Transient absorption of vibrationally excited ice <em>Ih</em>

The ultrafast dynamics of HDO:D2O ice Ih at 180 K is studied by midinfrared ultrafast pump-probe spectroscopy. The vibrational relaxation of HDO:D2O ice is observed to proceed via an intermediate state, which has a blueshifted absorption spectrum. Polarization resolved measurements reveal that the intermediate state is part of the intramolecular relaxation pathway of the HDO molecule. In addition, slow dynamics on a time scale of the order of 10-100 ps is observed, related to thermally induced collective reorganizations of the ice lattice. The transient absorption line shape is analyzed within a Lippincott-Schroeder model for the OH-stretch potential. This analysis identifies the main mechanism behind the strong spectral broadening of the vOH=1-->2 transition

Synthesis and Spectroscopic Characterization of 1,​8-​Naphthalimide Derived "Super" Photoacids

The ground- and excited-​state acid-​base properties of three novel naphthalimide-​based "super" photoacids were studied using steady-​state and time-​resolved spectroscopy. The compds. exhibit pKa = 8.8-​8.0 and pK*a = -​1.2 to -​1.9. The decrease in both ground- and excited-​state pKa is achieved by attachment of an electron withdrawing group (sulfonate) on the arom. system. All compds. are deprotonated upon excitation in alcs. and DMSO. Good correlation is established between the pK*a and the ratio of the neutral and anion emission intensities in a certain solvent. The excited-​state intermol. proton transfer to solvent (H2O and DMSO) is explained by a two-​step model. In the first step, short-​range proton transfer takes place, resulting in the formation of a contact ion pair. Free ion pairs are formed in the diffusion controlled second step

Organizing product-oriented environmental management from a resource-based perspective

More and more the biophysical environment is being acknowledged as a critical business concern, while the environmental performance of products is becoming increasingly important to all parts of the product chain. Systematical attempts to decrease the environmental impact of a product throughout its life cycle could contribute to a firm's sustainable development potential, since product-oriented environmental management (POEM) addresses different themes of sustainable industrial development. POEM is defined as an approach to organizing a firm in such a way that improving the environmental performance of its products and processes becomes an integral part of both operations and strategy

Packaging signals in single-stranded RNA viruses: nature’s alternative to a purely electrostatic assembly mechanism

The formation of a protective protein container is an essential step in the life-cycle of most viruses. In the case of single-stranded (ss)RNA viruses, this step occurs in parallel with genome packaging in a co-assembly process. Previously, it had been thought that this process can be explained entirely by electrostatics. Inspired by recent single-molecule fluorescence experiments that recapitulate the RNA packaging specificity seen in vivo for two model viruses, we present an alternative theory, which recognizes the important cooperative roles played by RNA–coat protein interactions, at sites we have termed packaging signals. The hypothesis is that multiple copies of packaging signals, repeated according to capsid symmetry, aid formation of the required capsid protein conformers at defined positions, resulting in significantly enhanced assembly efficiency. The precise mechanistic roles of packaging signal interactions may vary between viruses, as we have demonstrated for MS2 and STNV. We quantify the impact of packaging signals on capsid assembly efficiency using a dodecahedral model system, showing that heterogeneous affinity distributions of packaging signals for capsid protein out-compete those of homogeneous affinities. These insights pave the way to a new anti-viral therapy, reducing capsid assembly efficiency by targeting of the vital roles of the packaging signals, and opens up new avenues for the efficient construction of protein nanocontainers in bionanotechnology