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  1. Abstract

    Abrupt monsoon onsets/retreats are indispensable targets for climate prediction and future projection, but the origins of their abruptness remain elusive. This study establishes the existence of three climatological Madden-Julian Oscillation (CMJO) episodes contributing to the rapid Australian summer monsoon retreat in mid-March, the South China Sea (or East Asian) summer monsoon onset in mid-May, and the Indian summer monsoon onset in early June. The CMJO displays a dynamically coherent convection-circulation structure resembling its transitionary counterpart, demonstrating its robustness as a convectively coupled circulation system and the tendency of the transient MJOs’ phase-lock to the annual cycle. The CMJO is inactive during the boreal winter due to destructive year-to-year modulations of El Niño-Southern Oscillation. We hypothesize that the interaction between atmospheric internal variability (MJO) and the insolation-forced slow annual cycle generates the sudden monsoon withdrawal/onset during the boreal spring. Understanding the factors determining the timing and location of the MJO’s phase-locking and its variability is vital for monsoon forecasting and climate projection.

     
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  2. Free, publicly-accessible full text available October 1, 2024
  3. We combine computational and experimental methods to study the acid-catalyzed conversion of polyalcohols to provide insights into the selective functionalization and conversion of multi-layered plastic films.

     
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    Free, publicly-accessible full text available July 31, 2024
  4. Abstract Background

    Analysis of the relationship between chromosomal structural variation (synteny breaks) and 3D-chromatin architectural changes among closely related species has the potential to reveal causes and correlates between chromosomal change and chromatin remodeling. Of note, contrary to extensive studies in animal species, the pace and pattern of chromatin architectural changes following the speciation of plants remain unexplored; moreover, there is little exploration of the occurrence of synteny breaks in the context of multiple genome topological hierarchies within the same model species.

    Results

    Here we used Hi-C and epigenomic analyses to characterize and compare the profiles of hierarchical chromatin architectural features in representative species of the cotton tribe (Gossypieae), includingGossypium arboreum,Gossypium raimondii, andGossypioides kirkii, which differ with respect to chromosome rearrangements. We found that (i) overall chromatin architectural territories were preserved inGossypioidesandGossypium, which was reflected in their similar intra-chromosomal contact patterns and spatial chromosomal distributions; (ii) the non-random preferential occurrence of synteny breaks in A compartment significantly associate with the B-to-A compartment switch in syntenic blocks flanking synteny breaks; (iii) synteny changes co-localize with open-chromatin boundaries of topologically associating domains, while TAD stabilization has a greater influence on regulating orthologous expression divergence than do rearrangements; and (iv) rearranged chromosome segments largely maintain ancestralin-cisinteractions.

    Conclusions

    Our findings provide insights into the non-random occurrence of epigenomic remodeling relative to the genomic landscape and its evolutionary and functional connections to alterations of hierarchical chromatin architecture, on a known evolutionary timescale.

     
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    Free, publicly-accessible full text available December 1, 2024
  5. Abstract

    The unique biophysical and biochemical properties of intrinsically disordered proteins (IDPs) and their recombinant derivatives, intrinsically disordered protein polymers (IDPPs) offer opportunities for producing multistimuli‐responsive materials; their sequence‐encoded disorder and tendency for phase separation facilitate the development of multifunctional materials. This review highlights the strategies for enhancing the structural diversity of elastin‐like polypeptides (ELPs) and resilin‐like polypeptides (RLPs), and their self‐assembled structures via genetic fusion to ordered motifs such as helical or beta sheet domains. In particular, this review describes approaches that harness the synergistic interplay between order‐promoting and thermoresponsive building blocks to design hybrid biomaterials, resulting in well‐structured, stimuli‐responsive supramolecular materials ordered on the nanoscale.

     
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  6. Because of the increasing demand, high-power, high-rate energy storage devices based on electrode materials have attracted immense attention. However, challenges remain to be addressed to improve the concentration-dependent kinetics of ionic diffusion and understand phase transformation, interfacial reactions, and capacitive behaviors that vary with particle morphology and scanning rates. It is valuable to understand the microscopic origins of ion transport in electrode materials. In this review, we discuss the microscopic transport phenomena and their dependence on ion concentration in the cathode materials, by comparing dozens of well-studied transition metal oxides, sulfides, and phosphates, and in the anode materials, including several carbon species and carbides. We generalize the kinetic effects on the microscopic ionic transport processes from the phenomenological points of view based on the well-studied systems. The dominant kinetic effects on ion diffusion varied with ion concentration, and the pathway- and morphology-dependent diffusion and capacitive behaviors affected by the sizes and boundaries of particles are demonstrated. The important kinetic effects on ion transport by phase transformation, transferred electrons, and water molecules are discussed. The results are expected to shed light on the microscopic limiting factors of charging/discharging rates for developing new intercalation and conversion reaction systems. 
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    Free, publicly-accessible full text available June 1, 2024
  7. Abstract

