Stability Analysis of the Serchio River Flood Plain Embankments (Tuscany, Italy)

Following the geotechnical characterization of 30 km long flood - plain embankments of the Serchio River (Tuscany – Italy), a number of numerical analyses have been carried out. The embankments have been constructed since the XVIII century and have experienced several failures in the years (the last in December 2009). The geotechnical characterization of the river embankments and the 2009 flood are described in a companion paper in this Conference. This paper shows the results of numerical analyses that have been carried out for various purposes. More specifically, the numerical analyses were carried out a) to clarify the causes of the December 2009 failures, b) to design appropriate repair of the failures and retrofit of the embankments in proximity of the failures (about 6 km) and c) to identify the most risk areas considering the whole extension of the embankments (30 km). The limit equilibrium method was used to assess the stability of the embankments under steady state flow conditions (areas close to the failures). For this analysis three different types of commercial software were used. The stability analyses were carried out using the Bishop simplified method with circular sliding surfaces. The different codes indicated very similar failure surfaces corresponding to the minimum (meaningful) values of the global safety factor. Some differences on the values of the global safety factor were observed by comparing the results obtained from the three codes. More specifically, the analyses results show that, for the selected cross sections, the safety factors are rather small and approaching to unity, if the seepage forces are not considered. In the case of steady state flow, safety factor drastically reduces becoming lower than one. This result apparently contradicts the fact that the considered embankments are standing up since centuries and failures occurred only in the occasion of floods. The FEM analysis (PLAXIS Flow) shows that the safety margins of the considered sections, in absence of filtration, are assigned to the partial saturation of the embankment. Unfortunately, an appropriate characterization of the material under conditions of partial saturation was not available. Therefore, the FEM analyses were also aimed at determining the necessary time to approach the steady state flow conditions. For the case under consideration it was estimated that 10 days are necessary to approach the steady state flow conditions. This time is apparently much longer than the duration of the longest flood event (few hours). From the above it is possible to conclude that the hypothesis of permanent flow is generally too cautious. Anyway for the failures under consideration, that have occurred with the concurrence of various adverse factors like the melting of the snow because of a sudden temperature increase and the contemporary long raining period (two consecutive floods), it is reasonable to assume that the permanent flow conditions were probably reached. In addition to the numerical analyses, evidences of the considered event and the susceptibility of the analyzed soil to piping phenomena have also been considered to find out all the possible causes and to design in an appropriate way both repair of the failures and retrofitting of the surrounding areas. Assessment of the most risky areas, considering the whole extension of the embankments (30 km), has been carried out following expeditious criteria which were based on the embankment geometry and the mechanical soil characteristics

Geotechnical Characterization of the Flood Plain Embankments of the Serchio River (Tuscany, Italy)

The flood plain embankments of the Serchio river have been constructed since the XVIII century and construction details are not known. These embankments have experienced failures several times during their life (last in December 2009). After the last event a detailed geotechnical investigation has been carried out. This paper discusses the necessary criteria for a cost – effective campaign considering the total length of the embankments (30 km) and the requested level of detail. In fact levee failure, although it is of limited extension, causes the achievement of the ultimate limit state of the entire embankment system. The campaign, in addition to laboratory tests, included boreholes, CPTu, permeability tests, 2D geo-electric tomography and 15 tests performed by the use of the continuous core drilling system. This last has proved to be a very useful tool for obtaining the more accurate evaluation of the in situ soil density (as confirmed by CPTu results). CPTu test, economical and expeditious, has proved to be an indispensable tool for delineating soil stratigraphy. In fact, their results combined with the borehole logs and laboratory testing provide extensive information. Geo-electric investigations can be very useful to highlight anomalies and heterogeneities in the cross section. Eventually, it is worthwhile to stress that embankments have generally a height of less than 4 m and a width between 1.2 and 3 m. This has restricted the investigation tools that could be used in this peculiar case

