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In response to the current policy of high storage capacity, two-dimensional (2D) materials have revealed promising prospects as high-performance electrode materials. MoB, as a type of such material, is widely regarded as an anode candidate for Li-ion batteries due to its large specific surface area and abundant ion diffusion channels; the long-term cycling stability, however, is poor owing to material pulverization during the cycle. Therefore, MoB/Si3N4heterojunction in this work is proposed as an anode material, with Si3N4acting as a skeleton, maintaining the stability of the structure, while retaining the high energy storage properties of MoB as well. In addition, a certain built-in electric field is formed between them, which can play a role in regulating charge transfer, improving the ion transport channel, and accelerating the migration rate. Herein, the structural, electronic, and electrochemical properties are systematically investigated by first-principles calculations; the final results indicate that the heterojunction anode material does indeed have built-in electric fields, which promote the anode material to possess excellent electrical conductivity and outstanding electrochemical property. Meanwhile, the introduction of vacancy defects can bolster the diffusion kinetic performance of ion transport and greatly reduce the diffusion energy barrier of Li ions, which is conducive to the realization of rapid charge and discharge for the Li ion battery. Based on the synergistic effect of two single-component materials, the synthesized anode material displays a high theoretical capacity of 461 mAh/g, and the calculated open-circuit voltage is 0.66 V, within the range of the negative electrode criterion of 0–1 V, which can effectively play a role in preventing the formation of Li dendrites; these properties are comparable to other 2D anode materials as well. Given these intriguing properties, the MoB/Si3N4heterojunction is an exceptional candidate for advanced LIB high-performance anode materials.

Searching for lightweight and high-temperature stable electromagnetic wave-absorbing materials with broad absorbing bandwidth and high efficiency is of significance for applications in daily life and industry. Optimizing the dielectric properties of SiC nanowire aerogel by both compositional and structural designs is an efficient way to obtain simultaneous efficient wave-dissipation ability and good impendence matching and thus the desired properties. However, due to the complex effects of dielectric parameters on the wave-absorbing properties, rational design of high-performance electromagnetic wave-absorbing materials remains challenging. Herein, we propose a genetic algorithm-based approach to predict broadband and highly efficient electromagnetic wave-absorbing materials in a SiC@SiO2nanowire aerogel-based system. The obtained SiC@SiO2nanowire aerogels exhibit a gradient multilayered structure with a low dielectric outer layer, a medium layer with alternatively distributed electromagnetic wave transparent and attenuation layers, and an inner high attenuation layer, giving it a broadband electromagnetic wave-absorbing performance covering almost all the 2–18 GHz bandwidth and simultaneous high efficiency. The results show that the genetic algorithm-based approach is efficient in predicting high-performance electromagnetic wave-absorbing ceramic aerogels.

Independent identification of carbon emission peaks determined from fuel inventories is a challenging goal. Because of the complete depletion of radiocarbon (14C) in fossil fuel sources, the measurement of atmospheric 14CO2has proven to offer a means of achieving this goal. Here, we present a study identifying peak carbon emissions from two Chinese cities using urban tree-ring Δ14C time series during 2000–2019. After subtracting background atmospheric Δ14C from urban tree-ring Δ14C to isolate local Δ14C (Δ14Clocal), we find a minimum in 2010 (−51.1 ± 4.5‰) in Beijing and in 2013 in Xi’an (−52.5 ± 0.5‰). These levels correspond to an urban carbon emission peak in 2010 and in 2013 in the two respective cities. The urban carbon emission peaks are further identified by the declines of the mean absolute interannual rate of decrease of tree-ring Δ14C during a period, with the respective values of 3.6 and 6.4 ‰/yr after and before a turning point in Beijing and 3.0 and 6.0 ‰/yr after and before a turning point in Xi’an. This study provides an observation method to identify carbon emission peaks in basin cities.

Two fully fused acceptor–donor–acceptor (A–D–A) architecture conjugated derivatives (NPFand NCF) comprising an electron-withdrawing naphthalimide (NMI) and two different electron-donating cores, phenanthrene and carbazole, respectively, were conveniently synthesized by bismuth(III)-catalyzed selective cyclization of vinyl ethers. Compared with their corresponding single bond-linked A–D–A molecules NPSand NCS, both having a moderately twisted aromatic configuration, the ring fusion strategy leads to fully coplanar conjugated skeletons and greatly changes the electronic structures, photophysical properties, self-assembling behaviors, and molecular packing motifs. In particular, the naphthalimide/carbazole derivative NCFexhibits intriguing 2D brickwork packing and significantly enhanced self-assembling properties.

The tensile properties of biphasic nickel-based nanopolycrystalline alloys (Ni–Ni3Al) at different temperatures were simulated by molecular dynamics. The results show that the tensile properties of the dual-phase nano-polycrystalline alloy are obviously better than those of the conventional nickel metal. The γ 'phase (Ni3Al) is LI2type structure, which shows higher stability and reduces grain boundary migration during deformation due to the lower atomic potential energy of γ′ phase. As the temperature increases, the mechanical behavior of the biphasic alloy and nickel metal shows the same decreasing trend. Dislocation is an important factor affecting the strength of γ 'phase plastic deformation. The current study provides an atomic perspective on the deformation process and mechanism of biphasic nickel-based nanopolycrystalline alloys, and provides a new perspective for the design of novel superalloys with excellent mechanical properties.

Three new donor–acceptor–donor (D–A–D) architecture regioisomers comprising a large planar electron-withdrawing core tribenzo[a,c,i]phenazine and two identical electron-donating triphenylamines with different substitution patterns were designed and synthesized. Employing this regioisomerization strategy, the intramolecular charge-transfer interactions are effectively tuned and result in a significant bathochromic shift of photoluminescence maximum over 100 nm, which induces the corresponding emission band extending into the near-infrared region as well as giving a high solid-state quantum yield of 25%. Meanwhile, it is found that the supramolecular interactions of this series of regioisomers with planar electron-donor pyrene are greatly affected by the substitution pattern.

Research into new high-entropy alloys (HEAs) holds significant promise for advancing aerospace materials. Nevertheless, the complexity of their composition presents formidable challenges in designing HEAs with both high strength and plasticity. In this study, molecular dynamics (MD) simulation was used to explore the optimal composition combination of FeCoNiTi high-entropy alloys with non-equiatomic ratios. Shear modulus (G) characterizes strength, while stacking fault energy (SFE) characterizes plasticity and ductility. Through molecular dynamics (MD) simulations, elastic constants (C11, C12, and C44) and generalized stacking fault energies (GSFEs) for 18 alloy variants were computed. Additionally, the elastic modulus (G, E, and B) for all components was estimated using the Voigt–Reuss–Hill (VRH) averaging method. Following standard guidelines, the composition for the FeCoNiTi alloy was predicted as Ni: 30%–60 %, Co: 30%–50 %, Fe: 5%–10 %, and Ti: 5%–10 %. Subsequently, five optimized variants underwent tensile calculations to identify the most suitable composition. The results indicate that the Fe0.05Co0.4Ni0.5Ti0.05 HEA exhibits the best combination of strength and plasticity. Microscopically, its enhanced plasticity is attributed to the twinning-induced plasticity (TWIP) effect. While Fe0.1Co0.4Ni0.4Ti0.1 HEA does not outperform the other variants, it displays a martensitic transformation and deformation twins with increased strain, which are mechanisms not observed in other components. The study of non-equiatomic FeCoNiTi HEAs offers a theoretical foundation for future alloy development. This innovative alloy design method fosters the rapid development of high-performance HEAs, facilitating their rapid development and application.

