Pressure-Induced Free Exciton Emission in a Quasi-Zero-Dimensional Hybrid Lead Halide.

Structural dimensionality and electronic dimensionality play a crucial role in determining the type of excitonic emission in hybrid metal halides (HMHs). It is important but challenging to achieve free exciton (FE) emission in zero-dimensional (0D) HMHs based on the control over the electronic dimensionality. In this work, a quasi-0D HMH (C7 H15 N2 Br)2 PbBr4 with localized electronic dimensionality is prepared as a prototype model. With increasing pressure onto (C7 H15 N2 Br)2 PbBr4 , the broad and weak self-trapped exciton (STE) emission at ambient conditions is considerably enhanced before 3.6 GPa, which originates from more distorted [PbBr4 ]2- seesaw units upon compression. Notably, a narrow FE emission in (C7 H15 N2 Br)2 PbBr4 appears at 3.6 GPa, and then this FE emission is gradually strengthened up to 8.4 GPa. High pressure structural characterizations reveal that anisotropic contraction of (C7 H15 N2 Br)2 PbBr4 results in a noticeable reduction in the distance between adjacent [PbBr4 ]2- seesaw units, as well as an obvious enhancement of crystal stiffness. Consequently, the electronic connectivity in (C7 H15 N2 Br)2 PbBr4 is sufficiently promoted above 3.6 GPa, which is also supported with theoretical calculations. The elevation of electronic connectivity and enhanced stiffness together lead to pressure-induced FE emission and subsequent emission enhancement in quasi-0D (C7 H15 N2 Br)2 PbBr4 .

Distinct Excitonic Emissions in 2D (C7 H7 N2 )2 PbX4 (X = Cl, Br) under Compression.

Two dimensional (2D) hybrid metal halides (HMHs) usually exhibit free excitonic (FE) emission, and self-trapped excitonic (STE) emission can also be achieved by adopting appropriate halogens and organic cations. Recently, significant efforts have been made to modulate and then clarify the transformation and connection between these two types of excitonic emissions in 2D HMHs. In this study, intriguing pressure-tuned transitions between FE emission and STE emission are observed in 2D (C7 H7 N2 )2 PbCl4 . In contrast, only FE emissions with tunable emission energies are observed in 2D (C7 H7 N2 )2 PbBr4 which possesses a similar structure with (C7 H7 N2 )2 PbCl4 under compression. Such distinct halide-dependent optical responses under pressure are experimentally revealed to arise from the intricate interplay among several factors in these HMHs, including the stiffness of the structure, the Coulomb force between the organic cations and the inorganic octahedra, and the magnitude of inorganic octahedral distortion. These high-pressure optical explorations can unravel the underlying interrelationship between the crystal structure and excitonic emission in 2D HMHs.

Ordered Van der Waals Hetero-nanoribbon from Pressure-Induced Topochemical Polymerization of Azobenzene.

Pressure-induced topochemical polymerization of molecular crystals with various stackings is a promising way to synthesize materials with different co-existing sub-structures. Here, by compressing the azobenzene crystal containing two kinds of intermolecular stacking, we synthesized an ordered van der Waals carbon nanoribbon (CNR) heterostructure in one step. Azobenzene polymerizes via a [4 + 2] hetero-Diels-Alder (HDA) reaction of phenylazo-phenyl in layer A and a para-polymerization reaction of phenyl in layer B at 18 GPa, as evidenced by in situ Raman and IR spectroscopies, X-ray diffraction, as well as gas chromatography-mass spectrometry and the solid-state nuclear magnetic resonance of the recovered products. The theoretical calculation shows that the obtained CNR heterostructure has a type II (staggered) band gap alignment. Our work highlights a high-pressure strategy to synthesize bulk CNR heterostructures.

Solar X-ray and EUV imager on board the FY-3E satellite.

