Anomalous Dependence of Translational Diffusion on the Water Mole Fraction for Solute Molecules Dissolved in a 1‑Butyl-3-methylimidazolium Tetrafluoroborate/Water Mixture

Translational diffusion coefficients of carbon monoxide (CO), diphenylacetylene (DPA), and diphenylcyclopropenone (DPCP) were determined in mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]BF4) and water using transient grating spectroscopy at different mole fractions of water (xw). While DPA exhibited a larger diffusion coefficient than DPCP at low water mole fractions (xw < 0.7), as observed for conventional liquids and ionic liquids (ILs), it was smaller at high mole fractions (xw > 0.9). The apparent molecular radius of DPA determined using the Stokes–Einstein equation at xw > 0.9 is close to the radius of an IL cluster in a water pool as determined from small-angle neutron scattering experiments (J. Bowers et al., Langmuir, 2004, 20, 2192–2198), suggesting that the DPA molecules are trapped in IL clusters in the water pool and move together. The solvation state of DPCP in the mixture was studied using Raman spectroscopy. Dramatically strong water/DPCP hydrogen bonding was observed at higher water mole fractions, suggesting that DPCP is located near the cluster interfaces. The large diffusion coefficient of DPCP suggests that hopping of DPCP between IL clusters occurs through hydrogen bonding with water

ASSESSMENT OF BASILAR ARTERY HEMODYNAMICS IN TYPE 2 DIABETIC PATIENTS WITH NO HISTORY OF CEREBROVASCULAR DISEASE BY USING TRANSCRANIAL DOPPLER ULTRASOUND

We compared intracranial hemodynamics in 121 type 2 diabetic patients who had no history of cerebrovascular disease with findings in 123 matched control subjects. Mean blood flow velocity (MFV) and Fourier pulsatility index were determined by using transcranial Doppler ultrasonography (TCD). MFV in the basilar artery was significantly lower in diabetic than in nondiabetic subjects (p＜0.01), while Fourier PI of the basilar artery was significantly higher in diabetic than in nondiabetic subjects (p＜0.01). In multivariate regression analysis, increased Fourier PI and decreased MFV were associated with higher age, female gender, and longer duration of diabetes. Decreased MFV was also associated with microalbuminuria. These findings demonstrated deterioration of basilar artery hemodynamics in patients with type 2 diabetes who have no stroke history. Additionally, repeated TCD may prove to be useful for monitoring cerebrovascular impairments in these patients