A vibrationally resolved C 1s(-1) auger spectrum of CO2

The high-resolution Auger spectrum of CO(2) subsequent to C 1s(-1) photoionization is reported along with the corresponding photoelectron spectrum. Auger transitions to seven quasi-stable final states are observed. They are assigned on the basis of theoretical results in combination with the assumption that the Auger spectrum is dominated by transitions to singlet states. From the vibrational progressions in the Auger spectrum, the vibrational energies h omega, the anharmonicities xh omega and the equilibrium distances R(e) for the dicationic final states are derived in a fit analysis assuming Morse potentials

Statistical properties of inter-series mixing in helium: From integrability to chaos

The photoionization spectrum of helium near the double-ionization threshold shows structure which indicated a transition towards quantum chaos

Evolutionary mix-and-match with MFS transporters II

One fundamentally important problem for understanding the mechanism of coupling between substrate and H(+) translocation with secondary active transport proteins is the identification and physical localization of residues involved in substrate and H(+) binding. This information is exceptionally difficult to obtain with the Major Facilitator Superfamily (MFS) because of the broad sequence diversity of the members. The MFS is the largest and most diverse group of transporters, many of which are clinically important, and includes members from all kingdoms of life. A wide range of substrates is transported, in many instances against a concentration gradient by transduction of the energy stored in an H(+) electrochemical gradient using symport mechanisms, which are discussed herein. Crystallographic structures of MFS members indicate that a deep central hydrophilic cavity surrounded by 12 mostly irregular transmembrane helices represents a common structural feature. An inverted triple-helix structural symmetry motif within the N- and C-terminal six-helix bundles suggests that the proteins may have arisen by intragenic multiplication. In the work presented here, the triple-helix motifs are aligned in combinatorial fashion so as to detect functionally homologous positions with known atomic structures of MFS members. Substrate and H(+)-binding sites in symporters that transport substrates, ranging from simple ions like phosphate to more complex peptides or disaccharides, are found to be in similar locations. It also appears likely that there is a homologous ordered kinetic mechanism for the H(+)-coupled MFS symporters