Raspberry Pi based automatic temperature measurement and logging system for solar thermal purposes

For automatic temperature measuring and logging purposes in solar thermal experiments, a single board computer - Raspberry Pi based and sensor system is proposed. Different data sets are observed for sensors, thermometers, and thermocouples and they are compared. The consistency of the automated temperature measurement system is also verified.

Dosymmetric estimates of 99mTc (MAA) and 133Xe in newborn lungs using Cristy-Eckerman / Segars representations

Using the Cristy-Eckerman (C-E) / Segars anatomical representations and the MIRD formalism, the Absorbed doses in lungs of newborn patients scanned with radiopharmaceuticals 133Xe (ventilation) and 99mTc (MAA) (perfusion) are estimated. These representations are phantoms used in Monte Carlo calculations to determine specific absorbed fractions, which, associated with the pharmaceutical residence time, determine the absorbed dose. Concerns about the dosimetric impact of using these ventilation / perfusion agents, as well as the use of different phantoms, were explored in newborn patients. When the lungs were scanned with 99mTc (MAA), the relative difference in total dose between the C-E / Segars anatomical representations was 1.0%. When the lungs were scanned with 133Xe, the relative difference in total dose between the anthropomorphic representations of C-E / Segars was 0.5%. Regardless of the radiopharmaceutical used for the pulmonary studies of a newborn patient, the substitution of the C-E representation for that of Segars does not reflect very significant changes in the calculation of the absorbed dose in the lungs, where the greatest dosimetric contribution is its self-dose, which is supplied mainly by the electrons produced during the 99mTc and 133Xe decay.

Morphology, composition and structure of the fibers of a Chimu culture textile

In this work we studied the microfibers of a textile (T-shirt) of the Chimú culture. This culture developed on the northern coast of Peru. To determine the raw material and structural quality of the microfibers, the results of the Chimú textile were compared with the corresponding results for the microfibers of cotton from the northern coast of Peru (native cotton). Scanning electron microscopy images revealed that the Chimú textile yarns are composed of a set of interwoven microfibers. Energy dispersive X-ray spectroscopy and pulsed laser-induced plasma spectroscopy techniques allowed the identification of characteristic cellulose atoms in the microfibers of Chimú textile and native cotton. Only for the Chimú textile, these spectroscopic techniques allowed the identification of atoms corresponding to natural dyes and powder residues. Attenuated total reflection Fourier transform infrared spectroscopy identified the same molecular bonds for the microfibers of Chimú textile and native cotton. For the microfibers of Chimú textile and native cotton, the X-ray diffractograms showed peaks characteristic of the cellulose Iβ polymorphism of of monoclinic P21 structure. The raw material of the Chimú textile is cotton and the microfibers of this material show significant structural stability.

Caracterización del grado de complejidad del sistema solar mediante la ley de Zipf/Mandelbrot

La ley de Zipf/Mandelbrot ha permitido caracterizar fenómenos con una organización hiperbólica en las ciencias biomédicas y los lenguajes naturales, entre otros; sin embargo, su aplicación podría extenderse a estudiar características planetarias. Por tanto, el objetivo de esta investigación consiste en aplicar la ley de Zipf/Mandelbrot para caracterizar el grado de complejidad del período orbital, la velocidad orbital media planetaria y la distancia media al sol de los planetas del sistema solar. Para ello, se tomaron los valores del período orbital, la velocidad orbital media y la distancia media al sol de los planetas del sistema solar para evaluar su distribución hiperbólica. Posteriormente, se aplicó la ley de Zipf/Mandelbrot para calcular la dimensión fractal de ambas variables. Se comprobó que los valores del período orbital, la velocidad orbital y la distancia media planetaria se distribuyen jerárquicamente, lo cual permitió calcular los valores de dimensión fractal, que fueron 0.28, 0.88 y 0.42, con coeficientes R2 de 0.92, 0.87 y 0.92, respectivamente. Lo anterior sugiere que la aplicación de la ley de Zipf/Mandelbrot revela la existencia de órdenes matemáticos no descritos en la cinemática celeste al encontrar un mayor grado de complejidad de la velocidad media orbital con respecto a la distancia media planetaria al sol y el período orbital, de donde se puede inferir que los parámetros de análisis de los sistemas planetarios podrían complementarse con este enfoque.

Letter to the editor: The 2021 Physics Nobel Prize and the understanding of complex physical systems

The 2021 Physics Nobel Prize was awarded to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their “groundbreaking contributions to our understanding of complex physical systems.” Here we review some of the ideas and results which served as the scientific basis to the award. We also comment on the works by our research group on the complex systems properties of random lasers and random fiber lasers.

