Graphene quantum dot modified Bi2WO6 with enhanced photocatalytic activity by reinforcing the charge separation

The GQDs/BWO composites consisting of size-controllable GQDs and Bi₂WO₆ nanosheets were synthesized, and they exhibited an excellent photocatalytic activity.

Ag-Catalyzed minisci C–H difluoromethylarylation of N-heteroarenes

A mild silver-catalyzed decarboxylative C–H difluoromethylarylation of electron-deficient N-heteroarenes.

The intrinsic magnetism, quantum anomalous Hall effect and Curie temperature in 2D transition metal trihalides

It has been theoretically demonstrated that 2D transition metal trihalides can host the QAH effect.

Difference Analysis of Gas Molecules Diffusion Behavior in Natural Ester and Mineral Oil Based on Molecular Dynamic Simulation

Natural ester, as a new environmentally green insulating oil, has been widely used in transformer. In an oil-immersed transformer, the normal aging, thermal failure, and discharge failure could easily lead to the decomposition of the oil-paper insulation system and produce different kinds of gases. Studying gas dissolution in natural ester and mineral oil could provide assistance in applying criteria to make a diagnosis of different kinds of faults in the transformer. In this paper, the molecular dynamics method was used to investigate the diffusion behavior of seven fault characteristic gases (including H₂, CO, CH₄, C₂H₂, CO₂, C₂H₄, C₂H₆) in natural ester and mineral oil. The simulation parameters of free volume, interaction energy, mean square displacement, and diffusion coefficient were compared between the natural ester and mineral oil. Meanwhile, the influence of temperature on the diffusion of gas molecules in two kinds of oils was also analyzed. Results showed that the free volume, the interaction energy, and the relative molecular mass of gas molecules were the factors influenced by the diffusion of gas molecules in natural ester and mineral oil. The order of the diffusion coefficients of gas molecules in natural ester was as follows: H₂ > CH₄ > CO > C₂H₂ > C₂H₄ > CO₂ > C₂H₆ and that in mineral oil was as follows: H₂ > CH₄ > CO> C₂H₂ > C₂ H₄ > C₂H₆ > CO₂. By comparing the diffusion behavior of gas molecules in natural ester and mineral oil, it was found that the smaller free volume and higher interaction energy of gas molecules in natural ester were the major reasons for the gas molecules to be more difficult to diffuse in natural ester. The rising temperature could enhance the free volume and reduce the interaction energy between gas molecules and oil. The diffusion coefficient of gas molecules increased exponentially with the follow of temperature. However, the temperature didn’t affect the ordering of diffusion coefficient, free volume, and interaction energy of gas molecules in natural ester and mineral oil.

Detection of hepatitis E virus genotypes 3 and 4 in donkeys in northern China

BACKGROUND

Hepatitis E virus (HEV) is the causative agent of acute self-limiting hepatitis in humans in developing countries. Hepatitis E virus RNA was first detected in donkeys in Spain, but little is known about the possible presence of HEV in donkeys in China.

OBJECTIVES

To investigate the prevalence of HEV in donkeys in northern China.

STUDY DESIGN

Investigation of the prevalence of HEV in donkeys using serological, molecular and phylogenetic approaches.

METHODS

A total of 401 donkey serum specimens were tested for serological and molecular detection of HEV via enzyme-linked immunosorbent assay and quantitative reverse transcription polymerase chain reaction. The amplified products were cloned in pMD18-T vector and sequenced. The alignment and phylogenetic analysis of partial HEV ORF2 genes were compared with the corresponding sequences of the obtained HEV representative strains.

RESULTS

Serological results showed that 49 donkeys (12.22%, 95% CI: 9.18-15.83%) were positive for anti-HEV-specific antibodies, and 17 donkeys (4.24%, 95% CI: 2.49-6.70%) were positive for HEV viral RNA. On the basis of sequence alignment and phylogenetic analysis, all isolated HEV strains belonged to genotype 3 (HEV-3) or HEV-4, sharing more than 76.2-96.3% identities with 67 other HEV representative strains of HEV-1 to HEV-8.

