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Two-dimensional (2D) ferrovalley semiconductor materials with intrinsic spontaneous valley polarization offer new prospects for valley electronics applications. However, there are only a limited number of known promising candidate materials, which are in urgent need of expansion. In particular, the room-temperature 2D ferrovalley materials are still lacking. In this study, we predicted novel 2D ferromagnetic CeX 2 (X=Fe,Cl,Br) monolayers by using first-principles calculations. The monolayer CeX 2 is a bipolar magnetic semiconductor with robust dynamical and thermal stabilities, and easy magnetization direction is in the plane. Due to the simultaneous breaking of both inversion symmetry and time-reversal symmetry, the monolayer CeX 2 is exhibiting a spontaneous intrinsic valley polarization when magnetized along the out-of-plane z direction. Interestingly, monolayer CeBr 2 is a spontaneous intrinsic ferrovalley material with a room temperature of 334 K and an obvious valley splitting of 32 meV. Due to the non-zero valley-contrast Berry curvature, monolayer CeBr 2 is a candidate materials for realizing the anomalous valley Hall effect under a suitable applied electric field. Our study provides a theoretical reference for the design of valley electronic devices with anomalous valley Hall effect based on hole-doped CeX 2. [ABSTRACT FROM AUTHOR]

ObjectiveTo analyze the surveillance results of influenza-like illness （ILI） cases in a sentinel hospital in Nantong from 2014 to 2021 and to understand the seasonal and etiological characteristics of influenza.MethodsThe routine ILI case information in a sentinel hospital in Nantong from 2014 to 2021 was collected from China Influenza Surveillance Information system， and the surveillance results were described and analyzed.ResultsA total of 64 110 ILI cases were reported in the hospital from 2014 to 2021， and accounted for 3.93% of outpatient and emergency visits. ILI is mainly concentrated in children under 15 years old， accounting for 55.39% of the total ILI cases. ILI% roughly showed two epidemic peaks in spring and winter. A total of 8 639 nasopharyngeal swab samples of ILI cases were collected during 2014‒2021， of which 838 were influenza positive， with an average positive rate of 10.01% （3.27%‒16.75%）. The epidemic strains varied from year to year and in different age groups. In 2014 and 2015， H3N2 influenza was the epidemic strain； in 2016 and 2017， H3N2 influenza and B-Victoria influenza were the co-epidemic strains； in 2018， H1N1 influenza was the epidemic strain； and in 2019‒2021， B Victoria influenza was the epidemic strain. The epidemic strain in 0‒4 years old， 15‒24 years old， 25‒59 years old and >60 years old was H3N2， and the epidemic strain in 5‒14 years old was B Victoria. There was a significant difference in the positive rate between different gender groups （χ2=7.364， P=0.006）.ConclusionInfluenza often occurs in winter and spring in a sentinel hospital in Nantong. Influenza subtypes are prevalent alternately in different age groups and different years. We need to closely monitor the etiology of influenza virus in Nantong to provide a basis for influenza prevention and control.

GdI 2 monolayer is a promising material for spintronics applications due to its robust room-temperature ferromagnetism and sizable valley polarization. In two-dimensional van der Waals magnets, interlayer magnetic coupling plays a crucial role in device applications. The performance of these devices can be effectively tuned by adjusting the stacking order, charge doping, and strain. By performing first-principles calculations, we have demonstrated that the interlayer magnetic coupling in bilayer GdI 2 is highly dependent on the stacking order, which can be tuned between ferromagnetic (FM) and antiferromagnetic orders through lateral shifting. Furthermore, the interlayer magnetic coupling can also be tuned by charge doping and strain, where both electron and hole doping can enhance the FM coupling interaction between layers, and the interlayer FM coupling can be strengthened with increasing biaxial tensile strain. These results show that bilayer GdI 2 has rich tunable interlayer magnetic interactions, which can be used in designing interesting spin tunnel field-effect transistor devices. [ABSTRACT FROM AUTHOR]

Plant communities are complex systems shaped by a combination of deterministic and stochastic ecological processes. Bryophytes are an essential component of plant diversity in natural ecosystems, yet our understanding of their community ecology needs to catch up to that of other organisms. The unique geological history, alpine climatic conditions, and high habitat heterogeneity of Tibet provide suitable areas for bryophytes to survive in the alpine regions. Therefore, field surveys were conducted across 184 plots in forest, thicket, and herbaceous vegetation of Tibet to investigate the role of deterministic processes such as biological interactions and abiotic effects, along with stochastic processes, in shaping the distribution of bryophyte assemblages. We employed various analytical methods, including mixed effects models, partial least squares path modeling, null model analysis, and neutral community models. The study showed that bryophyte richness was highest in forests. Bryophyte assemblages showed greater segregation in forest and thicket environments compared to herbaceous vegetation. As the influence of stochastic processes increased, that of deterministic processes decreased from forests through thickets to herbaceous vegetation. Deterministic processes were the main driving forces for the bryophyte assemblage pattern. Soil properties and climatic factors, particularly pH played a key role in determining bryophyte patterns in Tibet. This study has deepened our comprehension of how deterministic and stochastic ecological processes interplay and shape bryophyte distribution patterns in Tibet. [ABSTRACT FROM AUTHOR]

