A prospective study of two-dimensional ultrasonography combined with shear wave elastography for pregnancy-related diastasis recti abdominis

ObjectivesTo compare the inter-rectus distance (IRD), rectus abdominis thickness (RAT), and stiffness in women during pregnancy and postpartum and identify the risk and protective factors affecting diastasis recti abdominis (DRA).Materials and methodsA total of 171 pregnant women who volunteered to participate in this study were recruited. Using an ultrasonographic diagnostic instrument with shear wave elastography function, IRD, RAT and the Young’s modulus of the rectus abdominis muscles were measured at 12 weeks, 37 weeks of pregnancy, and 6 weeks postpartum.ResultsThe IRD at 37 weeks was significantly higher than that at 12 weeks and then decreased at 6 weeks postpartum, but it was still higher than that at 12 weeks (p < 0.001). RAT and Young’s modulus decreased significantly at 37 weeks compared with those at 12 weeks and then recovered at 6 weeks postpartum, but they were lower than those at 12 weeks (p < 0.001). IRD at 12 weeks was significantly higher in multiparae than in primiparae (p < 0.001). Moreover, positive correlation between the RAT and Young’s modulus of rectus abdominis muscles at 12 and 37 weeks of gestation and 6 weeks postpartum (p < 0.001) was observed. Multiple linear regression analysis showed that the regression equation was significant (f = 24.856, p < 001).ConclusionOur study identified differences in IRD, thickness and stiffness of the rectus abdominis muscle between early and advanced pregnancy and the postpartum period. The risk and protective factors of DRA may guide pregnant women’s protection and treatment

A New Calculation Method for the Soil Slope Safety Factor

Based on the unified strength theory, a new method to calculate the plane soil slope safety factor was derived that considers the effect of intermediate principal stress σ2 and at-rest lateral pressure coefficient K0. Calculation examples from the literature were used to compare the new calculation method and the current slice method; the results showed that both provided good consistency. The new method can provide a reference for slope stability evaluation. The new method was used to calculate the soil slope safety factors for different values of intermediate principal stress parameter b, double shear stress parameters uτ′, and static lateral pressure coefficient K0. The results showed that the safety factor Fs increased when b was increased; Fs first increased and then decreased when uτ′ was increased; and Fs increased when K0 was increased. These results show that the intermediate principal stress as well as the stress state and its changes cannot be ignored during soil slope stability analysis. The slope soil characteristics and stress state should be considered to determine the unified strength theoretical parameters and static lateral pressure coefficient, maximize the potential of slope soil strength, and effectively reduce the costs of soil slope engineering

Synthesis of N-(2,4-Dinitrophenyl)-N '-(substituted-phenyl)hydrazones and Their Anion Sensing

Four N-(2,4-dinitrophenyl)-N-(substituted-phenyl)hydrazones (substituent R=H, o-OCH(3), o-Cl and o-OH) were synthesized as absorption spectral chemosensors for receptors. The binding properties of these receptors with anions such as F(-) and AcO(-) in CH(3)CN were investigated by UV-visible absorption spectroscopy. Results showed that a distinct color change occurred from yellow to light yellow upon addition of F(-) and AcO(-). Substituent was found to exert influence on the spectral response sensitivity and selectivity, with receptor 2 bearing an o-OCH(3) substituent showing the highest selectivity and good sensitivity for F(-). Job plots indicated a 1 : 1 anion binding stoichiometry of the receptors, for which a hydrogen bonding interaction was identified from the (1)H NMR titrations and the effect of competitive solvent MeOH on anion binding. As a distinct solution color change occurs it is possible to detect anions such as fluoride by naked eyes