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91.
Federico Cozzi Italo Pellegrini Gianpiero Adami Edoardo Reisenhofer Massimo Bovenzi Pierluigi Barbieri 《Central European Journal of Chemistry》2009,7(3):395-401
Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to identify sulphur compounds in PM10 samples
collected simultaneously at two sites with different environmental situations in the province of Trieste (NE of Italy), during
summer and winter seasons respectively. The first site is an industrial site located near a steel mill plant and the second
is a coastal site. The sulphur speciation at the industrial site has shown the presence of the following sulphur compounds
in both seasons: organic compounds (thiophenes or Polycyclic Aromatic Sulphur Heterocycles — PAHs) and sulphates while in
the winter season sulphites were also present. In the coastal site organic compounds (thiophenes or PASHs) and sulphate were
found during winter season, moreover bisulphates were found during summer season. Relative percentages of the different sulphur
compounds have shown that sulphate is the most abundant form of sulphur in the industrial site samples during both seasons
and in the coastal site sample collected during the winter season (> 98%); in the coastal site sample collected during the
summer season the relative percentages of bisulphate and sulphate were around 40% and 60% respectively.
相似文献
92.
Here we define the concept of Qregularity for coherent sheaves on a smooth quadric hypersurface Qn⊂Pn+1. In this setting we prove analogs of some classical properties. We compare the Qregularity of coherent sheaves on Qn with the Castelnuovo-Mumford regularity of their extension by zero in Pn+1. We also classify the coherent sheaves with Qregularity −∞. We use our notion of Qregularity in order to prove an extension of the Evans-Griffiths criterion to vector bundles on quadrics. In particular, we get a new and simple proof of Knörrer’s characterization of ACM bundles. 相似文献
93.
Menozzi E Busi M Massera C Ugozzoli F Zuccaccia D Macchioni A Dalcanale E 《The Journal of organic chemistry》2006,71(7):2617-2624
The self-assembly between bidentate cavitand ligands and mono/dinuclear metal precursors to give cavitand frameworks has been explored. For this purpose, two new cavitands bearing AB and AC phenylpyridyl moieties at the upper rim have been synthesized. A series of self-assembled molecular dimers featuring fac-Re(CO)(3)Br as metal corners have been prepared and characterized. Two possible dimeric structures (C-shaped and S-shaped) are possible when AB cavitand 2 is used in the self-assembly reaction; only one is obtained in the case of AC cavitand 3. In addition, the self-assembly of AB-dibridged cavitand 2 with dinuclear Pd/Pt metal precursors 5a and 5b has been studied. At this level of complexity, the self-assembly can lead to more than one structure. Several different final structures have been envisioned and their formation analyzed in silico and in solution. Out of the three possible cyclic structures (dimer, trimer, and tetramer), only the entropically favored dimer 6a (6b) is formed, as predicted from molecular modeling and demonstrated by PGSE NMR experiments. 相似文献
94.
Adami G Capriglia L Barbieri P Cozzi F Lo Coco F Acquavita A Reisenhofer E 《Annali di chimica》2006,96(9-10):601-612
The following metals: Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by inductively coupled plasma - atomic emission spectroscopy (ICP-AES) in fluvial sediments of Rosandra Creek, using two different, strong and mild sediment decomposition methods. The purpose was to obtain information about the contamination by metals and distribution paths of pollutants in the area crossed by Rosandra Creek: this little river is the unique epigeous watercourse in the Italian Karst and very few data can be found in literature. In this area, we can find a natural park, but also agricultural activities and an industrial district that was recently defined as "polluted site of national interest". By comparing the results of the strong and mild extraction we have obtained the percentage of extraction and enrichment factors for each metal in the different sediments of the sites R2 and R3 exposed to pollution, while the site R1 was considered as a pristine one because situated in the natural park. The computed enrichment factors are generally not very high, but copper, lead and zinc have factors that require attention. The principal component analysis (PCA) shows that the typically anthropogenic metals (as Cr, Pb, Cu and Zn) constitute the first factor, while the lithogenic metals, as Fe and Ni, constitute the second one; moreover the score plots permit to classify and distinguish the 3 sites: site R3, possibly the more exposed to contamination, has high scores both for anthropogenic and lithogenic metals. 相似文献
95.
