Organoboron compounds are highly valuable in synthetic chemistry. In particular, α-borylcarbonyl compounds have shown versatile synthetic applications, owing to fruitful chemistries of both the boryl ...and carbonyl moieties. However, the synthesis of these molecules still remains tedious and time-consuming. Here we report a straightforward and practical route to synthesize α-borylcarbonyl molecules based on a regioselective radical α-borylation of α,β-unsaturated carbonyl compounds. The reaction features unusual α-regioselectivity and high functional-group compatibility. Further synthetic applications of new α-borylated products were also demonstrated. DFT and kinetic studies implicated that the α-regioselectivity of β-aryl-α,β-unsaturated carbonyl compounds was determined by the thermodynamically more favorable radical α-addition step, whereas the formation of α-addition products from β-alkyl-α,β-unsaturated carbonyl compounds was driven by an energetically favored hydrogen atom transfer step. Given that α,β-unsaturated carbonyl compounds can be easily obtained in abundance and variety, this method enjoys great advantages in diverse and economical synthesis of valuable α-borylcarbonyl molecules.
Li−CO2 batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO2 and ...the Li2CO3 product leads to a low operating voltage (<2.5 V) and poor energy efficiency. In addition, the reversibility of Li2CO3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel “trinity” Li−CO2 battery system was developed by synergizing CO2, soluble redox mediator (2,2,6,6‐tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO2 to Li2C2O4. The designed Li−CO2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li2CO3, and an ultrahigh round‐trip efficiency of 97.1 %. The superior performance of Li−CO2 batteries is attributed to the TEM RM‐mediated preferential growth mechanism of Li2C2O4, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO2‐deficient environments, which provides an avenue for the rationally design of CO2 conversion reactions and a feasible guide for next‐generation Li−CO2 batteries.
The “trinity” strategy provides a new perspective for the development of Li−CO2 batteries. The addition of a soluble mediator, TEM RM, was used to modulate the three‐phase interface and facilitate the conversion of CO2 to Li2C2O4. This strategy avoids a series of issues associated with the Li2CO3 product, contributing to excellent cycling performance for Li−CO2 battery.
Long noncoding RNAs (lncRNAs) evolve more rapidly than mRNAs. Whether conserved lncRNAs undergo conserved processing, localization, and function remains unexplored. We report differing subcellular ...localization of lncRNAs in human and mouse embryonic stem cells (ESCs). A significantly higher fraction of lncRNAs is localized in the cytoplasm of hESCs than in mESCs. This turns out to be important for hESC pluripotency. FAST is a positionally conserved lncRNA but is not conserved in its processing and localization. In hESCs, cytoplasm-localized hFAST binds to the WD40 domain of the E3 ubiquitin ligase β-TrCP and blocks its interaction with phosphorylated β-catenin to prevent degradation, leading to activated WNT signaling, required for pluripotency. In contrast, mFast is nuclear retained in mESCs, and its processing is suppressed by the splicing factor PPIE, which is highly expressed in mESCs but not hESCs. These findings reveal that lncRNA processing and localization are previously under-appreciated contributors to the rapid evolution of function.
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•Subcellular localization of conserved lncRNAs is different in hESCs and mESCs•Cytoplasmic hFAST but not nuclear mFast promotes WNT signaling in hESC pluripotency•PPIE regulates distinct FAST processing in hESCs and mESCs•RNA processing and localization contribute to lncRNA functional evolution
A pair of lncRNA orthologs exhibits different subcellular localization in human and murine ESCs because of differential RNA processing, which, in turn, leads to their functional divergence in the context of pluripotency regulation. The findings highlight how conserved lncRNAs may achieve functional evolution through non-conserved RNA processing.
A dual temperature‐ and light‐responsive C2H2/C2H4 separation switch in a diarylethene metal–organic framework (MOF) is presented. At 195 K and 100 kPa this MOF shows ultrahigh C2H2/C2H4 selectivity ...of 47.1, which is almost 21.4 times larger than the corresponding value of 2.2 at 293 K and 100 kPa, or 15.7 times larger than the value of 3.0 for the material under UV at 195 K and 100 kPa. The origin of this unique control in C2H2/C2H4 selectivity, as unveiled by density functional calculations, is due to a guest discriminatory gate‐opening effect from the diarylethene unit.
Photochromic diarylethene units were used to identify C2H2, leading to ultrahigh C2H2/C2H4 selectivity and promising application in C2H2/C2H4 separation at low temperature. The photochromic material can be further used as a temperature‐ and light‐responsive switch for C2H2/C2H4 separation.
