Progress in control and data acquisition for the ITER neutral beam test facility

SPIDER, the ion source test bed in the ITER neutral beam test facility, is under construction and its operation is expected to start in 2014. Control and data acquisition for SPIDER are undergoing final design. SPIDER CODAS, as the control and data acquisition system is referred to, is requested to manage 25 plant units, to acquire 1000 analogue signals with sampling rates ranging from a few S/s to 10 MS/s, to acquire images with up to 100 frames per second, to operate with long pulses lasting up to 1 h, and to sustain 200 MB/s data throughput into the data archive with an annual data storage amount of up to 50 TB. SPIDER CODAS software architecture integrates three open-source software frameworks each addressing specific system requirements. Slow control exploits the synergy among EPICS and Siemens S7 programmable controllers. Data handling is by MDSplus a data-centric framework that is geared towards the collection and organization of scientific data. Diagnostics based on imaging drive the design of data throughput and archive size. Fast control is implemented by using MARTe, a data-driven, object-oriented, real-time environment. The paper will describe in detail the progress of the system hardware and software architecture and will show how the software frameworks interact to provide the functions requested by SPIDER CODAS. The paper will focus on how the performance requirements can be met with the described SPIDER CODAS architecture, describing the progress achieved by carrying out prototyping activities.     

Production,Characterization and Synthetic Application of a Purine Nucleoside Phosphorylase from Aeromonas hydrophila

Purine nucleoside phosphorylase (PNP) from Aeromonas hydrophila encoded by the deoD gene has been over‐expressed in Escherichia coli, purified, characterized about its substrate specificity and used for the preparative synthesis of some 6‐substituted purine‐9‐ribosides. Substrate specificity towards natural nucleosides showed that this PNP catalyzes the phosphorolysis of both 6‐oxo‐ and 6‐aminopurine (deoxy)ribonucleosides. A library of nucleoside analogues was synthesized and then submitted to enzymatic phosphorolysis as well. This assay revealed that 1‐, 2‐, 6‐ and 7‐modified nucleosides are accepted as substrates, whereas 8‐substituted nucleosides are not. A few transglycosylation reactions were carried out using 7‐methylguanosine iodide ( 4 ) as a D ‐ribose donor and 6‐substituted purines as acceptor. In particular, following this approach, 2‐amino‐6‐chloropurine‐9‐riboside ( 2c ), 6‐methoxypurine‐9‐riboside ( 2d ) and 2‐amino‐6‐(methylthio)purine‐9‐riboside ( 2g ) were synthesized in very high yield and purity.     

Catalytic Electrophilic Halogenation of Silyl‐Protected and Terminal Alkynes: Trapping Gold(I) Acetylides vs. a Brønsted Acid‐Promoted Reaction

In the presence of a cationic gold(I) catalyst and N‐halosuccinimide, both trimethylsilyl‐protected and terminal alkynes are converted into alkynyl halides. Further experiments showed that silyl‐protected alkynes undergo electrophilic iodination and bromination under Brønsted acid catalysis, whilst terminal alkynes require a cationic gold catalyst. The former reactions probably proceed via activation of the electrophile, whilst the latter reactions proceed via a gold(I) acetylide intermediate. Gold‐catalysed halogenation was further combined with gold‐catalysed hydration and subsequent annulation to provide convenient routes to iodomethyl ketones and five‐membered aromatic heterocycles.     

Completely automated multiresolution edge snapper--a new technique for an accurate carotid ultrasound IMT measurement: clinical validation and benchmarking on a multi-institutional database

