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101.
Ielpo P Cassano D Lopez A Pappagallo G Uricchio VF De Napoli PA 《Chemistry Central journal》2012,6(Z2):S5
Background
Ground waters are an important resource of water supply for human health and activities. Groundwater uses and applications are often related to its composition, which is increasingly influenced by human activities.In fact the water quality of groundwater is affected by many factors including precipitation, surface runoff, groundwater flow, and the characteristics of the catchment area. During the years 2004-2007 the Agricultural and Food Authority of Apulia Region has implemented the project “Expansion of regional agro-meteorological network” in order to assess, monitor and manage of regional groundwater quality. The total wells monitored during this activity amounted to 473, and the water samples analyzed were 1021. This resulted in a huge and complex data matrix comprised of a large number of physical-chemical parameters, which are often difficult to interpret and draw meaningful conclusions. The application of different multivariate statistical techniques such as Cluster Analysis (CA), Principal Component Analysis (PCA), Absolute Principal Component Scores (APCS) for interpretation of the complex databases offers a better understanding of water quality in the study region.Results
Form results obtained by Principal Component and Cluster Analysis applied to data set of Foggia province it’s evident that some sampling sites investigated show dissimilarities, mostly due to the location of the site, the land use and management techniques and groundwater overuse. By APCS method it’s been possible to identify three pollutant sources: Agricultural pollution 1 due to fertilizer applications, Agricultural pollution 2 due to microelements for agriculture and groundwater overuse and a third source that can be identified as soil run off and rock tracer mining.Conclusions
Multivariate statistical methods represent a valid tool to understand complex nature of groundwater quality issues, determine priorities in the use of ground waters as irrigation water and suggest interactions between land use and irrigation water quality.102.
Bellussi G Millini R Montanari E Carati A Rizzo C Parker WO Cruciani G de Angelis A Bonoldi L Zanardi S 《Chemical communications (Cambridge, England)》2012,48(59):7356-7358
ECS-14, a crystalline microporous hybrid organic-inorganic aluminosilicate, has been synthesized by using 1,4-bis-(triethoxysilyl)-benzene (BTEB) as a source of silica. Its structure contains a system of linear channels with 12-membered ring openings, running along the [001] direction, resembling the pore architecture of the AFI framework type. 相似文献
103.
Livieri A Boiocchi M Desimoni G Faita G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(2):516-520
Diels–Alder and 1,3‐dipolar cycloadditions involving (E)‐3‐aryl‐1‐(pyridin‐2‐yl‐N‐oxide)prop‐2‐en‐1‐ones as the 2π components are efficiently catalysed by bis(oxazoline)–CuII complexes. The cycloadducts are obtained in quantitative yields with up to 98 % ee; absolute configurations were determined by X‐ray analysis. The structure of the reactive complex, determined by X‐ray analysis, is fully consistent with the stereochemical outcome of the catalysed process (approach of the diene or nitrone to the less hindered face of the coordinated pyridine‐N‐oxide derivative). 相似文献
104.
Marina Mastragostino Giuseppe Casalbore Sergio Valcher Luciana Pastorelli 《Journal of Electroanalytical Chemistry》1978,90(3):439-448
The anodic chlorination of aromatic compounds in anhydrous acetic acid has been further investigated. Evidence has been found for two different methods of electrochemical chlorination, in the systems Cl2/aromatic compounds and Cl?/aromatic compounds. These methods were also compared with the uncatalyzed chemical chlorination reaction. The yields of monochlorinated products and the related isometric distributions were taken into account. Since the isomeric distributions are equal with chemical and electrochemical chlorination methods, the formation of the same intermediate was proposed for both. 相似文献
105.
Lattice-dynamical, calculations for evidently non-rigid molecules of aromatic hydrocarbons have been carried out on tetracene and pentacene. In these substances, “out-of plane” vibrations mix extensively with lattice vibrations, and significant differences can be noted between results from a “rigid-body” and a “non-rigid” treatment. For tetracene crystals, whose Raman spectral data are given in the literature, the agreement with experiment is satisfactory. This confirms the validity of such procedures for interpreting and/or predicting spectroscopic behaviour, starting from empirical atom—atom potentials and valence force fields. 相似文献
106.
SD Reilly AJ Gaunt BL Scott G Modolo M Iqbal W Verboom MJ Sarsfield 《Chemical communications (Cambridge, England)》2012,48(78):9732-9734
Complexation of Pu(iv) with TMDGA, TEDGA, and TODGA diglycolamide ligands was followed by vis-NIR spectroscopy. A crystal structure determination reveals that TMDGA forms a 1?:?3 homoleptic Pu(iv) complex with the nitrate anions forced into the outer coordination sphere. 相似文献
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110.
Mirka Bergamo Tiziana Beringhelli Giuseppe D'Alfonso Luca Garavaglia Pierluigi Mercandelli Massimo Moret Angelo Sironi 《Journal of Cluster Science》2001,12(1):223-242
Three and tetranuclear ring clusters have been obtained by treatment of [Re2(CO)8(THF)2] with carbonyl-rhenates containing two terminal hydrides. The reaction with [ReH2(CO)4]- provided a selective route to the previously known [Re3(-H)2(CO)12]- triangular cluster anion 1. The reaction with [Re2H2(-H)(CO)8]- gave the novel [Re4(-H)3(CO)16]- anion 2, containing a rare example of a puckered-square metal cluster. Protonation of 1 is known to afford the neutral [Re3(-H)3(CO)12] species 3. Analogously the reaction of 2 with a strong acid afforded the previously known square metal clusters [Re4(-H)4(CO)16] 4. The reaction could not be reversed by treatment with bases. Photolysis of 4 gave the unsaturated complex [Re2(-H)2(CO)8] 5: this is the reverse of the dimerization reaction, that in THF at room temperature produces 4 from 5. Thermal treatment (reflux in cyclohexane for 24 h) left 4 almost unchanged. A single crystal X-ray analysis of [NEt4]2 showed a s/e/s/s (e=eclipsed, s=staggered) conformation of the Re(CO)4 units, leading to a puckered geometry of the ring, at variance with the square-planar geometry of 4 (all eclipsed). Two of the three hydrides of 2 have been located as bridging the Re–Re edges from inside the metal ring, as previously observed in 4. Density functional computations indicated a puckered conformation as the most stable for both 2 and 4, with very low activation energies for ring inversion (6.6 and 2.2 kcal·mol-1, respectively), but ruled out solid state fluxionality for 4, whose observed planar geometry must be attributed to packing stabilization. 相似文献