We report a cooperative catalytic system comprising a PdII complex, XPhos, and the potassium salt of 5‐norbornene‐2‐carboxylic acid that enables the use of epoxides as alkylating reagents in the ...Catellani reaction, thereby expanding the existing paradigm of this powerful transformation. The potassium salt of inexpensive 5‐norbornene‐2‐carboxylic acid acts as both mediator and base in the process. This mild, chemoselective, scalable, and atom‐economical protocol is compatible with a wide variety of readily available functionalized aryl iodides and epoxides, as well as terminating olefins. The resulting products undergo facile oxa‐Michael addition to furnish ubiquitous isochroman scaffolds.
A little cooperation can go a long way: A cooperative catalytic system comprising a PdII/XPhos complex and the potassium salt of 5‐norbornene‐2‐carboxylic acid, which serves dual roles as a mediator and a base, enabled the use of epoxides as alkylating reagents in the Catellani reaction (see scheme). The products could also undergo oxa‐Michael addition to furnish valuable isochroman scaffolds.
Mixed matrix membranes (MMMs), conjugating the advantages of flexible processing‐ability of polymers and high‐speed mass transfer of porous fillers, are recognized as the next‐generation ...high‐performance CO2 capture membranes for solving the current global climate challenge. However, controlling the crystallization of porous metal‐organic frameworks (MOFs) and thus the close stacking of MOF nanocrystals in the confined polymer matrix is still undoable, which thus cannot fully utilize the superior transport attribute of MOF channels. In this study, the “confined swelling coupled solvent‐controlled crystallization” strategy is employed for well‐tailoring the in‐situ crystallization of MOF nanocrystals, realizing rapid (<5 min) construction of defect‐free freeway channels for CO2 transportation in MMMs due to the close stacking of MOF nanocrystals. Consequently, the fabricated MMMs exhibit approximately fourfold enhancement in CO2 permeability, i.e., 2490 Barrer with a CO2/N2 selectivity of 37, distinctive antiplasticization merit, as well as long‐term running stability, which is at top‐tier level, enabling the large‐scale manufacture of high‐performance MMMs for gas separation.
A facile and efficient “confined swelling coupled solvent‐controlled crystallization” strategy is demonstrated to control the in situ crystallization of metal‐organic frameworks nanocrystals in polyethylene oxide membranes, realizing rapid construction of defect‐free freeway channels for CO2 transportation in mixed matrix membranes (MMMs). The optimized MMM showed fourfold enhancement in CO2 permeability, i.e., 2705 Barrer, with a CO2/N2 selectivity of 37.
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•CoB/CNs Schottky junction with interfacial Co-N bond was prepared;•CoB/CNs presents excellent performance for photocatalytic S. aureus inactivation;•Interfacial Co-N bond can ...efficiently modulate the charge transfer dynamics;•Two-step single-electron induced O2 reduction (O2 → ·O2– → H2O2) is enhanced.
Interfacial engineering plays a critical role in modulating the electron transfer dynamics of photocatalysis, but has been rarely explored. Herein, a novel cobalt boride/graphitic carbon nitride nanosheet (CoB/CNs) Schottky junction with interfacial Co-N bond was successfully prepared to uncover the function of interfacial chemical bond in photocatalytic antibacterial process. Density functional theory (DFT) calculation and experimental investigation demonstrate that the interfacial Co-N bond can act as an electron transfer channel to efficiently steer the electron transfer from CNs to CoB, and then an upward band bending with the height of 0.26 eV is formed in CoB/CNs Schottky junction. The formed upward band bending can rapidly separate the photogenerated electron-hole pairs by preventing electrons from flowing back to the CNs, which causes the surface electron transfer efficiency (ηtrans) to increases from 41.8% (CNs) to 57.7% (CoB/CNs-2). Rotating disk electrode (RDE) results demonstrate that compared with CNs (n = 2.38), the oxygen reduction reaction in CoB/CNs-2 (n = 2.19) is more selective to a two-electron transfer route. Meanwhile, further research on reactive oxygen species reveals that it is an indirect two-step single-electron oxygen reduction process, which is beneficial for the generation of ·O2– and H2O2. As a result, 7 × 107 CFU/mL of Staphylococcus aureus (S. aureus) can be completely inactivated by CoB/CNs-2 with 125 min under visible light irradiation. It is expected that our work will provide some guidance for the exploitation of more advanced hybrid photocatalysts system through interfacial engineering.