MAIN LIMITATIONS

Further studies about the prevalence of HEV in organs or faecal samples from donkeys are needed to evaluate the possible role of HEV reservoir and to determine the risk factors associated with the transmission of this zoonotic virus in donkeys in China.

CONCLUSIONS

This is the first report documenting the molecular analysis of donkey HEV strains worldwide and the serological evidence of HEV infection in donkeys in northern China. The results suggest that young donkeys are more susceptible to HEV infection compared with older donkeys. Further investigation is required to determine whether donkeys should be considered reservoirs for zoonotic HEV. The Summary is available in Chinese - see Supporting information.

Prediction of pressure-induced phase transformations in Mg3As2

Pressure is a fundamental tool that can induce structural and electronic transformations, which is helpful to search for exotic materials not accessible at ambient conditions. Here, we have performed an extensive structural study on cubic Mg3As2 in a pressure range of 0-100 GPa by using a combination of structure predictions and first-principle calculations. Interestingly, two novel structures with space groups C2/m and P1̄ were uncovered that become energetically most stable at pressures of 12 GPa and 30 GPa, respectively. Phonon dispersions demonstrate that the three phases are dynamically stable in their respective low-enthalpy pressure ranges. The electronic calculations show that Mg3As2 keeps semiconductor properties at pressures up to 100 GPa. The interesting thing is that the direct semi-conducting property of Mg3As2 transforms into indirect semi-conducting when the pressure is above 12 GPa. The current results provide new insights for understanding the behavior of Mg3As2 at high pressures.

Computational Design of Novel Hydrogen-Rich YS-H Compounds

The recent successful findings of H3S and LaH10 compressed above 150 GPa with a record high T c (above 200 K) have shifted the focus on hydrogen-rich materials for high superconductivity at high pressure. Moreover, some studies also report that transition-metal ternary hydrides could be synthesized at a relatively low pressure (∼10 GPa). Therefore, it is highly desirable to investigate the crystal structures of ternary hydrides compounds at high pressure since they have been long considered as promising superconductors and hydrogen-storage materials with a high T c, and can be possibly synthesized at low pressure as well. In this work, combining state-of-the-art crystal structure prediction and first-principles calculations, we have performed extensive simulations on the crystal structures of YSH n (n = 1-10) compounds from ambient pressure to 200 GPa. We uncovered three thermodynamically stable compounds with stoichiometries of YSH, YSH2, and YSH5, which became energetically stable at ambient pressure, 143, and 87 GPa, respectively. Remarkably, it is found that YSH contains monoatomic H atoms, while YSH2 and YSH5 contain a mixture of atomlike and molecular hydrogen units. Upon compression, YSH, YSH2, and YSH5 undergo a transition from a semiconductor to a metallic phase at pressures of 168, 143, and 232 GPa, respectively. Unfortunately, electron-phonon coupling calculations reveal that these compounds possess a weak superconductivity with a relatively low T c (below 1 K), which mainly stem from the low value of density of states occupation at the Fermi level (E F). These results highlight that the crystal structures play a critical role in determining the high-temperature superconductivity.

Aerosol optical properties and the mixing state of black carbon at a background mountainous site in Eastern China

In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 Mm^-1 for scattering coefficient (σ_{sp, neph, 550}), hemispheric backscattering coefficient (σ_{hbsp, neph, 550}), and absorption coefficient (σ_ap, 550), respectively, were obtained. Atmospheric aging process resulted in the increase of σ_ap, 550 but the decrease of the single scattering albedo (ω₅₅₀) at constant aerosol concentration. However, the proportion of non-light-absorbing components (non-BCs) was getting higher during the aging process, resulting in the increase of aerosol diameter, which also contributed to relatively higher σ_{sp, neph, 550} and ω₅₅₀. Diurnal cycles of σ_{sp, neph, 550} and σ_ap, 550 with high values in the morning and low values in the afternoon were observed closely related to the development of the planetary boundary layer and the mountain-valley breeze. BC mixing state, represented by the volume fraction of externally mixed BC to total BC (r), was retrieved by using the modified Mie model. The results showed r reduced from about 70% to 50% when the externally mixed non-BCs were considered. The periodical change and different diurnal patterns of r were due to the atmospheric aging and different air sources under different synoptic systems. Local biomass burning emissions were also one of the influencing factors on r. Aerosol radiative forcing for different mixing state were evaluated by a "two-layer-single-wavelength" model, showing the cooling effect of aerosols weakened with BC mixing state changing from external to core-shell mixture.

