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991.
Riccardo Salvio Sven Krabbenborg Wouter J. M. Naber Aldrik H. Velders David N. Reinhoudt Wilfred G. van der Wiel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(33):8235-8240
The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single‐layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X‐Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large‐area platelet films of single‐layer graphene. 相似文献
992.
Riccardo Di Corato Philomena Piacenza Mariarosaria Musarò Raffaella Buonsanti Pantaleo Davide Cozzoli Massimo Zambianchi Giovanna Barbarella Roberto Cingolani Liberato Manna Teresa Pellegrino 《Macromolecular bioscience》2009,9(10):952-958
Nanostructures displaying fluorescence and magnetic properties at the same time are potentially useful for achieving simultaneous bio‐separation and bio‐sensing (e.g., magnetic separation coupled with multiplexing optical detection of different tumour cell populations). Spherical nanobeads that display both fluorescent and magnetic features are reported; they are fabricated by grafting fluorescent oligothiophene molecules to an amphiphilic polymer that is then used to enwrap iron oxide nanoparticles, which acts as the magnetic domain. By tuning experimental conditions, control over the number of magnetic nanoparticles per bead and over the bead diameter (30–400 nm) was achieved. A cell separation efficiency of the level required for cell sorting applications is also reported.
993.
Luciano Callipo Patrizia Foglia Riccardo Gubbiotti Roberto Samperi Aldo Laganà 《Analytical and bioanalytical chemistry》2009,394(3):811-820
A method for carbonic anhydrase II (CA II) absolute quantification in human serum is presented. This method is based on high-performance
liquid chromatography (HPLC)-Chip microfluidic device incorporating a nanoelectrospray source interfaced to a triple quadrupole
mass spectrometer. The fraction containing CA II was isolated by preparative reversed-phase HPLC, and peptides obtained from
the tryptic digest of the protein mixture were separated by the HPLC-Chip system. The multiple-reaction monitoring acquisition
mode of a selected suitable CA II peptide and peptide internal standard allowed the selective and sensitive determination
of a CA II. Absolute recovery of the method was 52 ± 12%, while analytical recovery was 81 ± 10%. For the eight samples analyzed,
the matrix effect was found to be only −14 ± 6%. A comparison among three regression lines type which were obtained by external
calibration, matrix-matched calibration, and standard addition method, respectively, demonstrated that the first one is adequate
in obtaining good accuracy and precision. Method quantification limit for CA II in serum was estimated to be 2 fmol/mL. CA
II mean concentration in sera from eight healthy subjects was found to be 56 pmol/mL (relative standard deviation 24%). 相似文献
994.
Riccardo Fazio 《Applied mathematics and computation》2009,215(4):1513-1521
Blasius problem is the simplest nonlinear boundary-layer problem. We hope that any approach developed for this epitome can be extended to more difficult hydrodynamics problems. With this motivation we review the so called Töpfer transformation, which allows us to find a non-iterative numerical solution of the Blasius problem by solving a related initial value problem and applying a scaling transformation. The applicability of a non-iterative transformation method to the Blasius problem is a consequence of its partial invariance with respect to a scaling group. Several problems in boundary-layer theory lack this kind of invariance and cannot be solved by non-iterative transformation methods. To overcome this drawback, we can modify the problem under study by introducing a numerical parameter, and require the invariance of the modified problem with respect to an extended scaling group involving this parameter. Then we apply initial value methods to the most recent developments involving variants and extensions of the Blasius problem. 相似文献
995.
