Improved perturbed uncoupled Hartree-Fock (IUCHF) methods for second-order physical properties

Two different kinds of improved uncoupled Hartree-Fock methods (IUCHF-I and IUCHF-II) are proposed for the calculation of second-order physical properties. These methods provide a better approximation to the coupled Hartree-Fock (CHF) second-order energy than the ordinary uncoupled Hartree-Fock (UCHF) theory.     

A study on the inhibition of cellulolytic activities by lignin

It is well known that cellulolytic enzymes hardly attack lignocellulose. Hitherto knowledge, however, has not yet fully elucidated the mechanisms of the inhibition; whether it depends on a steric hindrance or protein-binding inhibition. For the purpose of acceleration of enzymatic digestion of lignocellulose biomass, the study was carried out using partially purified cellulase of Meicelase and milled wood lignin from soft or hard wood. Milled wood lignin was prepared from soft wood,Picea jezoensis, or from hard wood,Quercus serrata, by the method of Björkman. Lignin was dissolved in methyl cellosolve, since the solvent has little effect on cellulolytic activities, and enzymic activities were followed with partially purified Meicelase. The results show that cellobiose activities of enzymes fromTrichoderma viride are markedly depressed by both lignin of soft and hard wood, and the former lignin inhibits the reaction stronger than the latter. Lignins show no inhibition in the reaction with CMC and debris of filter paper. Liberation of glucose from filter paper by the enzyme in the presence of lignin is also depressed, and addition of cellobiase instead of lignin in the above enzyme reaction shows the delay of time for breakdown of filter paper. This phenomenon indicates that lignin inhibits enzymic decomposition of cellobiose in the degradation pathway of cellulose and accumulated cellobiose gives a feedback function to digestion of fibers of paper.     

Recoil effects in high-energy photoemission beyond single-site approximation

Recoil effects of photoelectrons excited by high-energy X-rays are studied beyond the simplest approximation where elastic scatterings of photoelectrons are completely neglected (single-site approximation). At first we have shown that the simple free atom energy shift is accurately obtained within the harmonic and the single-site approximations. Beyond the single-site approximation, this simple formula does not work, but still simple classically acceptable formula can be used to explain the recoil energy shift. Illustrative numerical calculations show that the energy shifts caused by the photoelectron diffraction amounts to 5–8 meV for graphite-like carbon and about 100 meV for LiI₆${\text{LiI}}_6$ cluster at _?k=5${?}_k=5$–7 keV, and show oscillations as functions of the photoelectron energy. Furthermore we discuss the recoil effects in photoemission from extended levels by use of the tight-binding approach. Our approach naturally provides not only Debye–Waller factors but also the recoil factors. In addition to the phonon excitation, we also study the recoil effects associated with plasmon losses where intrinsic and extrinsic processes can interfere each other. Only the latter can contribute to the recoil energy shift.     

Total synthesis of lamellarins D, L, and N

Total synthesis of cytotoxic marine alkaloids, lamellarins D, L, and N, has been achieved by using Hinsberg-type pyrrole synthesis and palladium-catalyzed Suzuki-Miyaura coupling of the 3,4-dihydroxypyrrole bistriflate 6 as the key reactions. The total yields of lamellarins D, L, and N from the common intermediate 6 are 54, 58, and 50%, respectively.     

Compact optical duplicate system for satellite-ground laser communications: application of averaging effects

In recent years, there has been considerable interest in satellite-ground laser communication due to an increase in the quantity of data exchanged between satellites and the ground. However, improving the quality of this data communication is necessary as laser communication is vulnerable to air fluctuation. We first verify the spatial and temporal averaging effects using light beam intensity images acquired from middle-range transmission experiments between two ground positions and the superposition of these images using simulations. Based on these results, we propose a compact and lightweight optical duplicate system as a multi-beam generation device with which it is easy to apply the spatial averaging effect. Although an optical duplicate system is already used for optical correlation operations, we present optimum design solutions, design a compact optical duplicate system for satellite-ground laser communications, and demonstrate the efficacy of this system using simulations.     

Self-regulated Ni cluster formation on the TiO2(1 1 0) terrace studied using scanning tunneling microscopy

We have studied the growth mode and morphology of Ni clusters on a TiO₂(1 1 0) surface with a wide terrace using scanning tunneling microscopy (STM) at a low coverage (less than 3 atoms nm⁻²). The Ni clusters are formed on the terrace at the low coverage of 0.2 atoms nm⁻². Their average dimensions are constant in three directions up to 1 atoms nm⁻². The Ni clusters have an oval shape with average sizes of 1.8 nm (along [0 0 1]) × 1.4 nm (along (in the [1 1 0] directions). Above the coverage of 1.0 atoms nm⁻², an increase in the cluster height occurs, retaining an almost constant lateral size. It is proposed that the interaction of the Ni cluster and the support surface regulates the Ni cluster size.     

Origin of the stability of Ge(105) on si: a new structure model and surface strain relaxation

The structure of Ge(105)-(1 x 2) grown on Si(105) is examined by scanning tunneling microscopy (STM) and first-principles calculations. The morphology evolution with an increasing amount of Ge deposited documents the existence of a tensile surface strain in Si(105) and its relaxation with increasing coverage of Ge. A detailed analysis of high-resolution STM images and first-principles calculations produce a new stable model for the Ge(105)-(1 x 2) structure formed on the Si(105) surface that includes the existence of surface strain. It corrects the model developed from early observations of the facets of "hut" clusters grown on Si(001).