Synthesis of substituted quinolines by electrophilic cyclization of N-(2-alkynyl)anilines

Quinolines substituted in the 3-position by an iodo or phenylseleno group are readily prepared in good to excellent yields by the reaction of propargylic anilines with appropriate electrophiles under mild reaction conditions. [reaction: see text]     

Evidence for muon neutrino oscillation in an accelerator-based experiment

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).     

Elliptic Problems with Singular Potential and Double-Power Nonlinearity

We prove the existence of positive symmetric solutions to the semilinear elliptic problem

Mapping phosphorylation sites: a new strategy based on the use of isotopically labelled DTT and mass spectrometry

Phosphoproteomics, nowadays, represents a front line in functional proteomics as testified by the number of papers recently appearing in the literature. In an attempt to improve and simplify the methods so far suggested we have set up a simple isotope-coded approach to label and quantitate phospho-Ser/-Thr residues in protein mixtures. First of all, after appropriate oxidation of cysteine/cystine residues followed by tryptic hydrolysis, we have optimised and simplified the beta-elimination reaction to get the corresponding alkene moiety from the phosphate esters. This was achieved by (a) separating the elimination reaction from the addition reaction, (b) the use of Ba(OH)(2) as alkali reagent and (c) its further elimination by the simple addition of solid CO(2) to the peptide mixture. The Michael reaction was then performed, after the removal of BaCO(3) by centrifugation, by adding dithiothreitol (DTT) to the peptide mixture. Finally, the direct purification of the modified phosphopeptides was performed on a thiol-sepharose column. The availability of fully deuterated DTT, introducing a 6 Da difference with respect to the non-deuterated species, allows quantitation of the differential extent of signalling modification when analysed by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) and liquid chromatography/mass spectrometry. The entire procedure has been set up by using bovine alpha-casein, and resulted in the identification of all the phosphorylated tryptic peptides, including the tetraphosphorylated peptides, which escaped all previously reported procedures     

Synthesis of fused polycycles by 1,4-palladium migration chemistry

Novel palladium migration/arylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that these palladium-catalyzed C-H activation reactions parallel electrophilic aromatic substitution.     

Spectroscopic ellipsometry study of liquid crystal and polymeric thin films in visible and near infrared

In this work, we propose spectroscopic ellipsometry as a suitable method for measuring optical properties in soft materials, polymers and liquid crystals, specially selected for use in photonics applications. We show the results of our measurements on some multilayered samples, in the range from visible to the near-IR region, of interest for telecom applications. We point out potentialities and limits of the technique and compare the obtained results with another experimental method, the m-lines spectroscopy, and/or with existing data in the literature. The results about the optical parameters for the analysed materials (the nematic liquid crystal 5CB, one commercial and one lab made optical polymer, and an Indium Tin Oxide film) are useful and interesting by themselves. In fact, as a paradigmatic example, we briefly discuss how an incomplete knowledge of this kind of data can lead to a wrong design of a Bragg grating device. However, more than in the provided data, we put the interest of the present analysis in the warnings about spectroscopic ellipsometry utilization and eventually the necessity of getting complementary information.Received: 13 May 2004, Published online: 29 June 2004PACS: 78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) - 78.66.Qn Polymers; organic compounds - 07.60.Fs Polarimeters and ellipsometers     

Chirped-pulse oscillators: a route to high-power femtosecond pulses without external amplification

We demonstrate a Kerr-lens mode-locked Ti:sapphire oscillator that generates 130-nJ, 26-fs and 220-nJ, 30-fs pulses at a repetition rate of 11 MHz. The generation of stable broadband, high-energy pulses from an extended-cavity oscillator is achieved by the use of chirped multilayer mirrors to produce a small net positive dispersion over a broad spectral range. The resultant chirped picosecond pulses are compressed by a dispersive delay line that is external to the laser cavity. The demonstrated peak powers, in excess of 5 MW, are to our knowledge the highest ever achieved from a cw-pumped laser and are expected to be scalable to tens of megawatts by an increase in the pump power and (or) a decrease in the repetition rate. The demonstrated source permits micromachining of any materials under relaxed focusing conditions.     

BSE control: detection of gelatine-derived peptides in animal feed by mass spectrometry

The epidemic of bovine spongiform encephalopathy (BSE) is thought to have resulted from feeding scrapie-infected sheep to cattle. This has led to a ban of feeding animals with "processed animal protein"(PAP). We report a novel approach for the mass spectrometric detection of PAP contamination in animal feedstuffs by detecting gelatine, a derivative of the major animal protein collagen. A method was developed to hydrolyse gelatine standards with hydrochloric acid, followed by detection of the derived hydrolytic peptides at m/z 828, 915, 957 and 1044 by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS-MS). The marker peptides can be detected at concentrations of 100 ng ml(-1) gelatine in water with MALDI. The procedure was adapted to obtain a suitable peptide map of gelatine extracted from spiked feed. The ratio of signal area of the gelatine-derived peptide at m/z 1044 to the internal standard at m/z 556 is shown to relate to the total amount of gelatine present in the sample.     

Using micelles for a new approach to fluorescent sensors for metal cations

A new approach based on self-assembly inside micelles has been individuated to prepare a system behaving as a water-operating selective fluorescent sensor for Cu2+ and Ni2+.