The aim of this paper is to describe a novel and completely automated technique for carotid artery (CA) recognition, far (distal) wall segmentation, and intima-media thickness (IMT) measurement, which is a strong clinical tool for risk assessment for cardiovascular diseases. The architecture of completely automated multiresolution edge snapper (CAMES) consists of the following two stages: 1) automated CA recognition based on a combination of scale-space and statistical classification in a multiresolution framework and 2) automated segmentation of lumen-intima (LI) and media-adventitia (MA) interfaces for the far (distal) wall and IMT measurement. Our database of 365 B-mode longitudinal carotid images is taken from four different institutions covering different ethnic backgrounds. The ground-truth (GT) database was the average manual segmentation from three clinical experts. The mean distance ± standard deviation of CAMES with respect to GT profiles for LI and MA interfaces were 0.081 ± 0.099 and 0.082 ± 0.197 mm, respectively. The IMT measurement error between CAMES and GT was 0.078 ± 0.112 mm. CAMES was benchmarked against a previously developed automated technique based on an integrated approach using feature-based extraction and classifier (CALEX). Although CAMES underestimated the IMT value, it had shown a strong improvement in segmentation errors against CALEX for LI and MA interfaces by 8% and 42%, respectively. The overall IMT measurement bias for CAMES improved by 36% against CALEX. Finally, this paper demonstrated that the figure-of-merit of CAMES was 95.8% compared with 87.4% for CALEX. The combination of multiresolution CA recognition and far-wall segmentation led to an automated, low-complexity, real-time, and accurate technique for carotid IMT measurement. Validation on a multiethnic/multi-institutional data set demonstrated the robustness of the technique, which can constitute a clinically valid IMT measurement for assistance in atherosclerosis disease management.     

Inactivation of Spoiling Yeasts of Fruit Juices by Pulsed Ultrasound

This paper reports on the use of ultrasound (US) as a suitable strategy to control the growth of spoiling yeasts in fruit juices. In a first phase, US technique was tested towards Saccharomyces cerevisiae inoculated in different juices (strawberry, orange, apple, pineapple and red-fruits): the treatment was performed by modulating the level of the power (20–60 %), the duration of the treatment (2–6 min) and the pulse (2–6 s), according to a fractional design. Then, the best treatment was applied against some other spoiling yeasts (Pichia membranifaciens, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Candida norvegica). Finally, a challenge test for a commercial beverage (red-fruit juice), inoculated with Z. bailii and containing a citrus extract, was conducted evaluating the effect of US on the sensory scores of the beverage. The results showed that the effect of US was mainly influenced by the power and the duration of the treatment; on the other hand, the effect of pulse was less significant and slight. The highest reduction of S. cerevisiae was found in the following combination of the design: power 60 %/time 4 min/pulse 2 s and power 60 %/time 6 min/pulse 6 s; this result was confirmed for the other spoiling yeasts. US and citrus extract could be combined to prolong the shelf life of the red-fruit juice and control the growth of Z. bailii. The two hurdles exerted a different role and acted in different times: US reduced the initial contamination, whilst citrus extract controlled the yeast within the storage.     

Simultaneous Determination of 18 Bioactive Compounds in Italian Bitter Liqueurs by Reversed-Phase High-Performance Liquid Chromatography–Diode Array Detection

A simple, fast and accurate method has been developed to simultaneously determine 18 bioactive compounds in Italian bitter liqueurs containing gentian, cinchona, cinnamon, rhubarb, clove, star anise or orange, by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection (DAD). HPLC analysis was performed with a C18 column using methanol and aqueous phosphoric acid (pH 2.5) as mobile phase. Selected wavelengths, i.e. 210, 232, 275, 285, 291, 310 and 368 nm, were used for quantification of compounds. The column temperature was controlled at 30 °C. The correlation coefficients (R ²) of the calibration curves of the analysed compounds were ≥0.9999 in a relatively wide concentration range (0.5–50 μg/ml). The proposed method proved successful in simultaneously analysing 18 bitter liqueurs produced in Italy. The concentration of the most important bitter principles, gentiopicroside, amarogentin, quinine and naringin, ranged as follows: 1.17–299.20, 0.25–32.24, 1.44–6.93 and 0.28–39.99 μg/ml, respectively.     

