Aerosol characterisation in Italian towns by IBA techniques

The composition of particulate matter in the atmosphere of four major Italian towns (Florence, Genoa, Milan and Naples) has been studied with the extensive application of IBA techniques. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which provide the separation of the particulate matter in two fractions. The concentrations in air of about 20 elements, and the total particulate mass, have been extracted in the PM2.5 and PM10 fractions with hourly resolution by PIXE, PIGE and optical analyses of about 2700 samples. IBA analyses have been performed at the 3 MeV external proton beam of the INFN accelerator facility at the University of Florence.     

Evidence against colonic mucosa colonisation by Helicobacter pylori. Lack of a specific antibody response in homogenates of rectal endoscopic biopsies

Aim of this study is to provide indirect evidence that human colonic mucosa harbour Helicobacter pylori. The antibody response of IgG and IgA class against Helicobacter pylori was examined in autologous homogenate of gastric and rectal endoscopic biopsies from 26 patients and in rectal samples of a further 36. All had a documented (histology and/or serology) Helicobacter pylori status. Helicobacter pylori specific IgG and IgA were measured by an in-house ELISA. In Helicobacter pylori positive patients having both gastric and rectal homogenate, mean level of Helicobacter pylori IgG and IgA was higher in gastric than in rectal samples (0.810 +/- 0.668 optical density vs 0.329 +/- 0.509 optical density for IgG, p = 0.007 and 0.660 +/- 0.477 vs 0.116 +/- 0.229 for IgA, p < 0.001, respectively). In each patient, level of the two isotypes was clearly higher in gastric than in autologous rectal sample. In the overall study population, mean level of Helicobacter pylori IgG in rectal homogenate was not significantly (p = 0.16) different between Helicobacter pylori positive (48/62, 77%, 0.243 +/- 0.388 optical density) and negative (14/62, 23%; 0.095 +/- 0.088) patients. In same material, levels of Helicobacter pylori IgA were very low and undetectable either in Helicobacter pylori positive or negative patients. Although Helicobacter pylori IgG are detectable in rectal homogenates of Helicobacter pylori positive patients, present data suggest that these antibodies may not be local in origin but rather reflect circulating response. These observations do not support the view that large bowel mucosa is colonised by Helicobacter pylori.     

Fracture Behaviour of Nickel-Titanium Laser Welded Joints

In this study, the effects of Nd:YAG laser welding on the fracture behavior of Ni-rich nickel-titanium sheets are analyzed by experimental investigations. The welding was carried out in open air conditions by using a special shielding/clamping system to avoid the chemical contamination of the molten zone and the formation of hot cracks. Mechanical tests of standard dog bone-shaped and single edge crack specimens were carried out to measure the stress-strain response and the fracture resistance of both the base and the welded materials. Furthermore, scanning electron microscopy observations of the fracture surfaces were carried out in order to better understand the failure mechanisms. Finally, systematic comparative studies between base and laser-welded materials were carried out.     

Issues in the characterization of power quality instruments

This paper analyzes some issues related to the metrological characterization of instruments for power quality monitoring, in order to move a step toward the definition of a full performance verification protocol. This protocol should include not only the test situations reported in corresponding standards, but also an array of different voltage and current fluctuations – linked to common power quality issues – that may be encountered in actual power systems. This performance analysis is particularly interesting because it can be found that different power quality instruments, fully meeting characteristics prescribed in standard, still may significantly disagree in some actual measurements. This is due for the existence of unresolved technical and theoretical issues related to the metrological characterization through the classical approaches of these instruments. The aim of the discussion carried out in this paper is also the specification of requirements of a test system devoted to calibration and verification of a power quality monitor, such as it is done in type testing. After a preliminary discussion about technical and theoretical issues related to the performance analysis of these instruments, a proposal of test protocol definition, with reference to some power quality phenomena and based on the design of experiment, is presented.     

Cultural evolutionary design of adaptive wavelet filters based on lifting scheme for micro-instruments

An evolutionary procedure based on cultural algorithms for the optimal design of adaptive wavelet filters based on lifting scheme is proposed. Numerical results of characterization, based on statistical experiment design, as well as validation, based on the comparison with a genetic optimization algorithm, are presented. Experimental results of the validation on two case studies for reducing uncertainty arising from noise in on-field corrosion rate measurements are highlighted.     

