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101.
Investigation of anthropic effects connected with metal ions concentration, organic matter and grain size in Bormida river sediments 总被引:9,自引:0,他引:9
Emilio Marengo Maria Carla Gennaro Elisa Robotti Piero Rossanigo Caterina Rinaudo Manuela Roz-Gastaldi 《Analytica chimica acta》2006,560(1-2):172-183
An investigation on the sediment composition and grain size was carried out along the Bormida river (Piedmont, Northern Italy). The samples were taken both in the riverbed and on its banks. Multivariate statistical exploratory methods permitted to identify possible sources of primary pollution. In particular, principal component analysis (PCA) showed that there are probably at least three anthropogenic main causes of pollution, one connected with Cr, Ni and Sn, the second with cadmium and the last one with mercury. Some correlations were found between heavy metal ion concentrations and organic matter and/or the sediment grain size. Differences between the samples collected in the riverbed and on the banks were identified and the relationships between the principal components and the distance of the samples from the riverbed and from the hot spot represented by the ACNA industrial site were also analyzed. 相似文献
102.
Gulmini M Appolonia L Framarin P Mirti P 《Analytical and bioanalytical chemistry》2006,386(6):1815-1822
Twelve finds from archaeological excavations carried out in the Aosta region (Italy) were studied by scanning electron microscopy
coupled with energy-dispersive X-ray detection (SEM–EDS). The archaeological samples were shards of glazed pottery dating
from the fourth to the seventh century AD. Analysis of ceramic bodies revealed a general homogeneity in composition among
the studied samples and the use of a noncalcareous clay for their manufacture; however, two shards stand out due to their
high iron contents. Glazes proved to be high-lead products with more than 70% PbO in all of the samples investigated but one.
For the latter, a composition poorer in lead and richer in silicon, aluminium and iron was found. SEM observation of the contact
region between body and glaze suggests that the vitreous coatings were mostly obtained by applying the glazing components
onto the unfired clay body; moreover, a comparison between clay and glaze compositions suggests the use of a lead compound
mixed with a silica-rich material, not a lead compound by itself. 相似文献
103.
Sheng Yao Chun-Ping Tang Yang Ye Tibor Kurtn Attila Kiss-Szikszai Sndor Antus Gennaro Pescitelli Piero Salvadori Karsten Krohn 《Tetrahedron: Asymmetry》2008,19(17):2007-2014
Nine bis-9,10-dihydrophenanthrene and 9,10-dihydrophenanthrene/(dihydro)stilbene derivatives, including the new phochinenins G-L 1–6, were isolated from the whole plant of Pholidota chinensis. Their structures were elucidated on the basis of extensive spectroscopic investigations (1D, 2D NMR, and HR-EIMS). Owing to the sterically hindered rotation around the biaryl axis, some of these biaryl compounds can exist as a pair of enantiomers, but were isolated as racemates. Computed inversion barriers of selected atropisomeric derivatives suggested that phochinenins K 5, gymconpin C 7, and flavanthrin 9 have stable atropisomers. Their racemates were separated by HPLC on an optically active stationary phase, and were stereochemically characterized on-line by circular dichroism (CD) spectroscopy (LC-CD coupling), in conjunction with quantum-mechanics CD calculations. 相似文献
104.
Collini D De Biani FF Dolzhnikov DS Femoni C Iapalucci MC Longoni G Tiozzo C Zacchini S Zanello P 《Inorganic chemistry》2011,50(7):2790-2798
The previously ill-characterized [H(x)Rh(22)(CO)(35)](4-/5-) carbonyl cluster has been obtained as a byproduct of the synthesis of [H(3)Rh(13)(CO)(24)](2-) and effectively separated by metathesis of their sodium salts with [NEt(4)]Cl. Although the yields are modest and never exceed 10-15% (based on Rh), this procedure affords spectroscopically pure [H(3)Rh(22)(CO)(35)](5-) anion. Formation of the latter in mixture with other Rh clusters was also observed by electrospray ionization-mass spectrometry (ESI-MS) in the oxidation of [H(2)Rh(13)(CO)(24)](3-) with Cu(2+) salts. The recovery of further amounts of [H(3)Rh(22)(CO)(35)](5-) was hampered by too similar solubility of the salts composing the mixture. Conversely, the reaction in CH(3)CN of [H(2)Rh(13)(CO)(24)](3-) with [Cu(MeCN)(4)](+)[BF(4)](-) leads to the [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) bimetallic cluster. The X-ray crystal structures of [H(4)Rh(22)(CO)(35)](4-), [H(3)Rh(22)(CO)(35)](5-), and [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) are reported. From a formal point of view, the metal frame of the former two species can be derived by interpenetration along two orthogonal axes of two moieties displaying the structure of the latter. The availability of [H(8-n)Rh(22)(CO)(35)](n-) salts prompted their detailed chemical, spectroscopic, and electrochemical characterization. The presence of hydride atoms has been directly proved both by ESI-MS and (1)H NMR. Moreover, both [H(4)Rh(22)(CO)(35)](4-) and [H(3)Rh(22)(CO)(35)](5-) undergo distinctive electrochemically reversible redox changes. This allows to assess electrochemical studies as indisputable though circumstantial evidence of the presence of (1)H NMR-silent hydride atoms in isostructural anions of different charge. 相似文献
105.
