1,721,017 research outputs found
Supported gold nanoparticles catalysts for alkynes hydroamination.
No full textOur research group has previously reported the preparation of gold nanoparticles (AuNPs) supported on different functionalized silica supports. We started using commercial polyethyleneimine-functionalized silica bead [1] and we continued preparing silica nanoparticles functionalized with alkynyl carbamate moieties. [2]
Recently, we have focused on the straightforward synthesis of AuNPs anchored on commercial, micrometric oxide supports (i.e. SiO2, Al2O3, TiO2) previously modified with the di-functional organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) by a grafting procedure. After being thoroughly characterized by several complementary techniques (XPS, TEM, SSNMR, AAS etc.), the catalytic activity of these systems (Au/OS@Yne) has been evaluated in the oxidation of alcohols both in batch and continuous-flow systems. [3]
Furthermore, we have extended the same synthetic procedure to the preparation of a novel and magnetically recoverable catalyst, consisting of AuNPs supported on functionalized nano-magnetite (Au/Fe3O4@Yne).
We now present the latest results obtained in the study of the catalytic application of Au/SiO2@Yne and Au/Fe3O4@Yne in the alkynes hydroamination reaction, which is considered the most atom efficient process for the formation of a series of nitrogen-containing compounds.
Indeed, this transformation takes place without the formation of any side product and leads to the production of enamine, imine or substituted amines, which have a significant importance as bulk and fine chemicals or building blocks in organic synthesis.
[1] S. Fazzini , D. Nanni , B. Ballarin , M. C. Cassani , M. Giorgetti , C. Maccato, A. Trapananti, G. Aquilanti and S. I. Ahmed, J. Phys. Chem. C. 2012, 116, 25434−25443; M. Giorgetti, G. Aquilanti, B. Ballarin, M. Berrettoni, M. C. Cassani, S. Fazzini, D. Nanni and D. Tonelli, Anal. Chem. 2016, 88, 6873-6880;
[2] S. Fazzini, M. C. Cassani, B. Ballarin, E. Boanini, J. S. Girardon, A.S. Mamede, A. Mignani and D. Nanni, J. Phys. Chem. C. 2014, 118, 24538-24547; M. C. Cassani, B. Ballarin, D. Barreca, E. Boanini, E. Bonansegna, G. Carraro, S. Fazzini, A. Mignani, D. Nanni, D. Pinelli, RSC Adv. 2016, 6, 25780-25788.
[3] B. Ballarin, D. Barreca, E. Boanini, M. C. Cassani, P. Dambruoso, A. Massi, A. Mignani, D. Nanni, C. Parise, A. Zaghi, ACS Sus. Chem. Eng. 2017, 5, 4746-4756
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
An HRP-based amperometric biosensor fabricated by thermal inkjet printing
No full textDirect inkjet printing of a complete andworking amperometric biosensor for the detection of hydrogen peroxide, based on horseradish peroxidase
(HRP), has been demonstrated. The device has been realized with a commercial printer. A thin layer of PEDOT:PSS, which was in turn covered
with HRP, was inkjet printed on top of an ITO-coated glass slide. The active components of the device retained their properties after the thermal
inkjet printing. The whole device has been encapsulated by means of a selectively permeable cellulose acetate membrane.
The successful electron transfer between the PEDOT:PSS covered electrode and the enzyme has been demonstrated, and the biosensor evidenced
very good sensitivity, in line with the best devices realized with other techniques, and a remarkable operational stability. This result paves the way
for an extensive application of “biopolytronics”, i.e. the utilization of conductive/semiconductive polymers and biologically active molecules to
design bioelectronic devices using a common PC, and exploiting normal commercial printers to print them out
Supported gold nanoparticles catalysts for organic transformations
No full textOur research group has recently developed a convenient method for the anchoring of gold nanoparticles (AuNPs) on different oxide supports (SiO2, Al2O3, TiO2, Fe3O4) previously modified with a propynyl-carbamate organic functionality. The alkynyl-carbamate moieties anchored on the surface of the support are capable of straightforwardly reducing the gold precursor chloroauric acid (HAuCl4) to afford Au/OS@Yne (OS = Oxide Support, Yne = organic functionalization), without the need of additional reducing or stabilising agents.[1,2]
After being thoroughly characterized by several complementary techniques (XPS, TEM, SSNMR, AAS etc.), the catalytic activity of these systems has been evaluated in the oxidation of alcohols and in the hydroamination of alkynes, both in batch and continuous-flow conditions.[1,3
A new Cu(II)-MOF based on a propargyl carbamate-functionalized isophtalate ligand as nitrite electrochemical sensor
No full textA PROMISING MATERIAL FOR SENSORS AND BIOMEDICAL DEVICES
No full textThe excellent properties of a metal-free cellulose modified with polyaniline material (Cell/PANI)
have been demonstrated by realizing proof of concept for touch sensors, humidity sensors,
biomedical devices by successfully building electrocardiogram electrodes and sensors
for monitoring the respiratory rate
Thermal inkJet microdeposition of PEDOT:PSS on ITO-coated glass and characterization of the obtained film
No full textIn view of direct inkjet printing of low-cost sensors, we describe here the thermal printing of a thin film of a commercially available
conjugated polymer (poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, PEDOT:PSS). The printed film has been investigated by
optical microscopy, AFM and cyclic voltammetry. The results have been compared to the ones obtained for a continuous film of the same
polymer deposed by spin-coating. No appreciable differences were noted between the electrochemical behaviour of the two samples, indicating
that the thermal printing of the polymer did not alter appreciably the material properties. Our findings indicate that the thermal printing route
may be then a good alternative for the controlled deposition of thin films of conjugated polymers
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