A new correlation method for high sensitivity current noise measurements

The properties of a differential transconductance amplifier coupled with a four channel measurement system are exploited in order to reach a very high sensitivity in current noise measurements. In particular, it is demonstrated that, in proper conditions, the noise contributions coming from the active and passive devices that make up the transresistance amplifier can be virtually eliminated. Moreover, the proposed measurement method allows the evaluation of the impedance of the device under test from noise measurement data. Actual measurement results are also reported that demonstrate the effectiveness of the proposed approach.     

Fabrication of photoactive heterostructures based on quantum dots decorated with Au nanoparticles

Silica based multifunctional heterostructures, exhibiting near infrared (NIR) absorption (650–1200 nm) and luminescence in the visible region, represent innovative nanosystems useful for diagnostic or theranostic applications. Herein, colloidal synthetic procedures are applied to design a photoactive multifunctional nanosystem. Luminescent silica (SiO₂) coated quantum dots (QDs) have been used as versatile nanoplatforms to assemble on their surface gold (Au) seeds, further grown into Au spackled structures. The synthesized nanostructures combine the QD emission in the visible region, and, concomitantly, the distinctive NIR absorption of Au nanodomains. The possibility of having multiple QDs in a single heterostructure, the SiO₂ shell thickness, and the extent of Au deposition onto SiO₂ surface have been carefully controlled. The work shows that a single QD entrapped in 16 nm thick SiO₂ shell, coated with Au speckles, represents the most suitable geometry to preserve the QD emission in the visible region and to generate NIR absorption from metal NPs. The resulting architectures present a biomedical potential as an effective optical multimodal probes and as promising therapeutic agents due to the Au NP mediated photothermal effect.     

Interferometer for ground-based observations of emitted spectral radiance from the troposphere: evaluation and retrieval performance

We evaluate the spectral quality, radiometric noise, and retrieval performance of a Fourier transform infrared spectrometer, which has been developed for recording spectrally resolved observations in a region of the spectrum which is important both for the science of Earth's climate and applications, such as the remote sensing of temperature and atmospheric gas species. This spectral region extends from 100 to 1600 cm(-1) and encompasses the two fundamental, rotation and vibration, absorption bands of water vapor. The instrument is a customized version of a Bomem AERI (Atmospheric Emitted Radiance Interferometer) spectrometer, whose spectral coverage has been extended in the far infrared with the use of uncooled pyroelectric detectors. Retrieval examples for water vapor and temperature profiles are shown, which also allow us to intercompare the retrieval performance of both H(2)O vibration and rotation bands.     

Salivary immunoglobulin G assay to diagnose Helicobacter pylori infection in children

An in-house enzyme-linked immunosorbent assay (ELISA) for measurement of Helicobacter pylori-specific immunoglobulin G (IgG) and IgA in saliva was evaluated by comparison with histopathologic (Giemsa staining) and biochemical (urease quick test) examination of gastric biopsy specimens obtained from 112 children referred for diagnostic gastroscopy. Serum H. pylori IgG was also measured in a subgroup of 50 children by the same ELISA. Salivary H. pylori IgG levels were significantly higher in H. pylori-positive (n = 57) than in H. pylori-negative (n = 55) children (P < 0.001). The sensitivity and specificity of the salivary IgG test were 93 and 82%, respectively; the positive and negative predictive values were 84 and 92%, respectively; and the accuracy was 87.5%. Salivary H. pylori IgA did not distinguish H. pylori-positive from H. pylori-negative children. The performance of serum H. pylori IgG was slightly (3 to 6%) better than that of salivary H. pylori IgG. The salivary IgG test can be considered a useful tool for the screening of H. pylori infection in children.     

On the determination of mechanical properties of composite laminates using genetic algorithms

This paper describes a method which combines finite element analysis and genetic algorithms (GAs) for identifying the elastic constants of composite laminates by using vibration test data. A procedure updates the elastic constants in a numerical model so that the output from the numerical code fits the results from vibration testing. In this approach, the elastic constants can be readily identified in a single test without damaging the structure. The GA, developed on a personal computer using the language MATLAB, applies the general-purpose numerical code MSC-NASTRAN to carry out the modal analysis.