Current Issue : April - June Volume : 2013 Issue Number : 2 Articles : 8 Articles
Elimination of bacteria and other microbes effectively is important to our daily life and a variety of medical applications. Here,\r\nwe introduce a new kind of trimolybdate nanowires, namely Ag2-x(NH4)xMo3O10 �· 3H2O, that carry a large amount of Ag atoms\r\nin the lattice and Ag-rich nanoparticles on the surface. These nanowires can eliminate bacteria of E. coli, Staphylococcus aureus,\r\nand unknown microbes in raw natural water with high efficiency. For example, they can inactivate more than 98% of E. coli with\r\na nanowire concentration of only 5 ppm in the solution. The excellent sterilization performance is attributed to the combined\r\neffects of Ag ions, Mo ions, and Ag-rich nanoparticles of the Ag2-x(NH4)xMo3O10 �· 3H2O nanowires. These nanowires are not\r\ndissolvable in deionized water but can be dissolved by the metabolic materials released from bacteria, making them attractive for\r\nmany biological applications....
A series of SiO2 nanostructures codoped with Eu3; Mg2 ions were obtained by a sol-gel method. The gels synthesized by the\r\nhydrolysis of Si(OC2H5)4, Eu(NO3)3Ã?·6H2O, and Mg(NO3)2 were heated in air at 600?C for 2 hours. Firstly, the total amount of\r\nEu3 ions was varied from 0 to 2.0 mol% to investigate the effect of self-damping, while in the second case, the Eu3 ions were kept\r\nconstant in the experiment at 0.5 mol% total doping and Mg2+ ions varied. The samples were characterized by X-ray diffraction,\r\nTEM, EDS, and UV lamp-excited luminescence spectroscopy. The Eu3+ ions were homogeneously dispersed in the silica and\r\ninteracting with the small (1ââ?¬â??5 nm) amorphous silica matrix. Strong red emissions located at 614nm and 590nm for doped and\r\ncodoped SiO2 were observed from the UV light excitation at room temperature. The composition of around 1.25 mol% Eu3+ gave\r\nhighest emission intensity. SiO2; Mg2+ ions portray strongly enhanced emissions due to energy transfer from Mg2+ to Eu3+, which\r\nis due to radiative recombination. An increase in luminescence intensity was observed as the Mg2+-to-Eu3+ ratio increased for the\r\nrange investigated. The results show Eu3+ ion is located inside or at the surface of disordered SiO2 nanoparticles....
This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymerbonded\r\nNd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by\r\ncompression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small\r\nexchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure\r\nof Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing\r\nconcentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more\r\nprominenty for composites with stoichiometric Nd-Fe-B content....
Streptococcus mutans is the microorganism mostly responsible for initiation of tooth decay and also for the progression of an\r\nestablished lesion. Silver has been used for its antibacterial properties for many years, in different forms: ionised and elementary\r\nforms, as silver zeolites or as nanoparticles. The purpose of this study was to evaluate the antibacterial activity of three dental\r\ncements modified by nanosilver. Three cements were used: Sealapex, RelyX ARC, and Vitrebond. The cements were incorporated\r\nwith 0.05mL of silver nanoparticles solution. Control groups were prepared without silver. Six Petri plates with BHI were\r\ninoculated with S. mutans using sterile swabs. Three cavities were made in each agar plate (total = 18) and filled with the\r\nmanipulated cements. They were incubated at 37?C for 48 h, and the inhibition halos were measured. The paired t-Test was used\r\nfor statistical analysis (P < 0.05). No inhibition halos were obtained for Sealapex and Rely X, but Vitrebond showed bactericidal\r\nactivity without silver and enhanced effect with silver incorporation....
ZnO nanoparticles were prepared using a novel sol-gel method. Chemical reactions were carried out between zinc acetate and\r\nmethanol under ambient conditions using monoethanol amine (MEA) as surfactant and subsequent heating at 200?C. The\r\npowders were calcined, pressed into pellets, and presintered. The properties of the product were characterized by X-ray diffraction\r\n(XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectra. For gas sensing experiment, ethanol\r\nwas used as testing gas. The gas sensing results showed that the maximum value for detecting of 1000 ppm ethanol vapor was 25\r\nat an operating temperature of 370?C....
We investigate the influence of salt, acidic, and basic solutions (citrate, NaOH, and HCl) on the size of gold nanoparticles (AuNPs)\r\nsynthesized by laser ablation in aqueous media. We found that NP size increases from 3 nm to 13 nm when Zeta potential varies\r\nfrom -100 mV to -10 mV whatever the concentration and the nature of chemical solution are namely, citrate, NaOH, and HCl.\r\nThese results demonstrated that the final size of gold NPs produced by laser ablation in liquid media is mainly governed by the\r\ncharge-dependent growth mechanism....
TiO2 nanoparticles undergo a single-phase transition: from amorphous to anatase when calcined at 450?C. It can be noticed from\r\nthe XRD and AFM results that the particle size of TiO2 is below 30 nm. Results from viscometer and UV-Vis analysis showed that\r\nthe film thickness is closely related to the viscosity of dip-coating solutions. It was found that the contact angle for water decreased\r\nafter being illuminated with UV light at certain periods of time. This indicates that these films exhibit hydrophilic properties\r\nthat can be used on self-cleaning surfaces and antifogging mirrors. Heterogeneous photocatalytic oxidation allows the oxidation\r\nof airborne volatile organic compounds (VOCs) into carbon dioxide and water in the presence of a semiconductor catalyst and\r\nUV light source. Titanium dioxide, due to its chemical stability, nontoxicity, and low cost, represents one of the most efficient\r\nphotocatalysts. Photocatalytic activity of the TiO2 thin films was evaluated by using toluene and results showed that this film is\r\nsuccessful in decomposing toluene....
Zinc oxide (ZnO) nanoparticle gas sensor was formed by spin coating.We annealed the film at 400, 600, and 800?C for 1 hour in air\r\nto make gas sensor. The responses of gas sensor to ethanol with UV light illumination were investigated. It could be observed that\r\nthe ZnO nanoparticle film annealing at 800?C has the highest sensitivity. It can be attributed to the defects of ZnO nanoparticle\r\nfilm annealing at 800?Cmuch more than other annealing temperatures. The study shows that the ZnO nanoparticles have potential\r\napplications as RT ethanol sensors...
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