Shape-Controlled Synthesis of Covalent Organic Frameworks Enabled by Polymerization-Induced Phase Separation.

The shape and morphology modulations of covalent organic frameworks (COFs) are both difficult, but are of significance to tackle to realize high-performance and practical applications. Here, a two-step method is reported that separates the phase separation and crystallization processes for the shape-controlled synthesis of COFs. The insight into the polymerization-induced phase separation (PIPS) allows for the flexible shaping of COFs into column, rod, film and others, as well as for constructing hierarchically porous structure. The as-synthesized COF monoliths are crack-free, no powder detaching, and show 214 MPa of compressive modulus. The resulting good permeability and mechanical flexibility enable COF films to apply for flow-through adsorption and extraction of pollutants at high flow rates. This work successfully resolves the contradiction between PIPS and crystallization, offering a general approach for scalable production of COFs with desired shapes, sizes, and morphologies.

[Relationship between occupational noise exposure and hypertension in male steel workers].

OBJECTIVE: To analyze the effect of occupational noise exposure on hypertension in male steel workers. METHODS: The general information, noise exposure and blood pressure were collected through questionnaires and physical examinations. Chi-square test was used to investigate the prevalence of hypertension under different cumulative noise exposure, and the effect of noise exposure and other factors on hypertension was analyzed by the restrictive cubic spline(RCS) combined with multivariatenon-condition Logistic regression model. RESULTS: The prevalence of hypertension in noise exposure group was higher than that in noise non-exposure group(P<0. 001). After adjusting for multiple factors, the restricted cubic spline model showed a dose-response relationship between cumulative noise exposure(CNE) and hypertension(overall correlation χ~2=75. 76, P<0. 001, and nonlinear χ~2=24. 17, P<0. 001). Compared with the steel workers exposure to lowest dose, the risk of hypertension of steel workers exposure to 82-94 and 95-107 dB(A) in group was 1. 81(95%CI 1. 31-2. 52) times and 2. 60(95%CI 1. 84-3. 68) times. CONCLUSION: There is a non-linear dose-response relationship between cumulative noise exposure and hypertension.