Spin Density Topology

Despite its role in spin density functional theory and it being the basic observable for describing and understanding magnetic phenomena, few studies have appeared on the electron spin density subtleties thus far. A systematic full topological analysis of this function is lacking, seemingly in contrast to the blossoming in the last 20 years of many studies on the topological features of other scalar fields of chemical interest. We aim to fill this gap by unveiling the kind of information hidden in the spin density distribution that only its topology can disclose. The significance of the spin density critical points, the 18 different ways in which they can be realized and the peculiar topological constraints on their number and kind, arising from the presence of positive and negative spin density regions, is addressed. The notion of molecular spin graphs, spin maxima (minima) joining paths, spin basins and of their valence is introduced. We show that two kinds of structures are associated with a spin-polarized molecule: the usual one, defined through the electron density gradient, and the magnetic structure, defined through the spin density gradient and composed in general by at least two independent spin graphs, related to spin density maxima and minima. Several descriptors, such as the spin polarization index, are introduced to characterize the properties of spin density critical points and basins. The study on the general features of the spin density topology is followed by the specific example of the water molecule in the 3 B 1 triplet state, using spin density distributions of increasing accuracy

Sabellidae (Annelida) from the Faro coastal lake (Messina, Ionian Sea), with the first record of the invasive species Branchiomma bairdi along the Italian coast

In the present paper, morphological and ecological observations on 4 sabellid taxa, Branchiomma bairdi, B. luctuosum,Megalomma lanigera and Myxicola sp., collected from the coastal lake of Faro (Messina, Ionian Sea) (26-36 psu), are reported. Megalomma lanigera, Myxicola sp. and B. luctuosum were collected from the soft bottom in shallow water and B. bairdi from the hard bottom of an internal channel. The presence of the latter is remarkable, as there is no previous record of this species along the Italian coast, and it confirms the lake of Faro as a very favourable environment for the introduction of alien species, which has occurred frequently as a result of aquaculture. High intraspecific variation was observed for M. lanigera, whilst more extensive analysis is required to ascertain the taxonomic status of the Myxicola specimens, including a review of all Mediterranean data currently attributed to M. infundibulum

Source function applied to experimental densities reveals subtle electron delocalization effects and appraises their transferability properties in crystals

