RESUMEN
A material with the "hidden" negative linear compressibility (NLC) will expand along a specific crystal direction upon uniformly compression to a critical pressure; such materials are thought to be promising candidates for non-linear actuators, switches and sensors. Herein, we use density functional theory (DFT) calculations to uncover the hidden NLC in a V-shaped molecular crystal, bis(5-amino-1,2,4-triazol-3-yl)methane (BATZM). The calculations indicate that the crystal is normally compressed over the pressure range of 0-3 GPa while it expands along the b-axis when the external hydrostatic pressure exceeds 3 GPa. The compressive behavior of the BATZM crystal is modulated by inter-molecular hydrogen bonds, which act as highly compressible springs at low pressures but robust struts at high pressures. Hence, the crystal prefers to compress the hydrogen bonds coupled with PLC at first and flatten the molecules, coupled with later NLC to resist the increasing external pressure. The compressive behavior of BATZM provides a strategy to design more hidden NLC materials via the rational use of the hydrogen bonds.
RESUMEN
In many practical applications, dielectric electromagnetic (EM) windows are usually under large-angle incidence of EM waves rather than normal incidence. To guarantee normal operation of devices inside, high transmission must be maintained under large incident angles, especially for TE-polarized waves. In this work, we propose a method of achieving broadband transmission of TE-polarized waves under large incident angles by embedding meta-atoms within dielectric plates. To this end, long metallic wires and S-shaped structures are embedded in the original dielectric plate, the former of which will dilute the effective permittivity due to plasma oscillation and the latter will increase the effective permeability due to induced strong current loops under large incident angles. In this way, two consecutive transmission peaks can be generated, forming a broad transmission band under large incident angles. A proof-of-principle Ku-band prototype was designed, fabricated, and measured to verify this strategy. Both simulated and measured results show that the prototype can operate in the whole Ku-band under incident angle [60°, 85°] for TE-polarized waves, with significantly enhanced transmission. This work provides an effective method of enhancing large-angle transmission of EM waves and may find applications in radar, communications and others.
RESUMEN
BACKGROUND: Lower work readiness is tied to anxiety, high turnover and nurse transition failure. An assessment of work readiness is necessary. To date, no relative scale exists in China. Thus, a work readiness related scale is urgently needed. OBJECTIVES: To assess the psychometric properties of the scale, and look into the status of Chinese graduate nurse work readiness and factors associated with work readiness. DESIGN, SETTINGS, AND PARTICIPANTS: Both psychometric assessment and associated factors are designed with cross-sectional studies. 832 and 435 graduate nurses were recruited in the above two studies, respectively. METHODS: Brislin's transition model was utilized for the transition process, and a six-expert panel and preliminary survey were conducted for face validity and testing the transition version respectively. Exploratory factor analysis, confirmatory factor analysis, internal consistency reliability and test-retest reliability were applied for reliability and validity testing. Additionally, a linear regression method was carried out for analyzing influencing factors of work readiness of graduate nurses across China. RESULTS: A 37-item Chinese version scale was proven to have great psychometric qualities. Five factors were extracted by exploratory factor analysis, which can explain 68.637% of the total variance. Furthermore, the confirmatory factor analysis demonstrates the fit indices of a five factors mode: X2/df = 1.769, RMSEA = 0.067, NFI = 0.859, RFI = 0.839, IFI = 0.934, CFI = 0.933, TLI = 0.923. Intra-class correlation coefficient, Cronbach's α and Guttman Split-half were 0.805, 0.960 and 0.903, respectively. Interpersonal relationships, leadership experience, scholarship, work experience and willingness to be nurses were associated with the potential to achieve higher work readiness. CONCLUSION: The Chinese version of WRS-GN with good validity and reliability can be utilized for assessment of work readiness. Besides, improving work readiness of graduate nurses based on above five associated factors, educators and hospital managers could help graduate nurses having a smooth transition for a stable nursing workforce.