Thermal catalytic oxidative dehydrogenation of ethane with O2has been extensively studied as an approach for ethene production, but this approach is energy intensive and has disadvantages of overoxidation, high-cost and safety concerns. Herein, we present ZnO-supported Pt nanoparticles that are highly active and selective for dehydrogenating ethane to ethene with simulated sunlight viaa photo-supported Mars–van Krevelen mechanism. The Pt/ZnO catalyst achieves a high ethane-to-ethene conversion rate of 867.8 μmol h−1g−1and an excellent selectivity of 97.56%. Besides, it is also coking-resistant and can be readily revived by exposure to O2for refilling the consumed lattice oxygen to preserve its original activity. It is revealed that the Pt species facilitate C2H4desorption from the catalyst to inhibit overoxidation and enhance separation of light-induced charges to boost the photocatalytic efficiency. Whilst the photogenerated holes on ZnO are captured by surface lattice oxygen to generate active O−species, H atoms were extracted from adsorbed C2H6to produce C2H4. In situdiffuse reflectance infrared Fourier transform spectroscopy is applied to detect the key intermediates and thus propose the possible catalytic EDH process over the Pt/ZnO photocatalyst.

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(Hetero)cycloarenes possessing rigid molecular skeletons and large π-systems are the potential active materials in various electronic devices. However, the development of their organic electronics still lags far behind the synthetic chemistry. Herein, in order to bridge this gap, we reported the study of organic semiconductor materials based on heterocycloarenes in detail about the relationship between structure, properties, and device performance. Three varying straight alkyl chain substituted butterfly-shaped heterocycloarenes PTZs were strategically synthesized. Compared with bulky aryl(mesityl) substituted PTZ1, PTZs show additional self-assembly behavior. Concentration-dependent 1H NMR spectra indicated that the self-assembly behavior can be modulated by the alkyl chain length. Medium alkyl chain length substituted heterocycloarene PTZ-C6showed the strongest association constants of 490 M−1in solution, and a similar trend was also observed in solid state by thin film absorption spectra. Remarkably, despite the nonplanar conjugated backbones, solution-processing thin film transistor based on PTZ-C6exhibits hole mobility up to 0.13 cm2V−1s−1and considerable current on/off ratio of 105. Our study demonstrates that substituent engineering of heterocycloarenes is a powerful strategy for modulating self-assembling structures and promoting transistor device performance.

We study the mechanical behavior of gradient spacing twin-structured single-crystal Ni nanopillars under the conditions of different loading methods, temperatures, and twin defects via molecular dynamics simulations. The insights indicate that the yield strength and Young’s modulus of single-crystal Ni nanopillars are greatly improved when loading along the gradient direction, which is due to the nucleation of many dislocations induced by Thompson tetrahedrons. In addition, with the temperature increases, the atomic energy in the nanocrystals and the number of disordered atoms increases, resulting in difficulty in the nucleation of dislocations and decrease in mechanical properties. In addition, the presence of void in the twin boundary leads to a decrease in the mechanical properties of nanocrystalline Ni. The position of the void has relatively little impact on the mechanical properties. However, when the void occurs in a twin boundary with a large spacing, the formation of dislocations is suppressed, mainly reflected in the fact that the initial dislocation density of the volume decreases as the twin spacing increases. These findings provide positive theoretical guidance for the design of gradient twin structures in nanosingle crystals.

The physiochemical properties and catalytic performance of zeolite rely on the judicious selection of organic structure-directing agents (OSDAs), among which alcoholamines are rarely used. Here, we report that 6-amino-1-hexanol (AH) can be used as an OSDA for the generation of commercially viable ZSM-22 with a Si/Al ratio window of 35–150. Compared with ZSM-22 derived from commonly used 1,6-diaminohexane (DAH), the samples generated using AH possess improved crystallinity and more intermediate-to-strong acid site, which can be attributed to the stronger host–guest interactions between AH and zeolite framework. In addition, the crystallization process can be accelerated by the use of AH. ZSM-22 catalysts derived from AH outperform the counterpart generated from DAH in hydroisomerization of n-heptane, and improved catalytic activity and isomer yield can be achieved thanks to the presence of abundant acid sites and high crystallinity.

The thermally/mechanically-driven structural instability of nano- and coarse-grained polycrystalline metals originates from the unstable grain boundaries (GBs). GB segregation of solute elements could not only stabilize but also embrittle GBs. To improve GB stability and cohesion in parallel via solute segregations, in this work the segregation behavior of six non-metallic impurities Xat the Σ5 [001](210) GB of nickel-based alloys, their co-segregations with Re element that has no GB segregation tendency, and segregation-induced changes in GB properties were investigated comprehensively from first-principles calculations. We discovered that these nonmetallic elements can segregate to the Ni GB and thus stabilize it, but they are GB embrittlers except B. Annealing temperature and bulk concentration have no effect on the S segregation. With the Xpre-segregations, induced GB segregations of Re were observed, which lowers the excess energy and enhances the cohesive strength of all X-segregated GBs. The attractive interactions between C/N/B and Re atoms promote the Re segregation. The stabilizing and strengthening mechanisms of Re segregation were mainly attributed to the changes in Fermi level location and the increased interplanar bonding, respectively. Our findings may gain more insights into the atomic-scale GB co-segregations and stabilization of polycrystalline Ni-based alloys.

In the present contribution, a certain amount of Co atoms was added to the grains (GI) of nano-polycrystalline Ni by a molecular dynamics method to study the effect of solute atom content on the mechanical properties of the alloy. It was found that the tensile strength and yield strength of the alloy increased with the increase of Co atomic content. With the increase of Co content, the grain boundary atomic potential energy decreased and the grain boundary became more stable. As the strain increased, the Co atoms in the grain migrated to the grain boundary, the lattice distortion at the grain boundary increased, and the dislocation nucleation at the grain boundary increased, forming a stable dislocation network and hindering the grain boundary migration. The 1/6⟨112⟩ Shockley incomplete dislocation formed at the grain boundary became the stacking fault source, which was also the source of transformation from the internal stacking fault to the external stacking fault, finally transforming into deformation twins. As the strain increased, the content of Shockley incomplete dislocations in the crystal increased, interacting with other dislocations to dominate the deformation process.

