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It is a challenge to find the relationship between the microscopic property of atoms in monolayers and the macroscopic piezoelectricity of monolayer. By first-principles calculation, we find not only the super-dipole moment (SDM) effect but also the electronegative polar moments (EPMs) effect, which can lead to the remarkable piezoelectricity in TiSXY monolayers. The SDM and EPM effects can deepen the understanding of the piezoelectric physical mechanism and provide the design strategy for ultrathin nano-devices. [ABSTRACT FROM AUTHOR]

The lack of out-of-plane piezoelectricity in most two-dimensional (2D) piezoelectric materials gravely hinders their applications. Two-dimensional materials exhibit high absorption coefficients within specific wavelength ranges; however, achieving broad-spectrum absorption spanning the infrared to ultraviolet range remains a significant challenge. Using first-principles calculations, we designed the CrCSiX2Y2 (when X = Y, X = Y = N, P, As; X ≠ Y, X = P, Y = N) monolayers by substituting atoms within the 2D MA2Z4 (M = Mo, W, V, Nb, Ta, Ti, Zr, Hf or Cr; A = C, Si, Ge; and Z = N, P, As) monolayers, and greatly enhanced the out-of-plane piezoelectricity, directional carrier mobility and optical properties. Therefore, the CrCSiX2Y2 monolayers are predicted to serve as promising candidates for advanced electromechanical coupling devices, directional high-speed electronics, and as a solution to the limited optical absorption capability of 2D materials across the entire optical spectrum. Besides, the CrCSiX2Y2 monolayers exhibit diverse absorption characteristics, demonstrating the tunability of these monolayers in optoelectronic properties. Such features allow the purposeful selection of the optimal material based on specific requirements in the design of optoelectronic devices. This work provides a paradigm for designing a multifunctional solar-blind UV detector, offering substantial potential for applications in both military defense and civilian sectors. [ABSTRACT FROM AUTHOR]

The development of piezoelectric materials is limited by incomplete internal mechanisms and a lack of vertical piezoelectricity. This study introduces Janus PdXY (X, Y= O, S, Se, Te; X ≠ Y) monolayers as innovative candidates for superior piezoelectric performance, as predicted by density functional theory. Our study reveals that these materials possess exceptional in-plane and out-of-plane piezoelectric properties, with the out-of-plane coefficient d 33 being up to two orders of magnitude greater than that of conventional Janus materials. This enhancement is attributed to the electron contributions and correlates with the Bader charge difference and electronegativity difference ratio, which conforms to the P-R mechanism. Additionally, the impact of layer thickness on piezoelectric coefficients is evaluated. These findings highlight the potential of Janus PdXY monolayers for advanced nanoscale flexible piezoelectric devices and offer valuable insights for the design of transition metal dichalcogenide-based Janus materials with robust out-of-plane piezoelectricity. [ABSTRACT FROM AUTHOR]

Objective To explore effects of Dihydromyricetin (DHM) on experimental colitis and regulatory B cells(Breg) of mice. Methods The mice were randomly divided into control group, DSS group, DSS+DHM group and DSS+ mesalazine group (4% DSS for 7 days). After 7 days, the mice were respectively gavaged with water (0.2 mL/d),DHM (40 mg/kg·d) and mesalazine (520 mg/kg·d) for 7 consecutive days and the disease activity index (DAI) was continuously recorded. The animals were sacrificed on the 14th day and the colon length was measured. The colon tissue sections were microscopied with HE staining. CD19+B lymphocytes and Breg(CD19+CD5+CD1d+) were determined by flow cytometry in splenic single cell suspension; real-time fluorescent quantitative PCR (RT-qPCR) was used to detect the relative mRNA level of IL-10,TGF-β,IL-6 and IFN-γin spleen cells. The effect of DHM on the proliferation of spleen cells was measured by CCK8. DHM (40 μmol/L) was selected to act on the spleen cell suspension for 24 h. flow cytometry was used to detect the ratio of Breg (CD19+CD5+CD1d+). Results Compared with the normal group, DAI and pathological score of DSS group were significantly higher, and the colon length was significantly decreased(P＜0.05); The proportion of CD19+ B cells vs. Breg (CD19+CD5+CD1d+) was significantly decreased, the inflammatory factors were significantly increased, and the anti-inflammatory factors were obviously decreased (P＜0.05). Compared with DSS group, DSS+DHM group and DSS+Mesalazine group significantly reversed the situation (P＜0.05); It was fond in vitro experiment that DHM significantly promoted the proliferation of spleen cells and Breg (P＜0.05). Conclusions DDHM has obvious therapeutic effect in experimental colitis mice, which may be related to the promotion of Breg proliferation and of secretion of anti-inflammatory factors IL-10 and TGF-β.

Materials with both ferromagnetism and excellent piezoelectricity can be classified as multifunctional materials and have been a focus of recent studies. At present, reported research studies focus mainly on three-dimensional materials. Herein, we report a series of two-dimensional (2D) multifunctional materials. Using first-principles calculations, we designed and predicted that 2D CrXSYBrZ (X = Cr or Mo, Y = S or Se and Z = H, F, Cl or Br) exhibit ferromagnetism and excellent out-of-plane piezoelectricity, and also have high carrier mobility. Importantly, the out-of-plane piezoelectric stress coefficient e33 of CrXBrYSZ is positively correlated with the difference in the sum electronegativity of the upper and lower parts in CrXBrYSZ. This physical mechanism is defined as the electronegativity difference effect, which reflects the intensity of the asymmetric charge transfer in CrXSYBrZ. Furthermore, the magnetic moment enhancement of Cr and Mo inhibits the asymmetric polarization charge transfer inside CrMoS2Br2 along the z-axis, and thereby significantly decreases the out-of-plane piezoelectricity of CrMoS2Br2. The coupling mechanism between ferromagnetism and out-of-plane piezoelectricity of CrMoS2Br2 is most obvious among CrXSYBrZ monolayers. Additionally, the out-of-plane piezoelectric stress coefficient e33 and atomic magnetic moments of these monolayers can be manipulated through biaxial strain. Therefore, CrXSYBrZ exhibit potential applications in multifunctional electromechanical and magnetic nanodevices. [ABSTRACT FROM AUTHOR]

Academic burnout seriously affects the academic performance and mental health of college students. This study developed a multi-mediation model to investigate the relationship between academic self-efficacy and academic burnout. A total of 1431 undergraduate students (51.85% female) were recruited to participate in this study. And we used SPSS PROCESS developed by Hayes to examine the mediating role of academic self-efficacy and academic burnout. The results indicated that academic self-efficacy can negatively predict academic burnout. Moreover, intrinsic motivation and learning engagement have a significant mediating effect between academic self-efficacy and academic burnout. Finally, we constructed a model comprising four variables and found that it explained 47.62% of the variance in academic burnout. These findings can be conducive to a suitable intervention path to reduce academic burnout of Chinese college students, so as to develop effective instructional strategies to improve their learning performance. [ABSTRACT FROM AUTHOR]