Search results for "silver"

Andrea e gli argentieri Memingher in Sicilia

2018

Andrea Memingher è una tra le più enigmatiche figure di argentieri attivi a Palermo nella seconda metà del XVII secolo. Si può ritenere che la famiglia avesse origini nordiche e che, dopo un passaggio a Napoli, si stabilisse definitivamente a Palermo, inserendosi nella maestranza degli orafi e argentieri della città, probabilmente grazie ad un matrimonio con una figlia o una sorella o una vedova di un membro palermitano della maestranza. La presenza di Paolo Memingher nel capoluogo siciliano è attestata già nel 1660, due anni prima della data di inizio della sua attività, protrattasi fino al 1678. Il più importante esponente della famiglia fu Andrea, figlio di Paolo, il quale dovette la sua…

Interaction of metal ions with D-glucobenzothiazoline: isolation and characterization of the resultant products

2002

Six different metal-ion complexes of D-glucobenzothiazoline were synthesized and characterized by analytical and spectral techniques. Formation of different types of species (ML and ML2) were observed with Cu2+, Ag+, Cd2+, Hg2+, and Zn2+ ions. Existence of an anomeric mixture in the case of the Cu2+ complex is identified from the EPR spectra, and the results were further supported by the simulated spectra. The structures were proposed based on different studies.

Ag5 nanoclusters with dual catalytic antiradical activities

2022

Silver nanoclusters of five atoms (Ag5) display outstanding catalytic activities for the deactivation of radicals. Using 2,2-diphenyl-1‑picrylhydrazyl (DPPH) radical as a model system, we observed a fast radical reduction to DPPH anions using only [Ag5] 3 to 4 orders of magnitude less than [DPPH]. Moreover, nanoclusters remain stable at the end of the reaction, and can deactivate again DPPH radicals at the same rate, indicating that they act as anti-radical catalysts. The radical scavenger catalytic activity of Ag5 proceeds selectively through the oxidation of methanol (used to dissolve the radical) to formaldehyde, which is supported by DFT calculations. The obtained catalytic rate constan…

Antibacterial and white spot lesions preventive effect of an orthodontic resin modified with silver-nanoparticles

2021

Background To evaluate the antibacterial property of a modified orthodontic resin with different concentrations of silver-nanoparticles (AgNPs), and quantify its preventive effect on the formation of white spot lesions (WSLs). Material and Methods An orthodontic resin (Transbond XT) was modified with four concentrations of AgNPs (1%, 0.5%, 0.1%, and 0.05%), the orthodontic resin without AgNPs was used as control. Polymerized resin discs (n=80) were submitted to Agar diffusion test on Petri dishes inoculated with Streptococcus mutans and Lactobacillus acidophilus. In addition, resin discs of each group (n=40) were placed in 96-well plates with bacterial suspensions to evaluate the colony-for…

Effect of an orthodontic resin modified with silver-nanoparticles on enamel color change

2021

Background: To evaluate the effect of an orthodontic resin modified with various concentrations of silver-nanoparticles (AgNPs) on enamel color. Material and Methods: Twenty lower premolars were collected and divided into four groups (n = 5) according to the concentration of AgNPs (0.05%, 0.1%, 0.5%, and 1% wt/wt). Additionally, a group bonded with a conventional resin was used as control (n=5). Previous to the bracket bonding, enamel color was measuring with a spectrophotometer. Specimens were stored for 6 months in deionized water. Brackets were debonded and color changes of enamel were calculated with the CIEDE 2000 formula (ΔE00). One-way ANOVA and Tukey test were used to assess the col…

Synergistic effect with antibiotics and inhibition of bacterial biofilm formation by polyaminocyclodextrin-silver nanoparticles

2018

Plant extracts as green reductants for the synthesis of silver nanoparticles: lessons from chemical synthesis.

2018

The increasing use of silver (Ag) nanoparticles (NPs) in daily-life applications, electronics, or catalysis calls for green and cost-efficient synthetic methods. Ag NPs are used especially in biomedicine because of their antibacterial, antifungal, or anticancer properties. Chemical synthesis allows tuning the particle morphology, size, and crystallinity, but requires toxic and hazardous chemicals. Bioinspired synthetic protocols have shown promise to minimize environmental impact, but biological protocols for the synthesis of Ag NPs lack control on the morphology and crystallinity. This review briefly compiles the chemical synthesis of Ag NPs and contrasts it with "green" protocols based on…

Ag+ Complexes as Potential Therapeutic Agents in Medicine and Pharmacy

2019

Silver is a non-essential element with promising antimicrobial and anticancer properties. This work is a detailed summary of the newest findings on the bioinorganic chemistry of silver, with a special focus on the applications of Ag+ complexes and nanoparticles. The coordination chemistry of silver is given a reasonable amount of attention, summarizing the most common silver binding sites and giving examples of such binding motifs in biologically important proteins. Possible applications of this metal and its complexes in medicine, particularly as antibacterial and antifungal agents and in cancer therapy, are discussed in detail. The most recent data on silver nanoparticles are also summari…

Electrochemical conversion of pressurized CO2 at simple silver-based cathodes in undivided cells: study of the effect of pressure and other operative…

2020

Abstract Electrochemical reduction of pressurized CO2 is proposed as an interesting approach to overcome the main hurdle of the CO2 electrochemical conversion in aqueous solution, its low solubility (ca. 0.033 M), and to achieve good faradaic efficiency in CO using simple sheet silver cathodes and undivided cells, thus lowering the overall costs of the process. The effect on the process of CO2 pressure (1–30 bar), current density, nature of the supporting electrolyte and other operative conditions, such as the surface of the cathode or the mixing rate, was studied to enhance the production of CO. It was shown that pressurized conditions allow to improve drastically the current efficiency o…

El prestigio de los objetos: mangos de marfil en el mundo ibérico

2020

El estudio se centra en una serie de mangos de marfil de características morfotécnicas similares, recuperados en espacios de hábitat y funerarios ibéricos y datados entre el s. IV y el s. II a. C. Se trata de objetos de prestigio al alcance de una élite aristocrática, que han sido elaborados con materias primas exóticas (marfil) y técnicas decorativas inusuales que indican una especialización. A través de análisis de composición por infrarrojo cercano por Transformada de Fourier (FT-NIR) y de fluorescencia de rayos X (pXRF) se ha podido documentar la presencia de incrustaciones de ámbar adheridas a la superficie de los mangos mediante el uso del estaño como soldadura blanda y el empleo de a…