17O-excess (?17O = ?17O ? 0.52 × ?18O) of sulfate trapped in Antarctic ice cores has been proposed as a potential tool for assessing past oxidant chemistry, while insufficient understanding atmospheric formation around Antarctica hampers its interpretation. To probe influences regional specific we compared year-round observations ?17O non-sea-salt aerosols (?17O(SO42?)nss) at Dome C and Dumont ...

—Amutual information based approach for the analysis of signals obtained by nuclear quadrupole resonance (NQR) measurements to detect TNT content is proposed. We apply the method to real NQR data obtained under laboratory conditions and compare ROC curves for the presented method with those of the popular demodulation technique and the matchedlter detector. Our results show mutual information t...

We have obtained oxygen-17 (17O) nuclear magnetic resonance (NMR) spectra of C17O ligands bound to ferrous horseradish peroxidase isozyme A, isozyme C, and ferrous chloroperoxidase, as a function of pH. Our results show that the peroxidases exist in two distinct states, the acidic and alkaline forms, which undergo reversible acid-base-induced transitions characterized by a single pK value. The ...

Using a superregenerative NQR spectrometer, the temperature dependence of I NQR spectra in [N(CH3)4]2ZnI4 was measured between 167 and 335 K. The measurements confirm two known structural phase transitions at 219 and 257.5 K. The correspondence between the distinct regions of iodine NQR spectra and the crystal structure is discussed. The relation of [N(CH3)4]2ZnI4 to the incommensurate family w...

Nuclear Quadrupole Resonance (NQR) signal detection can be severely obstructed by interference in real life settings, especially when the interference is strong, nonstationary, and its frequencies are close to that of the NQR signal. A novel algorithm is proposed to effectively remove (or reduce) interference components in the data and facilitate a valid detection of the NQR signal. The propose...

For reliable detection of explosives, a combination of methods integrated within a single measurement platform may increase detection performance. However, the efficient field testing of such measurement platforms requires the use of inexplosive simulants that are detectable by a wide range of methods. Physical parameters such as simulant density, elemental composition and crystalline structure...

The Strangeness S=−2 J-PARC E07 emulsion experiment published recently two new Ξ−–14N capture events, IRRAWADDY and IBUKI, identified by observing weak-decay sequences of pairs single-Λ hypernuclei interpreted as Ξ1s− Ξ1p− nuclear bound states, respectively, with binding energies BΞ−1s=6.27±0.27 MeV BΞ−1p=1.27±0.21 MeV. Ξ− events in play a major role determining the Ξ-nuclear ΛΛ potential stren...

CONTEXT The terrestrial planets, comets, and meteorites are significantly enriched in 15N compared to the Sun and Jupiter. While the solar and jovian nitrogen isotope ratio is believed to represent the composition of the protosolar nebula, a still unidentified process has caused 15N-enrichment in the solids. Several mechanisms have been proposed to explain the variations, including chemical fra...

Multiple pulse sequences are widely used for signal enhancement in NQR detection applications. Since the various (14)N NQR relaxation times, signal decay times and frequency of each NQR line have a major influence on detection sequence performance, it is important to characterise these parameters and their temperature variation, as fully as possible. In this paper we discuss such measurements f...

The Polymer Diagnostics Section (Code 6122) of the U.S. Naval Research Laboratory (NRL) has expertise in solid state nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), and nuclear quadrupole resonance (NQR). In 1983, NRL established an interagency agreement with the Federal Aviation Administration (FAA) to advise the FAA on NMR methods to detect explosives. We were aware of ear...