Many developments have been made to improve the quality and adherence of CVD diamond films onto WC-Co hard metal tools by the removing the cobalt from the substrate surface through substrate ...pretreatments. Here we compare the efficiency of three chemical pretreatments of WC-Co substrates for this purpose. First, the work was focused on a detailed study of the composition and structure of as-polished and pretreated substrate surfaces to characterize the effects of the substrate preparation. Considering this objective, a set of WC-9% Co substrates, before and after pretreatment, was analyzed by FEG-SEM, EDS and x-ray diffraction (XRD). The second stage of the work was devoted to the evaluation of the influence of seeding process, using 4 nm diamond nanoparticles, on the morphology and roughness of the pretreated substrates. The last and most important stage was to deposit diamond coatings with different crystallite sizes (nano and micro) by hot-filament CVD to understand fully the mechanism of growth and adhesion of CVD diamond films on pretreated WC-Co substrates. The transition from nano to microcrystalline diamond was achieved by controlling the CH4 H2 gas ratio. The nano and microcrystalline samples were grown under same time at different substrate temperatures 600 °C and 800 °C, respectively. The different substrate temperatures allowed the analysis of the cobalt diffusion from the bulk to the substrate surface during CVD film growth. Furthermore, it was possible to evaluate how the coating adhesion is affected by the diffusion. The diamond coatings were characterized by Raman spectroscopy, XRD, EDS, FEG-SEM, atomic force microscope and 1500 N Rockwell indentation to evaluate the adhesion.
The cosmic rays spectrometer AMS-02 will be placed on the ISS Space Station in April 2011 and should take data for at least 10 years. After a short review of the impressive observational data ...collected in the last few years by satellites and underground experiments in the quest for Dark Matter (DM), we describe the AMS-02 space spectrometer with its powerful particle identification capabilities. The performances of the experimental apparatus and the perspectives opened by this new powerful observational instrument for the DM search will be briefly reviewed. In particular the extension at the TeV scale of the positron and electron spectra with high statistical significance well beyond the PAMELA results will hopefully clarify the quest for Dark Matter evidence in cosmic rays. Finally the present status of the AMS-02 payload for the Shuttle transportation and installation on the International Space Station, and the implementation of the Control Center for data collection and analysis is reviewed.
The problem of identification of partial discharge (PD) phenomena occurring in an insulation system is addressed in this paper. PD distributions coming from different sources, such as internal voids, ...as well as surface and corona discharges, are compared. In particular, the investigation focuses on the Weibull probability function applied to pulse charge-height distribution. It is shown that the different discharge sources can be identified on the basis of the value of the shape parameter of the Weibull distribution and that identification holds even when two PD sources are combined, i.e. are active simultaneously. In this case, the application of the 5-parameter Weibull function permits separation of PD phenomena, and recognition by means of the shape parameter value associated to each phenomenon. Finally, the proposed procedure is applied to practical objects, i.e. insulation systems of rotating machines, with real insulation defects, showing promising on-field application prospective.
Partial discharge (PD) measurements constitute one of the most promising tools for electrical insulation diagnosis. This paper describes how a procedure based on PD measurements can provide early ...detection of electrical trees in polymeric insulation systems. Such an application relies upon a new methodology, which provides enhanced tools for the identification of PD generating defects. Tree inference is carried out stepwise. Acquired signals are primarily separated according to their waveform, thus achieving data sets related to a specific PD typology. Then, fuzzy algorithms are applied to PD height and phase derived quantities belonging to these homogeneous data sets, in order to assign a membership degree to specific output categories. If the data set is relevant to an internal defect, a further analysis is performed in order to establish whether or not this defect is a treed region. The algorithm described in this paper was developed resorting to tests performed on artificial test specimens and electrical apparatus. In particular, the rules to detect the presence of electrical trees were derived from experiments carried out on needle-plane objects, constituted by slabs of cross-linked polyethylene (XLPE) where a needle is inserted and partially extracted in order to generate a cavity in front of the needle tip. Tests were also performed on cables having artificial defects., as well as on other insulation systems, such as high frequency transformers. Applications of the proposed approach to MV cables and to HV transformers show that electrical trees can be detected successfully before final breakdown.
The fundamental requirements of a diagnostic procedure composed by defect identification, noise and disturbance rejection, separation of multiple sources, set-up conditions and test prescriptions, ...are described in this paper. This procedure allows to overcome problems found when practical objects are tested using the apparent charge measurement approach according to Std.IEC 60270. Definitions, methodologies and validation procedures relevant to the different diagnostic steps, are presented and discussed considering also a possible future development of fully automated instruments.
