A two-level additive Schwarz method for the Morley nonconforming element approximation of a nonlinear biharmonic equation

In this paper, we consider the well known Morley nonconformingelement approximation of a nonlinear biharmonic equation whichis related to the well-known two-dimensional Navier–Stokesequations. Firstly, optimal energy and H¹-norm estimates areobtained. Secondly, a two-level additive Schwarz method is presentedfor the discrete nonlinear algebraic system. It is shown thatif the Reynolds number is sufficiently small, the two-levelSchwarz method is optimal, i.e. the convergence rate of theSchwarz method is independent of the mesh size and the numberof subdomains.     

Electronic spectroscopy of highly polar aromatics. XI. Luminescence of the cyanoanilines

The absorption and emission spectra of the three isomeric cyanoanilines have been investigated. Quantum yields and decay lifetimes are reported for both fluorescence and phosphorescence processes. It is shown that the lowest energy absorption band of p-cyanoaniline consists of two distinct electronic transitions of the ¹π^*←¹π type, whereas, in the o- and m-cyanoanilines, the lowest energy absorption band consists of a single electronic transition of the ¹π^*←¹π type. These conditions are consistent with absorption data, emission data and kinetic analyses. The largest ?_P/?_F ratio is exhibited by the p-cyanoaniline and this observation is rationalized.     

Rapid near-infrared Raman spectroscopy system for real-time in vivo skin measurements

A rapid dispersive-type near-infrared (NIR) Raman spectroscopy system and a Raman probe were developed to facilitate real-time, noninvasive, in vivo human skin measurements. Spectrograph image aberration was corrected by a parabolic-line fiber array, permitting complete CCD vertical binning, thereby yielding a 3.3-16-fold improvement in signal-to-noise ratio. Good quality in vivo cutaneous NIR Raman spectra free of interference from fiber fluorescence and silica Raman scattering can be acquired in less than 1 s, which greatly facilitates practical noninvasive tissue characterization and clinical diagnosis.     

Creep and thermal cycling fixture design for metal matrix composites

A creep-thermal cycling system with a constant stress cam has been designed to be inexpensive and easily fabricated in order to identify the creep and thermal-cycling damage mechanisms in metal-matrix composites (MMCs) with high ductility. The current system can be modified to be a stress thermal cycling (or fatigue) system.     

In vivo video rate multiphoton microscopy imaging of human skin

We present a multiphoton microscopy instrument specially designed for in vivo dermatological use that is capable of imaging human skin at 27 frames per second with 256 pixels × 256 pixels resolution without the use of exogenous contrast agents. Imaging at fast frame rates is critical to reducing image blurring due to patient motion and to providing practically short clinical measurement times. Second harmonic generation and two-photon fluorescence images and videos acquired at optimized wavelengths are presented showing cellular and tissue structures from the skin surface down to the reticular dermis.     

Synthesis, structure, and biological evaluation of C-2 sulfonamido pyrimidine nucleosides

The C-2 sulfonamido pyrimidine nucleosides were prepared by opening the 2,2′- or 2,3′-bond in anhydronucleosides under nucleophilic attack of sulfonamide anions. Reaction of the sodium salt of p-toluenesulfonamide or 2-(aminosulfonyl)-N,N-dimethylnicotinamide with 2,2′-anhydro-1-(β-d-arabinofuranosyl)cytosine gave the C-2 sulfonamido derivatives in excellent yields. Ring opening of the less reactive 2,2′-anhydrouridine and 2,3′-anhydrothymidine could be accomplished with DBU/CH₃CN activation of p-toluenesulfonamide, giving moderate yields for C-2 sulfonamido derivatives. The action of acetic acid or ZnBr₂/CH₂Cl₂ on 5-methyl-N²-tosyl-1-(2-deoxy-5-O-trityl-β-d-threo-pentofuranosyl)isocytosine led to the cleavage of both the protection group and the nucleoside bond, yielding 5-methyl-N²-tosylisocytosine as the major product. Structures of the prepared C-2 sulfonamido nucleosides were confirmed by the 1D and 2D NMR experiments, and X-ray structural analysis of 4-imino-N²-tosylamino-1-(β-d-arabinofuranosyl)pyrimidine. Both methods confirmed β-configuration and anti-conformation of the 2-sulfonamido nucleosides. The investigated compounds displayed moderate inhibition of tumor cell growth in vitro, as determined by the MTT assay using six different human tumor cell lines.     

Stabilization of the N-1-substituted cytosinate iminooxo form in dinuclear palladium complexes

The synthesis, as well as chemical and structural characterization, of 1-(p-toluenesulfonyl)cytosine (1) and its dinuclear complexes of the composition Pd₂(1-TosC^?–N3,N4)₄ (3) and Pd₂(1-TosC^?–N3,N4)₂DMSO₂Cl₂ (4) by means of ESI-MS, IR, ¹H NMR and X-ray single crystal analysis are described. Ligand 1 exists in the preferred aminooxo tautomeric form, while both dinuclear complexes reveal the presence of the iminooxo form of the ligand, where 1-TosC^? stands for the anion of the cytosine derivative of 1, bridging two palladium atoms. Complex 3 has a paddlewheel structure with two square-planar coordination spheres, consisting of four N atoms each, mutually parallel and perpendicular to the interpalladium vector. Complex 4 is characterized by two mutually parallel square-planar coordination spheres consisting of two nitrogens, sulfur from the solvent molecule and a chloride. A feasible chemical route for the formation of 3 and 4 via the kinetically favoured mononuclear complex Pd(1-TosC–N3)₂Cl₂ (2) is proposed, based on the IR, ¹H NMR, mass spectrometry, elemental analysis and X-ray structure analysis data.     

Combined X-ray diffraction and QM/MM study of the Burkholderia cepacia lipase-catalyzed secondary alcohol esterification

To understand the origin of high enantioselectivity of Burkholderia cepacia lipase (BCL) toward secondary alcohol, (R,S)-1-phenoxy-2-hydroxybutane (1), and its ester (E1), we determined the crystal structure of BCL complexed with phosphonate analogue of S-E1 and accomplished a series of MM, MC, and QM/MM studies. We have found that the inhibitor in the S configuration binds into the BCL active site in the same manner as the R isomer, with an important difference: while in case of the R-inhibitor the H-bond between its alcohol oxygen and catalytic His286 can be formed, in the case of the S-inhibitor this is not possible. Molecular modeling for both E1 enantiomers revealed orientations in which all hydrogen bonds characteristic of productive binding are formed. To check the possibility of chemical transformation, four different orientations of the substrate (two for each enantiomer) were chosen, and a series of ab initio QM/MM calculations were accomplished. Starting from the covalent complex, we modeled the ester (E1) hydrolysis and the alcohol (1) esterification. The calculations revealed that ester release is possible starting with all four covalent complexes. Alcohol release from the BCL-E1 complex in which the S-substrate is bound in the same manner as the S-inhibitor in the crystal structure however is not possible. These results show that the crystallographically determined binding modes should be taken with caution when modeling chemical reactions.