A first-principles approach is a powerful means of gaining insight into the intrinsic structure and properties of materials. However, with the implementation of material genetic engineering, it is still a challenging road to discover materials with high satisfaction. One alternative is to employ machine-learning techniques to mine data and predict performance. In this present contribution, the method is taken to predict the band gap opening value of graphene in a heterostructure. First, the data of 2076 binary compounds in the Materials Project library are used to achieve visual dimensionality reduction of the data set through a t-distributed stochastic neighbor embedding (t-SNE) algorithm in unsupervised learning. Then, a series of semiconductor components are screened out and form heterostructures with graphene. Second, by means of the ensemble learning EXtreme Gradient Boost (XGBoost) algorithm and support vector machine (SVM) technology, two prediction frameworks are built to predict the band gap opening value of the graphene in the system. Finally, density functional theory (DFT) is used to calculate the energy band and density of states for comparison. Analysis shows that the prediction model has an accuracy rate of 88.3%, and there is little difference between prediction results and calculation results. We anticipate that this framework model would have fascinating applications in predicting the electronic properties of various multiphase materials.

Proton pump inhibitors (PPI) are widely used for gastroesophageal varices in patients with cirrhosis after endoscopic therapy, although the effect of PPI on these patients remains controversial. This study aimed to evaluate the effect of PPI on gastroesophageal varices in patients with cirrhosis after endoscopic therapy, including variceal bleeding and adverse events. Cirrhotic patients with endoscopically confirmed gastroesophageal varices were enrolled in this study between May 2017 and June 2019. Eligible patients were randomized into two groups: one group received PPI for 14 days and the other group did not receive PPI treatment (n= 53 in each group). All patients were followed for 8 weeks. During the follow‐up period, three patients (5.66%) in the PPI group experienced variceal bleeding on days 9, 16, and 25 after endoscopic therapy, including two patients with acute bleeding and one with primary prophylaxis. In the non‐PPI group, three patients (5.66%) experienced variceal bleeding on days 7, 42, and 56 after endoscopic therapy, including one patient with acute bleeding and two with secondary prophylaxis (p= 0.990). The incidence of adverse events was similar between the two groups (37.74% vs. 28.30%, p= 0.30). PPI did not appear to reduce variceal bleeding and adverse events in patients with cirrhosis after endoscopic therapy. Proton pump inhibitors (PPI) are widely used after endoscopic therapy for gastroesophageal varices in patients with cirrhosis, though their effectiveness is debatable. According to this study, PPI use is not associated with a decreased risk of variceal bleeding and adverse events in such patients. Significant findings of the study Proton pump inhibitors (PPI) are widely used after endoscopic therapy for gastroesophageal varices in patients with cirrhosis, though their effectiveness is debatable. According to this study, PPI use is not associated with a decreased risk of variceal bleeding and adverse events in such patients. Proton pump inhibitors (PPI) are widely used after endoscopic therapy for gastroesophageal varices in patients with cirrhosis, though their effectiveness is debatable. According to this study, PPI use is not associated with a decreased risk of variceal bleeding and adverse events in such patients. What this study adds? Unnecessary PPI administration is not beneficial in cirrhotic patients with gastroesophageal varices and requires more attention from physicians. Unnecessary PPI administration is not beneficial in cirrhotic patients with gastroesophageal varices and requires more attention from physicians.

Two-dimensional (2D) MoB are considered to an alternative to lithium-ion batteries (LIBs) electrode materials due to large specific surface area, uniformly layered structure, and abundant active surfaces although some metal atoms are exposed to the surface. In the present contribution, we construct an asymmetric Janus MoB structure functionalized with bifunctional groups to improve the electrochemical performance, and the electronic, adsorption and diffusion properties of MoBXY are investigated by first-principles method. The results reveal that the diffusion barriers of Li ions on the surface of O and S are 0.38 and 0.36 eV, respectively, the values are significantly lower than 0.55 eV of initial MoB, which is conducive to rapid charge and discharge of the battery. The specific capacity is increased to 519 mAh/g compared with the original one, and the metal ions are evenly distributed on the electrode surface. Additionally, the open circuit voltage (OCV) is in the range of 0–1 V, preventing the formation of Li dendrites and ensuring the safety of the battery in operation. These properties are attributed to the functionalized Janus structure redistributing the surface charge of the material, resulting in an evenly uniform interaction force between the adsorbed atoms and the matrix, thereby improving the adsorption stability of lithium ions. In a nutshell, the study sheds light on the mechanism of energy storage performance toward O and S-functionalized MBene electrode materials on a microscopic scale, which lays the corresponding foundation for subsequent experimental preparation.

Cycloarenes and heterocycloarenes display unique physical structures and hold great potential as organic semiconductors. However, the synthesis of (hetero)cycloarenes remains a big challenge, and there are limited reports on their applications. Herein, a series of nitrogen- and sulfur-codoped cycloarenes NS-Octulene-n(n= 2, 3, 4) with branched alkyl substituents containing linear spacer groups from C2to C4have been conveniently synthesized. Compared with their isoelectronic analogues Octuleneand S-Octulene, both having a saddle-shaped configuration, the coincorporation of two nitrogen atoms and two sulfur atoms leads to a fully coplanar aromatic backbone structure. Each of these three planar heterocycloarenes acts as a supramolecular host for encapsulation of both fullerenes C60and C70with a stronger donor–acceptor interaction for the complexation between the heterocycloarene and C70due to the unique molecular geometry and defined cavity. Meanwhile, the electron-rich nitrogen atoms also slightly increase the energies of both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in this series of planar heterocycloarenes, indicating that they can be used as p-type semiconductors. Most importantly, benefitting from the planar π-conjugated backbone structure accompanied by excellent crystallinity and ordered molecular packing, as well as upon the engineering of the alkyl chain branching position, thin-film field-effect transistors of NS-Octulene-3with moderate alkyl branching point exhibit the maximum hole mobility of 0.86 cm2V–1s–1, which is the highest for (hetero)cycloarene-based organic semiconductors. This study will shed new light on designing novel high-performance macrocyclic polycyclic aromatic hydrocarbon (PAH) semiconductors.

