Numerical analysis of GeO2-concentration effects in arc-induced long-period fiber gratings under external refractive-index changes

We present a numerical analysis of the response of arc-induced long-period fiber gratings (LPFGs) under ambient refractive-index changes using standard fibers with SiO₂ as cladding material and different GeO₂ concentration in the SiO₂-GeO₂ doped core. We obtain that the LPFG-sensitivity is increased using lower GeO₂ concentrations and it follows a parabolic behavior. Also, we identify two linear regimes using an external index of 1.37: for GeO₂ concentrations between 2 and 3.5 mol %, the LPFG-sensitivity changes with a rate of 3.614 nm per mole fraction of GeO₂, while for higher concentrations the sensitivity changes with a rate of 1.39 nm/mol %. Additionally, for fibers with 2 mol% of GeO₂, the sensitivity calculated is comparable to this obtained in previous works using corrugated and tapered LPFGs in SMF28 fibers. These results are of interest for the design of improved LPFG-sensors.     

Comparison of grand unified theories with electroweak and strong coupling constants measured at LEP

Using the renormalization group equations one can evolve the electroweak and strong coupling constants, as measured at LEP, to higher energies in order to test the ideas of grand unified theories, which predict that the three coupling constants become equal at a single unification point. With data from the DELPHI Collaboration we find that in the minimal non-supersymmetric standard model with one Higgs doublet a single unification point is excluded by more than 7 standard deviations. In contrast, the minimal supersymmetric standard model leads to good agreement with a single unification scale of 10^16.0±0.3 GeV. Such a large scale is compatible with the present lower limits on the proton lifetime. The best fit is obtained for a SUSY scale around 1000 GeV and limits are derived as function of the strong coupling constant. The unification point is sensitive to the number of Higgs doublets and only the minimal SUSY model with two Higgs doublets is compatible with GUT unification, if one takes the present limits on the proton lifetime into account.     

High-T c Josephson junctions for electronic applications

Summary The current status of the electronic applications of high-T _c Josephson junctions is briefly reviewed. Recent results obtained by the authors on devices employing step-edge junctions are reported. In particular the design of a microwave oscillator based on a parallel array of junctions is discussed and preliminary experimental results are presented. Paper presented at the ?VII Congresso SATT? Torino, 4–7 October 1994.     

Analysis of the data recorded by the Mont Blanc neutrino detector and by the Maryland and Rome gravitational-wave detectors during SN1987A

Summary The data recorded by the gravitational wave and the neutrino detectors mentioned in the title have been analysed over a period of several days that includes the Mont Blanc 5ν burst occurrence time. A correlation is found during a period of about two hours roughly centred on the 5ν burst, independently between Maryland and Mont Blanc and Rome and Mont Blanc. The probability that these two correlations be due to chance is of the order of between 10⁻⁶ and 10⁻⁵. It is found that this effect is mainly due to a dozen of large Maryland and Rome events distributed during the above two-hour period.

---

Riassunto I dati registrati con le antenne gravitazionali ed i rivelatori di neutrini indicati nel titolo sono stati analizzati in un periodo di vari giorni, includendo il tempo di occorrenza dell'evento di 5 neutrini rivelato al Monte Bianco. è stata trovata una correlazione durante circa due ore centrata al tempo dei 5ν, indipendentemente Maryland/Monte Bianco e Roma/Monte Bianco. La probabilità che queste due correlazioni siano dovute al caso è dell'ordine di 10⁻⁶÷10⁻⁵. è stato trovato che questo effetto è dovuto essenzialmente ad una dozzina di segnali registrati a Roma e in Maryland durante il sopramenzionato periodo di due ore.

---

Резюме Проводится анализ данных, зарегистрированных нейтринным детектором на Мон Блане и детекторами гравитационных волн в Мэриленде и Риме, за период, охватывающий несколько дней, которые включают время появления 5ν вспышки на Мон Блане. Обнаружена корреляция в течение приблизительно двух часов, центр которой приблизительно совпадает со временем 5ν вспышки, независимо в данных Мэриленд и Мон Блан и в данных Рим и Мон Блан. Вероятность того, что эти две корреляции являются случайными, имеет порядок величины 10⁻⁶÷10⁻⁵. Обнаружено, чтот эффект обусловлен в основном дюжиной сигналов, зарегистрированных в Риме и Мэриленде в течение периода около двух часов.

     

Synthesis and stereochemistry of novel [1,2,4]oxadiazolo[4,5-a][1,5]benzodiazepine derivatives

An one-pot synthetic approach to the novel 3a,4,5,6-tetrahydro[1,2,4]oxadiazolo[4,5-a][1,5]benzodiazepine system, by 1,3-dipolar cycloaddition of benzonitriloxides to 1,5-benzodiazepine derivatives, is described. The structure and stereochemistry of the obtained adducts have been assigned by means of spectroscopic measurements.     

Tuning porphyrin/DNA supramolecular assemblies by competitive binding

Addition of an intercalating but nonaggregating porphyrin, AuT4, to a preformed adduct between DNA and a strongly aggregating porphyrin, t-H2Pagg, permits control of the extent of aggregation of the latter. The size and the intensity of the ICD and RLS signals depend linearly on the concentration of the intercalating dye and decrease markedly on increasing the concentration of the available binding sites on the biopolymer template.     

Surfactant effects on electrokinetic processes in clay-rich soils remediation

The present work concerns the realisation of an equipment suitable for the choice of surfactants to be employed in the remediation of polluted soils by soil washing processes. The experimental activity has been focused to verify the surfactants efficiency in electrokinetic processes applied in low porosity soils, polluted with used vehicle oil. The equipment consents to estimate low electroosmotic permeabilities, electrical current and to analyse the electrolytic solutions. The concentration of the chemical species reached in both anodic and cathodic cells allows a more accurate evaluation of the ion mobility through the soil. The apparatus realised has been shown to be a useful instrument capable of providing directions for the choice of surfactants in electrokinetic soil remediation. The choice of an anionic surfactant for the oil removal has shown promising result.     

Voltammetric behaviour of cis-diarylbis(triethylphosphine)platinum(II) complexes

The voltammetric behaviour of cis-[Pt(PEt₃)₂(YC₆H₄)₂] complexes in acetonitrile has been investigated by cyclic voltammetry and controlled potential coulometry. The oxidation potential increases linearly with increasing electron-withdrawing ability of the Y substituent in the platinum-bonded aryl ligand. The data are related to studies of electrophilic Pt—C bond cleavage.