The ITS-90 after definition of neon isotopic reference composition. Extent of the isotopic effect on previous inter-comparison results

Starting from the end of the past century, the importance has been recognized of the effect of isotopic composition on some of the temperature fixed points for the most accurate realizations of the ITS-90. In the original definition of the latter, dating back to 1990, only a generic reference was made to natural composition of the substances used for the realization of the fixed points, except for helium. The definition of a reference isotopic composition for three fixed points, e-H2, Ne and H2O, while eliminating the non-uniqueness of the Scale in this respect, induced detectable differences in the present and future realizations of the Scale, at the highest accuracy level, with respect to the previous realizations, when they affected the results of past key comparisons, namely the K1 and K1.1, and K2 and K2.1 to K2.5 and the related regional and supplementary ones. The paper provides evidence of the extent of this effect by using the results of the relevant key comparisons for Neon archived in the BIPM KCDB, and of other comparisons existing in the literature: 1979-1984, 2007-2012 and 2009-2010 sealed cell comparisons; and discusses the meaning and the outcomes of this evaluation.Comment: 19 pages, 4 figures, 4 tables. BIPM, Doc. CCT/17-1

Prediction of Lower Urinary Tract, Sexual, and Bowel Function, and Autonomic Dysreflexia after Spinal Cord Injury

Spinal cord injury (SCI) produces damage to the somatic and autonomic pathways that regulate lower urinary tract, sexual, and bowel function, and increases the risk of autonomic dysreflexia. The recovery of these functions has a high impact on health, functioning, and quality of life and is set as the utmost priority by patients. The application of reliable models to predict lower urinary tract, sexual, and bowel function, and autonomic dysreflexia is important for guiding counseling, rehabilitation, and social reintegration. Moreover, a reliable prediction is essential for designing future clinical trials to optimize patients' allocation to different treatment groups. To date, reliable and simple algorithms are available to predict lower urinary tract and bowel outcomes after traumatic and ischemic SCI. Previous studies identified a few risk factors to develop autonomic dysreflexia, albeit a model for prediction still lacks. On the other hand, there is an urgent need for a model to predict the evolution of sexual function. The aim of this review is to examine the available knowledge and models for the prediction of lower urinary tract, sexual, and bowel function, and autonomic dysreflexia after SCI, and critically discuss the research priorities in these fields

Black Carbon and Organic Components in the Atmosphere of Southern Italy: Comparing Emissions from Different Sources and Production Processes of Carbonaceous Particles

Initial measurements of black carbon (BC) content at both 880 and 370 nm, obtained in two sites in southern Italy by an aethalometer, have been analyzed. The sites are located in the same region (Basilicata), but are affected by different emission sources. In one case the main source of BC is related to vehicular traffic from a nearby freeway. Data were collected, although not continuously, during 2008, 2009 and 2010. In the second case, a fresh crude-oil pre-treatment plant continuously burns petroleum-derived products, thus contributing to emissions of both carbonaceous matter and its organic component. The corresponding data-set was collected in the period January–April 2011. At the first site, two daily peaks were found for the BC content, typical of vehicles emissions, with maximum values ranging from 2000 ng/m3 to 4700 ng/m3 found during weekdays. This behavior disappears at the weekend or when polluted air-masses from north-east Europe are transported over the measurement site. At the second site, two daily peaks were never found, suggesting that crude oil chemical processes were the main source of the emissions. In this case, the maximum BC values ranged between 1000–8000 ng/m3, depending on the processes occurring at the fresh crude-oil pre-treatment plant. Moreover, the estimated level of BC at 370 nm was higher than that of BC at 880 nm in all months, expect for April, indicating a clear organic component in atmospheric aerosols. Finally, based on a best-fit procedure applied to the seven wavelengths’ absorption coefficients, aerosols with different spectroscopic properties have been detected at these two sites

A facile method to oxidize carbon nanotubes in controlled flow of oxygen at 350 °C