ABSTRACTIt is important to know how much of the increased atmospheric CO2is derived from fossil fuel emissions. Here, we review the progress in atmospheric fossil fuel CO2(CO2ff) tracing over recent years by measurement of Δ14C in Chinese cities. In this paper we make progress by expanding the analysis from some locations to more regional views, by combining observations with modeling, and by making a preliminary comparison of observation-derived CO2ffwith inventory-derived CO2ff. We have obtained a general picture of Chinese urban CO2ffand characteristics of its spatio-temporal variations at different scale, and identified the corresponding influencing factors. Interestingly, we found that the weekend effect of CO2ffwas less evident in Chinese cities. In addition, we observed simultaneous variations in CO2ffand PM2.5in a winter haze event in Beijing and a simultaneous decrease in annual averages of CO2ffand PM2.5in Xi’an based on multi-year (2011–2016) Δ14CO2monitoring. We found that local coal combustion was the main source of CO2ffin Xi’an, which is located in the Guanzhong basin, by applying a WRF-Chem model and looking at δ13C signatures. Thus, reduction of coal consumption is a crucial target for carbon emissions reduction in China.

ABSTRACTLacustrine sediments are important archives for paleoclimate research, but there are evident carbon reservoir effects. Radiocarbon (14C) ages of lake sediments must be corrected for these effects before applying them to paleoclimate research. The authors review the lacustrine research from the last 20 years from different climatic regions in China, and systematically investigate the 14C age and correction methods used in the studies of 81 lakes. It is found that the climate-vegetation cover and distribution of carbonate around lakes are dominant factor controlling radiocarbon reservoir effects. In eastern China, the average 14C reservoir age is about 500 14C years and is associated with relatively dense vegetation. However, in northwest China and Qinghai-Tibet Plateau, widespread carbonate bedrock may markedly increase the radiocarbon reservoir age which frequently is about 1500 and 2500 14C years. A piecewise linear regression model provides more reliable 14C reservoir age correction that accounts for sedimentary facies and sedimentation rate changes. It is worth mentioning that when analyzing 14C ages deviated greatly from time sequence, the age anomalies may indicate important effects relevant to the study of climate and environmental changes.

Three novel BN-embedded V-shaped polycyclic aromatic hydrocarbons with different π-conjugation lengths were designed and successfully synthesized. Their single-crystal structures were confirmed by X-ray crystallographic analysis, and it is found that the molecular stacking structure can be effectively tuned by extending the length of π conjugation. Meanwhile, owing to the unique V-shaped molecular geometry, they exhibit moderate host–guest supramolecular interactions with both fullerenes C60and C70.

Polycyclic hydrocarbons (PHs) share the same hexagonal structure of sp2carbons as graphene but possess an energy gap due to quantum confinement effect. PHs can be synthesized by a bottom-up strategy starting from small building blocks covalently bonded into large 2D organic sheets. Further investigation of the role of the covalent bonding/coupling ways on their electronic properties is needed. Here, we demonstrate a surface-mediated synthesis of hexa-peri-hexabenzocoronene (HBC) and its extended HBC oligomers (dimers, trimers, and tetramers) via single- and triple-coupling ways and reveal the implication of different covalent bonding on their electronic properties. High-resolution low-temperature scanning tunneling microscopy and noncontact atomic force microscopy are employed to in situdetermine the atomic structures of as-synthesized HBC oligomers. Scanning tunneling spectroscopy measurements show that the length extension of HBC oligomers narrows the energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Furthermore, the energy gaps of triple-coupling HBC oligomers are smaller and decrease more significantly than that of the single-coupling ones. We hypothesize that the triple coupling promotes a more effective delocalization of π-electrons than the single coupling, according to density functional theory calculations. We also demonstrate that the HBC oligomers can further extend across the substrate steps to achieve conjugated polymers and large-area porous carbon networks.

A multicenter retrospective analysis of conventionally collected data. To identify the potential causes of hypoproteinemia after traumatic spinal cord injury (TSCI) and provide a diagnostic model for predicting an individual likelihood of developing hypoproteinemia. Hypoproteinemia is a complication of spinal cord injury (SCI), an independent risk factor for respiratory failure in elderly patients with SCI, and a predictor of outcomes in patients with cervical SCI. Few nomogram-based studies have used clinical indicators to predict the likelihood of hypoproteinemia following TSCI. This multicenter retrospective clinical analysis included patients with TSCI admitted to the First Affiliated Hospital of Guangxi Medical University, Wuzhou GongRen Hospital, and Dahua Yao Autonomous County People Hospital between 2016 and 2020. The data of patients from the First Affiliated Hospital of Guangxi Medical University were used as the training set, and those from the other 2 hospitals were used as the validation set. All patient histories, diagnostic procedures, and imaging findings were recorded. To predict whether patients with TSCI may develop hypoproteinemia, a least absolute shrinkage and selection operator regression analysis was conducted to create a nomogram. The model was validated by analyzing the consequences using decision curve analysis, calibration curves, the C-index, and receiver operating characteristic curves. After excluding patients with missing data, 534 patients were included in this study. Male/female sex, age ≥ 60 years, cervical SCI, pneumonia, pleural effusion, urinary tract infection (UTI), hyponatremia, fever, hypotension, and tracheostomy were identified as independent risk factors of hypoalbuminemia. A simple and easy-to-replicate clinical prediction nomogram was constructed using these factors. The area under the curve was 0.728 in the training set and 0.881 in the validation set. The predictive power of the nomogram was satisfactory. Hypoalbuminemia after TSCI may be predicted using the risk factors of male/female sex, age ≥ 60 years, cervical SCI, pneumonia, pleural effusion, UTI, hyponatremia, fever, hypotension, and tracheostomy.

The crux to practical application of geopolymer adsorbents for antibiotics that are easily protonated and deprotonated is to clarify the dynamic adsorption mechanism of geopolymer with intrinsic alkaline release. The adsorption properties, adsorption mechanism, adsorption-desorption cycle and waste adsorbent regeneration based on the geopolymer adsorbent for adsorbing tetracycline under the spontaneous dynamic pH conditions were systematically investigated by experiment, characterization and density functional theory. The results confirmed that the structures of tetracycline depended on dynamic pHs of adsorption systems changed by geopolymer adsorbent. The electrostatic interaction assisted by hydrogen-bonding and n-π interaction dominated the adsorption process when the dynamic pHs were less than 7. And the hydrogen-bonding and n-π interaction provided the possibility of weak adsorption effect in highly alkaline environments. The geopolymer powder exhibited outstanding adsorption efficiency (∼95.62%, 30 min) due to the strong electrostatic adsorption between electronegative skeleton of geopolymer and zwitterions species tetracycline under dynamic pH range of 4–6.3 and fitted the pseudo-second-order model. The outstanding competitive adsorption properties in NaCl solution, adsorption (4 times)-desorption (3 times) cycle properties and regenerative property of waste adsorbent were exhibited. The mechanism study based on the dynamic pHs which is closer to actual conditions can provide important reference for practical application of easy preparation and low cost geopolymer adsorbents.