The solar X-ray and Extreme Ultraviolet Imager (X-EUVI), developed by the Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), is the first space-based solar X-ray and Extreme ultraviolet (EUV) imager of China loaded on the Fengyun-3E (FY-3E) satellite supported by the China Meteorological Administration (CMA) for solar observation. Since started work on July 11, 2021, X-EUVI has obtained many solar images. The instrument employs an innovative dual-band design to monitor a much larger temperature range on the Sun, which covers 0.6-8.0 nm in the X-ray region with six channels and 19.5 nm in the EUV region. X-EUVI has a field of view of 42', an angular resolution of 2.5″ per pixel in the EUV band and an angular resolution of 4.1″ per pixel in the X-ray band. The instrument also includes an X-ray and EUV irradiance sensor (X-EUVS) with the same bands as its imaging optics, which measures the solar irradiance and regularly calibrates the solar images. The radiometric calibration of X-EUVS on the ground has been completed, with a calibration accuracy of 12%. X-EUVI is loaded on the FY-3E satellite and rotates relative to the Sun at a uniform rate. Flat-field calibration is conducted by utilizing successive rotation solar images. The agreement between preliminarily processed X-EUVI images and SDO/AIA and Hinode/XRT images indicates that X-EUVI and the data processing algorithm operate properly and that the data from X-EUVI can be applied to the space weather forecast system of CMA and scientific investigations on solar activity.

From Biomass to Functional Crystalline Diamond Nanothread: Pressure-Induced Polymerization of 2,5-Furandicarboxylic Acid.

2,5-Furandicarboxylic acid (FDCA) is one of the top-12 value-added chemicals from sugar. Besides the wide application in chemical industry, here we found that solid FDCA polymerized to form an atomic-scale ordered sp3-carbon nanothread (CNTh) upon compression. With the help of perfectly aligned π-π stacked molecules and strong intermolecular hydrogen bonds, crystalline poly-FDCA CNTh with uniform syn-configuration was obtained above 11 GPa, with the crystal structure determined by Rietveld refinement of the X-ray diffraction (XRD). The in situ XRD and theoretical simulation results show that the FDCA experienced continuous [4 + 2] Diels-Alder reactions along the stacking direction at the threshold C···C distance of ∼2.8 Å. Benefiting from the abundant carbonyl groups, the poly-FDCA shows a high specific capacity of 375 mAh g-1 as an anode material of a lithium battery with excellent Coulombic efficiency and rate performance. This is the first time a three-dimensional crystalline CNTh is obtained, and we demonstrated it is the hydrogen bonds that lead to the formation of the crystalline material with a unique configuration. It also provides a new method to move biomass compounds toward advanced functional carbon materials.

Pressure-Enhanced Photocurrent in One-Dimensional SbSI via Lone-Pair Electron Reconfiguration.

Understanding the relationships between the local structures and physical properties of low-dimensional ferroelectrics is of both fundamental and practical importance. Here, pressure-induced enhancement in the photocurrent of SbSI is observed by using pressure to regulate the lone-pair electrons (LPEs). The reconfiguration of LPEs under pressure leads to the inversion symmetry broken in the crystal structure and an optimum bandgap according to the Shockley-Queisser limit. The increased polarization caused by the stereochemical expression of LPEs results in a significantly enhanced photocurrent at 14 GPa. Our research enriches the foundational understanding of structure-property relationships by regulating the stereochemical role of LPEs and offers a distinctive approach to the design of ferroelectric-photovoltaic materials.

Pressure-Induced Hydrogen Transfer in 2-Butyne via a Double CH···π Aromatic Transition State.

Hydrogen transfer (H-transfer) is an important elementary reaction in chemistry and bioscience. It is often facilitated by the hydrogen bonds between the H-donor and acceptor. Here, at room temperature and high pressure, we found that solid 2-butyne experienced a concerted two-in-two-out intermolecular CH···π H-transfer, which initiated the subsequent polymerization. Such double H-transfer goes through an aromatic Hückel six-membered ring intermediate state via intermolecular CH···π interactions enhanced by external pressure. Our work shows that H-transfer can occur via the CH···π route in appropriate conformations under high pressure, which gives important insights into the H-transfer in solid-state hydrocarbons.

Crystalline C3N3H3 tube (3,0) nanothreads.

