1,721,017 research outputs found
Green synthesis of Silver nanoparticles with sucrose and maltose: morphological and structural charcaterization
No full textWe present a totally green approach toward the rapid synthesis and stabilization of metal nanoparticles
through the treatment of aqueous solutions of silver nitrate with two commonly available sugars, i.e.,
maltose and sucrose as reducing agents. The average size, size distribution, morphology and internal
crystalline structure of the nanoparticles are studied through high resolution transmission electron
microscopy, selected-area diffraction pattern and UV–Vis spectroscopic technique and are seen to be critically
dependent on the used sugar. The great majority of sucrose-assisted synthesized nanoparticles is
distributed in a size range less than 6.0 nm, with an arithmetic media of 5.2 nm and a statistical standard
deviation of 1.3 nm. For the maltose synthesized sample, the size distribution plot reveals that nanoparticles
are greater (with a mean size of 62.4 nm and a standard deviation of 9.5 nm) and exhibit a more
anisotropic morphology
Experimental results of UV laser cleaning on a silver Carlino coin
No full textSilver artefacts and particularly ancient silver artefacts present the serious problem of the black look due to ambient contamination. The black colour is the consequence of the layer forming on the surface made of acanthite and jalpaite, both compounds are sulphur composts. Recently UV laser cleaning technique has demonstrated to be very promising in processing of cultural artefacts. To operate on artefacts without to contaminate the bulk, first we determined the laser fluence threshold of the bulk, second we controlled the surface compounds and at the end we operated the laser irradiation. In this work we utilised certified silver and silver/copper samples in order to perform preliminary studies. The threshold fluence we found were 780 and 510 mJ/cm2 for the Ag pure and for the Ag/Cu alloy, respectively. The jalpaite concentration on Ag/Cu sample increased after the laser dose of 25 J/cm2, while for higher laser dose its value lowered pointing out that complex processes take part during the laser application. As a successful of our studies we applied the technique on a Carlino coin made of silver coined in 1689 under King Carlo II. The analyses were performed by two different techniques able to find the percentage of elements and the chemical compounds; the EDXRF and the XRD. We found that the sulphur concentration decreased on laser dose. Operating on the coin up to a dose of 280 J/cm2 the sulphur concentration deceases up to 20 %, while the coin look becomes clear just after a 50 J/cm2
Controlled synthesis and chain-like self-assembly of silver nanoparticles through tertiary amine
Full text linkIn this study, monodispersed silver nanoparticles with diameter in the range 4-10 nm were first synthesized by chemical reduction from silver nitrate using glucose as reducing agent and sucralose as capping agent, through microwave assisted method. Then, a strong enhancement of the yield of the synthesized nanoparticles and their self-assembly could be achieved through the injection into the colloidal solution, at room temperature, of a tertiary amine (triethylamine, TEA), which acted both as promoter and as directing agent for silver nanoparticles. The yield of the synthesized nanoparticles and the length of the chains could be tuned by facile adjustment of the TEA concentration and reaction time. The interaction between amine and silver nanoparticles made the non-uniform spatial distribution of stabilizers at nanoparticles surfaces and led to the 1D assembly. Transmission electron microscopy (TEM) and UV-Vis spectroscopy have been employed for monitoring the nanochains formation. This mechanism evidenced that sucralose capped silver nanoparticles could also be useful for the real-time naked-eye detection of amine
Experimental rehydroxylation and the dating of early medieval and Byzantine ceramics. A southern Italian case study
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Green synthesis of sucralose-capped silver nanoparticles for fast colorimetric triethylamine detection
No full textIn this study, a fast colorimetric triethylamine sensor based on localized surface plasmon resonance of silver nanoparticles is presented. The nanoparticles were synthesized by chemical reduction from silver nitrate using glucose as reducing agent and sucralose as capping agent
Synthesis of Tailored Phthalocyanines and Their Application as Spin Coated Films in Volatile Organic Compounds Detection
No full text29H,31H-(2,4-di-t-amylphenoxy)phthalocyanine, Zn(II) tetra-4-(2,4-di-t-amylphenoxy)phthalocyanine and Zn(II) tris-(2,4-di-t-amylphenoxy)-[4-(4-mercapto-phenyliminomethyl)-phenoxy]phthalocyanine were synthesized and their mol. structures were confirmed by LC-MS, 1H NMR, FTIR and UV-visible spectra. Spin coated layers of these phthalocyanines were used as optochem. interactive materials for volatile org. compds. detection in the UV-visible spectral range. The results show a good sensitivity and selectivity depending on both the metal and the peripheral substituents. Optical sensitivity towards tert-butylamine, diethylamine, dibutylamine, 2-butanone and HOAc was monitored
MODIFICATION OF Pd-H2 AND Pd-D2 THIN FILMS PROCESSED BY HE-NE LASER
No full textWe have performed experiments of absorption of hydrogen and deuterium gas by Pd thin films and we have studied the behavior of these samples compared with non processed ones. We have also employed, during the treatment, a continuous wave He-Ne laser to irradiate the samples inside the chamber in order to increase the gas absorption. By a scanning electron microscope (SEM) and an electron probe micro analyzer (EDX) we have observed, on the surface of the treated samples, the presence of structures like spots and inside them different elements from Pd. By these results we can say that the gas loading has been a very important condition to produce “transmutation” elements and the laser action has been very interesting in order to increase the morphological modifications of the treated samples
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