All O-methylated derivatives of emodin, including physcion, questin, and 1-O-methylemodin, show potential antifungal activities. Notably, emodin and questin are two pivotal intermediates of geodin biosynthesis in Aspergillus terreus. Although most of the geodin biosynthetic steps have been investigated, the key O-methyltransferase (OMT) responsible for the O-methylation of emodin to generate questin has remained unidentified. Herein, through phylogenetic tree analysis and in vitrobiochemical assays, the long-sought class II emodin-O-methyltransferase GedA has been functionally characterized. Additionally, the catalytic mechanism and key residues at the catalytic site of GedA were elucidated by enzyme–substrate–methyl donor analogue ternary complex crystal structure determination and site-directed mutagenesis. As we demonstrate, GedA adopts a typical general acid/base (E446/H373)-mediated transmethylation mechanism. In particular, residue D374 is also crucial for efficient catalysis through blocking the formation of intramolecular hydrogen bonds in emodin. This study will facilitate future engineering of GedA for the production of physcion or other site-specific O-methylated anthraquinone derivatives with potential applications as biopesticides.

Although molecular design strategies for highly bright near-infrared II (NIR-II) fluorophores were proposed, the lack of solid structural identification (single crystal) hinders the further development of this field. This thorny issue is addressed by performing the structure–function relationship of NIR-II dyes, as confirmed by molecular single crystal engineering. Single crystal structure analysis confirms that twisted architectures (large dihedral angles ∼70°) and loose packing patterns (intermolecular distance of ∼3.4–4.5 Å) are key elements to enhance the absolute quantum yield (QY) in the solid state. Through regulating donor–acceptor distance and donor–acceptor interactions, the resultant well-defined TBP-b-DFA fluorophore displays an absolute QY of 0.4% with an emission extending to 1400 nm, which is favorable for NIR-II bioimaging. The cerebrovascular function, including cerebral blood flow and cerebrovascular reactivity of different conditions, is accurately quantified by a NIR-II fluorescence wide-field microscope. Our study provides a sight for designing NIR-II fluorophores, which is useful for studying cerebrovascular function.

Ceramic aerogels are attractive candidates for high-temperature thermal insulation, catalysis support, and ultrafiltration materials, but their practical applications are usually limited by brittleness. Recently, reversible compressibility has been realized in flexible nanostructures-based ceramic aerogels. However, these modified aerogels still show fast and brittle fracture under tension. Herein, we demonstrate achieving reversible stretch and crack insensitivity in a highly compressible ceramic aerogel through engineering its microstructure by using curly SiC-SiOxbicrystal nanowire as the building blocks. The aerogel exhibits large-strain reversible stretch (20%) and good resistance to high-speed tensile fatigue test. Even for a prenotched sample, a reversible stretch at 10% strain is achieved, indicating good crack resistance. The aerogel also displays reversible compressibility up to 80% strain, ultralow thermal conductivity of 28.4 mW m–1K–1, and excellent thermal stability even at temperatures as high as 1200 °C in butane blow torch or as low as −196 °C in liquid nitrogen. Our findings show that the attractive tensile properties arise from the deformation, interaction, and reorientation of the curly nanowires which could reduce stress concentration and suppress crack initiation and growth during tension. This study not only expands the applicability of ceramic aerogels to conditions involving complex dynamic stress under extreme temperature conditions but also benefits the design of other highly stretchable and crack-resistant porous ceramic materials for various applications.

Cyclopenta[b]thiopyran, isomeric to benzo[b]thiophene while isoelectronic to azulene, is involved as a building block to construct soluble organic semiconductors for field-effect transistors. Two series of angular-shaped heteroarenes based on cyclopenta[b]thiopyran, that is, Cn-SS(n= 4, 6, 8, 10) with different linear alkyl groups and C8-SS-Clm(m= 2, 3, 4) with chlorides substituted at different positions, have been straightforward synthesized. The obtained seven S-heteroarenes exhibit intriguing and similar photophysical and electrochemical properties, such as near-infrared absorption and high-energy levels of the highest occupied molecular orbitals. Nevertheless, the S-heteroarenes with identical π-conjugated skeletons demonstrate completely different molecular packing structures, which is proofed to be the key determinate factor for the charge carrier mobilities. Upon the engineering of the pendant alkyl lengths, the highest hole mobility in the Cn-SSseries is achieved for C8-SS(1.1 cm2V–1s–1) with moderate alkyl length. The further incorporation of chlorides on C8-SSresults in the shortened intermolecular H···S contacts and the interplane distances. Most interestingly, when chlorine-containing chloroform and chlorobenzene are used as crystallization solvents, single crystals of C8-SS-Clmwith different packing structures are produced owing to the intermolecular interactions among the solute and solvent molecules. Upon further engineering of the chlorination position and the crystallization solvent, the maximum hole mobility in the ambient air improves to 2.7 cm2V–1s–1for C8-SS-Cl2crystallized from chlorobenzene, suggesting that the introduction of the accessible chlorides is a feasible pathway to engineering the crystal structures and controlling the charge transport characteristics.

The synthesis and characterization of two 1,8-naphthalene-bridged cyclic oligo-para-phenylenes with four or eight phenylene units are reported. Both molecules exhibit a highly strained structure with two nearly face-to-face arranged p,p′-biphenylylene/p,p′-quaterphenylylene chains. Their dications were obtained by chemical oxidation with NO·SbF6, and both showed open-shell singlet diradical character with a small singlet–triplet energy gap.

The exploration of two-dimensional (2D) anode materials with fascinating theoretical specific capacity and ion diffusion rate has been paid much attention in the domain of alkali ion batteries. In this present contribution, the potency of monolayer Janus SnXY (X/Y = O, S, Se, Te, X ≠ Y) to function as an anode material for Na-ion batteries (SIBs) is anticipated upon the ground of first-principles calculations. The outcomes indicate that the cohesion energies of all the SnXY are positive, signifying that they are energetically stabilized. The distribution of electrons in the SnXY structure is strongly dependent on the electronegativity of the atoms on both sides, and the higher the electronegativity, the more electrons are gathered. Meanwhile, the larger (smaller) charge transfer between Sn atoms and X/Y atoms enhances (weakens) the bond strength and leads to a decrease (increase) in the interlayer spacing. In service, Na atoms tend to be steadily adsorbed at the top of O, Sn, Se and Te, and a large number of electrons are transferred from Na atoms to SnXY. SnXY exhibits a metallic state after embedding, increasing its own electrical conductivity. Particularly, the SnSSe has a low diffusion barrier of 0.12 eV and a high Na storage capacity of 1380 mAh/g. These insights demonstrate that monolayer Janus SnXY is a prospective anode material for SIBs possessing high storage capacity and rapid charge/discharge rates.

