A new approach to impedance atomic spectroscopy

Resonant laser-induced changes of the dielectric constant of atomic or molecular gases are detected as deviations in the oscillation frequency of a circuit including the sample itself as a component. Heterodyne detection allows high sensitivity. The new non-intrusive technique is demonstrated in the spectroscopic investigation of neon and sodium atoms.Work partially supported by ENEL under contract n. U 815     

Su un tipo di applicazioni fra varietà differenziabili con atlante omografico

Si caratterizzano dal punto di vista geometrico due tipi di trasformazioni fra varietà differenziabili con atlante omografico e se ne ricavano le equazioni.     

Polyamides in solution. III. Viscometry of linear polycaprolactam

The viscometric behavior of linear polycaprolactam has been studied in the absence of the electroviscous effect in aqueous solvents containing 85% and 64.5% formic acid and in trifluoroethanol, as a function of temperature and also under unperturbed conditions. Results are discussed in terms of the existing theories; in particular, the negative temperature coefficient of the intrinsic viscosity arises only from the variation of the expansion coefficient, the molecule in the unperturbed state being a normal random coil. The absence of aggregation and draining effects in the above solvents has been varified.     

Double-reciprocal plot for enzyme-multiplied immunoassays

Enzyme-multiplied immunoassay systems can be described by a non-competitive enzyme-inhibition model, which allows a double-reciprocal plot to be used to interpolate the standard curve. Double-reciprocal linear parameters are related to the reagent composition of the assay mixture. The derived equation is validated by experimental data. This model can be used in addition to traditional approaches (logit/log or four parameters) to monitor assay conditions.     

Working methods: Complete extraction of arsenic species: a worthwhile goal?

Some issues regarding sample preparation for arsenic speciation analyses are briefly discussed. In particular, the use of a single set of extraction conditions for the many different arsenicals present in biological samples is questioned. Copyright © 2003 John Wiley & Sons, Ltd.     

LC–MS–MS Determination of Stabilizers and Explosives Residues in Hand-Swabs

The contribution of explosive trace detection in samples from the hands of suspects has been fundamental in several forensic cases involving terrorists. This paper describes a method for the rapid extraction and unequivocal confirmation of some high potential explosives (trinitrotoluene, cyclotrimethylenetrinitramine, pentaerythritol tetranitrate, nitroglycerin) and two stabilizer (diphenylamine and ethylcentralite) residues in hand-swabs using liquid chromatography–tandem mass spectrometry. The extraction procedure of the analytes from the swabs is realized by solvent elution and the extracts are directly analyzed. Recoveries from spiked swabs range from 78 to 96%; the limits of quantification are between 0.04 and 1.8 ng injected and the inter-day method precision is less than 15%. The developed procedure was applied to the detection of explosives traces in samples after handling tests.     

Aminopyrrolic Synthetic Receptors for Monosaccharides: A Class of Carbohydrate‐Binding Agents Endowed with Antibiotic Activity versus Pathogenic Yeasts

The biological activity of a set of structurally related aminopyrrolic synthetic receptors for monosaccharides has been tested versus yeast and yeast‐like microorganisms and compared to their binding affinity toward mannosides. Antibiotic activity comparable to that of well‐known polyene (amphotericin B) or azole (ketoconazole) drugs has been found for some members of the family, along with a general correlation with binding abilities. A systematic structure–activity–affinity investigation shed light on the structural and functional requirements necessary for antibiotic activity and identified the tripodal compound 1 as the most potent compound of the set. Together with toxicity tests and inhibitor localization experiments performed through fluorescence microscopy, these studies led to the characterization of a new class of carbohydrate binding agents possessing antibiotic activity, in which pyrrolic groups precisely structured on a tripodal architecture appear to be responsible for permeability through the cell wall of pathogens, as well as for antibiotic activity inside the cytoplasm.