This study has been performed in order to evaluate the land use changes and related environmental impacts which occurred in recent decades in the Lamone river basin (Northern Italian Apennines). ...Using the DPSIR indicator-based approach, agricultural land use changes and conversions occurred within the periods 1976–1994 and 1994–2003, have been associated with the shortage of water in the river and the modification of the landscape structure. Results show that Lamone river basin in 1976 was mainly dominated by forest (27.4%) and cropland (32.3%) and through the entire period the valley presented a strong persistence of land uses and the main conversions detected are afforestation and agricultural intensification. The hydrological balance analysis results indicate that the agricultural intensification process produced a water deficit in summer periods equal to 0.89
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3 in 2003. The landscape of the Lamone valley became more homogeneous, showing a decrease in diversity (Shannon Diversity Index values decreased from 1.81 to 1.58) and the riparian corridor became more human-dominated (Human Habitat values increased from 0.61 to 0.77). An integrated assessment of possible management options has been conducted, using the MULINO-DSS software as a support. Thirteen different management scenarios have been produced in order to solve the water balance issue and to enhance the riparian corridor. Attributing equal weight to the environmental, social and economical criteria, the best solution corresponds to the sole creation of artificial basins and the actual situation is placed at position 8 (out of 13).
A new system aimed at performing partial discharge measurements and condition assessment on electrical apparatus is presented. It is able to separate the conventional phase resolved partial discharge ...pattern into a series of sub-patterns, each of them containing partial discharge data generated by a single kind of defect, which makes easier identification of the source generating partial discharges. Application of the system to partial discharge data recorded on an hydrogenerator is reported to support its effectiveness.
A transgenic Saccharomyces cerevisiae was constructed containing the cDNAs coding for strictosidine synthase (STR) and strictosidine beta-glucosidase (SGD) from the medicinal plant Catharanthus ...roseus. Both enzymes are involved in the biosynthesis of terpenoid indole alkaloids. The yeast culture was found to express high levels of both enzymes. STR activity was found both inside the cells (13.2 nkatal/g fresh weight) and in the medium (up to 25 nkatal/l medium), whereas SGD activity was present only inside the yeast cells (2.5 mkatal/g fresh weight). Upon feeding of tryptamine and secologanin, this transgenic yeast culture produced high levels of strictosidine in the medium; levels up to 2 g/l were measured. Inside the yeast cells strictosidine was also detected, although in much lower amounts (0.2 mg/g cells). This was due to the low permeability of the cells towards the substrates, secologanin and tryptamine. However, the strictosidine present in the medium was completely hydrolyzed to cathenamine, after permeabilizing the yeast cells. Furthermore, transgenic S. cerevisiae was able to grow on an extract of Symphoricarpus albus berries serving as a source for secologanin and carbohydrates. Under these conditions, the addition of tryptamine was sufficient for the transgenic yeast culture to produce indole alkaloids. Our results show that transgenic yeast cultures are an interesting alternative for the production of plant alkaloids.
From Senecio bicolor, ssp. cineraria, cultivated in middle Europe, seven pyrrolizidine alkaloids (PA) were isolated and their structures elucidated by spectroscopical methods. Besides the already ...known senecionine, integerrimine, seneciphylline, jacobine, jacoline and jaconine the jacobine-acetate was found. On account of structure toxicity relationship all PA show toxic side-effects.
Cosmic rays’ interactions with the residual atmosphere surrounding the Earth produce a variety of particles, like electrons, positrons, protons, anti-protons, and Helium nuclei that can be observed ...below the local geomagnetic cutoff. In this work, we present new measurements of downward-going, albedo proton fluxes with kinetic energy in the range ∼40–∼250 MeV, performed by the High-Energy Particle Detector (HEPD-01) on board of the China Seismo-Electromagnetic Satellite - CSES-01 - at an altitude of ∼500 km. Employing a dedicated trajectory-tracing simulation routine, the protons collected by HEPD-01 are classified into quasi-trapped (QT), long lifetime (≳10 s) particles concentrating in the equatorial region of the Earth, and un-trapped (UT), distributed at all latitudes; the latter includes both precipitating short lifetime particles (UTS) and pseudo-trapped long lifetime (UTL) populations, abundant in the so-called penumbra regions. The temporal trend of re-entrant protons between 2018 and 2022 is also reported, assessing the stability of such population during the data-taking period of HEPD-01; this highlights their independence from the long-term modulating effect of the solar activity.
•A study of re-entrant albedo protons in the Earth’s magnetosphere as a function of energy with the HEPD-01 payload is presented.•A comparison with past experiments is carried out, with good results.•Time-profiles of re-entrant albedo protons show a general stability during the analyzed period.
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