Orthogonally Protected, Carboxy-Activated L-Homoisoserine, 2-Methyl-L-homoisoserine, and Homoisocysteine Derivatives. New Building Blocks for Peptide and Depsipeptide Modification

Starting from L-malic, L-citramalic, and rac. thiomalic acids routes to L-homoisoserine, 2-methyl-L-homoisoserine and rac. homoisocysteine have been developed. The new orthogonally protected and carboxy-activated building blocks are GABA as well as -hydroxy and -mercapto acid derivatives, suitable for the construction of peptide and depsipeptide surrogates.     

Study of hadronic events inpp collisions at\sqrt s = 62GeV and comparison with hadronic events ine + e − collisions

We present an analysis of minimum bias events from proton-proton collisions at \(\sqrt s = 7GeV\) in the CERN ISR. We remove the effects of both the leading protons and compare theB=0 mesonic residue of the events to the hadronic events of similar energy produced ine ⁺ e ^? collisions. This comparison is presented in terms of the standard jet-type analyses involving quantities such as sphericity and aplanarity. We find significant differences between these data and the data frome ⁺ e ^? annihilations. The data of this experiment are consistent with the predictions of a longitudinal phase space model.     

Production of vector and tensor mesons in proton-proton collisions at\sqrt s = 52.5 GeV

Inclusive production of ?⁰,f, andg ⁰ mesons and ofK _s ⁰ ,K ^*0 (892), ? andK ^*0(1430)mesons has been measured at <y>～2.6 and <p _T >～1.1 GeV/c in proton-proton interactions at \(\sqrt s = 52.5\) GeV. The negative particle from the two-body decays of these resonances were identified by a threshold Cerenkov counter and used for triggering. Starting from the measured differential cross section, total inclusive cross sections for the vector and tensor mesons were determined using various parametrizations for they andp _T dependence of the differential cross section. The experimental results are discussed in the framework of production models based on the parton picture. The strangeness suppresion factor λ=(0.30±0.10) due toSU(3) symmetry breaking of the quark sea is derived.     

Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods

Pristine and WO₃ decorated TiO₂ nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO₂ NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO₂ NRs and thermally oxidised to obtain WO₃ nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO₂ NRs with WO₃.     

Characterization of a peptide family from the skin secretion of the Middle East Tree Frog Hyla savignyi by composition‐based de novo sequencing

A new tryptophyllin‐like peptide family was found in the skin secretion of the tree frog Hyla savignyi. Peptides were characterized by database‐independent sequencing strategies and specific ion fragmentation features were investigated. Skin secretions from specimens of Hyla savignyi were collected by mild electrical stimulation. Peptides were separated by reversed‐phase nano‐high‐performance liquid chromatography (nanoHPLC) and mass spectra were acquired online by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS). Peptides were characterized by manual de novo sequencing and by composition‐based sequencing (CBS), appearing mostly as C‐terminal free acids and as their acid amide analogs. Amide peptides yielded lower intensities of y‐type ions after collision‐induced dissociation (CID) than their acid analogs. A mechanism of internal b‐ion formation (positive ion mode) and of CO₂ elimination (negative ion mode) is proposed. We also exemplified phenomena such as the proline effect and formation of non‐direct sequence ions after sequence rearrangements. The occurrence of rearrangement products, of internal ions and of the proline effect made the CID spectra highly complex. CBS analysis nevertheless resulted in successful and highly reliable sequence analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Hexafluoroacetone as Protecting and Activating Reagent. A New Approach to N-Glycosides

N-Glycosides of Asn and homologues have been synthesized starting from hexafluoroacetone-protected -activated Asp, Glu, and Aad derivatives and glycosylamines. The synthetic value of the new building blocks was demonstrated by the concise incorporation of N-glycosylated Asn, Gln, and Aad -amides into glycopeptides.     

Analytical scale ultrasonic standing wave manipulation of cells and microparticles

The ultrasonic standing-wave manipulation of suspended eukaryotic cells, bacteria and submicron latex or silica particles has been examined here. The different systems, involving plane or tubular ultrasonic transducers and a range of acoustic pathlengths, have been designed to treat suspension volumes of analytical scale i.e. 5 ml to 50 microliters for both sample batch and 'on-line' situations. Frequencies range from 1 to 12 MHz. The influence of secondary cell-cell interaction forces in determining the cell concentration dependence of harvesting efficiency in batch sedimentation systems is considered. Applications of standing wave radiation forces to (1) clarify cell suspensions, (2) enhance particle agglutination immunoassay detection of cells or cellular products and (3) examine and enhance cell-cell interactions in suspension are described.