Carbon nanothread (CNTh) is a "one-dimensional diamond polymer" that combines high tensile strength and flexibility, but it severely suffers from intrathread disorder. Here, by modifying the reactivity and the stacking ordering of the aromatic precursor, crystalline C3N3H3 CNTh with perfect hexagonal orientation and stacking was synthesized at 10.2 GPa and 573 K from s-triazine. By Rietveld refinement of X-ray diffraction data, gas chromatography mass spectrometry investigation, and theoretical calculation, we found that synthesized CNTh has a tube (3,0) structure, with the repeating s-triazine residue connected solely by C­N bonds along the thread. A "peri-cage" reaction, the concerted bonding between six C and N atoms, instead of [4 + 2] or [1,4] addition reactions, was concluded for the formation of CNThs, and the critical bonding distance between the nearest intermolecular C and N was ∼2.9 Å. The formation of a "structure-specific" crystalline CNTh with C and N orderly distributed highlighted the importance of reaction selectivity and stacking order of reactant molecules, which have great significance for understanding the polymerization of aromatic molecules under high pressure and developing new crystalline CNThs.

Correction: COVID-19 Vaccine Tweets After Vaccine Rollout: Sentiment-Based Topic Modeling.

[This corrects the article DOI: 10.2196/31726.].

Quality structural annotation for the metabolites of chlorogenic acid in rat.

Chlorogenic acid (CA) serves as a principal contributor for the health benefit spectrum of tea; however, its metabolism pattern hasn't been completely clarified. We attempted here to profile CA metabolism through fortifying isomer identification ability onto LC-MS/MS. Online energy-resolved MS was applied to configure full collision energy ramp-MS2 spectrum. Quantum structural calculation was undetaken to pursue the relationships between chemical structures and optimal collision energy/the maximum relative ion intensity. Thirty-seven metabolites were captured in biological matrices. Plausible structures were configured by applying the empirical mass fragmentation rules to m/z values and the summarized relationships were utilized to drive the plausible structures to confidence-enhanced identities. Hydrolysis, glucuronidation, sulfation, acyl migration, oxidation, and hydrogenation occupied primary metabolism channels. Together, the current study disclosed in depth the metabolism profile of CA and moreover, suggested a versatile analytical route for quality metabolite identification.

COVID-19 Vaccine Tweets After Vaccine Rollout: Sentiment-Based Topic Modeling.

BACKGROUND: COVID-19 vaccines are one of the most effective preventive strategies for containing the pandemic. Having a better understanding of the public's conceptions of COVID-19 vaccines may aid in the effort to promptly and thoroughly vaccinate the community. However, because no empirical research has yet fully explored the public's vaccine awareness through sentiment-based topic modeling, little is known about the evolution of public attitude since the rollout of COVID-19 vaccines. OBJECTIVE: In this study, we specifically focused on tweets about COVID-19 vaccines (Pfizer, Moderna, AstraZeneca, and Johnson & Johnson) after vaccines became publicly available. We aimed to explore the overall sentiments and topics of tweets about COVID-19 vaccines, as well as how such sentiments and main concerns evolved. METHODS: We collected 1,122,139 tweets related to COVID-19 vaccines from December 14, 2020, to April 30, 2021, using Twitter's application programming interface. We removed retweets and duplicate tweets to avoid data redundancy, which resulted in 857,128 tweets. We then applied sentiment-based topic modeling by using the compound score to determine sentiment polarity and the coherence score to determine the optimal topic number for different sentiment polarity categories. Finally, we calculated the topic distribution to illustrate the topic evolution of main concerns. RESULTS: Overall, 398,661 (46.51%) were positive, 204,084 (23.81%) were negative, 245,976 (28.70%) were neutral, 6899 (0.80%) were highly positive, and 1508 (0.18%) were highly negative sentiments. The main topics of positive and highly positive tweets were planning for getting vaccination (251,979/405,560, 62.13%), getting vaccination (76,029/405,560, 18.75%), and vaccine information and knowledge (21,127/405,560, 5.21%). The main concerns in negative and highly negative tweets were vaccine hesitancy (115,206/205,592, 56.04%), extreme side effects of the vaccines (19,690/205,592, 9.58%), and vaccine supply and rollout (17,154/205,592, 8.34%). During the study period, negative sentiment trends were stable, while positive sentiments could be easily influenced. Topic heatmap visualization demonstrated how main concerns changed during the current widespread vaccination campaign. CONCLUSIONS: To the best of our knowledge, this is the first study to evaluate public COVID-19 vaccine awareness and awareness trends on social media with automated sentiment-based topic modeling after vaccine rollout. Our results can help policymakers and research communities track public attitudes toward COVID-19 vaccines and help them make decisions to promote the vaccination campaign.