The functionalization of carbon nanotubes (CNTs) is a very important step in many applications but it is still a very complex and variable task. This work shows an efficient, easily reproducible and optimal method to introduce oxygenated functional groups to CNTs by treating them for 60′ at 350 °C with a mixture of 2% oxygen in argon. The oxidized nanotubes were characterized through FT-IR, Raman and TGA to verify the quality of the oxidation and the lattice integrity of the treated CNTs. The results demonstrate that the treated nanotubes are not damaged even after introducing a significant number of new groups. This methodology could be easily tuned to functionalize other types of graphitic materials

Physical and optical properties of atmospheric aerosols by in-situ and radiometric measurements

Physical and optical properties of atmospheric aerosols collected by using a high resolution (1.5 nm) spectroradiometer (spectral range 400–800 nm), a 13-stage Dekati Low Pressure Impactor (size range 30 nm–10 μm), and an AE31 Aethalometer (7 wavelenghts from 370 nm to 950 nm), have been examined in a semi-rural site in Southwest Italy (Tito Scalo, 40°35' N, 15°41' E, 750 m a.s.l.). In particular, daily averaged values of AOD and Ångström turbidity parameters from radiometric data together with mass-size distributions from impactor data and Black Carbon (BC) concentrations have been analyzed from May to October 2008. Furthermore, by inverting direct solar radiances, aerosol columnar number and volume size distributions have been obtained for the same period. The comparison of different observation methods, allowed to verify if, and in what conditions, changes in aerosol properties measured at ground are representative of columnar properties variations. Agreement between columnar and in-situ measurements has been obtained in case of anthropogenic aerosol loading, while in case of Saharan dust intrusions some discrepancies have been found when dust particles were located at high layers in the atmosphere (4–8 km) thus affecting columnar properties more than surface ones. For anthropogenic aerosols, a good correlation has been confirmed through the comparison of fine aerosol fraction contribution as measured by radiometer, impactor and aethalometer, suggesting that, in this case, the particles are more homogeneously distributed over the lower layers of atmosphere and columnar aerosol optical properties are dominated by surface measured component

A new algorithm for brown and black carbon identification and organic carbon detection in fine atmospheric aerosols by a multi-wavelength Aethalometer

A novel approach for the analysis of aerosol absorption coefficient measurements is presented. A 7-wavelenghts aethalometer has been employed to identify brown carbon (BrC) and black carbon (BC) and to detect organic carbon (OC) in fine atmospheric aerosols (PM2.5). The Magee Aethalometer estimates the BC content in atmospheric particulate by measuring the light attenuation in the aerosols accumulated on a quartz filter, at the standard wavelength λ = 0.88 μm. The known Magee algorithm is based on the hypothesis of a mass absorption coefficient inversely proportional to the wavelength. The new algorithm has been developed and applied to the whole spectral range; it verifies the spectral absorption behavior and, thus, it distinguishes between black and brown carbon. Moreover, it allows also to correct the absorption estimation at the UV wavelength commonly used to qualitatively detect the presence of mixed hydrocarbons. The algorithm has been applied to data collected in Agri Valley, located in Southern Italy, where torched crude oil undergoes a pre-treatment process. The Magee Aethalometer has been set to measure Aerosol absorption coefficients τaer (λ, t) every 5 min. Wavelength dependence of τaer (λ, t) has been analyzed by a best-fit technique and, excluding UV-wavelengths, both the absorption Angstrom coefficient α and the BC (or BrC) concentration have been determined. Finally, daily histograms of α provide information on optical properties of carbonaceous aerosol, while the extrapolation at UV-wavelengths gives information on the presence of semivolatile organic carbon (OC) particles

Fe-periclase reactivity at Earth's lower mantle conditions: Ab-initio geochemical modelling