Activated microglia can be polarized to the pro-inflammatory M1 phenotype and the anti-inflammatory M2 phenotype. Low-intensity pulsed ultrasound (LIPUS) can attenuate pro-inflammatory responses in ...activated microglia.
This study aimed to investigate the effects of LIPUS on M1/M2 polarization of microglial cells and the regulatory mechanisms associated with signaling pathways.
BV-2 microglial cells were stimulated by lipopolysaccharide (LPS) to an M1 phenotype or by interleukin-4 (IL-4) to an M2 phenotype. Some microglial cells were exposed to LIPUS, while others were not. M1/M2 marker mRNA and protein expression were measured using real-time polymerase chain reaction and western blot, respectively. Immunofluorescence staining was performed to determine inducible nitric oxide synthase (iNOS)-/arginase-1 (Arg-1)- and CD68-/CD206-positive cells.
LIPUS treatment significantly attenuated LPS-induced increases in inflammatory markers (iNOS, tumor necrosis factor-α, interleukin-1β, and interleukin-6) as well as the expression of cell surface markers (CD86 and CD68) of M1-polarized microglia. In contrast, LIPUS treatment significantly enhanced the expression of M2-related markers (Arg-1, IL-10, and Ym1) and membrane protein (CD206). LIPUS treatment prevented M1 polarization of microglia and enhanced or sustained M2 polarization by regulating M1/M2 polarization through the signal transducer and activator of transcription 1/STAT6/peroxisome proliferator-activated receptor gamma pathways.
Our findings suggest that LIPUS inhibits microglial polarization and switches microglia from the M1 to the M2 phenotype.
The waste shrimp shells (SS) were used as both carbon and nitrogen sources to directly synthesize N and P co-doped carbon networks with abundant mesopores and high specific surface area by simple ...acid pretreatment and carbonization. Using exogenous phosphorus as dopant, the prepared catalyst (PA-SS 900) favorably possessed a high oxygen reduction reaction (ORR) activity regarding half-wave potential (0.82 V) and limiting current (4.47 mA cm−2), which approached those of commercial 20 wt% Pt/C. For practical application in microbial fuel cell (MFC), the N, P co-doped PA-SS 900 achieved a maximum power density (MPD) of 802 mW m−2 and an open circuit voltage (OCV) of 653 mV, which also were close to that (892 mW m−2 and 752 mV) based on 20% Pt/C as cathode catalyst. Remarkably, the synthetic catalyst had a better long-term stability than that of 20% Pt/C in alkaline medium. These results demonstrated that N, P co-doped PA-SS 900 was an accessible and efficient ORR catalyst in air-cathode MFC for relatively desirable energy generation and wastewater treatment. Further, the direct utilization of waste shrimp shells replacing chitin or chitosan in energy conversion is worthy of in-depth study due to the advantages of simple process, environmental friendliness and availability.
The waste shrimp shells were used as both carbon and nitrogen source to directly synthesize efficient ORR catalyst for MFCs. Display omitted
•Shrimp shells as nitrogen source were directly used to prepare ORR catalysts.•Removing CaCO3 and in-situ pore in shrimp shells promoted the active sites.•Hydrothermal process with phosphoric acid facilitated similar spherical carbon.•N, P co-doped carbon exhibited good ORR property, stability and application in MFC.
A fundamental understanding of the fluid movement and dynamic partitioning process at fracture intersections is important to accurately predict water infiltration and contaminant transport in ...networks of fractures. We present an experimental study on the flow‐splitting behavior at a T‐shaped intersection. Different combinations of apertures of the vertical (bv) and horizontal (bh) fractures are considered. Experimental results confirm that the gravity‐driven flow in the vertical fracture transitions from droplet to rivulet mode as the flow rate increases. We quantify the flow dynamics through the intersection and especially focus on the partitioning efficiency (η) defined as the percentage of flow partitioned into the horizontal fracture. We identify three regimes of flow partitioning at the intersection for the case of bv < bh: total partitioning (η → 1), splitting or partial bypass (0 < η < 1), and total bypass (η → 0). The total bypass regime is associated with the rivulet mode with a flow rate higher than ~1.5 ml/min. We find a simple relationship between η and the flow rate Q for droplet flow, η = min(1, ChQ−1), where Ch is a threshold flow rate below which droplets almost completely imbibe into the horizontal fracture, leading to η → 1. A force balance analysis links Ch to a critical droplet length for the transition from complete partitioning to path splitting. The obtained relationship is further supported by numerical simulations of droplet flow through intersections. The results and analysis from this study may provide insights and physical constraints on construction of reduced order unsaturated flow models based on simplified discrete fracture networks.