Grain boundary segregation engineering (GBSE) is a promising approach for accurately manipulating chemical composition, structure and properties of grain boundaries (GBs). With the aim of attenuating or even removing disadvantages of GBs in nickel-based superalloys, the GB segregation behaviors of 3d(Ti–Co), 4d(Zr–Rh) and 5d(Hf–Ir) transition-metal (TM) solutes Xand their effects on the thermodynamic stability and fracture strength of Ni Σ3 [110](111) symmetrical tilt grain boundary were systematically investigated, using first-principles total-energy calculations based on density functional theory. We found that all TM solutes considered herein can segregate towards the Ni Σ3 [110](111) GB. For TM elements from same row of the periodic table, their segregation energies show a concave-up parabolic-like dependency on the atomic number of TM elements. The GB segregations of all considered solutes can lead to a reduction in GB energy and render the Ni GB more stable, and the GB energies of X-segregated GBs vary linearly with the GB segregation energies of solutes X. Except elements Zr, Hf and Rh, the GB segregations of the other 15 TM alloying elements increase the GB fracture strength. The Mn and Re segregations improve the GB fracture strength and thermodynamic stability to a maximum extent, respectively. The underlying mechanisms for segregation-induced GB stabilizing and strengthening effects were further revealed at the electronic level by analyzing the crystal orbital Hamiltonian populations and deformation charge densities. Our work could provide new insights into designing Ni-based superalloys with desired performances based on the concept of GBSE.

Influences of grain size and temperature on the mechanical properties of nano-polycrystalline Ni-Co alloy were investigated with molecular dynamics simulations. It is found that the critical grain size of Hall-Petch relationship is 4.3 nm, at which the maximum flow stress of 4.83 GPa is obtained. In samples with the d> 4.3 nm, the average flow stress increases with the decrease of d, according with the Hall-Petch relationship, caused by the dislocation glide and growth of deformation twin with the breaking of individual grain boundaries. For samples with the d< 4.3 nm, the evolution of flow stress and dis consistent with the inverse Hall-Petch relationship, attributed to the softening caused by the rotation of grain and migration of grain boundary, in which small grain merging can be observed, promoting grain boundary movement, and the extrusion of atoms leads to thinning of grain boundary. In addition, under high temperature loading, the fraction of grain boundary atoms increases, while the fraction of grain interior atoms decreases gradually. Also, the grain boundary will melt with the increase of the atomic disorder degree and the density of partial dislocation decreases. Simultaneously, the resistance to grain growth of samples at high temperature is lower than that of samples at low temperature. These conclusions have positive significance for the design of this fascinating nano-polycrystalline alloy.

The brightness of organic fluorescence materials determines their resolution and sensitivity in fluorescence display and detection. However, strategies to effectively enhance the brightness are still scarce. Conventional planar π-conjugated molecules display excellent photophysical properties as isolated species but suffer from aggregation-caused quenching effect when aggregated owing to the cofacial π–π interactions. In contrast, twisted molecules show high photoluminescence quantum yield (ΦPL) in aggregate while at the cost of absorption due to the breakage in conjugation. Therefore, it is challenging to integrate the strong absorption and high solid-state ΦPL, which are two main indicators of brightness, into one molecule. Herein, we propose a molecular design strategy to boost the brightness through the incorporation of planar blocks into twisted skeletons. As a proof-of-concept, twisted small-molecule TT3-oCB with larger π-conjugated dithieno[3,2-b:2′,3′-d]thiophene unit displays superb brightness at the NIR-IIb (1500–1700 nm) than that of TT1-oCB and TT2-oCB with smaller thiophene and thienothiophene unit, respectively. Whole-body angiography using TT3-oCB nanoparticles presents an apparent vessel width of 0.29 mm. Improved NIR-IIb image resolution is achieved for femoral vessels with an apparent width of only 0.04 mm. High-magnification through-skull microscopic NIR-IIb imaging of cerebral vasculature gives an apparent width of ∼3.3 μm. Moreover, the deeply located internal organ such as bladder is identified with high clarity. The present molecular design philosophy embodies a platform for further development of in vivobioimaging.

ABSTRACTMany bacteria and archaea possess an RNA-guided adaptive and inheritable immune system that consists of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins. In most CRISPR-Cas systems, the maturation of CRISPR-derived small RNAs (crRNAs) is essential for functionality. Cas6 endonucleases function as the most frequent CRISPR RNA maturation enzymes. In the cyanobacterium Anabaenasp. PCC 7120, ten CRISPR loci are present, but only two casgene cassettes plus a Tn7-associated eleventh array. In this study, we deleted the two cas6genes alr1482(Type III-D) or alr1566(Type I-D) and tested the specificities of the two corresponding enzymes in the resulting mutant strains, as recombinant proteins and in a cell-free transcription-translation system. The results assign the direct repeats (DRs) to three different groups. While Alr1566 is specific for one group, Alr1482 has a higher preference for the DRs of the second group but can also cleave those of the first group. We found that this cross-recognition limits crRNA accumulation for the Type I-D system in vivo.We also show that the DR of the casgene-free CRISPR array of cyanophage N-1 is processed by these enzymes, suggesting that it is fully competent in association with host-encoded Cas proteins. The data support the functionality of CRISPR arrays that frequently appear fragmented to multiple genomic loci in multicellular cyanobacteria and disfavour other possibilities, such as the nonfunctionality of these orphan repeat-spacer arrays. Our results show the functional coordination of Cas6 endonucleases with both neighbouring and remote repeat-spacer arrays in the CRISPR-Cas system of cyanobacteria.

Cyclohexane-1,2,4,5-tetracarboxylic diimide with a nonconjugated core has been incorporated to bridge two conventional triphenylamine units. The obtained monomer has successfully hypsochromically shifted the maximum absorption wavelength by 10 nm in comparison to the one with a pyromellitic diimide bridge. Consequently, a colorless electrochromic (EC) polymer poly(bis(N,N-diphenyl-4-aminophenyl)cyclohexane-1,2,4,5-tetracarboxylic diimide) (PTPA-HDI) was electropolymerized on indium tin oxide (ITO)-coated glass. The morphology, absorption, and spectroelectrochemistry properties of polymer PTPA-HDIfilms electropolymerized by different scan cycles have been systematically investigated. It is found that comprehensive properties, such as color contrast and initial transparence, can be achieved for the polymer film electropolymerized by 15 scan cycles. Moreover, to realize colorless-to-black electrochromism, an asymmetric viologen derivative 1-(4-cyanophenyl)-1′-hexyl-4,4′-bipyridinium dihexafluorophosphate (HVCN) has been designed and straightforward synthesized. With the introduction of a cyanophenyl group and a hexyl chain on the two pyridinium units, colorless-to-green electrochromism can be realized for this processible viologen derivative. The absorption band at 495 nm of colorated PTPA-HDIcompensates well for the valley in the absorption spectrum of colorated HVCN. Therefore, different types of colorless-to-black electrochromic devices (ECDs) are fabricated using polymer PTPA-HDI-deposited ITO electrode and HVCN-based gel electrolyte. Such a supporting electrolyte-free ECD with binary electrochromes exhibits fast coloration, high color contrast, and excellent reversibility. Furthermore, an encryption ECD is demonstrated by switching a black two-dimensional code. In addition, an autodigital display is integrated on a smart window and hence different functions can be realized in a single ECD. Overall, this study may facilitate the understanding of the EC behaviors of binary electrochromes and present a new path to design multifunctional displays.

