Whether there are links between geomagnetic field and Earth's orbital parameters remains unclear. Synchronous reconstructions of parallel long-term quantitative geomagnetic field and climate change records are rare. Here, we present 10Be-derived changes of both geomagnetic field and Asian monsoon (AM) rainfall over the last 870 kyr from the Xifeng loess-paleosol sequence on the central Chinese Loess Plateau. The 10BeGM flux (a proxy for geomagnetic field-induced 10Be production rate) reveals 13 consecutive geomagnetic excursions in the Brunhes chron, which are synchronized with the global records, providing key time markers for Chinese loess-paleosol sequences. The 10Be-derived rainfall exhibits distinct ~100 kyr glacial-interglacial cycles, and superimposed precessional (~23 kyr) cycles that match with those in Chinese speleothem δ18O record. We find that changes in the geomagnetic field and AM rainfall share a common ~100 kyr cyclicity, implying a likely eccentricity modulation of both the geomagnetic field and climate.
Abstract We report a new high‐resolution Holocene 10 Be record from Huguangyan Maar Lake in subtropical‐tropical South China, aimed to detect the atmospheric 10 Be production signal in low‐latitude regions. After minimizing climatic effects by regression analyses between 10 Be concentration and climatic proxies from the same archive, we successfully distinguished variations in geomagnetic field intensity and solar activity using 2,000‐year low‐ and high‐pass filtering, respectively, of the residual 10 Be record (a proxy of the atmospheric 10 Be production rate). The resulting 10 Be‐derived record of geomagnetic field intensity is generally comparable with geomagnetic models, and the solar‐modulated 10 Be signal shows significant correlations with solar activity proxies. The preservation of 10 Be production signal in the sediments of this low‐latitude maar lake highlights the largely unexplored potential as well as limitations of 10 Be as a tool to reconstruct variations in solar activity and geomagnetic field intensity.
A first-principles method is developed to study the spin transfer torques in magnetic noncollinear textured ferromagnet-superconductor heterostructure. We apply the method to study the long-range spin-triplet pairing $({S}_{z}=\ifmmode\pm\else\textpm\fi{}1)$ induced by the spin-flip scattering near the ferromagnet-superconductor interface. The long-range spin-triplet Andreev reflection will saturate to the same value as usual Andreev reflection with strong enough spin-flip scattering. We find that the giant magnetoresistance effect of a spin valve with a superconductor contact can be restored by a small amount of interfacial spin-flip scattering.
Abstract We report the first complete loess–paleosol record spanning the last 130 kyr from the southern extremity of the Hunshandake Sandy Land (HSL) in central‐eastern Mongolia. Our combined mineral magnetic and geochemical results demonstrate that during the last interglacial, the front of the East Asian summer monsoon (EASM) extended to central‐eastern Inner Mongolia, consistent with modern observations of climate change. However, during the last glacial, typical magnetic parameters (e.g., magnetic susceptibility and anhysteretic remanent magnetization and their ratios), which have been successfully adopted to denote the EASM variations on the Chinese Loess Plateau (CLP), show only muted temporal variations and cannot be readily correlated with equivalent records from the main body of the CLP. Remarkably, the Zr/Rb ratio, a robust geochemical indictor of the winter monsoon, is positively correlated with saturation isothermal remanent magnetization and saturation magnetization during the last glacial, demonstrating the strong control of wind vigor on high‐field magnetization signals dominated by lithogenic ferrimagnetic minerals. In contrast to the variable response of magnetic parameters to regional paleoclimatic fluctuations, the Rb/Sr and Ba/Sr ratios (two summer monsoon indicators) faithfully track weak chemical weathering processes and fine‐scale monsoon oscillations, especially during the last glacial. Additionally, we found that higher proportions of pedogenic high‐coercivity magnetic minerals were formed during the last interglacial, which may reflect relatively low rainfall but higher evapotranspiration in the southern extremity of the HSL compared with the CLP. We therefore attribute this complex magnetic record to a threshold response to the EASM variations in eastern Inner Mongolia.
