by
B. oleracea
, while the guilds of fungal function were altered by
B. campestris
significantly. These results showed that the diversity and structure of the
S. frugiperda
midgut microbial community were affected by cruciferous vegetable feeding. Our study provided a preliminary understanding of the role of midgut microbes in
S. frugiperda
larvae in response to cruciferous vegetables.
The assumption of a stationary global signal linked to El Niño–Southern Oscillation (ENSO) events is often used in paleo-ENSO proxy data interpretation. This paper attempts to investigate whether the ...assumption is valid during the last glacial maximum (LGM) over the region 60°S–90°N, 60°E–60°W. Using four models within phase 3 of the Paleoclimate Modeling Intercomparison Project framework that well reproduce ENSOinduced variabilities, differences from the preindustrial period to LGM in the ENSO-related sea surface temperature pattern and its impacts are investigated. Compared to the preindustrial period, the ENSO impacts are revealed to weaken and shift eastward during the LGM. According to multimodel medians, ENSO impacts on precipitation and near-surface air temperature are attenuated over most regions of concern, with percentage changes in both parameters averaging −21% for the whole region; the ENSO-induced Pacific–North America (PNA) teleconnection pattern is weakened, manifested by the 41% diminished center over the North Pacific and the almost vanished activity centers over the continent. Spatially, there is a zonal contraction of 138 for the sea surface warming of ENSO, as well as eastward migration over 108 for the ENSO-induced positive precipitation anomaly center over the tropical Pacific and the PNA teleconnection pattern outside the tropics. The aforementioned changes are linked to the altered climatic background during the LGM, which features a 16° eastward shift for the Pacific Walker circulation rising branch and a weakened waveguide in the midlatitudes. The results suggest that the hypothesis of stationary ENSO impacts should be applied cautiously to the past.
Abstract
Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) tumorigenesis involves a combination of multiple genetic alteration processes. Constructing a survival-associated ...competing endogenous RNA (ceRNA) network and a multi-mRNA-based prognostic signature model can help us better understand the complexity and genetic characteristics of CESC. In this study, the RNA-seq data and clinical information of CESC patients were downloaded from The Cancer Genome Atlas. Differentially expressed mRNAs, lncRNAs and miRNAs were identified with the edgeR R package. A four-mRNA prognostic signature was developed by multivariate Cox regression analysis. Kaplan–Meier survival with the log-rank tests was performed to assess survival rates. The relationships between overall survival (OS) and clinical parameters were evaluated by Cox regression analysis. A survival-associated ceRNA network was constructed with the multiMiR package and miRcode database. Kyoto encyclopedia of genes and genomes (KEGG) analysis and gene ontology analyses were used to identify the functional role of the ceRNA network in the prognosis of CESC. A total of 298 differentially expressed mRNAs, 8 miRNAs, and 29 lncRNAs were significantly associated with the prognosis of CESC. A prognostic signature model based on 4 mRNAs (OPN3, DAAM2, HENMT1, and CAVIN3) was developed, and the prognostic ability of this signature was indicated by the AUC of 0.726. Patients in the high-risk group exhibited significantly worse OS. The KEGG pathways, TGF-β and Cell adhesion molecules, were significantly enriched. In this study, a CESC-associated ceRNA network was constructed, and a multi-mRNA-based prognostic model for CESC was developed based on the ceRNA network, providing a new perspective for cancer pathogenesis research.
Atherosclerosis (AS) is a multifactorial chronic inflammatory disease, and hyperlipidemia is the important factors leading to AS, which can cause vascular endothelial dysfunction. Paeonol (Pae) is a ...potential therapeutic drug for AS, and we have previously shown that Pae regulated the expression of monocytes-derived exosomal microRNA-223 (miR-223). However, the mechanisms of the anti-AS effect of Pae are still not fully understood. In this study, we aim to investigate if Pae could inhibit NLRP3 inflammasome mediated inflammation via elevating hyperlipidemic rats plasma-derived exosomal miR-223. We used high-fat-diet induced hyperlipidemic rats as model for further investigation. Rats were treated with Pae (75, 150 or 300 mg/kg) orally, and then exosomes were isolated from hyperlipidemic rat plasma by ultracentrifugation. In vivo experiments confirmed that Pae markedly reduced serum TC, TG, IL-1β, and IL-6 levels. Both CCK-8 and trypan blue staining showed that the survival rate of rat aortic endothelial cells (RAECs) in the Pae-exo group was higher than that in the model group. Also, Pae-exo dose-dependently increased the survival rate of RAECs and reduced inflammatory cytokines level (IL-1β, and IL-6). Furthermore, Pae-exo successfully increased the expression of exosomal miR-223 and relieved inflammatory secretion. Finally, decreased expression of NLRP3, ASC, caspase-1 and ICAM-1 indicated that Pae-exo attenuated inflammatory reaction of RAECs by suppressing NLRP3 signaling pathway. Altogether, our results showed that Pae inhibited the downstream NLRP3 inflammasome pathway by increasing the level of miR-223 in plasma derived exosomes of hyperlipidemic rats, providing new insights in the treatment of AS with the use of Pae.
A novel graph model with time-varying altitudes is developed to interpret the trade disputes between China and the United States (US) during the period between 2017 and 2019. The implementation of ...strategies for China and the US was affected by their bilateral relations represented by mutual attitudes changing over time along the evolution of the disputes. The Goldstein scale, a numeral system for studying foreign policies and for describing the fluctuating diplomatic relations affected by historical events, is utilized for eliciting preference relations affected by the time-varying attitudes for the first time. By considering two decision makers (DMs) in the trade disputes, the time varying unilateral improvements (TVUIs) for each DM are initiated based on its judgement which reflects not only the gains or losses for the given DM, but also those for the other DM. In investigating the real-world trade disputes between China and the US, the reasoning of imposing retaliating tariffs for the two countries under time frame is explained. How the fluctuation of time-varying altitudes affects the course of the disputes is also demonstrated. The Phase one agreement legally prohibiting retaliation using tariffs from the two countries was signed when mutual attitude increased by positive interstate events, which eventually ended the tit-for-tat situation. This novel methodology extends the structure of attitudes in graph model by flexibly depicting the fluctuation of mutual attitudes using Goldstein scoring system. Meaningful implications can be provided for DMs to explain how equilibrium can be changed by the time-varying attitudes. In analyzing international disputes in particular, nations can be clearly guided to achieve desired outcomes by making efforts to change bilateral or multilateral relations.
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