On all-optical laser cleaning and inspection of contaminated concave metal surfaces

A technique for all-optical laser cleaning and surface quality monitoring of concave metal surfaces is suggested. Contaminated pharmaceutical punches from a tablet compression machine were cleaned using high-energy laser pulses. Image information obtained from a diffractive-optical-element-based sensor was used in inspection of the surface quality change of the concave punches due to laser cleaning. Alternative method for mechanical cleaning of punches is introduced, which is based on simultaneous laser cleaning and surface quality inspection of the punches.     

Review: Different types of ordering

Homogeneous structures A_xB_y with identical A–A or B–B self‐coordination numbers T₁, T₂, T₃, of nearest, next‐nearest and third neighbors are selected. The maximum T_i values are 2 2 2 (1D row), 6 6 6 (2D hexagonal net) and 12 6 24 (3D cubic close‐packing). Reduced T₁ or T₂ values for A_xB_y can be related with attractive or repulsive A–A (or B–B) interactions. A single set of T₁ T₂ T₃; y/x values was obtained for y/x = 1–4 and 6. The y/x = 2 structures of three equivalent positions A, B and C are unfavourable for A = ⊕ and B = ⊖ charge or direction of magnetic moments. The spatial distribution of positive and negative potential near A⁺ and B⁻ positions gives rise to neutral C positions. Frustrated magnetic moments at C positions are disordered. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

ASAXS study of styrene‐grafted sulfonated poly(vinylidene fluoride) membranes

Small‐angle and wide‐angle X‐ray scattering and anomalous small‐angle X‐ray scattering were used to investigate proton‐conducting membranes prepared by radiation‐induced styrene grafting and sulfonation of commercial poly(vinylidene fluoride) (PVDF‐g‐PS) films. The membranes retain the lamellar and highly oriented structure of the original PVDF films even through excessive grafting and sulfonation. The sulfonate groups aggregate in the central part of the amorphous layers, where they form a weakly ordered structure that does not show any preferred orientation. This structure is suggested to be lamellar with alternate metal‐sulfonated hydrate and PVDF‐g‐PS layers. The lamellar period is 15.1 Å. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1734–1748, 2000     

Lamellar thickening in nascent poly(acrylonitrile) upon annealing

No systematic study has been reported on the lamellar thickening in atactic poly(acrylonitrile) (PAN) upon annealing because PAN, in the form of solution‐cast films or their drawn products, generally shows no small‐angle X‐ray scattering (SAXS) maximum corresponding to the lamellar thickness. In this work, PAN crystals were precipitated during the thermal polymerization of acrylonitrile in solution. The nascent PAN film, obtained by the filtration of the crystal suspension, exhibited a clear SAXS maximum revealing the lamellar structure. The lamellar thickening upon annealing of the nascent PAN films was studied in the temperature range 100–180 °C, where the degradation was minimal, as confirmed by the absence of an IR absorption band at 1605 cm⁻¹ ascribed to the cyclized nitrile groups. Above 190 °C, the degradation of the samples was significant, and the SAXS became too broad to determine the scattering maximum. The long period was significantly affected by the annealing time (t_a) and the temperature (T_a). Depending on t_a, three stages were observed for the lamellar thickening behavior. The lamellar thickness stayed constant in stage I (t_a = 0.5–3 min, depending on T_a), rapidly increased in stage II (t_a = 0.5–8 min), and stayed at a constant value characteristic for each T_a at yet longer t_a's in stage III. The lamellar thickness characteristic for T_a increased rapidly with increasing T_a at 165 °C (or higher), which was 152 °C lower than the estimated melting temperature of PAN (T_m = 317 °C). A possible mechanism for such lamellar thickening in PAN far below the T_m is discussed on the basis of the enhanced chain mobility in the crystalline phase above the crystal/crystal reversible transition at 165–170 °C detected by differential scanning calorimetry and wide‐angle X‐ray diffraction. The structural changes associated with annealing are also discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2571–2579, 2000     

In Situ X-Ray Diffraction Study of the Initial Stages of Formation of MCM-41 in a Tubular Reactor

A continuous process for the synthesis of mesoporous silicates such as MCM-41 at room temperature has been achieved by employing a tubular reactor in which tetraethoxysilane was used as the silicate source (see schematic representation below). The formation of the hexagonal mesophase, which was monitored by using in situ XRD at different points of the tube, was completed in three minutes after mixing of the reactants. The product was stable to calcination, and N₂-sorption measurements confirmed the high surface area and narrow pore-size distribution.     