Semiconducting polymer nanoparticles (SPNs) emitting in the second near-infrared window (NIR-II, 1000–1700 nm) are promising materials for deep-tissue optical imaging in mammals, but the brightness is far from satisfactory. Herein, we developed a molecular design strategy to boost the brightness of NIR-II SPNs: structure planarization and twisting. By integration of the strong absorption coefficient inherited from planar π-conjugated units and high solid-state quantum yield (ΦPL) from twisted motifs into one polymer, a rise in brightness was obtained. The resulting pNIR-4 with both twisted and planar structure displayed improved ΦPLand absorption when compared to the planar polymer pNIR-1 and the twisted polymer pNIR-2. Given the emission tail extending into the NIR-IIa region (1300–1400 nm) of the pNIR-4 nanoparticles, NIR-IIa fluorescence imaging of blood vessels with enhanced clarity was observed. Moreover, a pH-responsive poly(β-amino ester) made pNIR-4 specifically accumulate at tumor sites, allowing NIR-IIa fluorescence image-guided cancer precision resection. This study provides a molecular design strategy for developing highly bright fluorophores.

Three high energy particle monitors (HPMs) employed onboard the Hard X-ray Modulation Telescope (Insight-HXMT) can detect the charged particles from South Atlantic Anomaly (SAA) and hence provide the alert trigger for switch-on/off of the main detectors. Here a typical design of HPM with high stability and reliability is adopted by taking a plastic scintillator coupled with a small photomultiplier tube (PMT). The window threshold of HPM is designed as 1 MeV and 20 MeV for the incident electron and proton, respectively. Before the launch of Insight-HXMT, we performed in details the ground calibration of HPM. The measured energy response and its dependence on temperature are taken as essential input of Geant4 simulation for estimating the HPM count rate given with an incident particle energy spectrum. This serves as a guidance for choosing a reasonable working range of the PMT high voltage once the real SAA count rate is measured by HPM in orbit. So far the three HPMs have been working in orbit for more than two years. Apart from providing reliable alert trigger, the HPMs data are used as well to map the SAA region.

The need for atmospheric carbon dioxide (CO2) reduction in the context of global warming is widely acknowledged by the global scientific community. Fossil fuel CO2(CO2ff) emissions occur mainly in cities, and can be monitored directly with radiocarbon (14C). In this research, annual plants [Setaria viridis(L.) Beauv.] were collected from 26 sites in 2013 and 2014 in the central urban district of Xi’an City. The Δ14C content of the samples were analyzed using a 3 MV Accelerator Mass Spectrometer, and CO2ffconcentrations were calculated based on mass balance equations. The results showed that the CO2ffmixing ratio ranged from 15.9 to 25.0 ppm (part per million, equivalent to µmol mol−1), with an average of 20.5 ppm in 2013. The range of measured values became larger in 2014, from 13.9 ppm to 33.1 ppm, with an average of 23.5 ppm. The differences among the average CO2ffconcentrations between the central area and outer urban areas were not statistically significant. Although the year-to-year variation of the CO2ffconcentration was significant (P< 0.01), there was a distinctly low CO2ffvalue observed in the northeast corner of the city. CO2ffemissions from vehicle exhaust and residential sources appeared to be more significant than two thermal power plants, according to our observed CO2ffspatial distribution. The variation of pollution source transport recorded in our observations was likely controlled by southwesterly winds. These results could assist in the optimal placement of regional CO2monitoring stations, and benefit the local government in the implementation of efficient carbon emission reduction measures.

Fungal polyketide synthase–nonribosomal peptide synthetase (PKS–NRPS) hybrids have been characterized to produce polyketide–amino acid compounds with striking structural features and biological activities. In this study, a PKS–NRPS hybrid enzyme was found in Aspergillus terreusby genome mining. By activating the cluster-specific transcriptional regulator, this cryptic PKS–NRPS gene cluster was successfully activated and ten products (1–10) were identified as pyranterreones. Using functional genetics, bioinformatics, and isotope-labeling feeding analysis, the biosynthetic pathway was revealed. This is the second PKS–NRPS hybrid identified in A. terreus.

The LH/chorionic gonadotropin receptor (LHCGR) is mainly expressed in gonads and plays important roles in estradiol production, ovulation, and luteal formation. Women with pathogenic LHCGR variants suffer from infertility, and successful fertility treatments for such women have never been reported.

The conceptualization and deployment of electrode materials for rechargeable sodium-ion batteries are key concerns for next-generation energy storage systems. In this contribution, the configuration stability of single-layer GeSiBi2is systematically discussed based on first-principles calculations, and its potential as an anode material is further investigated. It is demonstrated that the phonon spectrum confirms the dynamic stability and the adsorption energy identifies a strong interaction between Na atoms and the substrate material. The electronic bands indicative of inherent metallicity contribute to the enhancement of electronic conductivity after Na adsorption. The multilayer adsorption of Na provides a theoretical capacity of 361.7 mAh/g, which is comparable to that of other representative two-dimensional anode materials. Moreover, the low diffusion barriers of 0.19 and 0.15 eV further guarantee the fast diffusion kinetics. These contributions signal that GeSiBi2can be a compatible candidate for sodium-ion batteries anodes.

Donor–acceptor (D–A) conjugated systems have been extensively investigated and play important roles in organic electronics. Incorporating D–A structures into (hetero)cycloarenes endows them tunable electronic properties, while the well-defined cavity remains. However, the synthetic complexity of introducing electron-acceptor moieties into (hetero)cycloarenes limits their development and applications. In this paper, the first family of electronically tunable D–A heterocycloarenes (DAHCn, n= 1–5) based on pyrazine derivatives was facilely synthesized through cyclocondensation reaction from a tetraketone-functionalized heterocycloarene precursor prepared using the ketal-protection strategy. The effect of expanded conjugation and the inserted electron-withdrawing group on the electronic structures of the D–A heterocycloarenes was studied systematically by X-ray crystallographic analysis, various spectroscopic measurements, and theoretical calculations. Interestingly, the presence of an electron-withdrawing group polarizes the inner C(sp2)–H and significantly increases the binding affinities of D–A heterocycloarenes to the iodide anion. Meanwhile, the anion affinity can be further modulated by the type of attached substituents and the distance of polarization. More importantly, the dicyanopyrazine derivative DAHC3shows the highest binding strength to the iodide ion as a 2:1 sandwich complex (log β2= 12.3 and ΔG= −69.1 kJ mol–1), which is the strongest iodide receptor using C(sp2)–H hydrogen bonding interactions reported to date. Our finding provides a new strategy to design and synthesize D–A heterocycloarenes and strong anion receptors.

