Quantum mechanical scattering calculations on a spline-fitted ab initio surface: the He + H+2 (ν = 0, 1, 2) → HeH+ + H reaction

All-channel time-dependent quantum mechanical reaction probabilities are reported for the collinear He + H⁺₂(ν = 0, 1, 2) → HeH⁺ + H reaction at a total energy of 1.2 eV on previously reported diatomics-in-molecule (DIM) and spline fitted ab initio (SAI) surfaces. These results are in agreement with the previous quasiclassical trajectory results in that there is vibrational enhancement of the reaction probability on the SAI surface but not on the DIM surface. This agreement lends support to our previously drawn conclusion that small differences in the potential-energy surface can lead to substantially different dynamic results.     

Non-linear relaxation methods: III. Current-controlled perturbations

A functional expression is derived valid for evaluating all orders of perturbation in potential when a current of known profile is super-imposed. Generalised expressions for the distortion and the rectification potential are given. The problems of “iR-drop” and “charging current” compensation are also discussed.     

Polarographic reduction behaviour of copper in the presence of 1-amino-3-methoxypropane and 2-dimethylaminoethanol

1-Amino-3-methoxypropane (3MPA) and 2-dimethylaminoethanol (DMAE) are potential volatile amines for boiler water treatment and were investigated for their complexation behaviour with copper. Their pK_b values were 3.67 and 4.52 at 25°C and they formed coloured complexes with absorption in the region of 644 and 510 nm, respectively. In the pH range 10–11, the Cu-3MPA complex exhibited stepwise reduction and [Cu(3MPA)₂]⁺ was identified, with a stability constant of 10^9.52. In the pH range 8–10.5, the Cu-DMAE complex exhibited 2e^? reduction and the species [Cu(DMAE)₂(OH)₂] was identified, with a stability constant of 10^20.39. A correlation between visible and ESR spectra and reduction behaviour was established.     

Tuning the physical properties of a nematic liquid crystal elastomer actuator

In this report we demonstrate the ability to tune the physical properties of a liquid crystal elastomer (LCE) by varying the amount and type of crosslinking within the elastomer network. LCE films composed of a single mesogenic compound were capable of uniaxial contraction when thermally actuated through the nematic to isotropic phase of the material. We probed the physical properties of the LCE films while varying the amount and concentration of two crosslinking agents and measured actuation strains of 10–35%, elastic moduli of 3–14 MPa, and transition temperatures ranging between 75 and 60°C. The viscous losses of the elastomers and the estimated work capable of being produced by the films were also evaluated. The ability to tune the physical properties of the LCE films allows for a wide range of applications including robotics, microelectromechanical systems (MEMS), shape‐changing membranes, and/or microfluidics.     

An Easy Access to Oxime Ethers by Pd‐Catalyzed C—O Cross‐Coupling of Activated Aryl Bromides with Ketoximes and Chalcone Oximes

An efficient Pd‐catalyzed method for C—O cross‐coupling of ketoximes and chalcone oximes with activated aryl bromides and bromo‐chalcones has been developed. All oxime ethers were obtained in good to excellent yields by [(π‐allyl)PdCl]₂/tBuXPhos ( L7 ) catalyst system. TrixiePhos ( L11 ) was also found to be effective for the oxime coupling. This method offers an easy and smooth coupling of chalcone oximes with activated aryl bromides and bromo‐chalcones, which has not been previously explored.     

Improved measurement of the form factors in the decay lambda+c-->lambda + nue

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay lambda(+)(c)lambda--> e(+)nu(e). By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R= f(2)/f(1) = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M(pole) = [2.21 +/- 0.08(stat) +/- 0.14(syst)] GeV/c(2), and the decay asymmetry parameter of the lambda(+)(c), alpha (lambda(c)) = -0.86 +/-0.03(stat) +/- 0.02(syst), for q(2) = 0.67 (GeV/c(2))(2). We compare the angular distributions of the lambda(+)(c) and lambda(-)(c) and find no evidence for CP violation: A(lambda(c)) = (alpha(lambda(c)) + alpha (lambda(c)))/(alpha(lambda(c))-alpha(lambda(c))) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A(lambda), for ppi(-).     

Glycosylation of the Arg-gingipains of Porphyromonas gingivalis and comparison with glycoconjugate structure and synthesis in other bacteria

Post-translational modification of proteins by covalent attachment of sugars to the protein backbone (protein glycosylation) is the most common post-translational modification in the eucaryotic cell. However, the addition of carbohydrates to proteins of Eubacteria and Archaea has been demonstrated and accepted only recently. There is now a rapidly expanding list of bacterial glycoproteins that have been characterised from a variety of different organisms including many important pathogens. The Arg-gingipains of Porphyromonas gingivalis are recent additions to this list. In this review we present a summary of our investigations on the structure of the glycan additions to these proteolytic enzymes, the genetics of the glycosylation process and some of the effects on enzyme function and recognition. These findings are placed in the context of the current status of understanding of glycoconjugate structure and synthesis in other bacteria. Given the importance of glycosylation of eucaryotic proteins to their stability, structure, resistance to proteolysis and recognition, the modifications to the proteases described in the present report are likely to have a functional role in the properties of these enzymes in periodontal disease.     

Many-body effects in electrochemisorption: Part IV. Multi-boson formalism

Several channels provided by many-body couplings — both fermion-fermion and fermion-boson — for the evolution of the chemisorption system are discussed. This provides an opportunity of a systematic study of the effects of correlations reflected through the intricate pole structure of the absorbate Green functions. The results of Newns, Anda and others in the context of chemisorption are generalized.