The study and development of high thermoelectric properties is crucial for the next generation of microelectronic and wearable electronics. Derived from the recent experimental realization of layers of transition metal molybdenum and boride, we report the theoretical realization of advanced thermoelectric properties in two-dimensional (2D) transition metal boride Mo1−xB2 (x = 0, 0.05, 0.10, 0.125, 0.15)-based defect sheets. The introduction of metal vacancies results in stronger d–p exchange interactions and hybridization between the Mo-d and B-p atoms. Meanwhile, the ordered metal vacancies enabled transition metal borides (n-type Mo0.9B2) to widen the d-bandwidth and raise the d-band center, leading to a relatively high carrier mobility of 3262 cm2 V−1 s−1 and conductivity twice that of a bug-free n-type MoB2 layer, which indicates that it presents good electronic and thermal transport properties. Furthermore, investigations of the thermoelectric performance exhibit a maximum ZT of up to 3.29, which is superior to those of currently reported 2D materials. Modulation by defect engineering suggests that 2D transition metal boride sheets with ordered metal vacancies have promising applications in microelectronics, wearable electronics and thermoelectric devices. [ABSTRACT FROM AUTHOR]

As MoSSe has been successfully synthesized, it is expected that Janus structures would be newly developed as 2D materials with intriguing physical properties. Here, monolayer Janus GdXY (with X/Y = Cl, Br, I), a ferromagnetic semiconductor with a high Curie temperature, is predicted by density functional theory combined with Monte Carlo simulations. The calculations show that the cleavage energies of monolayers 2 H - GdX 2 (X = Cl, Br, I) and GdXY are about 0.21 J / m 2 , which are smaller than that of graphene. The Janus GdXY monolayers have semiconducting bandgaps and show in-plane ferromagnetic order with Curie temperatures of 167–181 K. The magnetic moment is as high as 8 μ B /Gd. In addition, GdXY monolayers also have strong Heisenberg exchange interactions in the range of 35–37 meV, which are larger than that of CrI 3. We also find that both of their magnetic anisotropy and Curie temperature can be largely altered by strain. High Curie temperatures and 100% spin polarization make Janus GdXY monolayers good platforms for the research studies of spintronics devices. [ABSTRACT FROM AUTHOR]

Organic small-molecule luminescent materials have high fluorescence quantum efficiency, are easy to purify, and show advantages related to brightness. However, the low mobility of hole carriers hinders their practical applications. To obtain luminescent materials with high fluorescence quantum efficiency, we investigated organic small-molecule thiophene oligomers with electron-donating or electron-accepting substituents at the terminal groups using the density functional theory. Compared with the electron-donating groups (–NH2, –CH3, –C2H5, and –C3H7), the electron-withdrawing groups (–NO2 and –COOH) resulted in unusual electronic and photoluminescent properties. The ultraviolet spectra of the thiophene oligomer derivatives could be modulated in the range of 200–500 nm, making them suitable for application in organic light-emitting devices. In particular, the group with the strongest electron-withdrawing effect (–NO2) resulted in blue light emission in the wavelength range of 400–480 nm, suitable for application in blue chips. Finally, the calculation results show that the donor–acceptor-modified oligomers are worthy of synthesis due to their relatively high electron mobilities. [ABSTRACT FROM AUTHOR]

To study the characteristics and laws of the extensive application of superior thermoelectric properties near room temperature in thermoelectric devices, element substitution in two-dimensional (2D) Bi2Te3-based materials was studied using density functional theory and semi-classical Boltzmann theory. It worth noting that substituting the VA family (P, As, and Sb) in Bi2Te3, resulting in BiPTe3, BiSbTe3, and BiAsTe3 alloys, resulted in lower lattice thermal conductivity (k = 0.36 W m−1 K−1, 0.30 W m−1 K−1, and 0.34 W m−1 K−1), which enhanced the merit figure of ZT value from 0.61 for the pure Bi2Te3 system to 1.01, 1.08 and 1.10 at 300 K, respectively. Our results indicated that the group-VA (X = P, As, and Sb)-substituted Bi2Te3 BiPTe3, BiSbTe3 and BiAsTe3 alloys are promising candidates for thermoelectric applications near room temperature and compressive strain can effectively improve the ZT value of n-type structures. Especially, the compressive strain effect on the TE performance of n-type BiAsTe3 single-layer alloy can improve its n-type ZT value up to 1.904 at 800 K, which shows that its application can be extended to thermoelectric devices. [ABSTRACT FROM AUTHOR]