Crystalline Fully Carboxylated Polyacetylene Obtained under High Pressure as a Li-Ion Battery Anode Material.

Substituted polyacetylene is expected to improve the chemical stability, physical properties, and combine new functions to the polyacetylene backbones, but its diversity is very limited. Here, by applying external pressure on solid acetylenedicarboxylic acid, we report the first crystalline poly-dicarboxylacetylene with every carbon on the trans-polyacetylene backbone bonded to a carboxyl group, which is very hard to synthesize by traditional methods. The polymerization is evidenced to be a topochemical reaction with the help of hydrogen bonds. This unique structure combines the extremely high content of carbonyl groups and high conductivity of a polyacetylene backbone, which exhibits a high specific capacity and excellent cycling/rate performance as a Li-ion battery (LIB) anode. We present a completely functionalized crystalline polyacetylene and provide a high-pressure solution for the synthesis of polymeric LIB materials and other polymeric materials with a high content of active groups.

Phase transition and chemical reactivity of 1H-tetrazole under high pressure up to 100 GPa.

The pressure-induced phase transition and polymerization of nitrogen-rich molecules are widely focused on due to their extreme importance for the development of green high-energy-density materials. Here, we present a study of the phase-transition behaviour and chemical reaction of 1H-tetrazole up to 100 GPa using in situ Raman, IR, X-ray diffraction, neutron diffraction techniques and theoretical calculations. A phase transition above 2.6 GPa was identified and the high-pressure structure was determined with one molecule in a unit cell instead of two molecules as reported before. The 1H-tetrazole polymerized reversibly below 100 GPa, probably through carbon-nitrogen bonding instead of nitrogen-nitrogen bonding. Our studies update the structure model of the high-pressure phase of 1H-tetrazole, and present the possible intermolecular bonding route for the first time, which gives new insights to understand the phase transition and chemical reaction of nitrogen-rich compounds, and is of benefit for designing new high-energy-density materials.

Scalable High-Pressure Synthesis of sp2-sp3 Carbon Nanoribbon via [4 + 2] Polymerization of 1,3,5-Triethynylbenzene.

Pressure-induced polymerization of aromatics is an effective method to construct extended carbon materials, including the diamond-like nanothread and graphitic structures, but the reaction pressure of phenyl is typically around 20 GPa and too high to be applied for large-scale preparation. Here by introducing ethynyl to phenyl, we obtained a sp2-sp3 carbon nanoribbon structure by compressing 1,3,5-triethynylbenzene (TEB), and the reaction pressure of phenyl was successfully decreased to 4 GPa, which is the lowest reaction pressure of aromatics at room temperature. Using experimental and theoretical methods, we figured out that the ethynylphenyl of TEB undergoes [4 + 2] dehydro-Diels-Alder (DDA) reaction with phenyl upon compression at an intermolecular C···C distance above 3.3 Å, which is much longer than those of benzene and acetylene. Our research suggested that the DDA reaction between ethynylphenyl and phenyl is a promising route to decrease the reaction pressure of aromatics, which allows the scalable high-pressure synthesis of nanoribbon materials.

Detailed nursing intervention on neonatal septicemia can improve the clinical symptoms of children and reduce the inflammatory reaction.

