Determination of Anionic, Neutral, and Cationic Species of Arsenic by Ion Chromatography with ICPMS Detection in Environmental Samples

Ion chromatographic methods developed to separate either cationic, neutral, and anionic arsenic species or soluble and suspended arsenic species were successfully used in DORM-2 standard reference material and in water samples of environmental interest. The most effective separation of the analytes within 10 min was achieved with a nitric acid gradient elution using a strong anion-exchange stationary phase with additional capacity for hydrophobic interactions (IonPac AS7). The elemental-specific detection mode allows the sensitive determination of the arsenic species in the submicrogram per liter range. The calibration results were compared with those obtained by an alkaline water-methanol mixed eluent combined with a weak anion-exchange column (IonPac AS4A-SC). Differences in sensitivities were eclipsed by the low level of the baseline and the noise when using nitric acid. The gradient method was used to determine arsenic species in highly ferrous/ferric-contaminated leachates of lignite spoil. The companion elements underwent parallel screening to explain the interactions of arsenic species with the major elements.     

Efficient simulation of low-velocity impacts on composite sandwich panels

For efficiently simulating the damage resistance of sandwich panels subjected to low-velocity impacts, the finite element based damage tolerance tool CODAC has been enhanced. While sandwich structures are very weight efficient and provide integrated acoustic and thermal insulation, impact damage can provoke a significant strength and stability reduction. Therefore, the objective of CODAC is to provide methodologies which reliably simulate impact events and predict impact damage sizes. Since frequent design loops require a quick analysis, efficient deformation and failure models are desired. To achieve a rapid and accurate stress analysis, a recently developed three-layered finite shell element is applied. Failure analysis is based on a progressive damage mechanics approach: Damage initiation is detected by stress-based failure criteria. Material resistance is reduced by appropriate, step-wise linear degradation models. An experimental impact test program on honeycomb sandwich panels is used to validate the impact simulation of the FE-tool CODAC. Comparisons between impact tests and simulations showed that CODAC is capable of accurately and rapidly simulating impact events, which induce barely visible damage. Furthermore, the onset of clearly visible damage is correctly predicted.     

Capability of a carbon-polyvinylchloride composite electrode for the detection of dopamine, ascorbic acid and uric acid

In this work, the composite carbon-polyvinylchloride (C-PVC) was used as an electrode for the detection of dopamine, ascorbic acid, uric acid and their mixtures by differential pulse voltammetry (DPV). The results showed that the untreated C-PVC electrode was selective and stable for the oxidation of dopamine in a mixture containing uric acid and an excess of ascorbic acid in acidic medium. The pre-treated C-PVC electrode in a neutral medium exhibited good resolution of the mixture components in the micro molar concentration range of DA. The ageing of the C-PVC electrode during longer time periods did not affect the peak potential and the detection of dopamine, uric acid and ascorbic acid in 0.1 M H₂SO₄. The practical analytical utility of the C-PVC electrode was demonstrated by the measurement of uric acid in human urine and serum samples without any preliminary pre-treatment.     

An Approach to T&E of Military SDR Platforms and Waveforms: the LANCERS Lab

Software Defined Radio (SDR) is currently one of the main topics of interest in military communications, as well as in civil ones. Since 2002, the Italian Ministry of Defense (MoD) has identified the SDR technology as a strategic capability. In this respect, Italy has become part of the major multinational programs related to military SDR and waveforms, such as ESSOR (European Secure Software Radio) and COALWNW (COALition Wideband Networking Waveform). In addition, the Italian national SDR program (SDR-N) aims at developing a complete family of SDR products, part of which are already available for fielding. In order to develop a governmental capability of Test and Evaluation (T&E) for future SDR, minimizing the risks related to the fielding of this new technology, a dedicated laboratory, called LANCERS lab, has been established in the premises of CSSN ITE (Centro Supporto e Sperimentazione Navale Istituto per le Telecomunicazioni e lElettronica), a research center of the Italian Navy. LANCERS lab gathers the expertise of military technical personnel and University researchers, to provide a twofold capability: developing T&E strategies and procedures for the new tactical communications based on SDR and maintaining knowledge about the state of the art of SDR, fostering new research and development. In this paper we describe the LANCERS lab in all the following aspects: plan of development, organization, current activities, and future perspectives.     