The Catellani reaction is a powerful strategy that allows the expeditious synthesis of highly substituted arenes, which are not easily accessible through traditional transition‐metal‐catalyzed ...cross‐coupling reactions. This reaction utilizes the synergistic interplay of palladium and norbornene catalysis to facilitate sequential ortho‐C−H functionalization and ipso termination of aryl iodides in a single operation. Since pioneering work by the group of Catellani in 1997, and later by the group of Lautens, this chemistry has attracted considerable attention from the synthetic chemistry community. Dramatic progress has been made by a number of groups in the past two decades. In this Minireview, the alkylating reagents employed in this intriguing reaction and the corresponding applications in organic synthesis are summarized; thus complementing existing reviews to inspire future developments.
Changing conventions: The Catellani reaction, such as depicted, is a powerful strategy that allows the expeditious synthesis of highly substituted arenes, which are not easily accessible through traditional transition‐metal‐catalyzed cross‐coupling reactions (NBE=norbornene). This review highlights the alkylating reagents employed in these reactions and related applications in organic synthesis.
Einstein’s general relativity theory provides a successful understanding of the flow of time in the gravitational field. From Einstein’s equivalence principle, the influence of the Sun and Moon ...masses on clocks is given in the form of tidal potentials. Two clocks fixed on the surface of the Earth, compared to each other, can measure the tidal effects of the Sun and Moon. The measurement of tidal effects can provide a test for general relativity. Based on the standard general relativity method, we rigorously derive the formulas for clock comparison in the Barycentric Celestial Reference System and Geocentric Celestial Reference System, and demonstrate the tidal effects on clock comparison experiments. The unprecedented performance of atomic clocks makes it possible to measure the tidal effects on clock comparisons. We propose to test tidal effects with the laboratory clock comparisons and some international missions, and give the corresponding estimations. By comparing the state-of-the-art clocks over distances of 1000 km, the laboratory may test tidal effects with a level of 1%. Future space missions, such as the China space station and FOCOS mission, can also be used to test tidal effects, and the best accuracy may reach 0.3%.
Background and Aims
Coronavirus disease 2019 (COVID‐19) is a new infectious disease. To reveal the hepatic injury related to this disease and its clinical significance, we conducted a multicenter ...retrospective cohort study that included 5,771 adult patients with COVID‐19 pneumonia in Hubei Province.
Approach and Results
We reported the distributional and temporal patterns of liver injury indicators in these patients and determined their associated factors and death risk. Longitudinal liver function tests were retrospectively analyzed and correlated with the risk factors and death. Liver injury dynamic patterns differed in alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin (TBIL). AST elevated first, followed by ALT, in severe patients. ALP modestly increased during hospitalization and largely remained in the normal range. The fluctuation in TBIL levels was mild in the non‐severe and the severe groups. AST abnormality was associated with the highest mortality risk compared with the other indicators of liver injury during hospitalization. Common factors associated with elevated liver injury indicators were lymphocyte count decrease, neutrophil count increase, and male gender.
Conclusion
The dynamic patterns of liver injury indicators and their potential risk factors may provide an important explanation for the COVID‐19‐associated liver injury. Because elevated liver injury indicators, particularly AST, are strongly associated with the mortality risk, our study indicates that these parameters should be monitored during hospitalization.
Mitochondria are recognized as one of the most important targets for new drug design in cancer, cardiovascular, and neurological diseases. Currently, the most effective way to deliver drugs ...specifically to mitochondria is by covalent linking a lipophilic cation such as an alkyltriphenylphosphonium moiety to a pharmacophore of interest. Other delocalized lipophilic cations, such as rhodamine, natural and synthetic mitochondria-targeting peptides, and nanoparticle vehicles, have also been used for mitochondrial delivery of small molecules. Depending on the approach used, and the cell and mitochondrial membrane potentials, more than 1000-fold higher mitochondrial concentration can be achieved. Mitochondrial targeting has been developed to study mitochondrial physiology and dysfunction and the interaction between mitochondria and other subcellular organelles and for treatment of a variety of diseases such as neurodegeneration and cancer. In this Review, we discuss efforts to target small-molecule compounds to mitochondria for probing mitochondria function, as diagnostic tools and potential therapeutics. We describe the physicochemical basis for mitochondrial accumulation of lipophilic cations, synthetic chemistry strategies to target compounds to mitochondria, mitochondrial probes, and sensors, and examples of mitochondrial targeting of bioactive compounds. Finally, we review published attempts to apply mitochondria-targeted agents for the treatment of cancer and neurodegenerative diseases.
