Search

A facile and automated solid-phase procedure for the labeling of oligonucleotides at the terminus with a substitutionally inert transition metal complex such as Ru(bpy)(sub 3)(super 2+) is discussed. Time-resolved step-scan Fourier transform infrared (S2FTIR) studies of the Ru(II) trisdiimine complex reveal the excited-state electron to be localized on the amide-substituted bipyridine. The metallo-oligonucleotides are well suited for energy- and electron transfer studies with complementary oligonucleotides containing quenchers such as Os(bpy)32+ or phenothiazine.

The facile preparation of a ruthenium-labeled nucleoside was reported. Spectroscopic studies of 5-(Ru(bpy)2-(4-m-4'-pa-bpy))2+-2'-deoxyuridine showed that favorable photophysical properties associated with Ru(bpy)(sub 3)(super 2+), such as being a potent oxidant and reductant in its excited state and possessing a significant, excited state lifetime, were retained. In addition, the excited electron was localized on the uridine-modified bipyridine, the excited-state dipole was directed toward the nucleoside and the excited state was long-lived.

Time-resolved vibrational spectroscopies were used on a series of questions connected with excited-state structure in the metal-to-ligand charge transfer (MLCT) excited states of polypyridyl complexes. These complexes contain bpy ligands which are either symmetrically or unsymmetrically derivatized with electron-withdrawing ester or amide substituents. Vibrational data obtained elucidated on the identification of the acceptor ligand, the localization or delocalization of the excited electrons, polarization in unsymmetrically subsituted acceptor ligands and excited-state electronic distribution.

Copyright of Journal of the American Institute for Conservation is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Previous studies on antigen-stimulated calcium changes in rat basophilic leukemia (RBL)-2H3 cells showed that calcium responses varied from cell to cell, and that this difference was due to the presence of antigens. Herein, a highly constrained mathematical model for calcium oscillations provided evidence that calcium responses in antigen-stimulated RBL-2H3 cells are determined by fluxes in the plasma membrane.

This study investigated the feasibility of substituting core layer strands of randomly oriented strand boards (OSB) with waste wood particles with respect to CSA 0437–Series 93 Standards on OSB and Waferboard requirements. Standard core layer strands have been substituted with four different levels (0, 25, 50 and 100%) of waste wood particles. Several mechanical properties of the OSB have been tested. Overall, it could be demonstrated that waste wood particles can successfully be used in the core layer of OSB. All properties met the requirements of CSA 0437-Series 93, except for thickness swell (TS) and water absorption (WA). From a mechanical and physical board properties perspective, it is possible to substitute up to 100% of the core layer strands in randomly OSB panels with unsorted contaminated waste wood particles. However, results showed high density variability within boards and between different core compositions. Internal bond (IB) met the standard's requirements, showed significant differences between the waste wood proportions and increased with the level of waste wood particles. The modulus of elasticity (MOE) and modulus of rupture (MOR) also met the requirements, and decreased with increasing waste wood particle levels. [ABSTRACT FROM AUTHOR]

Step-scan FTIR time-resolved spectroscopy (S(super 2)FTIR TRS) in acetonitrile-d(sub 3) is used to determine the acceptor ligand in metal-to-ligand charge transfer (MLCT) excited states of amide-substituted polypyridyl complexes of Ru(super II) and in analogues appended to polystyrene. The changes in v(C=O) for amide substituents between the ground and excited states confirm that the excited-state dipole orientation can be directed toward or away from the chemical link to the polymer by exploiting substituent effects.