OBJECTIVE: To explore the application effect of detailed nursing intervention in neonatal septicemia. METHODS: Altogether 60 neonates of neonatal septicemia admitted to our hospital from November 2019 to October 2020 were selected as the research participants, and all the children have received routine treatment, among which 30 neonates received routine nursing intervention as the regular group, and the remaining 30 received detailed nursing intervention as the detail group. The clinical effects, improvement of clinical symptoms, length of stay, and guardian satisfaction were compared, and the levels of serum inflammatory factors (TNF-α, IL-6 and IL-17) and immune function indicators (CD4+, CD8+) before and after nursing intervention were detected. RESULTS: The total effective rate in the detail group was higher than that in the regular group (P < 0.05). Compared with the regular group, the temperature stabilization time, blood culture turning negative time, improvement time of milk rejection and hospital stay in the detail group were significantly shortened (P < 0.05). The guardian satisfaction score in the detail group was higher than that in the regular group (P < 0.05). After nursing, the levels of TNF-α, IL-6 and IL-17 decreased in both groups, and the levels of these three in the detail group were lower than those in the regular group (P < 0.05). After nursing, CD4+/CD8+ of children in both groups increased, and CD4+/CD8+ in the detail group and regular group were higher than those in the regular group (P < 0.05). CONCLUSION: The adoption of detailed nursing modes in the treatment of neonatal septicemia can further improve the treatment effect, shorten the hospital stay and the improvement time of clinical symptoms, reduce the incidence of complications, improve the nursing satisfaction of guardians, reduce the inflammation of the body and improve the immune function of the body.

Shotgun chemome characterization of Artemisia rupestris L. Using direct infusion-MS/MSALL.

In comparison of liquid chromatography, direct infusion is a superior choice to achieve high-throughput measurements. The specificity and selectivity of tandem mass spectrometry (MS/MS) actually result in a so-called MS separation potential when chemical characterization of herbal medicines. Here, a MS/MSALL program was introduced to promote DI-MS/MS to be an eligible tool for shotgun chemome characterization of Artemisia rupestris L. that is currently drawing worldwide interests because of the promising antiviral activity. After MS1 spectral acquisition for the crude extract, the gas phase fractionation concept enabled the precursor ion cohort sequentially entered the collision cell with a stepped unit mass window (step-size as 1 Da) to generate MS2 spectra, thus generating a unique property integrating the advantages of both data-dependent and data-independent acquisition manners. Even though being free of chromatographic separation, spectrometric separations were accomplished for by MS/MSALL program unless the components shared identical nominal molecular weights. Extensive efforts such as the correlations of MS1 signals with MS2 spectra, structural annotations of fragment ion species, information retrieval in some accessible databases, and referring to the literature data, were devoted for chemical characterization, and as a result, 44 compounds, in total, were structurally identified from 50% aqueous methanol exact of A. rupestris, including 8 caffeoyl quinic acid derivatives, 13 flavonoids, 15 monomeric and dimeric sesquiterpenoids, 4 fatty acids, 2 penylpropanoids, along with 2 other compounds. However, isomers were assigned as an isomeric mixture because their precursor ions always co-existed in a single mass window. Above all, DI-MS/MSALL provides an alternative tool for chemome characterization of herbal medicines, in particular when the great measurement workload for a large sample cohort, attributing to the high-throughput advantage.

Distance-Selected Topochemical Dehydro-Diels-Alder Reaction of 1,4-Diphenylbutadiyne toward Crystalline Graphitic Nanoribbons.

Solid-state topochemical polymerization (SSTP) is a promising method to construct functional crystalline polymeric materials, but in contrast to various reactions that happen in solution, only very limited types of SSTP reactions are reported. Diels-Alder (DA) and dehydro-DA (DDA) reactions are textbook reactions for preparing six-membered rings in solution but are scarcely seen in solid-state synthesis. Here, using multiple cutting-edge techniques, we demonstrate that the solid 1,4-diphenylbutadiyne (DPB) undergoes a DDA reaction under 10-20 GPa with the phenyl as the dienophile. The crystal structure at the critical pressure shows that this reaction is "distance-selected". The distance of 3.2 Å between the phenyl and the phenylethynyl facilitates the DDA reaction, while the distances for other DDA and 1,4-addition reactions are too large to allow the bonding. The obtained products are crystalline armchair graphitic nanoribbons, and hence our studies open a new route to construct the crystalline carbon materials with atomic-scale control.

Enhanced removal of antibiotic resistance genes and mobile genetic elements during sewage sludge composting covered with a semi-permeable membrane.

