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91.
Digital holographic microscopy (DHM) has been successfully applied for the first time to characterize the radiative out-of-plane emission properties of a superdirective device. Complementarily to near-field microscopy, DHM allows us to reconstruct the beam in the far-field region. The angular dispersion of the light beam radiated from a grating composed of air and anti-air metamaterial has been determined, and the proposed technique has highlighted a collimation degree higher than 0.04°, as already evaluated in a previous work. Further considerations on the retrieved phase map of the beam in the acquisition plane are presented. 相似文献
92.
Pedro R. Aranda Ernesto Perino Franco A. Bertolino Julio Raba Irma E. De Vito 《Mikrochimica acta》2012,179(3-4):235-239
We report on a novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples. Cr(VI) is adsorbed - in a “batch mode” - on multiwalled carbon nanotubes covered with Aliquat 336 and then determined directly, i.e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling. The method combines the advantages of solid-phase extraction with the benefits of the XRF method in that the large areas required by the carbon nanotubes make them a promising solid sorbent for preconcentration. The enrichment factor was calculated after considering that the thin film obtained from the 10?mL solution of 1?mg?L?1 of Cr(VI) has a real thickness of 0.04?mm and a final diameter of 16.7?mm, so that the volume deposited on the pellet is 0.0088 cm3 and the preconcentration factor is 1000.
A novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples is proposed. Cr(VI) is adsorbed - in a “batch mode” - on multiwalled carbon nanotubes (MWCNTs) covered with Aliquat 336 and then determined directly, i.e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling. 相似文献
93.
Kiomars Zargoosh Mojtaba Shamsipur Morteza Hosseini Claudia Caltagirone Vito Lippolis 《Journal of luminescence》2012,132(8):2126-2129
Due to their multiple selectivities, high sensitivity, and instrumental simplicity peroxyoxalate chemiluminescence (PO-CL) reactions have been used as powerful detection systems in several separation techniques. However many of the PO-CL reactions have slow kinetics and impose extra flow elements in separation systems to obtain acceptable band resolution, overcome the peak broadening and observe the reaction in a reasonable time window at maximum emission intensity. Therefore slow chemiluminescence reactions cannot be used in constructing miniaturized separation systems. To achieve the fast and intense PO-CL reactions (suitable for miniaturized separation systems) careful selection of the fluorophore molecule and the reaction conditions is of great importance. In this work, the time-dependent light emission of the fast chemiluminescence (CL) arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with H2O2 in the presence of 3-1-aza-4,10-dithia-7-oxacyclododecane (L) as a novel fluorophore, and imidazole as catalyst, has been studied in ethyl acetate solution. To find the best time-intensity emission curves the concentration of TCPO, imidazole, hydrogen peroxide and L were optimized. The maximum CL intensity and minimum reaction time were obtained at the concentration of 0.2 M H2O2, 2.0×10?3 M TCPO, 1.0×10?3 M fluorophore and 5.0×10?3 imidazole. Under the optimum experimental condition, the entire CL reaction is completed in less than 3 s. 相似文献
94.
Joana Monterrosa José Daniel Martínez Mary Lorena Araujo Felipe Brito Giuseppe Lubes Mildred Rodríguez Lino Hernández Vito Lubes 《Journal of solution chemistry》2012,41(4):589-598
We studied speciation of the mixed-ligand complex formation equilibria of vanadium(III) with both 2,2??-bipyridine (Bipy) and the amino acids glycine (HGly), proline (HPro), ??-alanine (H??Ala), and ??-alanine (H??Ala) by means of electromotive forces measurements emf(H) using 3.0?mol?dm?3 KCl as the ionic medium at 25 °C. The experimental data were analyzed by means of the computational least-squares program LETAGROP, taking into account the hydrolysis of the vanadium(III) cation, the respective stability constants of the binary complexes, and the acid/base reactions of the ligands which were kept fixed during the analysis. In all four amino acid systems studied we observed the complexes [V2O(Bipy)(B)]3+, [V2O(Bipy)2(B)2]2+, [V(OH)(Bipy)(B)2] and [V(OH)2(Bipy)(B)], where B represents the deprotonated form of the amino acids studied in this work. The respective stability constants were determined and the species distribution diagrams as a function of pH are briefly discussed. 相似文献
95.
Vito VeceKhadija Ben Hadj Hassen Sylvain Antoniotti Elisabet Duñach 《Tetrahedron letters》2012,53(38):5102-5105
We described herein a Sn(NTf2)4-catalysed cyclisation of gem-(dialkoxymethyl)-1,6-dienes and derivatives where cyclohexane or tetrahydrofuran rings are formed following either a 6-enexo-endo-trig process or a 5-exo-trig process, respectively, depending on substitution patterns. The latter process features an unusual dealkylative ether cyclisation, triggered by the strong Lewis acid character of the tin(IV) triflimidate catalyst. 相似文献
96.
97.
Abdullah Al Nahain Vera Ignjatovic Paul Monagle John Tsanaktsidis George Vamvounis Vito Ferro 《Macromolecular bioscience》2020,20(9)
The glycosaminoglycan heparin is a clinically important anticoagulant drug, primarily used to reduce the risk of blood clots (thrombosis) during surgery. Despite its importance in medicine and its continuous use over many decades, heparin suffers from several limitations associated with its heterogeneity and its extraction from animal tissues. In order to address these limitations, reversible addition‐fragmentation chain transfer polymerization is utilized to prepare a library of heparin mimetic copolymers from the sulfonated monomers sodium 4‐styrene sulfonate, potassium‐3‐sulfopropyl acrylate, potassium‐3‐sulfopropyl methacrylate, and sodium‐2‐acrylamido‐2‐methyl‐1‐propane sulfonate. Copolymers are prepared using combinations of two different monomers in various ratios. Monomer reactivity ratios are also determined for some representative monomer combinations, and all polymers are characterized by 1H NMR spectroscopy and gel permeation chromatography. The anticoagulant activities of the copolymers are determined by activated partial thromboplastin time and thrombin clotting time assays and structure–activity relationships are explored. 相似文献
98.
P. Stoppa D. De Vito S. Giorgianni A. Baldacci A. Gambi R. Wugt Larsen 《Molecular physics》2020,118(18)
The high-resolution infrared spectrum of CHD2 79Br has been investigated by Fourier transform spectroscopy in the range 540–615?cm?1 at an unapodised resolution of 0.0035?cm?1. This spectral region is characterised by the ν6 fundamental (584.8510?cm?1), corresponding to C–Br stretching mode, and its hot band 2ν6?ν6 (578.4333?cm?1). The spectral analysis resulted in the identification of 3430 transitions (J’?≤?73 and K'a ?≤?18) for the ν6 fundamental and 1212 transitions (J’?≤?49 and K'a ?≤?11) for the hot band 2ν6?ν6. The assigned data have been fitted using the Watson’s S-reduced Hamiltonian in the Ir representation and new constants for the ground state from about 24,600 combination differences and sets of parameters for the v 6?=?1 and 2 vibrational states have been obtained. From spectral simulations the intensity ratio between 2ν6?ν6 and ν6 has been estimated to be 0.15?±?0.02. High-quality ab initio calculations have also been performed at the CCSD(T) level of theory in order to support the experimental investigation through the calculation of molecular parameters relevant to ro-vibrational spectroscopy. 相似文献
99.
We prove a weak form of the Frobenius reciprocity theorem for locally compact groups. As a consequence, we propose a definition of square-integrable representation modulo a subgroup that clarifies the relations between coherent states, wavelet transforms and covariant localisation observables. A self-contained proof of the imprimitivity theorem for covariant positive operator-valued measures is given.
100.