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81.
Alessia Aprea Valentina Colombo Simona Galli Norberto Masciocchi Angelo Maspero Giovanni Palmisano 《Solid State Sciences》2010,12(5):795-802
Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, was isolated as a polycrystalline material, and its crystal structure was determined by ab-initio X-ray powder diffraction (XRPD) methods. This species, upon deprotonation, was subsequently used in preparing the new coordination polymers Ag2(C6N2O4S2), Mn(C6N2O4S2)(H2O)2, Co(C6N2O4S2)(H2O)2, Cu(C6N2O4S2)(H2O) and Zn(C6N2O4S2)(H2O)2, fully characterized by analytical, thermal and XRPD structural methods – including in situ thermodiffractometry and simultaneous TGA and DSC. In the first-row transition metal derivatives, the [C6N2O4S2]2? anion systematically prefers the N,O-chelating, vs. the expected O,O′-bridging, coordination mode, not allowing the formation of porous 3D frameworks. Indeed, these species are dense 1D coordination polymers. At variance, the silver derivative possesses a complex, dense 3D framework, due to the presence of μ6-[C6N2O4S2]2? ligands showing two μ2-bridging carboxylates and two monohapto N-donor sites. When dehydration is viable, materials of En(C6N2O4S2) formulation are irreversibly recovered (n = 1 for E = Mn, Co, Zn, Cu; n = 2, for E = H). 相似文献
82.
Crociani B Antonaroli S Marini A Matteoli U Scrivanti A 《Dalton transactions (Cambridge, England : 2003)》2006,(22):2698-2705
The complexes [Pd(eta2-dmfu)(P-N)] [P-N = 2-(PPh2)C6H4-1-CH=NR, R = C(6)H(4)OMe-4; CHMe2; C6H3Me2-2,6; C6H3(CHMe2)-2,6] react with an excess of BrC6H4R1-4 (R1= CF3; Me) yielding the oxidative addition products [PdBr(C6H4R1-4)(P-N)] at different rates depending on R [C6H4OMe-4 > C6H3(CHMe2)-2,6 > CHMe2 approximately C6H3Me2-2,6] and R1 (CF3> Me). In the presence of K2CO3 and activated olefins (ol = dmfu, fn), the latter compounds react with an excess of 4-R2C6H4B(OH)2 (R2= H, Me, OMe, Cl) to give [Pd(eta2-ol)(P-N)] and the corresponding biaryl through transmetallation and fast reductive elimination. The transmetallation proceeds via a palladium(II) intermediate with an O-bonded boron anion, the formation of which is markedly retarded by increasing the bulkiness of R. The intermediate was isolated for R = CHMe2, R1 = CF3 and R2= H. The boron anion is formulated as a diphenylborinate anion associated with phenylboronic acid and/or as a phenylboronate anion associated with diphenylborinic acid. In general, the oxidative addition proceeds at a lower rate than transmetallation and represents the rate-determining-step in the coupling reaction of aryl bromides with arylboronic acids catalyzed by [Pd(eta2-dmfu)(P-N)]. 相似文献
83.
Alessandra Andreoni Alessia Allevi Maria Bondani 《Journal of Russian Laser Research》2009,30(5):418-426
We measure photon-number statistics of pulsed fields containing mesoscopic photon numbers in a time duration shorter than
any feasible measuring time. As the detector we use a photomultiplier tube delivering anodic outputs in whose pulse-height
spectrum only the zero detected-photon peak is resolved. We demonstrate that we can reconstruct the correct detected-photon
statistical distribution provided the maximum number of detected photons falls within the range of linear response of the
photomultiplier tube. 相似文献
84.
Alessia Garavaglia Alessia Moiana Stefano Camnasio Daniele Bolognini Roberto Papait Dorotea Rigamonti Elena Cattaneo 《BMC neuroscience》2010,11(1):7
Background
There is an urgent need of neuronal cell models to be applied to high-throughput screening settings while recapitulating physiological and/or pathological events occurring in the Central Nervous System (CNS). Stem cells offer a great opportunity in this direction since their self renewal capacity allows for large scale expansion. Protocols for directed differentiation also promise to generate populations of biochemically homogenous neuronal progenies. NS (Neural Stem) cells are a novel population of stem cells that undergo symmetric cell division in monolayer and chemically defined media, while remaining highly neurogenic. 相似文献85.
