A combination of crystallographic and mutagenesis studies on the HERG K+ channel, a key determinant of cardiac excitability, has suggested how the protein's extramembraneous amino-terminal domain might act as a 'molecular brake' that slows down channel deactivation.

We revisit the HD molecular ion by starting from a definition of the nonrelativistic adiabatic Hamiltonian that recovers the isotopic splitting. The Hamiltonian is written in prolate spheroidal coordinates with the origin at the nuclear center of mass. This prescription for the adiabatic Hamiltonian implicitly contains the symmetrybreaking effects arising from the mass difference between the pr...

Sir: In our laboratories two strategies for obtaining mass spectra of involatile and/or thermally unstable natural products have been used. One is an optimization of sample vaporization, which involves rapid sample heating followed by thermal desorption and ionization under chemical ionization (CI) conditions, that is emitter CI mass spectrometry (emitter CIMS). Recently, we have reported a pre...

We present high-precision non-relativistic variational calculations of bound vibrational-rotational state energies for the H2 + and D2 + molecular ions in each of the lowest electronic states of Σg, Σu, and Πu symmetry. The calculations are carried out including coupling between Σ and Π states but without using the Born-Oppenheimer or any adiabatic approximation. Convergence studies are present...

We have investigated the solvation shell dynamics of Na and Cl ion pairs in water DMSO mixtures of three compositions with xDMSO (mole fraction of DMSO) = 0.21, 0.35 and 0.48. Dynamical ion pair trajectories in these compositions are studied to analyze the diffusional behaviour of the solvent molecules in the primary and secondary solvation shells as well as the bulk solvent. As expected, the d...

The combination of mass spectrometry and ion mobility spectrometry (IMS) employing a temperature-variable drift cell or a drift tube divided into sections to make IMS-IMS experiments possible allows information to be obtained about the molecular dynamics of polyatomic ions in the absence of a solvent. The experiments allow the investigation of structural changes of both activated and native ion...

We present a new algorithm for vibrational control in deuterium molecules that is feasible with current experimental technology. A pump mechanism is used to create a coherent superposition of the D2 vibrations. A short, intense infrared control pulse is applied after a chosen delay time to create selective interferences. A ‘chessboard’ pattern of states can be realized in which a set of evenor ...

Using a simple model it is shown that the cost of constraining a hydrated potassium ion inside a narrow nanopore is smaller than the cost of constraining the smaller hydrated sodium ion. The former allows for a greater distortion of its hydration shell and can therefore maintain a better coordination. We propose that in this way the larger ion can go through narrow pores more easily. This is re...

Purification of extra-cellular cellulolytic enzymes from C e l l u l o mssp. strain 0, isolated from forest soil in the north of Iran , was studied by using gel filtration and ion-exchange chromatography. Two endo-glucanases (Endo-I & Endo-II) and one exo-glucanase (Exo-I) were purified to hornogenity . The purified enzymes had molecular weights of about 39.000,70.000 and 90.000 daltons for ...