Horizontal bridge-soil interaction assessment by dynamic testing

This paper presents a methodology to assess the real longitudinal stiffness of a bridge including the foundation-soil interaction. The method is based on a dynamic test of the bridge complemented by structural identification. The experimentally obtained natural frequencies of the bridge in the horizontal and vertical planes are used to derive, via a parameter identification procedure and a dynamic model of the bridge, the most approximate values of the Winkler coefficients simulating the interaction of foundation with ground. The theoretical background of the procedure is first presented and then demonstrated on a prestressed concrete highway bridge with a total length of 2040 m (normal span length of 40 m). The bridge is located near the sea coast, and large variations in the soil properties were observed between the piers. As a consequence, it was not possible to assess in a reliable way the actual global stiffness of this bridge (due to the interaction of deck, piers, abutments and foundations) in front of horizontal forces (vehicle braking, earthquake, wind and so on) based on the results of the geotechnical survey. The dynamic excitation in the longitudinal direction was easily achieved by means of controlled vehicle braking at different points on the bridge. The results show the feasibility of using dynamic testing with vehicle braking as excitation to deduce the correct behavior of the bridge under the effect of horizontal loads.     

Synthesis,characterization and antibacterial activity of 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoic acid and di‐isopropylammonium [3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoato] triphenylstannate(IV). The crystal structure of [HQ][SnPh3(o‐mpspa)]

Reaction of 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoic acid [H₂(o‐mpspa)] with SnPh₃OH in the presence of di‐isopropylamine resulted in the formation of the complex [HQ][SnPh₃(o‐mpspa)] (where HQ = di‐isopropylammonium cation and o‐mpspa = 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoato), which was characterized by mass spectrometry and vibrational spectroscopy, as well as by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. The single‐crystal X‐ray structural analysis of the new complex shows a trigonal‐bipyramidal coordination geometry around the Sn atom where o‐mpspa behaves as a bidentate chelating ligand. Dimeric units arise from the existence of N? H…O hydrogen bonds between the NH₂ group of the di‐isopropylammonium cation and the oxygen atoms of the two neighbouring carboxylato groups. The bacteriostatic activity of the complex is also reported. Copyright © 2007 John Wiley & Sons, Ltd.     

Methylmercury(II) complexes with 2-mercaptopyridinecarboxylic acids

The stability constants of the complexes [MeHgL]^?(H₂L = 2-mercaptopyridine-3-carboxylic acid, 2-mercaptopyridine-4-carboxylic acid, 2-mercaptopyridine-5-carboxylic acid and 2-mercaptopyridine-6-carboxylic acid) have been obtained by differential pulse polarography. The values of log β₁ are in the range 14.14–14.96 at 20°C and ionic strength 0.1 mol dm^?3. The complexes MeHgHL have been isolated and characterized by chemical analysis and mass and IR spectrometry.     

3-(Aryl)-2-sulfanylpropenoates of mercury(II) and phenylmercury(II)

Compounds [HQ]₂[Hg(L)₂] and [HQ][PhHg(L)] [where HQ = diisopropylammonium cation; L = pspa, fspa, tspa, where p = 3-(phenyl), f = 3-(2-furyl), t = 3-(2-thienyl), and spa = 2-sulfanylpropenoato] have been prepared by the reaction of mercury(II) acetate or phenylmercury(II) acetate with the corresponding acid in the presence of diisopropylamine in ethanol. The compounds have been characterized by elemental analysis, FAB mass spectrometry and IR and NMR (¹H, ¹³C) spectroscopy. The crystal structures of the [HQ]₂[Hg(L)₂] compounds show the presence of diisopropylammonium cations and [Hg(L)₂]²⁻ anions. In each anion the Hg atom is in an HgO₂S₂ environment and this can be described as nido-tbp. The crystal structures of the [HQ][PhHg(L)] compounds show the presence of diisopropylammonium cations and [PhHg(L)]⁻ anions in which the Hg atom adopts an HgCOS distorted T-environment. The NMR data suggest that the coordination mode of the ligand L²⁻ determined by X-ray diffractometry in the solid remains in solution.     