Quantum computation with universal error mitigation on a superconducting quantum processor

Medium-scale quantum devices that integrate about hundreds of physical qubits are likely to be developed in the near future. However, these devices will lack the resources for realizing quantum fault tolerance. Therefore, the main challenge of exploring the advantage of quantum computation is to minimize the impact of device and control imperfections without complete logical encoding. Quantum error mitigation is a solution satisfying the requirement. Here, we demonstrate an error mitigation protocol based on gate set tomography and quasi-probability decomposition. One- and two-qubit circuits are tested on a superconducting device, and computation errors are successfully suppressed. Because this protocol is universal for digital quantum computers and algorithms computing expected values, our results suggest that error mitigation can be an essential component of near-future quantum computation.

Comparative Study on the Thermal-Aging Characteristics of Cellulose Insulation Polymer Immersed in New Three-Element Mixed Oil and Mineral Oil

Cellulose paper, whose main component is cellulose polymer, has been widely used in oil-immersed power transformer that gradually deteriorates during transformer operation. Thermal aging is the main degradation form for cellulose paper immersed in insulation oil (oil–paper insulation) in a transformer. One of the most challenging issues in oil–paper insulation is inhibiting the aging of cellulose paper and extending its life. In this work, a comparative study was conducted on the thermal-aging characteristics of cellulose paper immersed in a novel three-element mixed insulation oil and mineral oil at 130 °C for 150 days. The key parameters of cellulose paper were analysed, including the degree of polymerization (DP), thermal-aging rate, surface colour, and AC breakdown voltage. The furfural content and acidity of the oil, as well as the AC breakdown voltage of the insulation oil were also analysed. The results show that the cellulose paper immersed in novel three-element mixed insulation oil had much higher DP values than that immersed in mineral oil after the same thermal-aging time. The mixed insulation oil could significantly inhibit the thermal aging of cellulose paper and prolong its life. The thermal-aging rate of the cellulose insulation polymer immersed in mixed insulation oil is significantly lower than that immersed in mineral oil, whether in the process of oil–paper insulation continuous aging or in the process of aging after oil replacement with unused insulation oil. The furfural generated by cellulose degradation in the novel three-element mixed insulation oil was also less than that in the mineral oil. The mixed insulation oil had a higher acidity value during the thermal-aging process, which was mainly due to the natural esters in the components of the mixed insulation oil. However, the AC breakdown voltage of the mixed insulation oil was always higher than that of the mineral oil. This study offers a new perspective in inhibiting the thermal aging of cellulose polymer in insulation oil.

Incorporation of Alkali Lignin in Polyacrylonitrile: Phase Separation, Coagulation, and Cyclization Kinetics

In this study, we systematically investigated the phase separation behaviors of polyacrylonitrile (PAN)/alkali lignin (AL)/dimethyl sulfoxide (DMSO) systems and found that the addition of AL causes phase separation and the systems form sea (PAN)/island (AL) types of structures. Interestingly, the AL-rich domains are very stable even after a long time of storage up to 15 days. Additionally, how the phase separation affected the solution rheology, the coagulation process and PAN cyclization were explored. The addition of AL in PAN/DMSO solutions changes the solution viscosity and gelation behaviors. Also, the existence of AL-rich domains accelerates the coagulation rate of the PAN solution in water. Because AL degrades at a lower temperature than PAN, it reduces the PAN cyclization temperature but leads to a higher cyclization activation energy, which could be caused by their different initiation mechanisms. These results would be useful to understand how the addition of AL affects the PAN solution structures, solution rheology, solution coagulation behaviors, and PAN stabilization reactions.