The Source Function (SF) [1] enables the electron density (ED) to be seen at a point as determined by source contributions from the atoms of a system, and it is therefore well linked to the chemist\u2019s awareness that any local property and chemical behaviour is to some degree influenced by all the remaining parts of a system [1-3]. The key feature of the SF is that its evaluation requires only knowledge of the ED of a system, enabling a comparison of ab initio and X-ray diffraction derived ED properties on a common, rigorous basis. We here apply the SF descriptor to X-ray derived EDs as a mean to reveal electron-delocalization effects (EDEs) in crystals. Use of the SF to detect them has been firmly assessed for isolated molecules and for theoretically-derived EDs [2,4-5], but extending to crystals and experimental EDs, although being reported at two conferences [6-7] and in two papers discussing heteroaromaticity in a benzothiazol-substituted phosphane [8] or antiaromaticity in cyclopentadienone derivatives [9] needs to be fully demonstrated. Still unanswered questions are whether the EDs from X-ray data may be accurate enough to reveal the subtle features caused by electron pairing and whether these are not only detectable, but also reproducible and transferable, whenever appropriate. To provide an answer we analyse the experimental SF patterns in benzene (BZ), naphthalene (NT) and (+/-)-8\u2019-benzhydrylideneamino-1,1\u2019-binaphtyl-2-ol (BAB) molecular crystals. We find that the SF tool recovers the characteristic SF% patterns caused by pi-electron conjugation in the first two paradigmatic aromatic molecules in almost perfect quantitative accord with those from ab initio periodic calculations [10]. Moreover, the effect of chemical substitution on the transferability of such patterns to the BZ- and NT-like moieties of BAB is neatly spotted by the observed systematic deviations, relative to BZ and NT, of only those SF contributions from the substituted C atoms [10]. The capability of the SF to reveal EDEs by using a promolecule ED (PED), rather than the \u201ctrue\u201d ED, is then tested; the PED seems unable to reproduce the SF trends anticipated by the increase of electron delocalization [10]. The SF has wider applications than those related to the nature of chemical bonds in more or less conventional situations [2-3]. Detection of EDEs is one such new direction, another being the extension of the SF machinery to retrieve the atomic sources of the spin ED [5,11]. Acknowledgements Prof. Sine Larsen and Prof. Mark Spackman are both warmly thanked for providing us with, respectively, the 135 K X-ray diffraction dataset of naphthalene crystal and the 110 K X-ray diffraction data set of benzene. The Danish National Research Foundation is also thanked for partial funding of this work through the Center for Materials Crystallography (DNRF93). References [1] Bader, R. F. W. & Gatti, C. (1998). Chem. Phys. Lett. 287, 233-238. [2] Gatti, C. (2012). Struct. Bond. 147, 193-286. [3] Gatti, C. (2013). Phys. Scripta 87, 048102 (38pp). [4] Monza, E., Gatti, C., Lo Presti, L. & Ortoleva, E. (2011). J. Phys. Chem. A 115, 12864\u201312878. [5] Gatti, C., Orlando, A. M., Monza, E. & Lo Presti, L. (2016). Applications of Topological Methods in Molecular Chemistry, edited by R. Chauvin, C. Lepetit, B. Silvi & E. Alikhani, p. XXXX-YYYY, in Springer series Challenges and Advances in Computational Chemistry and Physics 22, Springer International Publishing, DOI 10.1007/978-3-319-29022-5_5 [6] Gatti, C., Saleh, G., Lo Presti, L. et al. (2012). In: Abstracts (page 42) of the Sagamore meeting XVII on Charge Spin and Momentum Densities, Daini Meisui Tei, Sapporo, Hokkaido, Japan, 15-20 July. [7] Gatti, C. (2013). In: Abstracts of Natta\u2019s Seeds Grow, From the crystallography and modelling of stereoregular polymers to the challenges of complex systems, International symposium on occasion of the 50th anniversary of the award of the Nobel Prize for Chemistry to Giulio Natta and Ziegler, Politecnico di Milano, Italy, 21-22 November. [8] Hey, J., Leusser, D., Kratzert, D., Fliegl, H., Dieterich, J. M., Mata, R. A. & Stalke, D. (2013). Phys. Chem. Chem. Phys. 15, 20600-20610. [9] Pal, R., Mukherjee, S., Chandrasekhar, S. & Guru Row, T. N. (2014). J. Phys. Chem. A, 118, 3479\u20133489. [10] Gatti, C., Saleh, G. & Lo Presti, L. (2016). Acta Cryst. B72, doi:10.1107/S2052520616003450 [11] Gatti, C., Orlando, A. M. & Lo Presti, L. (2015). Chem. Sci. 6, 3845-3852

Source Function applied to experimental densities reveals subtle electron-delocalization effects and appraises their transferability properties in crystals