Transmission of antibiotic resistance genes (ARGs) via air media, such as particulate matter, has been intensively investigated due to human exposure through inhalation. However, whether particulate matter originating from the atmospheric environment of composting plants can impact ARG abundance during composting is unknown. Here, we investigated the effects of the atmospheric environment of composting plants on ARG abundance during sewage sludge composting using semi-permeable membrane-covered thermophilic composting (smTC) and conventional thermophilic composting (cTC). After smTC treatment, the total abundances of ARGs and mobile genetic elements (MGEs) decreased by 42.1 % and 38.1 % compared with those of the initial phase, respectively, but they increased by 4.5- and 1.6-fold after cTC, respectively. This result suggested that smTC was more efficient at decreasing ARGs and MGEs than cTC, mainly due to a significant reduction in bacterial contamination from the atmospheric environment of composting plants that accelerated the resurgence of ARGs and MGEs. Furthermore, culture experiments demonstrated that the abundance and diversity of antibiotic-resistant bacteria during the mature phase of smTC were also significantly (P <  0.05) lower than those in the cTC treatment. Thus, covering composting with a semi-permeable membrane could decrease the risk of ARGs spreading.

Wide-field auroral imager onboard the Fengyun satellite.

The newly launched Fengyun-3D (FY-3D) satellite carried a wide-field auroral imager (WAI) that was developed by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), which will provide a large field of view (FOV), high spatial resolution, and broadband ultraviolet images of the aurora and the ionosphere by imaging the N2 LBH bands of emissions. The WAI consists of two identical cameras, each with an FOV of 68° in the along-track direction and 10° in the cross-track direction. The two cameras are tilted relative to each other to cover a fan-shaped field of size 130° × 10°. Each camera consists of an unobstructed four-mirror anastigmatic optical system, a BaF2 filter, and a photon-counting imaging detector. The spatial resolution of WAI is ~10 km at the nadir point at a reference height of 110 km above the Earth's surface. The sensitivity is >0.01 counts s-1 Rayleigh-1 pixel-1 (140-180 nm) for both cameras, which is sufficient for mapping the boundaries and the fine structures of the auroral oval during storms/substorms. Based on the tests and calibrations that were conducted prior to launch, the data processing algorithm includes photon signal decoding, geometric distortion correction, photometric correction, flat-field correction, line-of-sight projection and correction, and normalization between the two cameras. Preliminarily processed images are compared with DMSP SSUSI images. The agreement between the images that were captured by two instruments demonstrates that the WAI and the data processing algorithm operate normally and can provide high-quality scientific data for future studies on auroral dynamics.

Orientin Reduces Myocardial Infarction Size via eNOS/NO Signaling and Thus Mitigates Adverse Cardiac Remodeling.

Orientin is a flavonoid extracted from Chinese traditional herb, Polygonum orientale L. Previous study has reported that orientin protected myocardial from ischemia reperfusion injury. However, whether orientin could protect against cardiac remodeling after myocardial injury remains unclear. The aim of our study is to investigate the effects of orientin in the progression of cardiac remodeling after myocardial infarction (MI). Mice cardiac remodeling model was established by left coronary artery ligation surgery. Experimental groups were as follows: vehicle-sham, orientin-sham, vehicle-MI, and orientin-MI. Animals were treated with vehicle or orientin (40 mg/kg) for 25 days starting 3 days after surgery. After 4 weeks of MI, mice with orientin treatment had decreased mortality and improved cardiac function. Significantly, at 4 weeks post-MI, orientin treatment decreased fibrosis, inflammatory response, and cardiomyocyte apoptosis. Furthermore, orientin treatment attenuated the hypoxia-induced neonatal rat cardiomyocyte apoptosis and increased cell viability. Additionally, orientin supplementation mitigated oxidative stress in remodeling heart tissue and cardiomyocytes exposed to hypoxia as measured by 2',7'-dichlorodihydrofluorescein diacetate fluorescent probe. Mechanistically, orientin promotes cardioprotection by activating the eNOS/NO signaling cascades, which was confirmed by eNOS inhibitor (L-NAME) in vitro and in vivo. Inhibition of oxidative stress by orientin via eNOS/NO signaling cascades in the heart may represent a potential therapy for cardiac remodeling.