Effect of kaolin waste annealing on the structural and thermal behavior of poly(ε−caprolactone)

The heat treatment effect on kaolin waste from mining was evaluated on the structural and thermal behavior of poly(ε-caprolactone) (PCL). The PCL/KW (kaolin waste) and PCL/HTKW (heat-treated kaolin waste) composites were processed in an internal mixer and subsequently characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The kaolin waste showed kaolinite and quartz in its composition, while the heat treatment at 1200°C modified it to mullite, quartz and silica-rich amorphous phase. By XRD, there was an increase in the intensity of the peak 2θ = 23.9° of the PCL/KW composites compared to neat PCL. In contrast, PCL/HTKW composites tended to reduce the intensity of the peak 2θ = 23.9°, especially at 5% HTKW. The crystalline melting temperature and the degree of crystallinity of PCL/KW and PCL/HTKW composites were practically unchanged, compared to PCL. However, the crystallization process was more effective with the kaolin waste (KW) without heat treatment, indicating that the HTKW amorphous phase inhibited crystallization. The PCL/KW development promoted an increase in crystallization temperature, relative crystallinity, and crystallization rate, surpassing PCL and the PCL/HTKW system. In view of this, kaolin waste has the potential to accelerate the PCL crystallization process, contributing to add value to a material that would otherwise be discarded and minimizing environmental impacts.

Prótesis de mano controlada con señales EEG

En este trabajo, se describe cómo las ondas cerebrales producidas en el lóbulo lateral izquierdo del cerebro humano y detectadas con un auricular NeuroSky MindFlex fueron usadas para controlar voluntariamente una prótesis de mano. En primera instancia, las señales EEG (electroencefalográficas) son detectadas por una BCI (Interfaz de control cerebral) y tras ser analizado con la ayuda de un microcontrolador ARDUINO su espectro de frecuencias es dividido en rangos Alfa, Beta, Theta y Gamma. Como resultado del análisis EEG, se encuentra que el parpadeo voluntario afecta principalmente los valores de potencia relacionados con la banda alfa , tal que finalmente se utiliza esta banda de frecuencias para dirigir en forma voluntaria y controlada los movimientos de abducción y aducción de los dedos de la prótesis.

Effect of the magnetic field on the synthesis of colloidal silver and gold nanoparticles by laser ablation in bidestilated water

The effect of magnetic field of 0.3 T on the concentration, distribution of sizes in suspension and zeta potential of colloidal gold and colloidal silver nanoparticles, obtained by considering the pulsed laser ablation in double distilled water was studied. The magnetic field was transverse to the direction of incidence of the laser radiation and parallel to the surface of a submerged target. An Nd: YAG laser was used (1064 nm in wavelength, 10 ns in duration, repetition rate of 10 Hz and 37 mJ of energy) to ablate targets. The colloids were characterized by inductively coupled plasma optical emission spectroscopy, ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential. Concentration analysis suggested that applying magnetic field of 0.3 T during nanoparticle synthesis leads to higher concentration. Applying magnetic field led to an eleven percent increase in the concentration of the colloid with gold nanoparticles and a five percent increase in the concentration of the colloidal silver nanoparticles. The absorption spectra suggested the presence of spherical nanoparticles. When analyzing the effect of the magnetic field on the hydrodynamic size distribution of the nanoparticles and the zeta potential of the colloids, no significant changes were evidenced. The magnetic confinement of the plasma induced by laser ablation caused changes in the characteristics of the colloids.

Dosimetry of radiopharmaceuticals used in adult patients with suspected pulmonary embolism

The absorbed dose of radiopharmaceuticals is estimated in adults with suspected pulmonary embolism explored by ventilation/perfusion studies. For pulmonary ventilation studies 81mKr, 133Xe, 99mTc (Technegas)-aerosol and 99mTc (DTPA)-aerosol are used. For perfusion agents, 99mTc(MAA), 99mTc (MSA) (macroaggregates and albumin microspheres) are used. For the dose calculation, the MIRD methodology and the anthropomorphic representation of the biokinetic organs of Cristy-Eckerman are used. In ventilation/perfusion studies, the lowest dose absorbed by the lungs with suspected embolism is due to 81mKr/ 99mTc (MSA), and the highest dose is due to 99mTc (Technegas)/99mTc (MAA) calculated for activities of 150 MBq for perfusion agents and 40 MBq for ventilation agents.

Intrinsic noise reduction of a Gamma-ray Backscattering imaging device

In order to increase the contrast and to improve the imaging capabilities of a Gamma-ray Backscattering device some changes are proposed with the aim of achieving a reduction of the intrinsic noise of the device. Simulated results suggest that the shielding system proposed, in addition to the use of a 68 Ge -γ ray source, produce a considerable reduction of the intrinsic noise of the device.