A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes

The development of a thermally activated delayed fluorescence (TADF) exciplex with high energy is of great significance in achieving highly efficient blue, green, and red organic light-emitting diodes (OLEDs) for use in full-color displays and white lighting. Highly efficient and stable blue and green phosphorescent OLEDs were demonstrated by employing a TADF exciplex (energy: 2.9 eV) based on 4-substituted aza-9,9'-spirobifluorenes (aza-SBFs). Blue PhOLEDs demonstrated a maximum current efficiency (CE) of 47.9 cd A-1 and an external quantum efficiency (EQE) of 22.5% at 1300 cd m-2 (2.5 times the values of aza-SBF-based systems), with the best blue PhOLED demonstrating a CE, power efficiency (PE) and EQE of 60.3 cd A-1, 52.7 lm W-1, and 26.2%, respectively. Green PhOLEDs exhibited a CE of 78.1 cd A-1 and EQE of 22.5% at 9360 cd m-2, with the best green PhOLED exhibiting a maximum CE, PE, and EQE of 87.4 cd A-1, 101.6 lm W-1, and 24.5%, respectively. The device operational lifetime was improved over 17-fold compared to reference devices because of the high thermal stability of the materials and full utilization of the TADF exciplex energy, indicating their potential for application in commercial OLEDs.

Lightweight, Superelastic Yet Thermoconductive Boron Nitride Nanocomposite Aerogel for Thermal Energy Regulation

Conventional three-dimensional (3D) thermal conductors or heat sinks are normally bulky solids with high density, which is cumbersome and not portable to satisfy current demands for soft and flexible electronic devices. To address this issue, here, a lightweight, superelastic yet thermally conductive boron nitride (BN) nanocomposite aerogel is designed by a facile freeze-drying method. The attained aerogel constituting of tailored interconnected binary inorganic-organic network structure exhibits low bulk density (6.5 mg cm^-3) and outstanding mechanical performances for compression, clotting, and stretching. Meanwhile, the aerogel has promising thermal stability and high thermal conductivity over wide temperature ranges (30-300 °C), validating the application even in extremely hot environments. Moreover, the aerogel can serve as a lightweight and elastic heat conductor for the enhancement of thermal energy harvest. Interestingly, during alternate strain loading/unloading under heating, the superelasticity and the anisotropy of thermal conductive transduction make the aerogel enable the elastic thermal energy capture and dynamic regulation. Therefore, our findings provide a potential use for the thermally conductive aerogel in future green energy applications.

Application of Silicon Quantum Dots in the Detection of Formaldehyde in Water and Organic Phases

Background:

Formaldehyde is widely acknowledged as a carcinogen, but as an important organic reagent, it has also been widely employed in the fields of chemical synthesis, industrial production and biomedicine. It is therefore of great practical significance for the detection of formaldehyde in food, clothing, daily necessities, construction materials and environments.

Methods:

The two silicon QDs, that are, DAMO-Si-QDs (with N-[3-(Trimethoxysilyl) propyl] ethylenediamine as silicon source) and APTMS-Si-QDs (with (3-Aminopropyl) trimethoxysilane as silicon source) as the fluorescence probe to detect formaldehyde in both water and organic phases.

Results:

Silicon QDs prepared by different silicon sources exhibit an obvious difference in their tolerances to the environment and the responses to formaldehyde. However, APTMS-Si-QDs show better selectivity in both water and organic phases. In Tris-HCl solution (20.00mmol•L-1, pH=5), the formaldehyde concentration maintains an excellent linear relationship with the fluorescence intensity of APTMS-Si-QDs in the range of 3.125×10-7-3.125×10-5 mol•L-1, with correlation coefficient R2= 0.9998. In methanol, the formaldehyde concentration maintains an excellent linear relationship with the fluorescence intensity of APTMS-Si-QDs in the range of 1.563×10-7-3.125×10-5 mol•L-1, with correlation coefficient R2= 0.9992.