The Source Function (SF), introduced in 1998 by Richard Bader and Carlo Gatti, is succinctly reviewed and a number of paradigmatic applications to in vacuo and crystal systems are illustrated to exemplify how the SF may be used to discuss chemical bonding in both conventional and highly challenging cases. The SF enables the electron density to be seen at a point determined by source contributions from the atoms or a group of atoms of a system, and it is therefore well linked to the chemist's awareness that any local property and chemical behaviour is to some degree influenced by all the remaining parts of a system. The key and captivating feature of the SF is that its evaluation requires only knowledge of the electron density (ED) of a system, thereby enabling a comparison of ab initio and X-ray diffraction derived electron density properties on a common and rigorous basis. The capability of the SF to detect electron-delocalization effects and to quantify their degree of transferability is systematically explored in this paper through the analysis and comparison of experimentally X-ray derived Source Function patterns in benzene, naphthalene and (\ub1)-8'-benzhydrylideneamino-1,1'-binaphthyl-2-ol (BAB) molecular crystals. It is shown that the SF tool recovers the characteristic SF percentage patterns caused by [pi]-electron conjugation in the first two paradigmatic aromatic molecules in almost perfect quantitative agreement with those obtained from ab initio periodic calculations. Moreover, the effect of chemical substitution on the degree of transferability of such patterns to the benzene- and naphthalene-like moieties of BAB is neatly shown and quantified by the observed systematic deviations, relative to benzene and naphthalene, of only those SF contributions from the substituted C atoms. Finally, the capability of the SF to reveal electron-delocalization effects is challenged by using a promolecule density, rather than the proper quantum mechanical density, to determine the changes in SF patterns along the cyclohexene, 1,3-cyclohexadiene and benzene molecule series. It is shown that, differently from the proper quantum density, the promolecular density is unable to reproduce the SF trends anticipated by the increase of electron delocalization along the series, therefore ruling out the geometrical effect as being the only cause for the observed SF patterns changes

Dosing fentanyl buccal tablet for breakthrough cancer pain: dose titration versus proportional doses

Abstract OBJECTIVES: The aim of this study was to compare the efficacy and safety of doses of fentanyl buccal tablet (FBT) proportional to doses of opioids used for background analgesia versus dose titration starting with the minimal dose for the management of breakthrough cancer pain (BTcP). METHODS: A total of 82 cancer patients with BTcP who were receiving strong opioids in doses of at least 60 mg of oral morphine equivalents and having acceptable background analgesia, were selected for a multicenter unblinded study. Forty-one patients were randomized to receive FBT in doses proportional to the daily opioid doses for four consecutive episodes of BTcP (group P). Forty-one patients underwent dose titration of FBT, with an initial dose of 100 µg, for four consecutive episodes (group T). Pain intensity and symptoms associated with opioid therapy were measured before administering any dose of FBT (T0) and 15 minutes after (T15). RESULTS: In all, 80 patients were considered for analysis (39 and 41 patients in group P and T, respectively). Patients were receiving a mean of 126 ± 100 mg of oral morphine equivalents (range 60-480 mg) for background analgesia. A total of 293 episodes of BTcP (144 and 149 in group P and T, respectively) were treated and considered for analysis. No differences were found in the decrease of pain intensity between the two groups. However, in patients receiving doses of oral morphine equivalents of >120 mg/day, a significant number of patients obtained a decrease in pain intensity >50% in group P in comparison with group T (p = 0.040). Also, the need for rescue medication was significantly more frequently reported in group T for the first episode of BTcP (p < 0.0005). No differences in the level of adverse effects were observed between the two groups. No differences in patients' satisfaction were reported. CONCLUSION: According to the data obtained in this study, there is no evidence for the use of dose titration in the management of BTcP in opioid-tolerant patients. Indeed, doses proportional to basal opioid regimen for background pain seem to be effective and safe in the majority of patients. Further studies should confirm this data in patients receiving higher doses of opioids, with other rapid-onset opioids, and in other settings

Insights on spin delocalization and spin polarization mechanisms in crystals of azido copper(II) dinuclear complexes through the electron spin density Source Function

