In this paper, we have investigated the surface energy and adhesion of one functional PFPE (Zdol) and two series of nonfunctional PFPEs (Z and D) on carbon-overcoated disk surfaces. The effects of end group functionality, backbone chain flexibility, molecular weight, and film thickness were systematically examined. Our results indicated that nonfunctional PFPEs have weak attraction with carbon overcoat. However, due to backbone chain effect, Z has slightly stronger attraction than D. Based on the surface energy analyses and bonded thickness results, schematic bonding models were proposed, which indicate strong hydrogen bonding∕ordered packing structure∕low mobility for functional PFPE films and weak attraction∕less-ordered packing structure∕high mobility for nonfunctional PFPE films.

The photochemical reactivity of alkyl phenylglyoxylates has been investigated using time-resolved step-scan Fourier transform infrared spectroscopy. The time-resolved FTIR spectra of hexane solutions of methyl (MPG), ethyl (EPG), and isopropyl (iPPG) phenylglyoxylates and benzene solutions of MPG display two major transient absorption peaks in the carbonyl fundamental region around 1661 and 2105 cm -1 . On the basis of the spectroscopic and kinetic evidence, the 1661 cm -1 transitions are assigned to the carbonyl fundamental of the triplet state of the corresponding alkyl phenylglyoxylate. The 2105 cm -1 band is attributed to the carbonyl stretch of R-hydroxyphenyl ketene, which is the postulated intermediate of the intramolecular hydrogen abstraction in alkyl phenylglyoxylates. These assignments are supported by the results of DFT calculations. From kinetic time profiles for the two observed transient infrared bands, the rate constants for the intra-and intermolecular γ-hydrogen abstraction were obtained and compared for methyl, ethyl, and isopropyl phenylglyoxylates. The reasons for the difference between the rate constants for glyoxylates and aromatic ketones are discussed. † Part of the special issue "George S. Hammond & Michael Kasha Festschrift". Dedicated in honor of George S. Hammond, whose brilliant insights are the basis for this work, on the occasion of his 81st birthday. Also in honor of Prof. Dr. J. W. Neckers, on the occasion of his 101st birthday and 80th year in science.

In conclusion, chitosan glutamate (1-3%) and chitosan glutamate (1%)/EDTA-Na2 (0.01%) are effective excipients to increase permeability of acyclovir across Caco-2 cell monolayers and the oral absorption in the rat in vivo.

Thickness and structure of Z03, Z-Dol, Z-tetraol and AM2001 lubricant layers dip-coated on amorphous carbon surfaces were studied as a function of the dwell time in solution and the pull-out speed. The results demonstrate that the lubricant layer is formed via the joint action of surface adsorption and viscous flow mechanisms. Surface adsorption creates the bonded layer in the case of functionalized lubricants, whose thickness was found to be dependent on dwell time. The observed kinetics of the surface adsorption was described as a reversible second order process. The viscous flow mechanism is responsible for the formation of the mobile layer, whose thickness only depends on the pull-out speed.

No abstract