Parabolic equations with non–linear, degenerate and space–time dependent operators

In this paper existence and regularity results for a class of degenerate nonlinear parabolic equations are proved. Indeed, the diffusion operator may degenerate as the solution diverges and may depend on space and time variables in a non–regular way, too. Some estimates on the behaviour of the solutions for t → +∞ are also given.     

Studies on oxidation of ergot alkaloids: oxidation and desaturation of dihydrolysergol—stereochemical requirements

A new method for the oxidation of ergoline alcohols to aldehydes was found (TFFA-DMSO, −78 °C, then DIPEA). Structural features of ergolines required for successful C7-C8 double bond introduction via Polonovski-Potier reaction of respective 6-N-oxides were defined and experimentally confirmed: (i) the presence of electron-withdrawing group at C-8; (ii) trans-diaxial orientation of N6-O and C7-H bonds (both requirements are fulfilled for dihydrolyserg-17-al and its 2,4-dinitrophenyl hydrazone prepared in this work).     

The Storing Matter technique: Preliminary results on PS and PVC

The Storing Matter technique has been developed recently in SAM to perform quantitative analyses with high sensitivity: the sample to be analysed is sputtered by ion bombardment and up to a sub-monolayer of emitted particles is deposited on a collector. In the present work, this collector is subsequently analysed by static Secondary Ion Mass Spectrometry (SIMS). We concentrate on the conservation of the molecular information throughout the deposition and analysis processes. The experiments are realised on PS and PVC films. The deposits have been clearly identified on the collector. The molecular information is partially conserved throughout the deposition and analysis processes. Higher fragmentation in the mass spectra of the collectors is due to double fragmentation in the sputter-deposition and analysis steps.     

Novel route to styrene/p‐aminostyrene copolymers

A novel route to styrene/p‐aminostyrene copolymers is described that involves the introduction of amino functionality into the structure of pure monodisperse polystyrene. The simple two‐step synthesis involves the introduction of a bromo group into the aromatic ring by electrophilic substitution and then a palladium‐catalyzed reaction with LiN(SiMe₃)₂ followed by an acid and base treatment to release the free amine. All reactions are carried out at room temperature. This approach avoids the difficulties often associated with the preparation of copolymers from incompatible monomers. The technique also gives a product with a precisely known molecular weight and polydispersity, important parameters governing many physical properties. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1282–1286, 2007     

Guanine Substitutions Prevent Conformational Switch from Antiparallel to Parallel G-Quadruplex

Guanine quadruplexes, recently reported to form in vivo, represent a broad spectrum of non-canonical conformations of nucleic acids. The actual conformation might differ between water solutions and crowding or dehydrating solutions that better reflect the conditions in the cell. Here we show, using spectroscopic techniques, that most guanine substitutions prevent the conformational switch from antiparallel or hybrid forms to parallel ones when induced by dehydrating agents. The inhibitory effect does not depend on the position of the substitution, but, interestingly, on the type of substitution and, to some extent, on its destabilising potential. A parallel form might be induced in some cases by ligands such as N-methyl mesoporphyrin IX and even this ligand-induced switch is inhibited by guanine substitution. The ability or inability to have a conformation switch, based on actual conditions, might significantly influence potential conformation-dependent quadruplex interactions.     

Skew Clifford algebras

We introduce a generalization, called a skew Clifford algebra, of a Clifford algebra, and relate these new algebras to the notion of graded skew Clifford algebra that was defined in 2010. In particular, we examine homogenizations of skew Clifford algebras, and determine which skew Clifford algebras can be homogenized to create Artin-Schelter regular algebras. Just as (classical) Clifford algebras are the Poincaré-Birkhoff-Witt (PBW) deformations of exterior algebras, skew Clifford algebras are the ${\mathbb{Z}}_2$-graded PBW deformations of quantum exterior algebras. We also determine the possible dimensions of skew Clifford algebras and provide several examples.     

Chirality-Controlled Self-Assembly of Amphiphilic Dibenzo[6]helicenes into Langmuir–Blodgett Thin Films

Racemic and highly enantioenriched 3-methoxycarbonyl, 3-carboxy, and 3-hydroxymethyl derivatives of dibenzo[6]helicene were prepared. The Langmuir layers of these helicenes were formed at the air–water interface and transferred onto solid substrates to afford Langmuir–Blodgett films, which were then studied by ambient atomic force microscopy and (chir)optical spectroscopy. Significant differences were found in the behaviour of the Langmuir layers as well as in the morphology, UV/Vis, electronic circular dichroism (ECD), and fluorescence spectra of the Langmuir–Blodgett thin films depending on the molecular chirality and nature of the polar group. The experimental results were supported by molecular dynamics simulations.