Dunkelberger AD Kieda RD Shin JY Rossi Paccani R Fusi S Olivucci M Crim FF 《The journal of physical chemistry. A》2012,116(14):3527-3533
Recent experimental and theoretical studies on N-alkylated indanylidene pyrroline Schiff bases (NAIP) show that these compounds exhibit biomimetic photoisomerization analogous to that in the chromophore of rhodopsin. The NAIP compounds studied previously isomerize rapidly and often evolve coherently on the ground-electronic surface after reaction. We present the results of transient electronic absorption spectroscopy on dMe-OMe-NAIP, a newly synthesized NAIP analogue that differs from other NAIP compounds in the substituents on its pyrrolinium ring. Following excitation with 400 nm light, dMe-OMe-NAIP relaxes from the electronic-excited state in less than 500 fs, which is slower than in other analogues, and does not show the prominent oscillations observed in other NAIP compounds. A reduction in the amount of twisting between the rings caused by removal of the methyl group is likely responsible for the slower isomerization. Measurements in solvents of varying viscosity and structure suggest that intramolecular processes dominate the relaxation of nascent photoproducts. 相似文献
996.
Nazif MA Rubbiani R Alborzinia H Kitanovic I Wölfl S Ott I Sheldrick WS 《Dalton transactions (Cambridge, England : 2003)》2012,41(18):5587-5598
The DNA binding modes and cleavage properties of novel dinuclear Ir(III) polypyridyl (pp) complexes [{(η(5)-C(5)Me(5))Ir(pp)}(2)(μ-B)](CF(3)SO(3))(4) depend on the lengths of their rigid bridging dipyridinyl ligands B. Mono-intercalation and strong DNA cleavage properties were observed for the dipyrido[2,3-a:2',3'-c]phenazine (dppz) complexes 1 (B = 4-[(E)-2-(4-pyridinyl)ethenyl]pyridine) and 3 (B = 4-(2-pyridin-4-ylethynyl)pyridine), whose intracationic Ir···Ir' distances are about 13.1 and 13.3 ?, respectively. In contrast, UV/Vis and CD spectra were in accordance with a stable intertwined bis-intercalation mode for pairs of cations of 5 (B = 1,4-di(2-pyridin-4-ylethynyl)benzene), whose much longer Ir···Ir' distance of 20.6 ? allows a stack of five aromatic chromophores to be sandwiched between its effectively parallel dppz ligands. Whereas both 1 and 3 cleaved DNA in the dark, complex 5 exhibited only photoinduced nuclease activity. A significantly higher antiproliferative activity towards MCF-7 breast carcinoma cells was observed for the nucleases 1 and 3, whose IC(50) values of 0.61 and 0.49 were much lower than that of 2.2 μM for bis-intercalator 5. Values of 3.8 μM, only slightly higher than that of 5, were recorded for the 5,6-dimethylphenanthroline complexes 4 and 6, whose bridging ligands are identical to those of 3 and 5, respectively. Marked antileukemic activity (IC(50) = 6-7 μM) associated with increased levels of reactive oxygen species and apoptosis induction was recorded for both 3 and 5 towards Jurkat cells at concentrations of 5 μM and above. Online studies with a sensor chip system indicated that 5 μM solutions of these complexes invoke a rapid and massive reduction in MCF-7 cell respiration. 相似文献
997.
998.
999.
Riccardo Fazio 《International Journal of Mathematical Education in Science & Technology》2013,44(5):752-760
The main aim of this note is to help students to gain an insight into the asymptotic stability concept by means of visual representation of the stability regions of different numerical methods. This facilitates understanding of the meaning of stability for constant step sizes and the related concept of stiffness in numerical initial-value problems. Moreover, the distinction between A and L-stability of numerical methods can be more easily understood. 相似文献
1000.
In this note we prove the genus 3 case of a conjecture of Farkas and Verra on the limit of the Scorza correspondence for curves with a theta-null. Specifically, we show that the limit of the Scorza correspondence for a hyperelliptic genus 3 curve C is the union of the curve ${\{x, \sigma(x) \mid x \in C\}}$ (where σ is the hyperelliptic involution), and twice the diagonal. Our proof uses the geometry of the subsystem Γ00 of the linear system |2Θ|, and Riemann identities for theta constants. 相似文献