In this study, we investigated reversible intermolecular proton shifting (IPS) coupled with spin transition (ST) in a novel Fe
complex. The host Fe
complex and the guest carboxylic acid anion were ...connected by intermolecular hydrogen bonds (IHBs). We extended the intramolecular proton transfer coupled ST phenomenon to the intermolecular system. The dynamic phenomenon was confirmed by variable-temperature single-crystal X-ray diffraction, neutron crystallography, and infrared spectroscopy. The mechanism of IPS was further validated using density functional theory calculations. The discovery of IPS-coupled ST in crystalline molecular materials provides good insights into fundamental processes and promotes the design of novel multifunctional materials with tunable properties for various applications, such as optoelectronics, information storage, and molecular devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this study, we investigated reversible intermolecular proton shifting (IPS) coupled with spin transition (ST) in a novel FeII complex. The host FeII complex and the guest carboxylic acid anion ...were connected by intermolecular hydrogen bonds (IHBs). We extended the intramolecular proton transfer coupled ST phenomenon to the intermolecular system. The dynamic phenomenon was confirmed by variable‐temperature single‐crystal X‐ray diffraction, neutron crystallography, and infrared spectroscopy. The mechanism of IPS was further validated using density functional theory calculations. The discovery of IPS‐coupled ST in crystalline molecular materials provides good insights into fundamental processes and promotes the design of novel multifunctional materials with tunable properties for various applications, such as optoelectronics, information storage, and molecular devices.
A crystalline material based on an FeII hydrazone complex was synthesized to observe intermolecular proton shifting. The complex exhibits reversible intermolecular proton shifting‐coupled spin transition. This study paves the way for the development of novel functional materials with tunable properties.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Imaging a large number of bio-specimens at high speed is essential for many biomedical applications. The common strategy is to place specimens at different lateral positions and image them ...sequentially. Here we report a new on-chip imaging strategy, termed depth-multiplexed ptychographic microscopy (DPM), for parallel imaging and sensing at high speed. Different from the common strategy, DPM stacks multiple specimens in the axial direction and images the entire z-stack all at once. In our prototype platform, we modify a low-cost car mirror for programmable steering of the incident laser beam. A blood-coated image sensor is then placed underneath the stacked sample for acquiring the resulting diffraction patterns. With the captured images, we perform blind recovery of the incident beam angle and model different layers of the stacked sample as different coded surfaces for object reconstruction. For in vitro experiment, we demonstrate time-lapse cell culture monitoring by imaging 3 stacked microfluidic channels on the coded sensor. For high-throughput cytometric analysis, we image 5 stacked brain sections with a 205-mm2 field of view in ∼50 s. Cytometric analysis is also performed to quantify the cellular proliferation biomarkers on the slides. The DPM approach adds a new degree of freedom for data multiplexing in microscopy, enabling parallel imaging of multiple specimens using a single detector. The demonstrated 6-mm depth of field is among the longest ones in microscopy imaging. The novel depth-multiplexed configuration also complements the miniaturization provided by microfluidics devices, offering a solution for on-chip sensing and imaging with efficient sample handling.
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•Depth-multiplexed strategy for imaging multiple stacked specimens all at once.•Programmable beam steering using a car mirror and blind recovery of the incident angle.•High-resolution, large field-of-view on-chip microscopy with a 6-mm ultralong imaging depth.•Simultaneous imaging of 3 stacked microfluidic channels for on-chip monitoring of live cell cultures.•Simultaneous imaging of 5 stacked brain sections for cytometric analysis on a chip.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Receiver ISB are investigated and modeled.•A new method for real-time satellite clock estimation is given which uses system time offset maintenance aiming at multi-GNSS time interoperability.•The ...clock products generated with the new method have stable system time offsets and higher time interoperability, which can greatly improve the positioning performance under poor visibility.