Key Points
We experimentally study unsaturated flow through fracture intersections with a focus on the flow‐partitioning behavior
We identify three regimes of partitioning behavior, including total partitioning, partial bypass, and total bypass, depending on flow rate
We find a simple relationship between partitioning efficiency and flow rate for droplet mode and elucidate the mechanism of partitioning
The 4f-electron delocalization plays a key role in the low-temperature properties of rare-earth metals and intermetallics, and it is normally realized by the Kondo coupling between 4f and conduction ...electrons. Due to the large Coulomb repulsion of 4f electrons, the bandwidth-control Mott-type delocalization, commonly observed in d-electron systems, is difficult in 4f-electron systems and remains elusive in spectroscopic experiments. Here we demonstrate that the bandwidth-control orbital-selective delocalization of 4f electrons can be realized in epitaxial Ce films by thermal annealing, which results in a metastable surface phase with reduced layer spacing. The quasiparticle bands exhibit large dispersion with exclusive 4f character near Formula: see text and extend reasonably far below the Fermi energy, which can be explained from the Mott physics. The experimental quasiparticle dispersion agrees well with density-functional theory calculation and also exhibits unusual temperature dependence, which could arise from the delicate interplay between the bandwidth-control Mott physics and the coexisting Kondo hybridization. Our work opens up the opportunity to study the interaction between two well-known localization-delocalization mechanisms in correlation physics, i.e., Kondo vs Mott, which can be important for a fundamental understanding of 4f-electron systems.
Plants are capable of regenerating adventitious roots (ARs), which is important for plant response to stress and survival. Although great advances in understanding AR formation of leaf explants have ...been made, the regulatory mechanisms of AR formation still need to be investigated. In this study, irr1‐1 (impaired root regeneration) was isolated with the inhibition of adventitious rooting from Arabidopsis leaf explants. The β‐glucuronidase (GUS) signals of IRR1pro::GUS in detached leaves could be detected at 2–6 days after culture. IRR1 is annotated to encode a Class III peroxidase localized in the cell wall. The total peroxidase (POD) activity of irr1 mutants was significantly lower than that of the wild type. Detached leaves of irr1 mutants showed enhanced reactive oxygen species (ROS) accumulation 4 days after leaves were excised from seedlings. Moreover, thiourea, a ROS scavenger, was able to rescue the adventitious rooting rate in leaf explants of irr1 mutants. Addition of 0.1 μM indole‐3‐acetic acid (IAA) improved the adventitious rooting from leaf explants of irr1 mutants. Taken together, these results indicated that IRR1 was involved in AR formation of leaf explants, which was associated with ROS homeostasis to some extent.
ABSTRACT
Faithful DNA replication is one of the most essential processes in almost all living organisms. However, the proteins responsible for organellar DNA replication are still largely unknown in ...plants. Here, we show that the two mitochondrion‐targeted single‐stranded DNA‐binding (SSB) proteins SSB1 and SSB2 directly interact with each other and act as key factors for mitochondrial DNA (mtDNA) maintenance, as their single or double loss‐of‐function mutants exhibit severe germination delay and growth retardation. The mtDNA levels in mutants lacking SSB1 and/or SSB2 function were two‐ to four‐fold higher than in the wild‐type (WT), revealing a negative role for SSB1/2 in regulating mtDNA replication. Genetic analysis indicated that SSB1 functions upstream of mitochondrial DNA POLYMERASE IA (POLIA) or POLIB in mtDNA replication, as mutation in either gene restored the high mtDNA copy number of the ssb1‐1 mutant back to WT levels. In addition, SSB1 and SSB2 also participate in mitochondrial genome maintenance by influencing mtDNA homologous recombination (HR). Additional genetic analysis suggested that SSB1 functions upstream of ORGANELLAR SINGLE‐STRANDED DNA‐BINDING PROTEIN1 (OSB1) during mtDNA replication, while SSB1 may act downstream of OSB1 and MUTS HOMOLOG1 for mtDNA HR. Overall, our results yield new insights into the roles of the plant mitochondrion‐targeted SSB proteins and OSB1 in maintaining mtDNA stability via affecting DNA replication and DNA HR.
The Arabidopsis mitochondrial single‐stranded DNA‐binding (SSB) proteins SSB1 and SSB2 interact each other and may act upstream of DNA POLYMERASE IA or IB to negatively regulate mitochondrial DNA replication. In addition, SSB1 and SSB2 likely compete with ORGANELLAR SINGLE‐STRANDED DNA‐BINDING PROTEIN 1 in maintaining homologous recombination of mitochondrial DNA.
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