Conclusion:

It is found that DAMO-Si-QDs show poor response to the presence of formaldehyde, while APTMS-Si-QDs got a strong, sensitive and selective response to that in both aqueous and organic phases. In the Tris-HCl buffer (20 mmol•L-1, pH=5), the linear range for formaldehyde detection reaches 3.125×10-7-3.125×10-5 mol•L-1, and for the detection in the organic phase, the linear range reaches 1.563×10-7-3.125×10-5 mol•L-1, in methanol solution. The paper provides a sensitive, selective and simple means for formaldehyde detection in both aqueous and organic phase

Restricting Lattice Flexibility in Polycrystalline Metal-Organic Framework Membranes for Carbon Capture

Although polycrystalline metal-organic framework (MOF) membranes offer several advantages over other nanoporous membranes, thus far they have not yielded good CO₂ separation performance, crucial for energy-efficient carbon capture. ZIF-8, one of the most popular MOFs, has a crystallographically determined pore aperture of 0.34 nm, ideal for CO₂ /N₂ and CO₂ /CH₄ separation; however, its flexible lattice restricts the corresponding separation selectivities to below 5. A novel postsynthetic rapid heat treatment (RHT), implemented in a few seconds at 360 °C, which drastically improves the carbon capture performance of the ZIF-8 membranes, is reported. Lattice stiffening is confirmed by the appearance of a temperature-activated transport, attributed to a stronger interaction of gas molecules with the pore aperture, with activation energy increasing with the molecular size (CH₄ > CO₂ > H₂ ). Unprecedented CO₂ /CH₄ , CO₂ /N₂ , and H₂ /CH₄ selectivities exceeding 30, 30, and 175, respectively, and complete blockage of C₃ H₆ , are achieved. Spectroscopic and X-ray diffraction studies confirm that while the coordination environment and crystallinity are unaffected, lattice distortion and strain are incorporated in the ZIF-8 lattice, increasing the lattice stiffness. Overall, RHT treatment is a facile and versatile technique that can vastly improve the gas-separation performance of the MOF membranes.

Macrophage migration inhibitory factor is involved in antineutrophil cytoplasmic antibody-mediated activation of C5a-primed neutrophils

Background

C5a is important for antineutrophil cytoplasmic antibody (ANCA)-mediated activation of neutrophils. The present study aimed to assess the role of macrophage migration inhibitory factor (MIF) in ANCA-mediated activation of C5a-primed neutrophils. The effects of MIF on ANCA-mediated neutrophil respiratory burst and degranulation were determined. In addition, the effect of a MIF antagonist on the activation of C5a-primed neutrophils was assessed.

Results

MIF treatment resulted in increased membrane proteinase-3 (mPR3) expression on neutrophils and enhanced myeloperoxidase (MPO) amounts in neutrophil culture supernatants. The concentration of MIF was significantly higher in the neutrophils supernatant primed with C5a (negative control: 14.2 ± 1.16 ng/ml; C5a: 45.8 ± 2.8 ng/ml, P < 0.001 vs. negative control; C5a + IgG: 44.8 ± 1.93 ng/ml, P < 0.001 vs. negative control; C5a + MPO-ANCA: 73.0 ± 5.5 ng/ml, P < 0.001 vs. C5a; and C5a + PR3-ANCA: 69.4 ± 5.35 ng/ml, P < 0.001 vs. C5a). MIF primed neutrophils to undergo respiratory burst and degranulation in response to ANCA. Indeed, mean fluorescence intensity (a measure of respiratory burst) was significantly higher in MIF-primed neutrophils activated with MPO-ANCA-positive IgG or PR3-ANCA-positive IgG compared with non-primed neutrophils. Meanwhile, a MIF antagonist reduced oxygen radical production in C5a-primed neutrophils treated with patient-derived ANCA-positive IgG.

Conclusions

MIF can prime neutrophils to undergo ANCA-mediated respiratory burst and degranulation. Blocking MIF resulted in reduced ANCA-mediated activation of C5a-primed neutrophils. These findings indicated that the interaction between MIF and C5a may contribute to ANCA-mediated neutrophil activation.