Green fluorescent protein (GFP) is widely used as a biomarker in living systems; however, GFP and its variants are prone to forming low-affinity dimers under physiological conditions. This undesirable tendency is exacerbated when fluorescent proteins (FP) are confined to membranes, fused to naturally-oligomeric proteins, or expressed at high levels in cells. Oligomerization of FPs introduces artifacts into the measurement of subunit stoichiometry, as well as interactions between proteins fused to FPs. Introduction of a single mutation, A206K, has been shown to disrupt hydrophobic interactions in the region responsible for GFP dimerization, thereby contributing to its monomerization. Nevertheless, a detailed understanding of how this single amino acid-dependent inhibition of dimerization in GFP occurs at the atomic level is still lacking. Single-molecule experiments combined with computational microscopy (atomistic molecular dynamics) revealed that the amino group of A206 contributes to GFP dimer formation via a multivalent electrostatic interaction. We further showed that myristoyl modification is an efficient mechanism to promote membrane attachment of GFP. Molecular dynamics-based site-directed mutagenesis has been used to identify the key functional residues in FPs. The data presented here have been utilized as a monomeric control in downstream single-molecule studies, facilitating more accurate stoichiometry quantification of functional protein complexes in living cells.
Studies on the chemical constituents of roots of Urtica triangularis HAND-MASS have led to the isolation of four new compounds. The structures, including the absolute configurations, of these constituents have been elucidated through spectral studies including 1H-NMR, 13C-NMR, 2D-NMR experiments (heteronuclear single-quantum coherence, heteronuclear multiple bonding connectivity and nuclear Overhauser effect spectroscopy), high resolution mass spectroscopy (HR-MS) and circular dichroism as (−)-4-methoxy-8′-acetyl olivil, (−)-4-methoxy-8′-acetyl olivil-4-O-α-arabinopyronosyl-(1→6)-β-glucopyranoside, (−)-olivil-9-O-β-glucopyranoside and cyclo-olivil-9-O-β-glucopyranoside.
Two new 3-oxo-α-ionol glucoside isomers, (6R,9R)-3-oxo-α-ionol-9-O-β-D-glucopyranosyl (1 → 2)-β-D-glucopyranoside (1) and (6S,9R)-3-oxo-α-ionol-9-O-β-D-glucopyranosyl (1 → 2)-β-D-glucopyranoside (2) were isolated from the aerial parts of Urtica laetevirens Maxim. Their structures, including stereochemistry, were established by spectral analyses (HR–ESI–MS, NMR and CD). Also, 3-oxo-α-ionol glucosides were isolated from Urtica species for the first time.
A new nanolithgraphy structure using surface plasmon interference with a planar silver lens is introduced by attaching a silver film to the output surface of SPRINT structure. The silver film in this structure can effectively enhance the evanescent field generated by the interference of surface plasmon, which acts as a ‘perfect lens’. It allows the large gap between the structure and the photoresist. The new structure not only inherits the merit of SPRINT, but also improves the tolerance of gap for the mechanical convenience.
Black phosphorus (BP), a promising two-dimensional (2D) layered semiconductor material, has gained enormous attention due to its impressive properties over the past several years. Although plenty of methods have been developed to synthesize high-quality BP, most of the currently available BP materials still suffer from unsatisfactory crystallization, purity, and stability in air, hindering their practical application. A facile approach to synthesizing ultrahigh-quality single-crystal BP is of significance to shed light on the nature of 2D semiconductor materials and their massive application. In this work, we present the facile and efficient circulating vapor growth approach to growing bulk single-crystal BP. The as-grown BP material features high crystallinity and ultrahigh purity (higher than 99.999 at %), exceeding those of all the previously reported and some commercially available BP crystals. It also maintains excellent stability in air and water after 15 consecutive days of test. Moreover, the as-synthesized BP material features good thermal stability, oxidation resistance, and excellent electrical properties, as well. This study provides a new approach for the fabrication of ultrahigh-quality BP material and thus promotes its application.
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