We consider the Max FS problem: For a given infeasible linear system A
x≤b, determine a feasible subsystem containing as many inequalities as possible. This problem, which is NP-hard and also difficult
to approximate, has a number of interesting applications in a wide range of fields. In this paper we examine structural and
algorithmic properties of Max FS and of Irreducible Infeasible Subsystems (IISs), which are intrinsically related since one must delete at least one constraint from each IIS to attain feasibility.
First we provide a new simplex decomposition characterization of IISs and prove that finding a smallest cardinality IIS is very difficult to approximate. Then we discuss
structural properties of IIS-hypergraphs, i.e., hypergraphs in which each edge corresponds to an IIS, and show that recognizing
IIS-hypergraphs subsumes the Steinitz problem for polytopes and hence is NP-hard. Finally we investigate rank facets of the
Feasible Subsystem polytope whose vertices are incidence vectors of feasible subsystems of a given infeasible system. In particular, using the IIS-hypergraph
structural result, we show that only two very specific types of rank inequalities induced by generalized antiwebs (which generalize
cliques, odd holes and antiholes to general independence systems) can arise as facets.
Received: December 2000 / Accepted: November 2002 Published online: February 14, 2003
RID="⋆"
ID="⋆" Part of this work was done while the first two authors were with the School of OR&IE, Cornell University, USA. A preliminary
version appeared in the Proceedings of the 10th IPCO conference [7], held in Graz, Austria, June 1999. This work was supported
by NSF grant DMS-9527124.
Key words. infeasible linear systems – feasible subsystems – Irreducible Infeasible Subsystem (IIS) – IIS-hypergraphs – independence
systems – feasible subsystem polytope – rank facets 相似文献
96.
97.
Edoardo Roncari Ulderico Mazzi Roberto Rossi Adriano Duatti Luciano Magon 《Transition Metal Chemistry》1981,6(3):169-173
Summary Some isomers of the ReOX2LPPh3 complexes [X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N'-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate] have been synthesized and characterized. Two different mechanisms for reaction of thetrans-ReOX3(PPh3)2 complexes (X = Cl or Br) with the Schiff bases are supported by qualitative studies on such parameters as the Schiff base ligand form, concentration of free triphenylphosphine ligand, reaction solvent and temperature. 相似文献
98.
99.
Corrado Sarzanini Maria Concetta Bruzzoniti Edoardo Mentasti 《Journal of chromatography. A》1999,850(1-2):197-211
A comparative study was made of the chromatographic behaviour of five haloacetic acids (mono-, dibromoacetic and mono-, di-, trichloroacetic acids). The techniques investigated included reversed-phase ion interaction chromatography with UV detection, suppressed and non-suppressed anion-exchange chromatography. The systems are discussed studying the retention as a function of the mobile phase parameters and the stationary phases used (LiChrospher 100 RP-18, IonPac AS9, AS10 and AS11). A preconcentration step, performed on different substrates, namely LiChrolut-EN and activated vegetal carbon, has been optimized in order to reduce the method detection limits. Results obtained for drinking water samples are shown. 相似文献
100.
Kristian Piscicchia Johann Marton Sergio Bartalucci Massimiliano Bazzi Sergio Bertolucci Mario Bragadireanu Michael Cargnelli Alberto Clozza Raffaele Del Grande Luca De Paolis Carlo Fiorini Carlo Guaraldo Mihail Iliescu Matthias Laubenstein Marco Miliucci Edoardo Milotti Fabrizio Napolitano Andreas Pichler Alessandro Scordo Hexi Shi Diana Laura Sirghi Florin Sirghi Laura Sperandio Oton Vazquez Doce Johann Zmeskal Catalina Curceanu 《Entropy (Basel, Switzerland)》2020,22(11)
The VIP collaboration is performing high sensitivity tests of the Pauli Exclusion Principle for electrons in the extremely low cosmic background environment of the underground Gran Sasso National Laboratory INFN (Italy). In particular, the VIP-2 Open Systems experiment was conceived to put strong constraints on those Pauli Exclusion Principle violation models which respect the so-called Messiah–Greenberg superselection rule. The experimental technique consists of introducing a direct current in a copper conductor, and searching for the X-rays emission coming from a forbidden atomic transition from the L shell to the K shell of copper when the K shell is already occupied by two electrons. The analysis of the first three months of collected data (in 2018) is presented. The obtained result represents the best bound on the Pauli Exclusion Principle violation probability which fulfills the Messiah–Greenberg rule. 相似文献