Unusual behavior in light scattering experiments of poly(<Emphasis Type="Italic">N</Emphasis>-vinylimidazole) prepared by precipitation polymerization

Poly(N-vinylimidazole) (PVI) was synthesized by the precipitation polymerization using 2,2’-azobis(isobutyronitrile) (AIBN; initiator) and benzene (solvent) at two different monomer/initiator ratios. The solution polymerization was also performed with the following initiator/solvent systems: AIBN/water–methanol mixture (1:1 by volume) and 4,4’-azobis(4-cyanovaleric acid)/aqueous HCl solution (pH 0.8). All the four preparations of PVI in ethanol and in 0.2 M NaCl (pH 3 with HCl) were examined by dynamic light scattering (DLS). The CONTIN analysis of DLS data for each preparation from the solution polymerization showed a unimodal distribution in both ethanol and aqueous solvents. A good agreement was obtained between the molar masses in these different solvents by static light scattering (SLS). However, the polymers from the precipitation polymerization exhibited a heterogeneous bimodal distribution in DLS under the same conditions as above, indicating that the SLS data as in reference [6] (Savin et al. Macromolecules 37:6565) cause a serious error in the understanding of solution behavior of PVI.     

Chemical and Genetic Study of Ligularia cyathiceps in Yunnan Province of China

Root chemicals and evolutionarily neutral DNA regions in L. cyathiceps samples collected in the Zhongdian (Shangrila) County of Yunnan, P. R. China, were examined. Twenty compounds were isolated, including three new ones, 1β,10β‐epoxy‐6β‐(propionyloxy)furanoeremophilan‐9‐one ( 6 ), 1β,10β‐epoxy‐8α‐ethoxyeremophila‐6,11‐diene ( 14 ), and 11αH‐6β‐isobutyryloxy‐1β,10β,7β,8β‐diepoxyeremophilan‐12,8α‐olide ( 15 ). The chemical diversity was found to be limited, with cacalol ( 1 ) and 6‐(acyloxy)furanoeremophilan‐9‐ones ( 4 and/or 5 ) being major components in all the samples. The nuclear ribosomal RNA gene was also found to harbor little variation, although two distinct sequence types were found for the plastid atpB‐rbcL intergenic region.     

A note on Markov type constants

We prove that, if a geodesic metric space has Markov type 2 with constant 1, then it is an Alexandrov space of nonnegative curvature. The same technique provides a lower bound of the Markov type 2 constant of a space containing a tripod or a branching point. Received: 28 November 2007     

4-(Pyrrolidinyl)methoxybenzoic acid derivatives as a potent, orally active VLA-4 antagonist

A novel series of benzoic acid derivatives as VLA-4 antagonists were synthesized. Optimization, focusing on activity and lipophilicity needed for cell permeability, resulted in the identification of 15b and 15e with good activity (IC50 = 1.6 nM each) and moderate lipophilicity (Log D = 2.0, 1.8). Furthermore, 15e demonstrated efficacy in murine asthma model by an oral dose of 30 mg/kg.     

Development of a lattice-sum method emulating nonperiodic boundary conditions for the treatment of electrostatic interactions in molecular simulations: a continuum-electrostatics study

Artifacts induced by the application of periodic boundary conditions and lattice-sum methods in explicit-solvent simulations of (bio-)molecular systems are nowadays a major concern in the computer-simulation community. The present article reports a first step toward the design of a modified lattice-sum algorithm emulating nonperiodic boundary conditions, and therefore exempt of such periodicity-induced artifacts. This result is achieved here in the (more simple) context of continuum electrostatics. It is shown that an appropriate modification of the periodic Poisson equation and of its boundary conditions leads to a continuum-electrostatics scheme, which, although applied under periodic boundary conditions, exactly mimics the nonperiodic situation. The possible extension of this scheme to explicit-solvent simulations is outlined and its practical implementation will be described in more details in a forthcoming article.