A study on the antimicrobial activity of thymol intended as a natural preservative

A quantitative investigation on the inhibitory activity of thymol against some microorganisms that could represent a potential spoilage risk both in acid and mild thermally treated foods is presented in this work. In order to assess potential biostatic or biocidal activity of thymol, both the growth kinetics and dose-response profiles were obtained and analyzed. A suitable macrodilution methodology based on a turbidimetric technique was adopted to produce inhibitory data used for characterizing microbial susceptibility against thymol at sub-MIC levels. Microbial growth was monitored through absorbance measurements at 420 nm as a function of contact time with the active compound. Moreover, for each tested microorganism, the noninhibitory concentration (NIC) and the MIC were quantified. Results prove that thymol can exert a significant antimicrobial effect on each phase of the growth cycle. The microbial susceptibility and resistance were found to be nonlinearly dose related. It is worth noting that significant biostatic effects were observed at sub-MIC levels.     

Mapping the density of scattering centers limiting the electron mean free path in graphene

Recently, giant carrier mobility μ (>10(5) cm(2) V(-1) s(-1)) and micrometer electron mean free path (l) have been measured in suspended graphene or in graphene encapsulated between inert and ultraflat BN layers. Much lower μ values (10000-20000 cm(2) V(-1) s(-1)) are typically reported in graphene on common substrates (SiO(2), SiC) used for device fabrication. The debate on the factors limiting graphene electron mean free path is still open with charged impurities (CI) and resonant scatterers (RS) indicated as the most probable candidates. As a matter of fact, the inhomogeneous distribution of such scattering sources in graphene is responsible of nanoscale lateral inhomogeneities in the electronic properties, which could affect the behavior of graphene nanodevices. Hence, high resolution two-dimensional (2D) mapping of their density is very important. Here, we used scanning capacitance microscopy/spectroscopy to obtain 2D maps of l in graphene on substrates with different dielectric permittivities, that is, SiO(2) (κ(SiO2) = 3.9), 4H-SiC (0001) (κ(SiC) = 9.7) and the very-high-κ perovskite strontium titanate, SrTiO(3) (001), briefly STO (κ(STO) = 330). After measuring l versus the gate bias V(g) on an array of points on graphene, maps of the CI density (N(CI)) have been determined by the neutrality point shift from V(g) = 0 V in each curve, whereas maps of the RS density (N(RS)) have been extracted by fitting the dependence of l on the carrier density (n). Laterally inhomogeneous densities of CI and RS have been found. The RS distribution exhibits an average value ～3 × 10(10) cm(-2) independently on the substrate. For the first time, a clear correlation between the minima in the l map and the maxima in the N(CI) map is obtained for graphene on SiO(2) and 4H-SiC, indicating that CI are the main source of the lateral inhomogeneity of l. On the contrary, the l and N(CI) maps are uncorrelated in graphene on STO, while a clear correlation is found between l and N(RS) maps. This demonstrates a very efficient dielectric screening of CI in graphene on STO and the role of RS as limiting factor for electron mean free path.     

XPS and UPS in situ study of oxygen thermal desorption from nanocrystalline diamond surface oxidized by different process

The chemistry of oxygen bonding on the diamond surface is a rich area of surface science research. It is well known that different surface terminations lead to strong variation of the material work function. This effect in diamond assumes peculiar consequences. In fact the oxidized diamond surface is hydrophilic, due to the high work function it shows a positive electron affinity and it is non conductive. On the contrary hydrogenation completely changes the orientation of the surface dipoles, the surface becomes hydrophobic, the work function lowers leading to a negative electron affinity. In addition hydrogen induces subsurface carriers which render the diamond surface semiconducting. These distinctive electronic properties make the diamond surface very interesting for the fabrication of surface field effect transistors just playing with the oxygen/hydrogen chemistry. Hydrogenation is generally obtained during the diamond synthesis in plasma reactors. Differently, the diamond surface oxidation may be accomplished with different processes (wet chemistry, plasma, UV irradiation).The realization of electronic devices calls for a complete understanding of the carbon-oxygen interactions, their stability and their influence on the electronic properties of diamond. Aim of this work is to explore the properties of diamond surfaces oxidized with piranha mixture, with O₂ plasma and with UV irradiation in a pure O₂ atmosphere. Each of these oxidized surfaces were annealed in situ at different temperatures and analyzed with photoelectron spectroscopies. Decreases of the oxygen concentration obtained via thermal desorption are then correlated with variations of the electronic properties obtained from UPS analyses.