Photochemical preparation of aluminium oxide layers via vacuum ultraviolet irradiation of a polymeric hexanoato aluminium complex

By means of photochemical conversion of thin layers of a polymeric hexanoato aluminium complex as the precursor, thin aluminium oxide layers were prepared onto silicon wafers. The precursor compound was synthesized and characterized by several analytical techniques like NMR, FTIR, XPS, ICP, and found to be a polymeric aluminium-containing coordination compound which has been proposed to be a hydroxo-bridged aluminium chain with pendant hexanoyl side-chains ascertained as catena-poly[{di(κ-O,O-hexanoato)aluminium}(μ-hydroxo)] (PHAH). Thin layers deposited from a solution of PHAH in toluene onto silicon wafers were irradiated using VUV radiation from a xenon excimer lamp. The layers were characterized by XPS, XRD, XRR, and spectroscopic ellipsometry. VUV radiation with a radiant exposure of E = 36 J cm⁻² led to almost carbon-free amorphous layers with a composition close to that of alumina having a density of about 2.1 g cm⁻³. Thus, using the example of a polymeric aluminium complex, the potential of the photochemical conversion of metal complexes into oxides could be shown as an alternative method, in addition to sol–gel techniques, for the generation of thin plane metal-oxide layers at normal temperature and pressure.     

Influence of sulfur and nitrogen supply on growth,nutrient status and concentration of benzyl‐isothiocyanate in cress (Lepidium sativum L.)

BACKGROUND: The supply of nitrogen (N) and sulfur (S) exerts an interactive effect on glucosinolate (GS) accumulation in Brassica vegetables, but the consequences for the concentration of isothiocyanates (ITCs), released after decomposition of GS by myrosinase, have rarely been investigated. In addition to their phytosanitary function GS have also been discussed as transient S reservoir. RESULTS: Cress (Lepidium sativum, L.) plants were cultivated with varied supply of N (0.5, 1.0 and 2.0 g pot^?1) and S (0, 0.05 and 0.2 g pot^?1). Concentrations of total N and S and hence the N/S ratio responded significantly, as did the concentrations of nitrate and sulfate. Concentrations of benzyl‐ITC, derived from glucotropaeolin (benzyl‐GS), ranged from 6.7 to almost 30 µmol (g dry matter)^?1 and were negatively affected by high N supply. For a given S supply the benzyl‐ITC concentration was inversely related to the N/S ratio, an indicator of the S nutritional status. CONCLUSION: The results do not support the view that GS act as a transient S reservoir. Rather, moderate N and adequate S supplies lead to increased concentrations of this pharmacologically important constituent of cress. Copyright © 2008 Society of Chemical Industry     

A frequency error resistant blind CDMA detector

This paper presents an enhanced version of the previously proposed blind anchored interference-mitigating detector (BAID) for code-division multiple-access transmission. Such a detector, named extended complex BAID (EC-BAID), features invariance to a phase error on the useful channel's carrier and reveals resistance to a large frequency shift (e.g., Doppler shift) on interfering carriers. The EC-BAID is also shown to bear a sensitivity to residual carrier frequency errors on the desired channel which is lower by three orders of magnitude with respect to the case of a data-aided minimum mean-square-error receiver. The performance of the EC-BAID is computed theoretically, and is validated by computer simulations under a variety of system configurations     

Adaptive pre- and post-compensation of nonlinear distortions for high-level data Modulations

In this letter, we show how different signal processing techniques can be combined to optimize the performance of a typical wideband nonlinear satellite link with spectrally efficient high-level modulation techniques. In particular, we follow two concurrent approaches: on one side, we pursue signal optimization in the form of special amplitude and phase shift keying (APSK) constellations to reduce the effect of nonlinear distortions, while on the other, we analyze the feasibility of adaptive data predistortion (DP) at the transmitter and adaptive nonlinear equalization (NLE) at the receiver. We demonstrate that the use of such optimized constellations relieves the complexity of the nonlinearity compensation techniques, and we also show that by clever adoption of these techniques the sensitivity to nonlinear distortion of both uncoded and turbo coded quadrature amplitude modulation and APSK constellations is greatly reduced.