Renal shear wave velocity by acoustic radiation force impulse did not reflect advanced renal impairment

[Aim] Acoustic radiation force impulse is a noninvasive method for evaluating tissue elasticity on ultrasound. Renal shear wave velocity measured by this technique has not been fully investigated in patients with renal disease. The aim of the present study was to compare renal shear wave velocity in end‐stage renal disease patients and that in patients without chronic kidney disease and to investigate influencing factors. [Methods] Renal shear wave velocities were measured in 59 healthy young subjects (control group), 31 subjects without chronic kidney disease (non‐CKD group), and 39 end‐stage renal disease patients (ESRD group). Each measurement was performed 10 times at both kidneys, and the mean value of eight of 10 measurements, excluding the maximum and minimum values, was compared. [Results] Renal shear wave velocity could be measured in all subjects. Renal shear wave velocity in the control group was higher than in the non‐CKD group and in the ESRD group, and no difference was found between the non‐CKD group and the ESRD group. Age and depth were negatively correlated to the renal shear wave velocity. In multiple regression analysis, age and depth were independent factors for renal shear wave velocity, while renal impairment was not. There was no difference between the non‐CKD group and the ESRD group, even when ages were matched and depth was adjusted. [Conclusion] Renal shear wave velocity was not associated with advanced renal impairment. However, it reflected alteration of renal aging, and this technique may be useful to detect renal impairment in the earlier stages

Quantitative Analysis of Conductivity and Viscosity of Ionic Liquids in Terms of Their Relaxation Times

The frequency-dependent viscosity and conductivity of various ionic liquids were measured experimentally, and their mean relaxation times were determined. The relaxation times of the viscosity and conductivity were approximately correlated with their respective zero-frequency limiting values. The Walden products, however, appeared to have no correlation with the ratio of the relaxation time of viscosity to that of conductivity in general. When the alkyl chain of the cation is as short as butyl, more viscous ionic liquids tend to show larger difference between two relaxation times and larger Walden products. Lengthening the alkyl chain of the cation decreases the Walden product while slightly increasing the relaxation time ratio, which was elucidated in terms of the decrease in the high-frequency shear modulus. In addition, the contribution of the mesoscopic structure to viscosity was suggested in the case of the ionic liquid with the longest alkyl chain studied in this work, 1-dodecyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­amide