Quantum chemical DFT study of 4-azatricyclo [5.2.2.02,6] undecane-3,5,8-trione

Fourier-transform-Raman and infrared spectrum of 4-azatricyclo [5.2.2.0^2,6] undecane-3,5,8-trione were recorded and analyzed. The vibrational wavenumbers were examined theoretically using the Gaussian03 set of quantum chemistry codes, and the normal modes were assigned by potential energy distribution (PED) calculations. The first hyperpolarizability, predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with reported values of similar structures which makes this compound an attractive object for future studies of nonlinear optics. Optimized geometrical parameters of the compound are in agreement with similar reported structures. The red shift of the NH stretching wavenumber in the infrared spectrum from the computational wavenumber indicates the weakening of NH bond.     

Electrophoretic deposition of bacterial cells

The possibility to use alternating current electrophoretic deposition (AC-EPD) to deposit living cells in the form of Staphylococcus aureus and Escherichia coli on stainless steel was assessed. The experimental results revealed that these bacteria can be successfully deposited on metallic surfaces from demineralized water and sucrose based solutions using asymmetric unbalanced electric fields. Cell viability of the deposited bacteria was influenced by the strain and deposition medium.     

Removal of the PsaF Polypeptide Biases Electron Transfer in Favor of the PsaB Branch of Cofactors in Triton X‐100 Photosystem I Complexes from Synechococcus sp. PCC 7002†

Continuous wave (CW) and transient electron paramagnetic resonance studies have implied that when PsaF is removed genetically, the double reduction of A_1A is facile, the lifetime of A_1A^? is shorter and the ratio of fast to slow kinetic phases increases in PS I complexes isolated with Triton X‐100 (Van der Est, A., A. I. Valieva, Y. E. Kandrashkin, G. Shen, D. A. Bryant and J. H. Golbeck [2004] Biochemistry 43 , 1264–1275). Changes in the lifetimes of A_1A^? and A_1B^? are characteristic of mutants involving the quinone binding sites, but changes in the relative amplitudes of A_1A^? and A_1B^? are characteristic of mutants involving the primary electron acceptors, A_0A and A_0B. Here, we measured the fast and slow phases of electron transfer from A_1B^? and A_1A^? to F_X in psaF and psaE psaF null mutants using time‐resolved CW and pump‐probe optical absorption spectroscopy. The lifetime of the fast kinetic phase was found to be unaltered, but the lifetime of the slow kinetic phase was shorter in the psaF null mutant and even more so in the psaE psaF null mutant. Concomitantly, the amplitude of the fast kinetic phase increased by a factor of 1.8 and 2.0 in the psaF and psaE psaF null mutants, respectively, at the expense of the slow kinetic phase. The change in ratio of the fast to slow kinetic phases is explained as either a redirection of electron transfer through A_1B at the expense of A_1A, or a shortening of the lifetime of A_1A^? to become identical to that of A_1B^?. The constant lifetime and the characteristics of the near‐UV spectrum of the fast kinetic phase favor the former explanation. A unified hypothesis is presented of a displacement of the A‐jk(1) α‐helix and switchback loop, which would weaken the H‐bond from Leu₇₂₂ to A_1A, accounting for the acceleration of the slow kinetic phase, as well as weaken the H‐bond from Tyr₆₉₆ to A_0A, accounting for the bias of electron transfer in favor of the PsaB branch of cofactors.     

Two remarks on generalized hexagons

In this paper, the point-distance-2-regular hexagons are characterized as the only hexagons for which the intersection sets have size one and containing on ovoidal subspace all the points of which are 3-regular. We also give a characterization of the finite split Cayley hexagon of even order.     

Combined Routeing and Scheduling for the Transportation of Containerized Cargo

A tractor-trailer problem, with full load, from the class of combined routeing and scheduling problems is described. Distinctive features of the problem are: movements must be carried out within certain time windows; subsets of movements are linked in the sense that they must be executed in a certain order; and different priorities are attached to different movements. A new bidirectional sequential constructive heuristic is developed for the solution of this problem. The method constructs routes and schedules for the available tractor fleet. The algorithm attempts to minimize the total time for all the movements by minimizing the time taken up by unproductive movements (so-called deadhead) and waiting time between movements. Some practical aspects of the implementation of the approach are discussed.