Pancreatic cancer (PC) is one of the most lethal malignancies. Recent studies indicate that patients with incidentally diagnosed PC have better prognosis than those with symptoms and that there is a ...sufficient window for early detection. However, effective early diagnosis remains difficult and depends mainly on imaging modalities and the development of screening methodologies with highly sensitive and specific biomarkers. This review summarizes recent advances in effective screening for early diagnosis of PC using imaging modalities and novel molecular biomarkers discovered from various “omics” studies including genomics, epigenomics, non‐coding RNA, metabonomics, liquid biopsy (CTC, ctDNA and exosomes) and microbiomes, and their use in body fluids (feces, urine and saliva). Although many biomarkers for early detection of PC have been discovered through various methods, larger scale and rigorous validation is required before their application in the clinic. In addition, more effective and specific biomarkers of PC are urgently needed.
Abstract
While general relativity predicts only two tensor modes for gravitational-wave (GW) polarization, general metric theories of gravity allow for up to four additional modes, including two ...vector and two scalar modes. Observing the polarization modes of GWs could provide a direct test of the modified gravity. The stochastic GW background (SGWB), which can be detected by space-based laser-interferometric detectors at design sensitivity, will provide an opportunity to directly measure alternative polarization. In this paper, we investigate the performance of the LISA-TianQin network for detecting alternative polarizations of stochastic backgrounds, and propose a method to separate different polarization modes. First, we generalize the small antenna approximation to compute the overlap reduction functions for the SGWB with arbitrary polarization, which is suitable for any time-delay interferometry combination. Then we analyze the detection capability of LISA-TianQin for the SGWB with different polarizations. Based on the orbital characteristics of LISA-TianQin, we propose a method to distinguish different polarization modes from their mixed data. Finally, simulation tests are performed to verify the effectiveness of the method. The results of the simulations demonstrate that LISA-TianQin, when employing our proposed method, has the ability to differentiate between various polarization modes, with a specific emphasis on the ability to distinguish between the breathing and longitudinal modes.
Herein, the authors synthesis an efficient and easily recycled CuCo/C catalyst through one-step carbonization of Cu@Co-MOF-71 (Abbreviated as Cu@Co-MOF in this work) precursor. The prepared CuCo/C ...has a high degradation efficiency of 90% for ciprofloxacin (CIP) by activating PMS in a wide value of pH 3–9 within 30 min. After pyrolysis, the carbon matrix as a dispersant can promote the highly uniform distribution of active metals. Additionally, the CIP removal efficiency was 85% after four cycles and the catalyst was easily separated from the solution by using magnets, showing the good stability and reusability. To further study the superiority of CuCo/C activated PMS in degrading CIP, the factors such as pH, the dosage of PMS and catalyst, temperature, inorganic ions and pollutant (CIP) concentration were investigated. Furthermore, the Liquid chromatography-mass spectrometry (LC-MS) was utilized to analyze the intermediate products and possible degradation pathways of CIP. Typically, the quenching experiments and electron paramagnetic resonance (EPR) technology were investigated to confirm the main reaction species including SO4▪−, OH▪ and O2▪− radicals as well as nonradical (1O2). This work put forward a simple method for synthesis of metal-organic framework (MOF) derived catalysts and its application in treatment of organic pollutants.
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•The CuCo/C catalyst was prepared by a facile one-step carbonization method.•The carbon derived from the organic ligands in the MOFs facilitates the highly distribution of active metals.•The CuCo/C catalyst showed a little bit higher reaction stoichiometric efficiency (RSE).•A high degradation efficiency for CIP by activating PMS.•This work put forward a simple method for synthesis of MOFs derived catalysts.
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