1,721,326 research outputs found
DTPA-Functionalized silica-based monoliths for the removal of transition and lanthanide ions from aqueous phase
Full text linkTransition and rare-earth metals are essential raw materials used in a wide range of technological applications; moreover, their consumption is often associated with high production of wastes. Therefore, their recycling and recovery from end-of-life products or metal-contaminated aqueous environments is of considerable importance from a circular economy perspective. In our study, synthetic mesoporous silica monoliths, obtained by sol-gel synthesis[1] and functionalized with chelating groups are used for the recovery of metal ions from aqueous matrices (MONO-DTPA). The monoliths were characterized using a multi-technique approach and were tested in the recovery of paramagnetic Gd3+, Cu2+ and Co2+ ions from aqueous solutions, using 1H-NMR relaxometry to evaluate their uptake performance in real time and in simple conditions[2]. Detailed information on the kinetics of the capture process was also extrapolated. Finally, the possibility to regenerate the solid sorbents was evaluated. The modified silica monoliths were able to recover an appreciable amount of both di- and trivalent metal ions. The best results were obtained in the case of Cu2+ after 24 hours of contact, with a recovered amount of 0.29 mmol/g corresponding to 18.48 mg/g (Fig. 1, A).
The capture performance of MONO-DTPA has been shown to be superior to that of natural or synthetic materials commonly used for metal ion removal (Fig 1, B).
[1] V. Miglio, C. Zaccone, C. Vittoni, I. Braschi, E. Buscaroli, G. Golemme, L. Marchese and C. Bisio, Molecules 2021, 26, 1316
[2] S. Marchesi, S. Nascimbene, M. Guidotti, C. Bisio and F. Carniato, Dalton Trans. 2022, 51, 4502–4509
Life after default. Private and official deals
No full textThis paper studies the relationship between sovereign debt default and annual GDP growth distinguishing between private and official deals. Using the Synthetic Control Method to analyze 23 official and private defaulters from 1970 to 2017, we find that private defaults generate output losses both during the crisis and persisting over time. Conversely, official defaulters do not show a permanent drop in GDP per capita, neither during the crisis nor in its aftermath. Using panel data analysis to control for the creditors’ loss (haircut), we confirm that official and private defaults may have different effects on GDP growth. © 2020 Elsevier Lt
Delegation of implementation in project aid
Full text linkIn this paper we explore the factors that determine delegation of implementation in project aid. In particular, focusing on the importance of informational asymmetry between levels of government, we empirically assess whether this choice is influenced by the relative importance of the local information at the recipient country level. Moreover, we test whether this choice can in turn influence project performance. Using information on more than 5800 World Bank projects for the period 1995-2014, and controlling for characteristics at both country and project level, we find that transparency does influence the probability that a project is implemented locally rather than nationally. More specifically, a one standard deviation decline in transparency increases the probability of a locally implemented project by three percentage points. We also find that a local implementing agency may increase the probability of a successful project only up to a certain level of a country’s transparency
Sovereign rating after private and official restructuring
No full textThis paper studies the relationship between sovereign debt (final) restructuring and sovereign ratings, by distinguishing between commercial and official debt and by considering the creditors’ loss (haircut). Institutional Investor's index is taken as a measure of a country's creditworthiness. We find that while a restructuring with private creditors seems to involve some reputational costs, ”official defaulters” are not affected (or may even benefit) by the restructuring episodes. Using the Synthetic Control Method, we find further evidence for the heterogeneity of the economic impact of debt restructurings, confirming that official and private restructurings may have different costs and then induce selective defaults
A bispectral approach to analyze nonlinear cochlear active mechanisms in transient evoked otoacoustic emissions
