Identification and structural characterization by LC-ESI-IONTRAP and LC-ESI-TOF of some metabolic conjugation products of homovanillic acid in urine of neuroblastoma patients

The levels of urinary catecholamine metabolites, such as homovanillic acid (HVA) and vanillylmandelic acid, are routinely used as a clinical tool in the diagnosis and follow-up of neuroblastoma (NB) patients. Recently, in the Clinical Pathology Laboratory Unit of G. Gaslini Children Hospital, a commercial method that employs liquid chromatography coupled to electrochemical detection (LC-EC) has been introduced for the measurement of these metabolites in the routine laboratory practice. Using this LC-EC method, an unknown peak could be observed only in samples derived from NB patients. To investigate the nature of this peak, we used a combination of liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) and liquid chromatography-ion trap tandem mass spectrometry (LC-IT-MS). The first approach was used to obtain the elemental composition of the ions present in this new signal. To get additional structural information useful for the elucidation of unknown compounds, the ion trap analyzer was exploited. We were able to identify not just one, but three unknown signals in urine samples from NB patients which corresponded to three conjugated products of HVA: HVA sulfate and two glucuronoconjugate isomers. The enzymatic hydrolysis with β-glucuronidase confirmed the proposed structures, while the selective alkaline hydrolysis allowed us to distinguish the difference between phenol- and acyl-glucuronide of HVA. The latter was the unknown peak observed in LC-EC separations of urine samples from NB patients.     

Expectations of Fermionic Fields with N Components

In this Letter, we show with a concrete example that the behaviour in N independent components (flavours) of the expectation of fermionic fields can be different from that suggested by its expansion in terms of Feynman graphs. To prove this result, we study the asymptotic behaviour of a nonautonomous discrete time map.     

Multiscale Formalism for Correlation Functions of Fermions. Infrared Analysis of the Tridimensional Gross–Neveu Model

We present a multiscale formalism for fermionic systems (with a smooth UV cutoff ) establishing a trivial link between the correlation functions and the effective potential flow, and study the k-point truncated functions of the tridimensional Gross–Neveu model. A new efficient method is used to bound these correlation functions and show polynomial tree decay for long distances. We are guided by a block lattice mechanism with a property of orthogonality between terms in different scales, which leads to simple formulas for the correlations.     

X-ray photoelectron spectroscopic study of poly[4,4′-isopropylidenebis(1,4-phenyleneoxyethylene) diacrylate] photocured in the presence of a fluorine containing monomer

A preliminary X-ray photoelectron spectroscopic (XPS) investigation on poly[4,4′-isopropylidenebis(1,4-phenyleneoxyethylene) diacrylate] samples obtained by photocuring on several substrates in the presence of a fluorine containing acrylic monomer is reported. Quantitative calculations based on F_1s/C_1s area ratios and C_1s peak fitting show a noticeable fluorine surface enrichment that ranges, depending on the substrate, from 17 wt.-% to 59 wt.-% of fluorine containing moiety. The calculations also reveal the presence of a concentration gradient at the surface.     

Engineered Green Fluorescence Proteins for Proteomics and Biomolecular Electronic Applications

The discovery of the photochromic characteristics of engineered green fluorescent proteins (GFPs) allows new proteomics and biomolecular electronic applications. In particular, photoreversibility among two distinct optical states can lead to the realization of a bio-optical high density storage memory. Here we review our recent work on an optically bistable GFP and we report the recent developments of self-assembly methods for spatial immobilization of proteins into well-definite 2D patterns.     

Preparation of coatings via cationic photopolymerisation: influence of alcoholic additives

Coatings obtained through photopolymerisation of vinylethers, propenyl ethers and epoxy resins are described. The influence of alcohols and of comonomers bearing OH groups on the cationic mechanism of the curing process is discussed. The final properties of the coatings are evaluated and correlated to the structures of the additives.     

PTFE nanoemulsions as ultralow-k dielectric materials

Modern integrated circuits require insulating materials with a dielectric constant as low as possible in order to obtain device speed improvements through lower RC delay. We have investigated the electrical and structural properties of PTFE thin films obtained from Algoflon^®-PTFE nanoemulsions, via spin coating deposition, followed by sintering. Films as thin as 160 nm with dielectric strength better than 4 MV/cm have been obtained.