Numerical analysis of a moving boundary problem in coastal hydrodynamics

A finite element model to tackle the moving boundary problem of wave run-up on moderately steep slopes is developed. The special aspects considered in this study are (1) the modification of shallow water equations to accommodate the effect of vertical accelerations and (2) the use of Lagrangian acceleration coupled with an element that adapts itself to the moving boundary closely. The pressure term in the one-dimensional momentum equation is derived using the Eulerian equation in the vertical direction. This takes care of the vertical accelerations which are significant during the motion of a wave on moderately steep slopes. The element near the boundary is allowed to change its dimension so that the fluid boundary is closely followed. Such a flexible element precludes the need for approximation of the variables with regard to the indefinite position of the boundary. This element is split into two when its dimension becomes unduly large compared to the unchanging elements. The need for such a splitting is shown by an examination of the entries in the global matrix. Results of water profile as a wave runs up a structure are given. A brief history of the work on similar problems is outlined.     

Optimal design of loudspeaker arrays for robust cross-talk cancellation using the Taguchi method and the genetic algorithm

An optimal design technique of loudspeaker arrays for cross-talk cancellation with application in three-dimensional audio is presented. An array focusing scheme is presented on the basis of the inverse propagation that relates the transducers to a set of chosen control points. Tikhonov regularization is employed in designing the inverse cancellation filters. An extensive analysis is conducted to explore the cancellation performance and robustness issues. To best compromise the performance and robustness of the cross-talk cancellation system, optimal configurations are obtained with the aid of the Taguchi method and the genetic algorithm (GA). The proposed systems are further justified by physical as well as subjective experiments. The results reveal that large number of loudspeakers, closely spaced configuration, and optimal control point design all contribute to the robustness of cross-talk cancellation systems (CCS) against head misalignment.     

A luminescent chemosensor with specific response for Mg2+

A novel chemosensor, a cyclometalated platinum(II) bipyridyl acetylide complex containing a monoazacrown moiety in the acetylide ligand, which can signal Mg(2+) specifically and display large changes both in color and in luminescence intensity upon complexation with Mg(2+), is described.     

Photocatalytic hydrogen production from hantzsch 1,4-dihydropyridines by platinum(II) terpyridyl complexes in homogeneous solution

1,4-Dihydropyridines have been photocatalytically oxidized to pyridines by platinum(II) terpyridyl complexes with the generation of hydrogen in homogeneous solution. The hydrogen production proceeds in quantitative yield and with great catalytic turnover.     

A first eigenvalue estimate for embedded hypersurfaces

Suppose that M is a compact orientable hypersurface embedded in a compact n-dimensional orientable Riemannian manifold N. Suppose that the Ricci curvature of N is bounded below by a positive constant k. We show that 2λ₁>k−(n−1)maxM|H| where λ₁ is the first eigenvalue of the Laplacian of M and H is the mean curvature of M.     

Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase: A chemistry–biology interdisciplinary study of the protein's structure–function–reaction mechanism relationships

The oxidosqualene cyclases (EC 5.4.99‐) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)‐2,3‐oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure–function relationships of the Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase‐catalyzed cyclization/rearrangement reaction. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 302–325; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20157     

Straightforward access to new vinca-alkaloids via selective reduction of a nitrile containing anhydrovinblastine derivative

A procedure to exclusively obtain 3′S-cyanoanhydrovinblastine 12 from two naturally occurring vinca-alkaloids (catharanthine and vindoline) in one step with good yield is described. Stereoselective reductions of 12, providing straightforward access to three new vinca-alkaloids, including two diastereomers 3′S-cyano-(4′R,5′-dihydro)-anhydrovinblastine and 3′S-cyano-(4′S,5′-dihydro)-anhydrovinblastine as well as (3′S-aminomethyl)-(4′S,5′-dihydro)-anhydrovinblastine in good yields is also reported.     

Copper ferrite superparamagnetic nanoparticles as a heterogeneous catalyst for directed phenol/formamide coupling

The copper ferrite-catalyzed, directed coupling of ortho-arylated phenols and dialkylformamides in the presence of a peroxide oxidant is described. Acyclic and cyclic amides were compatible with the reaction conditions. The copper ferrite catalyst is heterogeneous since substantial leaching was not detected and re-use of the catalyst for 9 consecutive reactions proceeded without a significant decrease in yield. To the best of our knowledge, this transformation has not been previously performed under heterogeneous catalysis conditions.     

A molecular dynamics simulation of a homogeneous organic-inorganic hybrid silica membrane

A new molecular dynamics simulation method was successfully applied to construct a homogeneous organic-inorganic hybrid silica membrane using the hybrid-pcff (h-pcff) potential function. Analysis suggested that the hybrid BTESE silica membrane provided a looser network and larger cavity size for the enhancement of gas permeability and selectivity.     

Asymmetric orbital-lattice interactions in ultrathin correlated oxide films

Using resonant x-ray spectroscopies combined with density functional calculations, we find an asymmetric biaxial strain-induced d-orbital response in ultrathin films of the correlated metal LaNiO3 which are not accessible in the bulk. The sign of the misfit strain governs the stability of an octahedral "breathing" distortion, which, in turn, produces an emergent charge-ordered ground state with an altered ligand-hole density and bond covalency. Control of this new mechanism opens a pathway to rational orbital engineering, providing a platform for artificially designed Mott materials.