Intrinsic and extrinsic stability of the (Mg,Fe)O solid mixture in the Fe-Mg-Si-O system at high P, T conditions relevant to the Earth\u2019s mantle is investigated by the combination of quantum mechanical calculations (Hartree- 26 Fock/DFT hybrid scheme), cluster expansion techniques and statistical thermodynamics. Iron in the (Mg,Fe)O binary mixture is assumed to be either in the low spin (LS) or in the high spin (HS) state. Un-mixing at solid state is observed only for the LS condition in the 23\u201342 GPa pressure range, whereas HS does not give rise to un-mixing. LS (Mg,Fe)O un-mixings are shown to be able to incorporate iron by subsolidus reactions with a reservoir of a virtual bridgmanite composition, for a maximum total enrichment of 0.22 FeO. At very high P (up to 130/3150 GPa/K), a predominant (0.7 phase proportion), iron-rich Fe-periclase mixture (Mg0.50Fe0.50)O is formed, and it coexists, at constrained phase composition conditions, with two iron-poor assemblages [(Mg0.90Fe0.10)O and (Mg0.825Fe0.175)O]. These theoretical results agree with the compositional variability and frequency of occurrence observed in lower mantle Fe-periclase from diamond inclusions and from HP-HT synthesis products. The density difference among the Fe-periclase phases increases up to 10%, between 24 and 130 GPa. The calculated bulk Fe/Mg partitioning coefficient between the bridgmanite reservoir and Fe-periclase, Kd, is 0.64 at 24 GPa; it then drops to 0.19 at 80 GPa, and becomes quasi-invariant (0.18\u20130.16) in the lowermost portion of the Earth\u2019s mantle (80\u2013 130 GPa). These Kd-values represent an approximate estimate for the Fe/Mg-partitioning between actual bridgmanite and Fe-periclase. Consequently, our Kd-values agree with experimental measurements and theoretical determinations, hinting that iron preferentially dissolves in periclase with respect to all the other iron-bearing phases of the lower mantle. The continuous change up to 80 GPa (2000 km depth) of the products (compositions and phase proportions) over the MgO-FeO binary causes geochemical heterogeneities throughout the lower mantle, but it does not give rise to any sharp discontinuity. In this view, anomalies like the ULVZs, explained with a local and abrupt change of density, do not seem primarily ascribable to the mixing behavior and reactivity of (Mg,Fe)O at subsolidus

Mechanical properties of mortar containing waste plastic (PVC) as aggregate partial replacement

The purpose of this work is the reuse of polyvinyl chloride (PVC) deriving from waste electrical and electronic equipment (WEEE) used as a partial substitute for the mineral aggregate to produce lightened mortars. PVC was recovered from copper electrical cables, ground and used as replacement of mineral aggregate in 5, 10, 15 and 20 % vol. in mortar. A thermal characterization of the starting material was carried out to understand its composition. The mortar samples were mechanically tested both using class G cement and ordinary Portland cement. The results showed a worsening of the mechanical properties of around 50 % for only 5 % in volume of sand substituted with PVC waste. A likely explanation to this phenomenon was found in the mechanical characteristics of the PVC used and to its poor adhesion with the matrix, that resulted in the creation of porosity. However, the mortar prepared contributes to the conservation of natural resources and maintains mechanical properties adequate for the use in non-structural applications (e.g. screed or substrate)

Polyvinyl butyral-based composites with carbon nanotubes: Efficient dispersion as a key to high mechanical properties

Even if the carbon nanotubes (CNTs) and their derivatives are commonly used as reinforcing phase in composite materials, also in commercial products, their tendency to agglomerate generally determines a scarce dispersion, thus not maximizing the effect due to the second phase. In this article, a perfect dispersion of highly entangled nanotubes was achieved by using a very simple approach: exploiting the dispersing effect of a low-cost polymer, polyvinyl butyral (PVB), coupled with standard ultrasound sonication. Several dispersion approaches were tested in order to develop a consistent and widely applicable dispersion protocol. The tape casting technology was subsequently used to produce 100 to 300 μm thick PVB-matrix composite tapes, reinforced by multiwall CNTs dispersed according to the optimized protocol. Their mechanical properties were evaluated, and a simple model was used to demonstrate that the effective dispersion of CNTs is the key to obtain significantly improved properties