Detailed normal‐coordinate analysis has been carried out on a large number of conformers of model molecules of poly(oxyethylene); the model molecules treated are CH3(OCH2CH2)nOCH3 with n = 2,3, and 6. The systematic treatment provides well‐defined correlations between conformation and vibrational spectra of poly(oxyethylene). The vibrations in the region 1050–800 cm−1, which are associated with the CO and CC stretching and CH2 rocking modes, are highly dependent on the conformation of the polymer chain. On the basis of these correlations, the infrared and Raman spectra of the molten state and of the aqueous solution are interpreted in terms of the conformational states. The analysis indicates that the following conformational fragments are present in these phases: GT‐TG (T: trans; G: gauche), TT‐TG, GT‐GG, TT‐TT, and TT‐GG for the CH2CH2OCH2CH2 group, and TGT and TGG for the OCH2CH2O group. Conformational fragments GT‐TG′ and GT‐G′G′ are also possible in the analogy to GT‐TG and GT‐GG.

No abstract

The newly developed population pharmacokinetic model should improve the quality of serum concentration monitoring of high-dose MTX to predict and control toxic events.

No abstract

Hydration of the oxyethylene chain was studied by a Brillouin-scattering method; hypersonic velocities in aqueous solutions of CH3(OCH2CH2)mOCH3 with m=1–4 and CH3(OCH2CH2)mOH with m=2 and 3 were measured. The concentration of the solution, at which the sound velocity gave a maximum value, led to the number of water molecules, at the highest hydration, per ether linkage in the oxyethylene chain. The experimental results showed that 1.8 water molecules take part in the hydration of each –CH2OCH2– group and that the number of the water molecules is virtually constant independently of the oxyethylene-chain length as far as the number of the oxyethylene units is limited up to four. These findings indicate that a sort of hydration complex of approximately 1 –OCH2CH2–:2 H2O is formed in the aqueous solution. It is suggested that the stabilization of the gauche conformation for the OCH2–CH2O group in aqueous solution, as evidenced by Raman-spectroscopic observations, is promoted greatly by the hydrogen bond of water molecules which are bridged between the adjacent ether oxygens in the oxyethylene chain.