Protein Adsorption on Derivatives of Hyaluronan

Summary: Serum protein adsorption and fibroblast cell adhesion on photo reactive hyaluronic acid (Hyal-N₃) and its sulfated derivative (HyalS-N₃₎ was analysed using a combination of quartz crystal microbalance (QCM) and cell adhesion assays. There was no significant differences in the amount of protein adsorbed onto the two polymers, however proteins were found to be more loosely bound to HyalS-N₃ compared with Hyal-N₃. Approximately 17% and 31% of the fibronectin interacting with Hyal-N₃ and HyalS-N₃ respectively was found to be irreversibly bound after rinsing with MilliQ water, SDS and urea. Proteins were exposed to the polymers before cell adhesion was monitored for a period of 2 hours in serum free conditions. Minimal cell adhesion was observed on albumin-coated materials as well as serum precoated Hyal-N₃. Precoating the materials with fibronectin enhanced cell adhesion, although HyalS-N₃ experienced higher levels of cell adhesion than Hyal-N₃ and similar results were found for the serum precoated materials.     

Modification of Au surfaces using new ferrocene derivatives

Gold surfaces have been modified by self-assembled techniques. Here the adsorption time of diasteroisomers (1R, 3S)-1-ferrocenyl-3-methyl-4,4-diphenyl-2,5-dioxacyclopentane and (1S, 3S)-1-ferrocenyl-3-methyl-4,4-diphenyl-2,5-dioxacyclopentane (Scheme 1, 3a and 3b) at a Au surface in ethanol solution was controlled. This study was followed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) analysis. The method used for the surface modification was the control of exposure time of a Au surface in the modifier/ethanol solution. It was demonstrated by EIS and XPS that the Au surface was modified with mixture of compounds 3a + 3b, avoiding the electron transference in the interface. It was also observed that the organometallic molecule indeed had been adsorbed on the Au surface. In addition, evidence seems to conclude that the molecule-Au interaction is through the electrons of cyclopentadienyl moiety, where the oxygen atoms are near the air-molecule interface and the iron atom is near the Au surface. This type of interaction of the ferrocene derivatives with gold surfaces has not been reported by any other author.     

Double-layer structure and mechanism of electrode reactions: I. Nitromethane reduction on mercury from aqueous solutions

Kinetic measurements of CH₃NO₂ electroreduction in aqueous solutions of pH values ranging from 1 to 9 were carried out with the polarographic technique under different experimental conditions. In particular, different concentrations of the supporting electrolytes NaClO₄ and NaCl, which are nonspecifically adsorbed at the potentials investigated, or else of the specifically adsorbed electrolyte KI, were employed to change the potential _d at the outer Helmholtz plane and/or the charge density q_i at the inner Helmholtz plane. The effects of these changes between pH 4 and 9 are consistent with a rate-determining protonation step $C{H}_{3}N{O}_2^{?}\stackrel{(+H^{+})}{\to }C{H}_{3}N{O}_{2}H$ taking place within the compact layer. As pH is gradually decreased from 4 to 1, double-layer effects are satisfactorily interpreted by assuming that the control of the overall electrode process passes from the above protonation step to the electron-transfer step CH₃NO₂+e→CH₃NO₂^?, again occurring within the compact layer.     

Structure and stability of (CuNO) isomers

Quantum-mechanical calculations have been performed on various isomers of the (CuNO)⁺ system. A ²Π ground state is found for the linear CuNO⁺ and CuON⁺ isomers and a ²A′ state for the bent CuNO⁺ and CuON⁺ isomers. Energy calculations indicate that the linear CuNO⁺ structure is the most stable, the bent CuNO⁺ and CuON⁺ and the linear CuON⁺ structures are at 0.86 eV, 0.99 eV and 1.04 eV above this respectively. In the CuNO⁺ → CuON⁺ interconversion between the linear isomers, three transition states are involved, whereas the bent CuNO⁺ isomer is found to be an intermediate species. The isomerization barriers, dissociation energies, equilibrium geometries and vibration frequencies are given for all isomers in their ground and first excited states.     

Recursive adaptive control of Markov decision processes with the average reward criterion

We are concerned with Markov decision processes with Borel state and action spaces; the transition law and the reward function depend on anunknown parameter. In this framework, we study therecursive adaptive nonstationary value iteration policy, which is proved to be optimal under thesame conditions usually imposed to obtain the optimality of other well-knownnonrecursive adaptive policies. The results are illustrated by showing the existence of optimal adaptive policies for a class of additive-noise systems with unknown noise distribution.This research was supported in part by the Consejo Nacional de Ciencia y Tecnología under Grants PCEXCNA-050156 and A128CCOEO550, and in part by the Third World Academy of Sciences under Grant TWAS RG MP 898-152.     

An efficient synthesis of chalcones based on the Suzuki reaction

A general method for the synthesis of chalcones based on the Suzuki reaction either between cinnamoyl chlorides and phenylboronic acids or between benzoyl chlorides and phenylvinylboronic acids is described.     

Organic synthesis with sulfones XXXII. A convenient route to α,β -unsaturated sulfones from saturated sulfones.

α-sulfonyl litiated anions are oxidized by cupric carboxylates into β, β-unsaturated sulfones. Primary sulfones lead to pure trans-vinylic sulfones.