Time interoperability is one of the important aspects of Global Navigation Satellite System (GNSS) compatibility and interoperability, which will greatly benefit the accuracy and availability of the positioning, navigation and timing (PNT) solution. In this paper, we proposed a real-time satellite clock estimation method using system time offset (STO) maintenance to help users realize GNSS time interoperability. First, receiver inter-system bias (ISB) was investigated and modeled for STO maintenance. Then, we presented clock estimation assessment results, which demonstrate that the new method can make the satellite clock product maintain a stable STO. Finally, precise point positioning (PPP) was used for further validation. The results show that in the condition of a 45° cutoff elevation angle, fixing the ISB can significantly reduce the convergence time, increase the availability by 21.5%, and improve the average positioning accuracy in horizontal and vertical by 37.7% and 44.4%, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Hilbert–Huang transform (HHT) has been used as a powerful tool for analyzing nonlinear and nonstationary time series. Soil loss is controlled by complicated physical processes and thus fluctuates ...with nonlinearity and nonstationarity over time. In order to further clarify the relationship between rainfall, surface runoff, and sediment yield, this study adopted the HHT to analyze these characteristics through multiple time scales and investigated their relationship through time-dependent intrinsic correlation (TDIC) in the time series. A six-year study (2015–2020) was conducted on sloping farmlands to explore the relationships between soil loss and rainfall in southwest China. Time series of soil loss and rainfall were identified as the relevant characteristics at different time scales based on the method of HHT. Local correlation between the soil loss and runoff was carried out by the method of TDIC. The original time series of the rainfall, runoff, and soil loss were decomposed into eight intrinsic mode functions (IMFs) and a residue by ensemble empirical mode decomposition (EEMD). The residue indicated that the rainfall and runoff increased and then decreased during the maize-growing season from 2015 to 2020, whereas the soil loss gradually decreased. IMF1 and IMF2 accounted for nearly 80% of the temporal variations in rainfall, runoff, and soil loss, indicating that the variables varied the most at short time scales. The TDIC analysis showed that strong and positive correlations between the soil loss, rainfall, and runoff prevailed over the entire time domain at the scales of IMF1 and IMF2, indicating the rapid response of the soil loss to rainfall and runoff at short time scales. Time-varying correlations were observed at the IMF3–IMF5 scales. At the IMF7 scale, an evident switchover in the nature of the correlation was identified during the years 2018 and 2019; this could be related to a sudden rainstorm under low vegetation coverage conditions. The EEMD-based TDIC tool is an effective means to clarify the relationship between soil loss, rainfall, and runoff. Our results provide a better understanding of the relationship between soil loss and rainfall varied with time at multiple time scales. Short-term heavy rainfall and rapid surface runoff are the important factors causing serious soil and water loss on a short time scale in a mountainous region with yellow soil, which is of great significance for the construction of a regional soil erosion prediction model.
Differential code bias (DCB) is an important error source in Global Navigation Satellite System (GNSS) data processing. Currently, DCBs are generally divided into satellite-specific and ...receiver-specific parts. However, the chip shape of live signal differs from the ideal rectangle. Such signal distortion on the chip shapes will lead to systematic bias in pseudorange observations, namely signal distortion bias (SDB), which affects the accuracy of DCB estimation when different receiver types are used. Therefore, this research aims to estimate satellite and receiver DCBs based on SDB calibration and to explore how SDB affects DCB. Theoretical analysis shows receiver DCB absorbs the average SDBs and satellite DCB absorbs the rest of SDBs. Thus, the existence of SDBs results in the inconsistency of DCB estimated by different types of receivers. Abundant GNSS observations from the year 2017 to 2019 are adopted to assess DCB estimation, and the results validate that there are large biases for GPS satellite DCBs among different receiver groups if SDBs are ignored. However, the biases greatly decrease once SDBs are corrected, and the average improvement is 60.0%. The long-term variations of some satellite DCB can be attributed to the SDBs and variations of receiver group proportions in the observation network. With SDB correction, the variations in satellite DCB time series greatly decrease, especially for those intra-frequency DCB products. As for the receiver DCB, the SDB only creates a systematic bias against it and generally remains unchanged unless the satellite is changed, the receiver is replaced, or the receiver firmware is updated. Overall, the accuracy of satellite DCB improves with SDB correction in terms of consistency among different receiver groups and their long-term stabilities.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A new photocurable coating process that combines ultra violet light emitting diode (UV-LED) and deliberately synthesized photocurable polyurethane acrylate (PUA) was developed in this study. The ...structures of the PUA were characterized by attenuated total reflectance flourier transformed infrared (ATR-FTIR), porton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). The structure-activity relationship of such PUA was studied by rheological measurements, photopolymerization performance, and mechanical tests. By adjusting the molecular weight and the number of functional groups in the PUA, balanced the wear resistance and flexibility of the photocured coatings were achieved. The optimal formula for photocurable coating was obtained as follows: the R-value (the molar ratio of –NCO/–OH) of PUA was 1.3, the ratio of PUA/HEA (2-hydroxyethyl acrylate) was 60 wt%/40 wt%, and the ratio of end-capped agent HEA/PETA (pentaerythritol triacrylate) was 2/1. With the optimized photocurable coating formula, textile artificial leathers were fabricated and exhibited excellent colorfastness to rubbing, and Martindale abrasion resistance and satisfied fabric handle.
