The Yang–Mills flow near the boundary of Teichmüller space

We study the behavior of the Yang-Mills flow for unitary connections on compact and non-compact oriented surfaces with varying metrics. The flow can be used to define a one dimensional foliation on the space of representations of a once punctured surface. This foliation universalizes over Teichmüller space and is equivariant with respect to the action of the mapping class group. It is shown how to extend the foliation as a singular foliation over the augmented boundary of Teichmüller space obtained by adding nodal Riemann surfaces. Continuity of this extension is the main result of the paper. Received May 18, 1998 / Revised August 30, 1999 / Published online July 20, 2000     

157-nm Laser ablation of polymeric layers for fabrication of biomolecule microarrays

A new methodology for protein microarray fabrication is proposed based on the ablation of polymer film using laser at 157 nm (F₂). The polymer has been selected among others with the criterion of negligible protein adsorption. Improved results have been obtained by pretreatment of the polymer surface with an inert protein. The use of 157-nm laser radiation allowed very good depth control during the polymeric layer ablation process. In addition the importance of laser ablation at 157 nm is based on the fact that irradiated surfaces indicate limited chemical change due to the fact that laser ablation at 157 nm is only photochemical, thus avoiding excessive surface heating and damage. Results of protein microarray fabrication are presented to illustrate the viability of the proposed method.     

Aromatic gold and silver "rings": hydrosilver(I) and hydrogold(I) analogues of aromatic hydrocarbons

Quantum chemical calculations suggest that a series of molecules with the general formula cyclo-Mn(mu-H)n (M = Ag, Au; n = 3-6) are stable. All cyclo-MnHn species, except cyclo-Au(3)H(3), have the same symmetry with the respective aromatic hydrocarbons but differ in that the hydrogen atoms are in bridging positions between the metal atoms and not in terminal positions. The aromaticity of the hydrosilver(I) and hydrogold(I) analogues of aromatic hydrocarbons was verified by a number of established criteria of aromaticity, such as structural, energetic, magnetic, and chemical criteria. In particular, the nucleus-independent chemical shift, the relative hardness, Deltaeta, the electrophilicity index, omega, and the chemical reactivity toward electrophiles are indicative for the aromaticity of the hydrosilvers(I) and hydrogolds(I). A comprehensive study of the structural, energetic, spectroscopic (IR, NMR, electronic, and photoelectron spectra), and bonding properties of the novel classes of inorganic compounds containing bonds that are characterized by a common ring-shaped electron density, more commonly seen in organic molecules, is presented.     

Keratan sulfate‐containing proteoglycans in sheep brain with particular reference to phosphacan and synaptic vesicle proteoglycan isoforms

Proteoglycans (PGs) are widely expressed in all areas of the brain. In this study, the keratan sulfate‐containing PGs (KS‐PGs) from cerebrum (CB), cerebellum (CL) and brainstem (BS) of young sheep brain were isolated, purified and characterized. The amount of KS‐PGs in CL was significantly lower than that in CB and BS. KS‐PGs were characterized by increased extent of glycosylation and heterogeneity of KS chains in CL. Western blot analyses demonstrated the presence of the KS‐PGs phosphacan, SV2A and SV2B isoforms of synaptic vesicle proteoglycan in all three areas of the young sheep brain. Phosphacan predominated in BS and CB, showing significant molecular heterogeneity. SV2A and SV2B were found in two forms of high and low molecular sizes according to their extent of glycosylation in sheep brain. SV2A predominated in CL, where forms with very high molecular sizes were detected. Immunohistochemical examination revealed that SV2A was localized in the extracellular matrix of both gray and white matter. In contrast, phosphacan and SV2B were mainly localized in the white matter in all brain regions. The results of the present study demonstrated that KS‐PGs are present in the three areas of the sheep brain, showing significant variations in their content, structure and localization among the distinct areas. These differences may be important for the physiology of the brain. Copyright © 2008 John Wiley & Sons, Ltd.     

Experimental study on interfacial waves in stratified horizontal oil–water flow

Interfacial wave characteristics were studied experimentally in horizontal oil–water pipe flows during stratified flow and at the transition to dual continuous flow, where drops of one phase appear into the other (onset of entrainment). The experimental investigations were carried out in a stainless steel test section with 38 mm ID with water and oil (density 828 kg/m³and viscosity 5.5 mPas) as test fluids. Wave characteristics were obtained with a high speed video camera and a parallel wires conductivity probe that measured the instantaneous fluctuations of the interface. Experiments were conducted at 2 m and at 6 m from the inlet. Visual observations revealed that no drops are formed when interfacial waves are absent. It was also found that waves have to reach a certain amplitude before drops can detach from their crests. Wave amplitudes are increased as the superficial velocities of both phases increase. In the stratified region, the mean wave amplitude decreases by increasing the oil–water input ratio while mean wavelength increases as the slip velocity between the two-phase decreases. At the onset of entrainment, the mean amplitude and length are found to be a function of the relative velocity between the oil and water layers and of the turbulence in each layer.     