The Source Function (SF) tool was applied to the analysis of the theoretical spin density in azido CuII dinuclear complexes, where the azido group, acting as a coupler between the CuII cations, is linked to the metal centres either in an end-on or in an end-end fashion. Results for only the former structural arrangement are reported in the present paper. The SF highlights to which extent the magnetic centres contribute to determine the local spin delocalization and polarization at any point in the dimetallic complex and whether an atom or group of atoms of the ligands act in favour or against a given local spin delocalization/polarization. Ball-and-stick atomic SF percentage representations allow for a visualization of the magnetic pathways and of the specific role played by each atom along these paths, at given reference points. Decomposition of SF contributions in terms of a magnetic and of a relaxation component provides further insight. Reconstruction of partial spin densities by means of the Source Function has for the first time been introduced. At variance with the standard SF percentage representations, such reconstructions offer a simultaneous view of the sources originating from specific subsets of contributing atoms, in a selected molecular plane or in the whole space, and are therefore particularly informative. The SF tool is also used to evaluate the accuracy of the analysed spin densities. It is found that those obtained at the unrestricted B3LYP DFT level, relative to those computed at the CASSCF(6,6) level, greatly overestimate spin delocalization to the ligands, but comparatively underestimate magnetic connection (spin transmission) among atoms, along the magnetic pathways. As a consequence of its excessive spin delocalization, the UB3LYP method also overestimates spin polarization mechanisms between the paramagnetic centres and the ligands. Spin delocalization measures derived from the refinement of Polarized Neutron Diffraction data seem in general superior to those obtained through the DFT UB3LYP approach and closer to the far more accurate CASSCF results. It is also shown that a visual agreement on the spin-resolved electron densities rho(alpha) and rho(beta) derived from different approaches does not warrant a corresponding agreement between their associated spin densities.Electron spin density at a point may be seen as determined by a local Source Function for such density, operating at all other points of space. Integration of the local source over Bader's quantum atoms measures their contribution in determining the spin density features at any system's location. This novel tool is able to provide interesting insights on the electron spin delocalization and polarization mechanisms along with their dependence from the spin density quality

Lipid peroxidation and nitric oxide metabolites in a group of subjects with obstructive sleep apnea syndrome

It is known that in OSAS the plasma lipid peroxidation has an opposite behavior in comparison with nitric oxide metabolites. In the re-examination of our survey of OSAS infjects we calculated the ratio between thiobarbituric acid reactive infstances (TBARS) and nitric oxide metabolites (NOx) in relation to OSAS severity. The study has regarded 48 OSAS infjects infdivided in two infgroups according to the apnea/hypopnea index-AHI-(Low=21 infjects with AHI 30). From the obtained data it is evident that the TBARS/NOx ratio is significantly higher in the H infgroup compared to L infgroup as well as this ratio is reduced in L infgroup in comparison with the whole group of OSAS infjects. In the entire group of OSAS infjects the TBARS/NOx ratio results positively correlated with AHI and ODI and inversely correlated with mSO2

Rationalizing the Lacking of Inversion Symmetry in a Noncentrosymmetric Polar Racemate : an Experimental and Theoretical Study

The total charge density of PYRAC, a polar (Pca21) organic racemate with Z\u2032 = 2, was derived from high-resolution single-crystal X-ray diffraction data at T = 100(2) K and periodic DFT calculations. The PYRAC asymmetric unit consists of a hydrogen-bonded pair of conformationally different enantiomers, A and Bi, where the subscript \u201ci\u201d indicates a reversed absolute configuration. The lattice stability was compared with that of centrosymmetric possibly competing structures, with the aim of understanding why a noncentrosymmetric lattice framework is obtained from a racemic mixture. The likelihood of specific intermolecular recognition processes among different conformers of PYRAC in the very first stages of nucleation was investigated by DFT simulations in vacuo. Two competing, equivalent interconversion pseudorotatory paths between the most stable A and the least stable B conformers were found. It results that molecules spend most of their time ( 4853%) in the A conformation, whereas the B one is far less populated ( 487%). Therefore, centrosymmetric AAi adducts are formed very frequently in the reaction liquor, whereas the BBi ones are rare. Nevertheless, AAi pairs produce crystal forms with cohesive energies and densities significantly less favorable than those estimated for the noncentrosymmetric heterochiral ABi ones. Therefore, preference for Z\u2032 = 2 in conjunction with noncentrosymmetric point and space groups results from the thermodynamic control of the crystallization process. The capability of forming extended hydrogen bond chains throughout the lattice appears to be a prerequisite to bind together the fundamental ABi repeating units