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•Eco-friendly photocurable textile artificial leather coating strategy is proposed.•The relationship between the structure of PUA and performance of coating film is clarified.•Oligomers for photocuring artificial leather coatings are designed and synthesized.•Satisfied application performance of photocuring artificial leather is achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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► 1-allyl-3-methylimidazolium–based ionic liquids ► The hydrogen bonding interactions between the anions and the H atoms of C
C–H group in ring and of –CH
2– group in alkyl side ...chain. ► The rotation of allyl group can lead the low viscosity of Amim
+–based ion pairs. ► The vibrational spectra of 1-allyl-3-methylimidazolium chloride and 1-allyl-3-methylimidazolium dicyanamide were reported.
In order to deepen the understanding of the cation–anion interaction in ionic liquids, the structures of cation, anions, and cation–anion ion-pairs of 1-allyl-3-methylimidazolium-based ionic liquids are optimized using density functional theory (DFT), and their most stable geometries are discussed. The structural parameters, hydrogen bonds and interaction energies of 1-allyl-3-methylimidazolium dicyanamide (AmimDCA), 1-allyl-3-methylimidazolium chloride (AmimCl), 1-allyl-3-methylimidazolium formate (AmimFmO) and 1-allyl-3-methylimidazolium acetate (AmimAcO) ion pairs are studied. The vibrational frequencies of AmimDCA and AmimCl have been calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Two-component signal transduction systems (TCSs) are a major mechanism used by bacteria in response to environmental changes. Although many sequenced archaeal genomes encode TCSs, they remain poorly ...understood. Previously, we reported that a methanogenic archaeon, Methanosaeta harundinacea, encodes FilI, which synthesizes carboxyl-acyl homoserine lactones, to regulate transitions of cellular morphology and carbon metabolic fluxes. Here, we report that filI, the cotranscribed filR2, and the adjacent filR1 constitute an archaeal TCS. FilI possesses a cytoplasmic kinase domain (histidine kinase A and histidine kinase-like ATPase) and its cognate response regulator. FilR1 carries a receiver (REC) domain coupled with an ArsR-related domain with potential DNA-binding ability, while FilR2 carries only a REC domain. In a phosphorelay assay, FilI was autophosphorylated and specifically transferred the phosphoryl group to FilR1 and FilR2, confirming that the three formed a cognate TCS. Through chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) using an anti-FilR1 antibody, FilR1 was shown to form in vivo associations with its own promoter and the promoter of the filI-filR2 operon, demonstrating a regulatory pattern common among TCSs. ChIP-qPCR also detected FilR1 associations with key genes involved in acetoclastic methanogenesis, acs4 and acs1. Electrophoretic mobility shift assays confirmed the in vitro tight binding of FilR1 to its own promoter and those of filI-filR2, acs4, and mtrABC. This also proves the DNA-binding ability of the ArsR-related domain, which is found primarily in Archaea. The archaeal promoters of acs4, filI, acs1, and mtrABC also initiated FilR1-modulated expression in an Escherichia coli lux reporter system, suggesting that FilR1 can up-regulate both archaeal and bacterial transcription. In conclusion, this work identifies an archaeal FilI/FilRs TCS that regulates the methanogenesis of M. harundinacea.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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