No full textA new approach to study nonlinearity in cochlear active mechanisms, as evaluated in transient evoked otoacoustic emissions (TEOAEs), is presented. TEOAEs are signals generated in the cochlea by a mix of linear and nonlinear mechanisms. This new approach was designed to complement the traditional TEOAE analysis performed by currently available systems used in objective hearing screening and assessment. Nonlinearity of TEOAEs was studied by means of the bispectrum, which is able to find out quadratic frequency couplings (QFCs) that occur when a frequency is not only generated by an independent cochlear source, but it is the result of the interaction among a number of cochlear sources. To fit with the technical constraints of currently available TEOAE systems, the bispectrum was estimated by the third-order scaled polyperiodogram. The proposed method was characterized with synthesized TEOAEs as a function of the main TEOAE parameters and then used to analyze TEOAEs recorded in normal hearing adults and full-term neonates. Results revealed the presence of QFCs in both adult and neonatal TEOAEs, with peculiar patterns and significantly different frequency content in the two groups: adults had QFCs mainly around 2 kHz and neonates had QFCs mainly in the range 3.5-4 kHz. © 2007-2012 IEEE
Compton-thick AGN in the NuSTAR Era. IV. A deep NuSTAR and XMM-Newton view of the candidate compton-thick AGN in ESO 116-G018
No full textWe present a 2-78 keV spectral analysis of the deep NuSTAR and XMM-Newton observation of a nearby Seyfert 2 galaxy, ESO 116-G018, which is selected as a candidate Compton-thick (CT) active galactic nucleus (AGN) based on a previous Chandra-Swift-BAT study. Through our analysis, the source is, for the first time, confirmed to be a CT AGN at a >3 sigma confidence level, with the "line-of-sight" column density N-H,N-Z = [2.46-2.76] x 10(24) cm(-2). The "global average" column density of the obscuring torus is N-H,N-S = [0.46-0.62] x 10(24) cm(-2), which suggests a clumpy, rather than uniform, distribution of the obscuring material surrounding the accreting supermassive black hole. The excellent-quality data given by the combined NuSTAR and XMM-Newton observations enable us to produce a strong constraint on the covering factor of the torus of ESO 116-G018, which is found to be f(c) = [0.13-0.15]. We also estimate the bolometric luminosity from the broadband X-ray spectrum to be L-bol = [2.57-3.41] x 10(44) erg s(-1)
Covered by lines and conic connected varieties
No full textWe study some properties of an embedded variety covered by lines
and give a numerical criterion ensuring the existence of a singular conic
through two of its general points. We show that our criterion is sharp.
Conic-connected, covered by lines, QEL, LQEL, prime Fano, defective,
and dual defective varieties are closely related. We study some relations
between the above mentioned classes of objects using celebrated results
by Ein and Zak
Surgical treatment of aseptic non-union in long bones: review of 193 cases
No full textThe surgical treatment of aseptic nonunion often represents a more challenging situation for the orthopaedic surgeon than treatment of the primary fracture. In fact, it may be necessary not only to "rivitalize" the nonunion area, but also to exchange the bone fixation devices and to place some refill material in the bone gap. Several surgical techniques and different kinds of bone gap refills have been reported in the literature for the treatment of long bone nonunion. We present the results of 193 cases of long bone nonunion that have been treated in a period of 11 years (1992–2003) by a mostly open approach to the nonunion site with or without autologous bone graft interposition. The site (27 humerus, 44 forearm, 48 femur, 74 tibia) and the type of nonunion (179 atrophic, 19 hypertrophic) were considered in the surgical planning as were the mechanic and biological problems. New osteosynthesis was performed in 139 cases: with plate and screws in 82 cases, with intramedullary nails in 31 cases, with external fixators in 15 cases and with other devices in 11 cases (e.g. interfragmentary screws, k-wires). Cancellous or corticocancellous bone graft, always autologous from the iliac crest or from the anterior tibial tuberosity, was used in 183 cases (94.8%). Healing of the nonunion was successful in 179 cases (92.7%) in a mean time of 5.8 months. 14 patients (7.2%), all atrophic nonunion, healed with further surgery in a mean time of 19.2 months. Best results were obtained by the use of the intramedullary nail (31 cases): 99% healed in 5.2 months for the lower limb and 100% healed in 7.4 months for the upper limb. Good results have been achieved by plate (82 cases): 89.5% healed in 4.5 months for the lower limb and 94.1% in 6 months for the upper one. The worst results were observed with external fixation (15 cases). However, this device was used in the most complex situations, when severe soft tissue sufference was present. In this group, the mean healing time was 7.1 months (69.2% of cases) in the lower limb and 8 months (50%) in the upper one. Bone graft alone (54 cases) led to healing in 34 of 35 cases (97%) in the lower limb in 6 months and in 17 of 19 cases (89.4%) in 6.4 months in the upper limb
- …