Geninatti-Crich S Alberti D Szabo I Deagostino A Toppino A Barge A Ballarini F Bortolussi S Bruschi P Protti N Stella S Altieri S Venturello P Aime S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(30):8479-8486
The upregulation of low-density lipoprotein (LDL) transporters in tumour cells has been exploited to deliver a sufficient amount of gadolinium/boron/ligand (Gd/B/L) probes for neutron capture therapy, a binary chemio-radiotherapy for cancer treatment. The Gd/B/L probe consists of a carborane unit (ten B atoms) bearing an aliphatic chain on one side (to bind LDL particles), and a Gd(III)/1,4,7,10-tetraazacyclododecane monoamide complex on the other (for detection by magnetic resonance imaging (MRI)). Up to 190 Gd/B/L probes were loaded per LDL particle. The uptake from tumour cells was initially assessed on cell cultures of human hepatoma (HepG2), murine melanoma (B16), and human glioblastoma (U87). The MRI assessment of the amount of Gd/B/L taken up by tumour cells was validated by inductively coupled plasma-mass-spectrometric measurements of the Gd and B content. Measurements were undertaken in vivo on mice bearing tumours in which B16 tumour cells were inoculated at the base of the neck. From the acquisition of magnetic resonance images, it was established that after 4-6 hours from the administration of the Gd/B/L-LDL particles (0.1 and 1 mmol kg(-1) of Gd and (10)B, respectively) the amount of boron taken up in the tumour region is above the threshold required for successful NCT treatment. After neutron irradiation, tumour growth was followed for 20 days by MRI. The group of treated mice showed markedly lower tumour growth with respect to the control group. 相似文献
106.
107.
108.
Prof. Angiolina Comotti Dr. Silvia Bracco Prof. Teng Ben Prof. Shilun Qiu Prof. Piero Sozzani 《Angewandte Chemie (International ed. in English)》2014,53(4):1043-1047
Porous organic frameworks perform a variety of functions, owing to their extremely large surface areas, but the dynamics of the structural elements have never been explored. Our discovery of ultra‐fast molecular rotors (106 Hz at 225 K) in their architectures allows us to look at them from a new perspective. The constructive elements are robust struts and rapid rotors, resulting in a dynamic material whose motion can be frozen or released at will. The rotational motion can be actively regulated in response to guests. As the temperature is increased, the rotors spin ever faster, approaching free‐rotational diffusion at 550 K. The unusual combination of remarkable nanoporosity with fast dynamics is intriguing for engineering oscillating dipoles and producing responsive materials with switchable ferroelectricity, and for applications spanning from sensors to actuators, which capture and release chemicals on command. 相似文献
109.
Ambrosi M Fratini E Alfredsson V Ninham BW Giorgi R Lo Nostro P Baglioni P 《Journal of the American Chemical Society》2006,128(22):7209-7214
A bolaform surfactant, 1,12-diascorbyl dodecanedioate (BOLA12), with ascorbic acid units as the polar headgroups was synthesized for the first time. Once dispersed in water above 0.5% w/w, BOLA12 forms hollow nanotubes as revealed by cryo-TEM experiments. These nanostructures transform into clear micellar solutions on heating. X-ray diffraction and SAXS experiments were performed both on the pure solid and on its aqueous dispersions. The critical aggregation concentration and the phase behavior were determined by conductivity and DSC experiments. The latter technique provided also the amount of strongly bound, solvating water molecules that surround the polar headgroups. BOLA12 shows the same reducing properties of ascorbic acid, as indicated by the antioxidant activity evaluated with the DPPH method. This feature was used for the reduction of Pd(II) ions on the surface of the nanoassemblies, which lead to the formation of large bundles homogeneously coated with palladium as observed in SEM micrographs. 相似文献
110.
Kretz T Bats JW Losi S Wolf B Lerner HW Lang M Zanello P Wagner M 《Dalton transactions (Cambridge, England : 2003)》2006,(41):4914-4921
Cationic dinuclear Cu(II) complexes 3 and 4 have been prepared using the novel hydroquinone-based imine chelators 2,5-((i)Pr(2)NCH(2)CH(2)N[double bond, length as m-dash]CH)(2)-1,4-(OH)(2)-C(6)H(2) (1) and 2,5-(pyCH(2)CH(2)N[double bond, length as m-dash]CH)(2)-1,4-(OH)(2)-C(6)H(2) (2), respectively (py = 2-pyridyl). X-Ray quality crystals of both complexes were grown from their DMF solutions. The sterically more encumbered compound crystallizes in the form of discrete dinuclear entities with Cu(II) centres in a distorted square-planar ligand environment (one coordination site is occupied by a DMF molecule). The pyridyl derivative 4 features dinuclear hydroquinone-bridged subunits similar to 3. However, the Cu(II) ions are now six-coordinate with two DMF molecules at an axial and an equatorial position of a Jahn-Teller-distorted octahedron. Moreover, the dinuclear subunits are no longer isolated but linked with each other via bridging hydroquinone oxygen atoms which occupy the second apical position of each octahedron. The structure suggests that the magnetic properties of the resulting coordination polymer of 4 could be described by a model valid for dimerized spin chains. As a result of this analysis the antiferromagnetic coupling constants J(1)/k(B) = 9.9 K (intradimer) and J(2)/k(B) = 0.9 K (interdimer) are obtained. Both in 3 and in 4, the hydroquinone --> semiquinone transition of the central bridging unit (E degrees ' = + 0.57 V, 3; E degrees ' = + 0.51 V, 4; DMF; vs. SCE) displays features of chemical reversibility. In the case of , reduction of Cu(II) centres requires a peak potential of E(p) = - 0.42 V. 相似文献