Designing ultrafine PdCo alloys in mesoporous silica nanospheres with peroxidase-like activity and catalase-like activity

The PdCo alloy homogenously distributed in MSNs as ultrafine and monodispersed particles exhibits excellent peroxidase- and catalase- like activity. The PdCo@MSNs show satisfied sensing performance in detecting glutathione from complex cell media.

Cantilever-Droplet-Based Sensing of Magnetic Particle Concentrations in Liquids

Cantilever-based sensors have attracted considerable attention in the recent past due to their enormous and endless potential and possibilities coupled with their dynamic and unprecedented sensitivity in sensing applications. In this paper, we present a technique that involves depositing and vaporizing (at ambient conditions) a particle-laden water droplet onto a defined sensing area on in-house fabricated and commercial-based silicon microcantilever sensors. This process entailed the optimization of dispensing pressure and time to generate and realize a small water droplet volume (Vd = 49.7 ± 1.9 pL). Moreover, we monitored the water evaporation trends on the sensing surface and observed total evaporation time per droplet of 39.0 ± 1.8 s against a theoretically determined value of about 37.14 s. By using monodispersed particles in water, i.e., magnetic polystyrene particles (MPS) and polymethyl methacrylate (PMMA), and adsorbing them on a dynamic cantilever sensor, the mass and number of these particles were measured and determined comparatively using resonant frequency response measurements and SEM particle count analysis, respectively. As a result, we observed and reported monolayer particles assembled on the sensor with the lowest MPS particles count of about 19 ± 2.

Фазовая диаграмма состояния и межфазные характеристики в бинарной наносистеме

The size effects on the composition of coexisting phases, the interfacial layer between them, and the interfacial tension in a binary system composed of a matrix and the monodispersed particles of arbitrary (including nanoscale) size are described in the context of a Gibbs method for dispersed systems. Obtaining the relevant relationships has allowed plotting the size-dependent phase state diagrams for a Cr–Ti system with a point of equal concentrations with a minimum. The coefficients of size composition of the nanoparticles and the matrix, as well as those of interfacial tension under the isobaric and isothermal conditions, are calculated at different degree of dispersion. The calculated data coincide with the experimental ones.

Predicting Particle Size Distribution in Nanofluid Synthesis

Wet chemistry approaches have been widely used to synthesize nanoparticle suspensions with different size and shape. Controlling particle size is crucial for tailoring the properties of the nanofluid. In this study, we simulated the particle size growth during a thermal-chemical nanofluid synthesis routine. The simulation was based on the population balance model for aggregation kinetics, which is coupled with thermal decomposition, nucleation and crystal growth kinetics. The simulation result revealed a typical burst nucleation mechanism towards self-assembly of supersaturated monomers in the nanoparticle formation process and the shift from monodispersed particles to polydispersed particles by the particle-particle coagulation.

Project and Construction of a Differential Mobility Analyzer to Produce Monosized Nanoparticles

The nanotechnology has become an important area, either because the special features of nanometric particles confer to products, or due to a maximum limit of emission of such particles in air. However, the reduced size of this kind of particle limit them to be separated by conventional techniques, and a good way to ensure an aerosol stream with monodispersed particles is to use the electrical mobility technique. This theory is based on the ability of a charged particle to cross an electrical field, thus depending of the size of particles, the bigger ones will arrive later in the central electrode than the smaller ones, and only a narrow band of sizes will be collected in a slit located in the bottom of the equipment. This work aimed to project and construct a Differential Mobility Analyzer (DMA) in order to produce an aerosol containing NaCl nanoparticles monodispersed, from a aerosol polydispersed produced by an atomizer. The operating principle is to charge NaCl nanoparticles with a neutralizer so that they can be collected according to the voltage applied to the DMA in a specific range of size distribution. The unit comprises a compressor for generating air current, high efficiency filters in order to generate ultrapure air, atomizer, reservoir of NaCl solution to generate aerosol, a diffusion dryer to remove moisture silica current gas, a source of X-rays to charge nanoparticles, a source of high voltage to be applied to the DMA, a DMA to classify the nanoparticles and a particle counter to perform the counting of particles before and after DMA. Preliminary results indicated the dependence of the particle size with the applied electric field. The results were very promising.