    Balancing kinetics, a crucial priority in catalysis, is frequently achieved by sacrificing activity of elementary steps to suppress side reactions and enhance catalyst stability. Dry reforming of methane (DRM), a process operated at high temperature, usually involves fast C-H activation but sluggish carbon removal, resulting in coke deposition and catalyst deactivation. Studies focused solely on catalyst innovation are insufficient in addressing coke formation efficiently. Herein, we develop coke-free catalysts that balance kinetics of elementary steps for overall thermodynamics optimization. Beginning from a highly active cobalt aluminum oxide (CoAl2O4) catalyst that is susceptible to severe coke formation, we substitute aluminum (Al) with gallium (Ga), reporting a CoAl0.5Ga1.5O4-R catalyst that performs DRM stably over 1000 hours without observable coke deposition. We find that Ga enhances DRM stability by suppressing C-H activation to balance carbon removal. A series of coke-free DRM catalysts are developed herein by partially substituting Al from CoAl2O4with other metals.

     
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  8. Abstract

    Boreal summer intraseasonal oscillation (BSISO) is a primary source of predictability for summertime weather and climate on the subseasonal-to-seasonal (S2S) time scale. Using the GFDL SPEAR S2S prediction system, we evaluate the BSISO prediction skills based on 20-yr (2000–19) hindcast experiments with initializations from May to October. It is revealed that the overall BSISO prediction skill using all hindcasts reaches out to 22 days as measured by BSISO indices before the bivariate anomalous correlation coefficient (ACC) drops below 0.5. Results also show that the northeastward-propagating canonical BSISO (CB) event has a higher prediction skill than the northward dipole BSISO (DB) event (28 vs 23 days). This is attributed to CB’s more periodic nature, resulting in its longer persistence, while DB events are more episodic accompanied by a rapid demise after reaching maximum enhanced convection over the equatorial Indian Ocean. From a forecaster’s perspective, a precursory strong Kelvin wave component in the equatorial western Pacific signifies the subsequent development of a CB event, which is likely more predictable. Investigation of individual CB events shows a large interevent spread in terms of their prediction skills. For CB, the events with weaker and fluctuating amplitude during their lifetime have relatively lower prediction skills likely linked to their weaker convection–circulation coupling. Interestingly, the prediction skills of individual CB events tend to be relatively higher and less scattered during late summer (August–October) than those in early summer (May–July), suggestive of the seasonal modulation on the evolution and predictability of BSISO.

    Significance Statement

    The advance of subseasonal-to-seasonal (S2S) prediction largely depends on dynamical models’ ability to predict some major intrinsic modes in the climate system, including the boreal summer intraseasonal oscillation (BSISO). Using a newly developed S2S prediction system, we thoroughly evaluated its performance in predicting BSISO, and revealed the skill dependence on the BSISO propagation diversity. Here we provide physical explanations of what influences the BSISO predictions and identify different precursory signals for two types of BSISO, which have important implications for operational forecasts.

     
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  9. Ptychographic coherent diffractive imaging enables diffraction-limited imaging of nanoscale structures at extreme ultraviolet and x-ray wavelengths, where high-quality image-forming optics are not available. However, its reliance on a set of diverse diffraction patterns makes it challenging to use ptychography to image highly periodic samples, limiting its application to defect inspection for electronic and photonic devices. Here, we use a vortex high harmonic light beam driven by a laser carrying orbital angular momentum to implement extreme ultraviolet ptychographic imaging of highly periodic samples with high fidelity and reliability. We also demonstrate, for the first time to our knowledge, ptychographic imaging of an isolated, near-diffraction-limited defect in an otherwise periodic sample using vortex high harmonic beams. This enhanced metrology technique can enable high-fidelity imaging and inspection of highly periodic structures for next-generation nano, energy, photonic, and quantum devices.

     
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  10. Deep convection in the Asian summer monsoon is a significant transport process for lifting pollutants from the planetary boundary layer to the tropopause level. This process enables efficient injection into the stratosphere of reactive species such as chlorinated very short-lived substances (Cl-VSLSs) that deplete ozone. Past studies of convective transport associated with the Asian summer monsoon have focused mostly on the south Asian summer monsoon. Airborne observations reported in this work identify the East Asian summer monsoon convection as an effective transport pathway that carried record-breaking levels of ozone-depleting Cl-VSLSs (mean organic chlorine from these VSLSs ~500 ppt) to the base of the stratosphere. These unique observations show total organic chlorine from VSLSs in the lower stratosphere over the Asian monsoon tropopause to be more than twice that previously reported over the tropical tropopause. Considering the recently observed increase in Cl-VSLS emissions and the ongoing strengthening of the East Asian summer monsoon under global warming, our results highlight that a reevaluation of the contribution of Cl-VSLS injection via the Asian monsoon to the total stratospheric chlorine budget is warranted.

     
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    Free, publicly-accessible full text available March 19, 2025