Free-boundary regularity on the focusing problem for the Gauss Curvature Flow with flat sides

We consider the motion of a compact weakly convex two-dimensional surface of revolution under the Gauss Curvature Flow. We assume that the initial surface has a flat side and as a consequence the parabolic equation describing the motion of the hypersurface becomes degenerate at points where the curvature is zero. Expressing the strictly convex part of the surface near the interface as the graph of a function , we show that if at ti me vanishes linearly at the flat side, then will become smooth up to the interface for $t >0$ and it will remain smooth up to the focusing time T of the flat side. We also show that at the focusing time of the flat side, the function g is of class for all and no better than . This implies that at the focusing time the surface is of class for all $\beta < $ and no better than . In the case of the evolution Monge-Ampère equation, we find the exact self-similar profile of the function g at its focusing time. Received July 1, 1999; in final form February 11, 2000 / Published online April 12, 2001     

Nonradial solvability structure of super-diffusive nonlinear parabolic equations

We study the solvability of the Cauchy problem for the nonlinear parabolic equation

when in , with a given nonnegative function. It is known from earlier works of the authors that the asymptotic radial growth , for the spherical averages of is critical for local solvability, in particular ensuring it if is radially symmetric. We show that if the initial data behaves in polar coordinates like , for large with nonnegative and -periodic, then the following holds: If vanishes on some interval of length 0$">, then there is no local solution of the initial value problem. On the other hand, if such an interval does not exist, then the initial value problem is locally solvable and the time of existence can be estimated explicitly.

     

Synthesis of a proline-rich [60]fullerene peptide with potential biological activity

A proline-rich [60]fullerene peptide was synthesized by use of (i) a 1,3-dipolar cycloaddition of an N-substituted glycine derivative to [60]fullerene, (ii) esterification of the isolated alcohol with the C-terminal amino acid of the desired peptide sequence, and finally (iii) coupling of the remaining hexapeptide to give the final product 8 as a TFA salt, with oxidized methionine. Product 8 was found to be biologically active against sera from MCTD and SLE patients (ELISA experiment).     

Physicochemical study of novel organoclays as heavy metal ion adsorbents for environmental remediation

Four organic-modified clays based on a SWy-2 montmorillonite were prepared by embedding ammonium organic derivatives with different chelating functionalities (NH(2), COOH, SH or CS(2)) in the interlayer space of montmorillonite. Organic molecules such as (a) hexamethylenediamine, (b) 2-(dimethylamino)ethenethiol, (c) 5-aminovaleric acid and (d) hexamethylenediamine-dithiocarbamate were used for the clay modification in order to study the effect of the chelating functionality on heavy metal ions binding from aqueous solutions. The organoclays were characterized by powder X-ray diffraction (XRD), infrared (FTIR) and NMR spectroscopies. The experimental data showed that the organic molecules are intercalated into the interlamelar space with the long dimension parallel to the clay sheets. Their sorbing properties were evaluated for the removal of heavy metals, Pb, Cd and Zn, from aqueous solutions as a function of the pH. When compared with the unmodified SWy-2 montmorillonite, the modified clays show significant improvement in terms of sorbing selectivity as well as of metal loading capacity. The fit to adsorption data by a Surface Complexation Model shows that the intercalated molecules act as specific binding sites in the clay. These contribute additional sorption capacity which is additive to the variable charge edge-sites of the clay in competition with the permanent charge sites.     

Beta-orcinol metabolites from the lichen Hypotrachyna revoluta

Four new beta-orcinol metabolites, hypotrachynic acid (1), deoxystictic acid (2), cryptostictinolide (3) and 8'-methylconstictic acid (4) along with the metabolites 8'-methylstictic acid (5), 8'-methylmenegazziaic acid (6), stictic acid (7), 8'-ethylstictic acid (8) and atranorin (9), that have been previously described, were isolated for the first time from the tissue extracts of the lichen Hypotrachyna revoluta (Fl?rke) Hale. The structures of the new metabolites were elucidated on the basis of extensive spectroscopic analyses. Radical scavenging activity (RSA) of the metabolites isolated in adequate amounts, was evaluated using luminol chemiluminescence and comparison with Trolox.