Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ≈4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%–7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (≈49–53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water.
Industry 4.0 and the Internet of Things have significantly increased the use of sensors and electronic products based on flexible substrates, which require electrical energy for their performance. This electrical energy can be supplied by piezoelectric vibrational energy harvesting (pVEH) devices. These devices can convert energy from ambient mechanical excitations into electrical energy. In order to develop, these devices require piezoelectric films fabricated with a simple and low-cost process. In this work, we synthesize ZnO nanorod film by a solvothermal method and deposit by spraying on ITO (indium-tin-oxide)/PET (polyethylene terephthalate) flexible substrate for a pVEH microdevice. The results of the characterization of the ZnO nanorod film using X-ray diffraction (XRD) confirm the typical reflections for this type of nanomaterial (JCPDS 36-145). Based on transmission electron microscopy (TEM) images, the size of the nanorod film is close to 1380 nm, and the average diameter is 221 ± 67 nm. In addition, the morphological characteristics of the ZnO nanorod film are obtained using atomic force microscopy (AFM) tapping images. The pVEH microdevice has a resonant frequency of 37 Hz, a generated voltage and electrical power of 9.12 V and 6.67 μW, respectively, considering a load resistance of 107.7 kΩ and acceleration of 1.5 g. The ZnO nanorod film may be applied to pVEH microdevices with flexible substrates using a low-cost and easy fabrication process.
Se sintetizaron nanopartículas de plata AgNPs a partir de nitrato de plata, empleando borohidruro de sodio como agente reductor y poli(etilendioxitiofeno):poli(estiren sulfonato de sodio), PEDOT:PSS, como estabilizador. Se variaron los siguientes parámetros de síntesis: 1) contenido relativo entre PEDOT y PSS, utilizando tres formulaciones comerciales; y 2) relación molar entre sal de plata y agente reductor. Por espectroscopia UV-Vis, se corroboró la formación de las AgNPs mediante la banda plasmónica a ~ 400 nm, además se observaron cambios espectrales para el PEDOT cuando se utilizan las formulaciones con mayor contenido de PEDOT, y relación sal/agente reductor de ~1, lo cual de acuerdo con los espectros Raman se asocia con un cambio conformacional del PEDOT hacia una estructura más benzenoide. En las demás condiciones, las propiedades espectroscópicas son similares a las de nanopartículas preparadas con puro PSS. Con base en los resultados, se plantea que las AgNPs se estabilizan con el PSS en exceso, afuera de los dominios PEDOT:PSS, cuando la formulación tiene más contenido de PSS o empleando bajas cantidades de NaBH4. Al incrementar el contenido de NaBH4, las AgNPs se forman también adentro de los dominios. El mecanismo de estabilización permite así modular las propiedades ópticas y eléctricas de las NPs.
A low-grade inflammatory phenomenon is a feature of overweight and metabolic syndrome. The involvement of a pro-inflammatory Th17 lymphocyte subset and the CD69 + T regulatory (Treg) cell subtype in patients with metabolic dysfunction associated or not to overweight has not been fully elucidated. The aim of this study was to perform a quantitative and functional analysis of pathogenic Th17 lymphocytes and CD69 + Treg cells in patients with metabolic dysfunction (insulin resistance and dyslipidemia). The number of pathogenic Th17 cells and the levels and function of CD69 + Treg cells were analyzed in blood samples from individuals with metabolic dysfunction, associated or not to overweight. Pathogenic and non-pathogenic Th17 lymphocytes as well as Th22 cells were determined by eight-color flow cytometry analysis, whereas the levels and the suppressive function of CD69 + Treg cells were also analyzed by multiparametric flow cytometry. We detected increased levels of pro-inflammatory Th17 pathogenic cells and Th22 lymphocytes in overweight unhealthy individuals (p<0.001, compared to normal weight healthy). Conversely, diminished numbers of CD69 + Treg lymphocytes were observed in metabolically unhealthy individuals, with or without overweight. Likewise, the immunosuppressive function of CD69 + Treg cells was also defective in these patients. The increased levels of pathogenic Th17 cells along with a diminished number and function of CD69 + Treg lymphocytes may significantly contribute to the low-grade inflammatory phenomenon of metabolically unhealthy patients.
The activation energy, enthalpy, entropy, and free energy for the diffusion of Ca2+ and Ce3+ ions and their respective chelates with ethylenediaminetetraacetic acid (EDTA) and trans-1,2-diaminocyclohexanetetraacetic acid (DCTA) in aqueous solution, and the activation energies for the viscous flow of these solutions have been obtained in the temperature range 10-35 °C. Some speculation is made regarding the comparison of these activation parameters with the ionic radii of the systems in terms of the structure and solvent interaction of these species. The hydrophobic contribution of the cyclohexane ring of DCTA complexes based on their activation entropy values is discussed.
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