A mesoporous 3D hybrid material with dual functionality for Hg2+ detection and adsorption

Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption. This hybrid solid is the chemodosimeter for Hg(2+) detection. Hg(2+) reacts with the APC fragment in U1 with release of the squaraine dye into the solution, which turns deep blue and fluoresces strongly. Naked-eye Hg(2+) detection is thus accomplished in an easy-to-use procedure. In contrast, U1 remains silent in the presence of other thiophilic transition metal ions, alkali and alkaline earth metal ions, or anions ubiquitously present in water such as chloride, carbonate, sulfate, and phosphate. Material U1 acts not only as chemodosimeter that signals the presence of Hg(2+) down to parts-per-billion concentrations, but at the same time is also an excellent adsorbent for the removal of mercury cations from aqueous solutions. The amount of adsorbed mercury ranges from 0.7 to 1.7 mmol g(-1), depending on the degree of functionalisation. In addition, hybrid material U1 can be regenerated for both sensing and removal purposes. As far as we know, U1 is the first example of a promising new class of polyfunctional hybrid supports that can be used as both remediation and alarm systems by selective signalling and removal of target species of environmental importance. Model compounds based on silica gel (G1), fumed silica (F1), and micrometre-sized MCM-41 scaffolds (M1) were also prepared and studied for comparative purposes.     

Synthesis of binuclear platinum complexes containing the ligands 8-naphthyridine, 2-aminopyridine, and 7-azaindolate. An experimental study of the steric hindrance of the bulky pentafluorophenyl ligands in the synthesis of binuclear complexes

The bidentate N-donor ligands 2-aminopyridine (2-ampy), 7-azaindolate (aza) and 1,8-naphthyridine (napy) have been used to study the steric effect of pentafluorophenyl groups in the synthesis of binuclear platinum(II) complexes. The 2-ampy and aza ligands bridge two "Pt(C 6F 5) 2" fragments with Pt...Pt distances of 4.1 and 3.4 A, respectively (complexes 1 and 3). Under the same reaction conditions the napy ligand shows chelating behavior and makes the mononuclear complex ( A) highly reactive because of its strained coordination. One of the Pt-N bonds of the chelating complex is broken on reaction with HX {X = Cl ( 4), Br ( 5)} because of protonation while the anion X (-) occupies a created vacant site. The resulting mononuclear complex eliminates C 6F 5H when refluxed, and a binuclear complex ( 6) with two napy ligands bridging two "Pt(C 6F 5)Cl" fragments is obtained. The reaction of A with HPPh 2 affords a mononuclear complex ( 7) analogous to complexes 5 and 6, but reflux gives a binuclear complex ( 8) with the two napy ligands terminally bound and the PPh 2 groups bridging the "Pt(C 6F 5)napy" moieties. The reaction of A with HCCPh gives a binuclear complex; moreover, the final product does not depend on the ratio of complex A to HCCPh. Complexes 1, 4, 6, 9 have been structurally characterized by X-ray diffraction.     

Some general models of traffic flow in an isolated network

Starting form basic principles, we obtain mathematical models that describe the traffic of material objects in a network represented by a graph. We analyze existence, uniqueness, and positivity of solutions for some implicit models. Also, some linear models and their equilibria are analyzed. Copyright © 2017 John Wiley & Sons, Ltd.     

Thermal and vibrational characterization of human skin

For a better understanding of the molecular and organizational changes in human dermis, biophysical methods were tested. The aim of this study was to find suitable and reproducible biomarkers for further clinical studies on intrinsic and extrinsic aging of dermis. Thermoporometry, hydric organization and thermal transitions of fresh and frozen skins were determined by differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to identify the absorption bands of the dermis especially in the 1800–1000 cm^?1 zone and to discriminate between the different secondary structures of proteins. A widening of the pore size distribution is evidenced with freezing, but there is no significant difference between the hydric organization and the endothermic collagen denaturation of fresh and frozen skins. The global FTIR spectra and the second derivative spectra in the scanned zone are also identical in fresh and frozen dermis, validating the storage protocol. DSC and FTIR are well-suited techniques to characterize human skin, giving accurate results with high reproducibility. The acquisition of thermal and vibrational biomarkers of the skin at the mesoscale and nanoscale contributes to its better knowledge and is promising for further studies on skin aging.     

Monitoring of the Alamillo cable-stayed bridge during construction

The Alamillo Bridge is one of the long-span bridges crossing the Guadalquivir River. It was built on the occasion of Expo '92 in 1992 in Sevilla, Spain. The bridge is a cable-stayed structure spanning 200 m without any intermediate supports. Its originality is the lack of back stays and the balancing of the front stays through the backward inclination of a massive pylon. This paper shows the importance of experimental in situ techniques when applied to unconventional civil engineering structures and how—with the help of an important amount of accurate instrumentation, monitoring the most important experimental variables—it was possible to build the bridge correctly, safely, and on schedule.