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In this study, we explore the substrate-mediated control of self-assembly behavior in diboron molecules (C12H8B2O4, B2Cat2) using scanning tunneling microscopy (STM). The structural transformation of B2Cat2 molecules from one-dimensional (1D) molecular chains to two-dimensional (2D) molecular arrays was achieved by changing the substrate from Au(111) to bilayer graphene (BLG), highlighting the key role of substrate interactions in determining the assembly structure. Notably, the B-B bond in the molecular arrays on BLG is distinctly pronounced, reflecting a more refined molecular resolution with distinct electronic states than that on Au(111). Density functional theory (DFT) calculations confirm the weak interaction between B2Cat2 molecules and the BLG substrate, which facilitates the formation of 2D molecular arrays on BLG. This work demonstrates how controlling substrate properties enables the formation of 1D chains and 2D arrays, providing valuable insights for the design of next-generation molecular electronics and catalysis systems. [ABSTRACT FROM AUTHOR]

This work aimed to establish an HILIC‐MS/MS method to simultaneously determine the levels of 13 endogenous amino acids and trimethylamine oxide in the biological samples from the mice. Electrospray ion source was used for the analysis of mass spectrometry. The 20 min separation was applied in a Dikma Inspire Hilic column (2.1 × 100.0 mm, 3 μM). Positive ion mode under an MRM model gave a satisfying response value. The limits of quantitation were evaluated by accuracy from −12.59% to 7.89% and precision from 1.77% to 14.00% as well as acceptable interday and intraday precision, matrix effect, recovery, and stability. Later, the assay was successfully used to measure the concentrations of the determinands in the biological samples. Individual and tissue distribution differences for these metabolites were observable. The amino acids had a consistent highest content in the spleens, while the lowest levels were found in the livers. Alanine was the most abundant amino acid in the serum, and taurine kept the highest content in all of the tissues. Trimethylamine oxide remained low level, especially in the liver samples. [ABSTRACT FROM AUTHOR]

In this study, we investigated the surface-confined coupling reactions of 1,8-dibromobiphenylene (BPBr2) on Cu(111) to elucidate the details of the organometallic intermediates via Ullmann reactions. We used scanning tunneling microscopy (STM) to characterize the resulting organometallic intermediates. Moreover, submolecular resolution of the non-contact atomic force microscopy (nc-AFM) qPlus technique enables the bond-resolving within the organometallic dimer product. Our findings reveal the debromination of BPBr2 on Cu(111), leading to the formation of an organometallic dimer intermediate at room temperature. Through nc-AFM measurements, we confirm and visualize the formation of the C-Cu-C bond. These insights enhance our understanding of Ullmann reaction and hold potential implications for the design of novel two-dimensional electronic devices. [ABSTRACT FROM AUTHOR]

Quantum spin liquids (QSLs) are in a quantum disordered state that is highly entangled and has fractional excitations. As a highly sought-after state of matter, QSLs were predicted to host spinon excitations and to arise in frustrated spin systems with large quantum fluctuations. Here we report on the experimental observation and theoretical modeling of QSL signatures in monolayer 1T-NbSe2, which is a newly emerging two-dimensional material that exhibits both charge-density-wave (CDW) and correlated insulating behaviors. By using scanning tunneling microscopy and spectroscopy (STM/STS), we confirm the presence of spin fluctuations in monolayer 1T-NbSe2 by observing the Kondo resonance as monolayer 1T-NbSe2 interacts with metallic monolayer 1H-NbSe2. Subsequent STM/STS imaging of monolayer 1T-NbSe2 at the Hubbard band energy further reveals a long-wavelength charge modulation, in agreement with the spinon modulation expected for QSLs. By depositing manganese-phthalocyanine (MnPc) molecules with spin S = 3/2 onto monolayer 1T-NbSe2, new STS resonance peaks emerge at the Hubbard band edges of monolayer 1T-NbSe2. This observation is consistent with the spinon Kondo effect induced by a S = 3/2 magnetic impurity embedded in a QSL. Taken together, these experimental observations indicate that monolayer 1T-NbSe2 is a new promising QSL material.Recently, signatures of quantum spin liquid have been reported in monolayer transition metal dichalcogenides. Here the authors report evidence of such state in 1T-NbSe2 via the measurements of the Kondo effect in a 1T-1H heterostructure, further supported by measurements for magnetic molecules on 1T-NbSe2. [ABSTRACT FROM AUTHOR]

Advanced atomic tracking techniques play a critical role in characterizing structural evolution, elucidating fundamental mechanisms of exotic phenomena and tailoring delicate properties. Thermally driven structural modulation in 2D crystals, such as the charge density wave (CDW), often leads to intriguing quantum properties, making them a valuable platform for exploring fundamental physics and potential device applications. However, despite their significance, experimental studies addressing atomic tracking of thermally‐driven structural evolution in 2D crystals have been limited. Herein, we utilize high‐accuracy variable‐temperature atomic tracking measurements with scanning tunneling microscopy (STM) to directly observe a series of structural transitions in a model 2D crystal, namely NbSe2. With the atomic tracking technique, we confirm the existence of the universal thermally‐driven CDW transition hysteresis between the heating and cooling cycles. This transition hysteresis, characterized by a constant temperature offset, represents a new phenomenon of structural evolution. Our findings provide a feasible method to track CDW transitions at the atomic scale in 2D crystals, significantly contributing to a better understanding and the potential modulation of these materials' functions in nanodevices. [ABSTRACT FROM AUTHOR]

This study investigated antimalarial efficacy and sensitization of chrysosplenetin against artemisinin‐resistant Plasmodium berghei K173 and potential molecular mechanism. Our data indicated a risk of artemisinin resistance because a higher parasitaemia% and lower inhibition% under artemisinin treatment against resistant parasites than those in the sensitive groups were observed. Two non‐antimalarial components, verapamil and chrysosplentin, being P‐gp inhibitors, possessed a strong efficacy against resistant parasites but it was not the case for Bcrp inhibitor novobiocin. Artemisinin‐chrysosplenetin combination improved artemisinin susceptibility of resistant P. berghei. Artemisinin activated intestinal P‐gp and Abcb1/Abcg2 expressions and suppressed Bcrp whereas chrysosplenetin reversed them. Resistant parasite infection led to a decreased haemozoin in organs or an increased heme in peripheral bloods compared with the sensitives; however, that in Abcb1‐deficient knockout (KO)‐resistant mice reversely got increased or decreased versus wild type (WT)‐resistant animals. Chrysosplenetin as well as rifampin (nuclear receptor agonist) increased the transcription levels of PXR/CAR while showed a versatile regulation on hepatic and enternal PXR/CAR in WT‐ or KO‐sensitive or ‐resistant parasites. Oppositely, hepatic and enteric NF‐κB p52 mRNA decreased conformably in WT but increased in KO‐resistant mice. NF‐κB pathway potentially involved in the mechanism of chrysosplenetin on inhibiting P‐gp expressions while PXR/CAR play a more complicated role in this mechanism. [ABSTRACT FROM AUTHOR]