Fractional Brownian motion, fractional Gaussian noise, and Tsallis permutation entropy 总被引:1,自引:0,他引:1
L. Zunino D.G. Pérez M.T. Martín M. Garavaglia A. Plastino O.A. Rosso 《Physica A》2008,387(24):6057-6068
In this work, we analyze two important stochastic processes, the fractional Brownian motion and fractional Gaussian noise, within the framework of the Tsallis permutation entropy. This entropic measure, evaluated after using the Bandt & Pompe method to extract the associated probability distribution, is shown to be a powerful tool to characterize fractal stochastic processes. It allows for a better discrimination of the processes than the Shannon counterpart for appropriate ranges of values of the entropic index. Moreover, we find the optimum value of this entropic index for the stochastic processes under study. 相似文献
86.
Andreotti A Bonaduce I Colombini MP Ribechini E 《Rapid communications in mass spectrometry : RCM》2004,18(11):1213-1220
Two analytical methods based on mass spectrometry were used in the characterisation of constituents of natural indigo prepared from the leaves of Indigofera tinctoria, and of shellfish purple prepared from the hypobranchial glandular secretions of Murex trunculus, following old recipes. On-line pyrolysis gas chromatography in the presence of hexamethyldisilazane followed by mass spectrometric analysis (Py-silylation/GC/MS), and direct exposure mass spectrometry (DE-MS), were used. Extensive fragmentation of indigoid dyes was obtained by Py-silylation/GC/MS. The following molecular markers were highlighted, which are useful for identification purposes: 1,2-dihydro-3H-indol-3-one for indigoid dyes, 1,3-dihydro-2H-indol-2-one for indirubine, and 6-bromo-1,2-dihydro-3H-indol-3-one for shellfish purple. Using DE-MS, 6,6'dibromoindigotine, monobromoindigotine and indigotine were identified as the main components, and the presence of tyrindoxyl, one of the dye precursors, was also assessed. 相似文献
87.
Isabel M. Gomez-Monterrey Alessia Bertamino Maria V. Diurno Paolo Grieco 《Tetrahedron》2006,62(34):8083-8088
A novel synthetic route of diaza-bridged heterocycles based on natural 3,9-diazabicyclo[3.3.1]non-6-ene scaffold has been accomplished. The synthetic approach consists of a Pictet-Spengler condensation of the l-Dopa-OMe with an appropriate aldehyde, Fmoc-Aa-H, followed by intramolecular lactamization. This approach generated two configurationally distinct products (cis and trans-isomers), increasing the stereochemical diversity of these compounds. The synthesized compounds are potentially useful in the discovery of novel pharmacologically active compounds. 相似文献
88.
The Carlo Alberto Canal connects Bormida and Tanaro rivers in Piedmont (ITALY). It was created for irrigation purposes but since its waters are suspected to be polluted, a sampling campaign was performed by the ARPA of Alessandria. The physico-chemical parameters analysed along 3 years (1998-2000) were investigated by multivariate chemometric methods. PCA showed that the waters situation depends heavily on the sampling period. Also a Kohonen self-organising map confirmed the clustering observed, providing insights into the causes of the clusterisation. New samplings are now being performed and a larger set of environmental variables is determined on each sample. 相似文献
89.
Colombini MP Carmignani A Modugno F Frezzato F Olchini A Brecoulaki H Vassilopoulou V Karkanas P 《Talanta》2004,63(4):839-848
The materials used in the decoration of three painted astragaloi (knucklebones) from the Koroneia cave (Greece) were investigated by means of sequential application of non-destructive and destructive techniques: optical microscopy, environmental scanning electron microscopy coupled with X-ray microanalysis (ESEM-EDX), Fourier transform infrared spectroscopy (FTIR) with micro-attenuated total reflection (μ-ATR) technique, high performance liquid chromatography (HPLC) coupled with UV-fluorescence and gas chromatography-mass spectrometry (GC-MS) were used.The main results highlighted that the three astragaloi were prepared with a ground of ochre or iron clay and painted with a proteinaceous matter such as binder egg tempera. Both FTIR and GC-MS agree in the detection of lipids that can be related to egg. Organic dyestuffs identified as madder lake and shellfish purple were used together with inorganic pigments. 相似文献
90.
Huang Q Fazio A Dai G Campo MA Larock RC 《Journal of the American Chemical Society》2004,126(24):7460-7461
A novel palladium migration methodology for the synthesis of complex fused polycycles has been developed. This process involves 1,4-palladium alkyl to aryl migrations via through-space C-H activation, followed by intramolecular arylation or an intermolecular Heck reaction providing a very efficient way to synthesize fused ring systems. 相似文献