The low specific capacity and Mg non-affinity of graphite limit the energy density of ion rechargeable batteries. Here, we first identify that the monolayer C12-3-3in sp2–sp3carbon hybridization with high Li/Mg affinity is an appropriate anode material for Li-ion batteries and Mg-ion batteries via the first-principles simulations. The monolayer C12-3-3can achieve high specific capacities of 1181 mAh/g for Li and 739 mAh/g for Mg, higher than those of most previous anodes. The Li storage reaction is an “adsorption–conversion–intercalation mechanism”, while the Mg storage reaction is an “adsorption mechanism”. The 2D carbon material of C12-3-3displays fast diffusion kinetics with low diffusion barriers of 0.41 eV for Li and 0.21 eV for Mg. As a new carbon-based anode material, the monolayer C12-3-3will promote the practical application of batteries with high-capacity and high-rate performance.

High energy X-ray telescope (HE) is one of the three instruments of Insight-HXMT (Hard X-ray Modulation Telescope) payload. The HE detector (HED) array is composed of 18 actively NaI(Tl)/CsI(Na) phoswich scintillators with a total geometric area of ∼5100cm2and cover the energy range 20∼250 keV. In this paper we describe the on-ground detector-level calibration campaigns and present the principal instrument properties of HEDs.

Aromaticity is one of the most important concepts in organic chemistry to understand the electronic properties of cyclic π-conjugated molecules. Over a century, different aromaticity rules have been developed and validated. For planar monocyclic conjugated polyenes (also known as [n]annulenes), they will be aromatic if they contain [4N+ 2] π electrons according to Hückel’s rule, or antiaromatic if they have [4N] π electrons. Topological change from a planar to a half-twisted Möbius strip will lead to [4N] ([4N+ 2]) aromaticity (antiaromaticity), which is just inverse to Hückel’s rule. When the molecules are excited into the first triplet excited state, the Hückel (anti)aromaticity observed in the ground state will become reversed according to Baird’s rule. Strictly speaking, these basic rules are only applicable for monocyclic conjugated systems, but some polycyclic systems such as porphyrinoids may also follow these rules if there is a dominant [n]annulene-like conjugation pathway. On the other hand, all-benzenoid polycyclic aromatic hydrocarbons usually display local aromaticity with π electrons predominantly localized at certain benzene rings according to Clar’s aromatic sextet rule.

The synthesis of carbon nanobelts (CNBs) with well-defined size and structure remains a challenging topic in nanocarbon chemistry and materials science. Herein, we report the synthesis, physical characterization, and supramolecular properties of two fully conjugated bowl-shaped CNBs (CNB1/CNB2), in which six/eight cyclopenta-rings are fused onto a macrocycle containing three/four alternately linked 2,7-pyrenyl and 2,7-phenanthryl units. The existence of five-membered rings results in a bowl-shaped geometry, as revealed by X-ray crystallographic analysis and density functional theory calculations. Both molecules contain an alternate aromatic phenanthrene-co-quinoidal pyrene structure to satisfy Clar’s aromatic sextet rule. The smaller size CNB1has a deeper bowl depth (d= 4.997 Å) than CNB2(d= 3.682 Å) and cannot undergo bowl-to-bowl (BTB) inversion below 373 K in toluene. However, the larger size CNB2shows a smaller BTB inversion barrier (∼12 kcal/mol) at the coalescent temperature (248 K), which was estimated by variable-temperature NMR measurements. Both compounds exhibit a small energy gap and amphoteric redox behavior with multiple redox waves. The dications of CBN1and CBN2, and the tetracation of CBN2, are experimentally accessible by chemical oxidation with NO·SbF6, all displaying unusual open-shell singlet diradical character with a small singlet–triplet energy gap (ΔES–T= −2.71 kcal/mol for CBN12+, −2.50 kcal/mol for CBN22+, and −2.00 kcal/mol for CBN24+). The dications are globally aromatic while the tetracations are globally antiaromatic according to NMR measurements and theoretical calculations (anisotropy of the induced current density, nucleus independent chemical shift, and 2D isochemical shielding surface). The small bowl-shaped CNB1demonstrates selective encapsulation of fullerene C70over C60, with a large association constant (Ka= 8.066 × 105M–1in toluene). However, the larger size CNB2does not exhibit any encapsulation with both C60and C70.

Graphene nanoplates (GNPs) and graphene oxide (GO) were used to investigate the effects of surface free energy (SFE) of nanoparticles on the cellular structure and mechanical properties of phenolic nanocomposite foams. The results showed that the SFE of nanoparticles is a key parameter in determining the interfacial action between fillers and matrix before foaming, which in turn determines the energy barrier of bubble nucleation during foaming process. It indicated that the higher interfacial energy of GO brought out the lower Gibbs free energy and smaller driving force for heterogeneous nucleation, leading to smaller cell size with more uniform distribution. According to the effect of SFE in foaming process, different mass fractions of GNPs and GO were used in phenolic foams to investigate the effects of heterogeneous nucleating agent on cell nucleation. As a result, phenolic foam with 0.6 wt% graphene oxide (GO-0.6/PF) exhibited the optimized mechanical properties and cell microstructure.

Finding the electromagnetic (EM) counterpart of binary compact star merger, especially the binary neutron star (BNS) merger, is critically important for gravitational wave (GW) astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope (HE) onboard Insight-HXMT (Hard X-ray Modulation Telescope) is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart (SSS17a/AT2017gfo) with very large collection area (~1000 cm2) and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity (ToO) observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy (0.2-5 MeV) radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints (~10‒7to 10‒6erg/cm2/s) for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.

Solute element segregation behavior significantly changes the mechanical properties and deformation mechanism of nanocrystals. In this work, we studied the effect of segregation structure on the deformation mechanism of NiCoAl nanocrystalline by molecular dynamics. The results show that the grain boundary stability of nanocrystals is the worst when Al is completely segregated within the grain, and the metastable grain boundary cannot effectively hinder the dislocation movement, resulting in poor mechanical properties of nanocrystals. When 4% of Al transitioned to the grain boundary, the grain boundary stability was greatly improved and many lamination structures were generated. At this time, the lamination structure and stable grain boundaries were effectively nailed to dislocations, resulting in nanocrystal strengthening. With the complete segregation of Al at the grain boundary, the grain boundary shows a stable ability significantly and inhibits the nucleation of dislocation, leading to a decline in the strength of nanocrystals. In this effort, the deformation mechanism of solute element segregation is investigated from the interaction of dislocation and solid solution element, which is conducive to the design of advanced materials with excellent properties. Our work provides fascinating insights into the mechanism of plastic deformation response under solute element segregation structure.