Kinetic modeling of the adsorption and desorption of metallic ions present in effluents using the biosorbent obtained from Syagrus romanzoffiana.

In this study, the kinetic mechanism of adsorption and desorption, as well as the equilibrium isotherms, of four metallic ions (Cd2+, Cu2+, Ni2+, and Zn2+) mono and multicomponent were investigated. The biosorbent used was produced from Jerivá (Syagrus romanzoffiana-commonly known as queen palm) coconut. A kinetic model that considers macropore diffusion as a control step was solved. The finite volume method was used in the discretization of the equations, and the algorithm was implemented in the Fortran programming language. The equilibrium time for monocomponent adsorption was 5 min; for the multicomponent tests, equilibrium occurred instantly (less than 2 min of adsorption). The pseudo-second-order model presented the lowest mean of the sum of normalized errors (SNE) and represented the experimental data of mono and multicomponent adsorption and desorption. Single and multicomponent Langmuir model represented the adsorption isotherms. The maximum capacity of adsorption of metallic ions, both mono and multicomponent, was higher for copper, and the multicomponent adsorption proved to be antagonistic; the presence of co-ions in the solution reduced the removal of metals due to competition between these contaminants. The capture preference order was justified by the physicochemical properties of the ions, such as electron incompatibility and electronegativity. All these situations justified the maximum adsorption of Cu2+, followed by Zn2+, Cd2+, and Ni2+ in the mixture.

In silico numerical simulation of ventilator settings during high-frequency ventilation in preterm infants.

OBJECTIVE: Despite the routine use of antenatal steroids, exogenous surfactants, and different noninvasive ventilation methods, many extremely low gestational age neonates, preterm, and term infants eventually require invasive ventilation. In addition to prematurity, mechanical ventilation itself can induce ventilator-induced lung injury leading to lifelong pulmonary sequelae. Besides conventional mechanical ventilation, high-frequency oscillatory ventilation (HFOV) with tidal volumes below dead space and high ventilation frequencies is used either as a primary or rescue therapy in severe neonatal respiratory failure. METHODS AND RESULTS: Applying a high-resolution computational lung modeling technique in a preterm infant, we studied three different high-frequency ventilation settings as well as conventional ventilation (CV) settings. Evaluating the computed oxygen delivery (OD) and lung mechanics (LM) we outline for the first time how changing ventilator settings from CV to HFOV lead to significant improvements in OD and LM. CONCLUSION: This personalized "digital twin" strategy advances our general knowledge of protective ventilation strategies in neonatal care and can support decisions on various modes of ventilatory therapy at high frequencies.

Uncertainties of a window mixing estimator for the noise power spectrum of digital signals.

The statistical characteristics of several estimators of the noise power spectrum are analysed in this work. Averaged periodogram, Kim's large subimage and small subimage methods [1] together with windowed periodogram methods using rectangular and Hamming windows and a new window mixing method are studied to obtain their biasing and standard deviation. Sample means and sample standard deviations of the NPS calculations following the different methods are obtained using synthetic images that simulate noise in digital radiography images. In addition, biasing and variance characteristics of the windowed periodograms and the window mixing methods are derived theoretically. Biasing, characteristic of estimators based in periodograms, is eliminated by modifying the periodogram in such a way that it is obtained as the discrete Fourier transform of the unbiased sampled covariance of the signal. Simulations show that Kim's methods considerably improve the precision of the averaged periodogram, obtaining an important reduction in the sampled standard deviation. Also, the window mixing method, using a convex combination of windowed periodograms with rectangular and Hamming windows, improves the Kim's methods in terms of standard deviation and has similar biasing. Finally, it is shown that NPS estimators based in the windowed periodogram and in the window mixing methods are unbiased and mean-square consistent, provided that the support of the autocorrelation function of the system PSF is finite.

His-GAN: A histogram-based GAN model to improve data generation quality.

Generative Adversarial Network (GAN) has become an active research field due to its capability to generate quality simulation data. However, two consistent distributions (generated data distribution and original data distribution) produced by GAN cannot guarantee that generated data are always close to real data. Traditionally GAN is mainly applied to images, and it becomes more challenging for numeric datasets. In this paper, we propose a histogram-based GAN model (His-GAN). The purpose of our proposed model is to help GAN produce generated data with high quality. Specifically, we map generated data and original data into a histogram, then we count probability percentile on each bin and calculate dissimilarity with traditional f-divergence measures (e.g., Hellinger distance, Jensen-Shannon divergence) and Histogram Intersection Kernel. After that, we incorporate this dissimilarity score into training of the GAN model to update the generator's parameters to improve generated data quality. This is because the parameters have an influence on the generated data quality. Moreover, we revised GAN training process by feeding GAN model with one group of samples (these samples can come from one class or one cluster that hold similar characteristics) each time, so the final generated data could contain the characteristics from a single group to overcome the challenge of figuring out complex characteristics from mixed groups/clusters of data. In this way, we can generate data that is more indistinguishable from original data. We conduct extensive experiments to validate our idea with MNIST, CIFAR-10, and a real-world numeric dataset, and the results clearly show the effectiveness of our approach.

Mechanical analysis of an MgB2 1.5 T MRI main magnet protected using Coupling Loss Induced Quench.

Mechanical analysis of the stress and strains developed in the coils were calculated for a ten coil 1.5 T MRI magnet design with magnesium diboride (MgB2) wire protected with Coupling Loss Induced Quench (CLIQ). The temperature distribution inside the coils was first simulated in MATLAB to solve the governing heat and circuit equations. Simulations were performed on the magnet, in which each coil was divided into two subsections, with two CLIQ units while the capacitor ranged from 5 to 20 mF and the initial charging voltage ranged from 2.6 kV to 1.3 kV in order to keep the total stored energy in the CLIQ system constant. The wire's filamentary twist pitch remained constant at 5 cm for all simulations. The exported temperature distribution was expanded to form a representative unit cell (RUC) representing the wire composite and then imported into ANSYS to calculate the 1st principle strain in the MgB2 filament and shear stress across the epoxy for the coils. A peak temperature of 191 K occurred inside the coil with the initial quench when the CLIQ unit had a 20 mF capacitor charged to 1.3 kV. According to the mechanical simulations, the largest resulting peak strain in the wire was 0.034%, and peak shear stress was 44 MPa.

[Biomechanical analysis through numerical simulation of rupture of the tibial posterior tendon in valgus flat foot: a cadeveric study]. / Análisis biomecánico a través de simulación numérica de la ruptura del tendón del tibial posterior en el pie plano valgo: estudio en cadáver.

The insufficiency of the posterior tibial tendon is the most common acquired cause of pain related to valgus flatfoot deformity in adults. The acquired flatfoot adult is a very painful symptomatic deformity resulting from a gradual stretching (attenuation) of the posterior tibial tendon and ligaments that support the arch of the foot. The progressive pain acquired flatfoot adult affects four times more women than men. Some factors that contribute to increased risk of acquired flatfoot in adults, are diabetes, hypertension and obesity. It is thought that the combination of the following events is the cause of acquired flatfoot adult. Johnson Strom classification modified by Mayerson evaluates in 4 stages. This study was divided into 3 stages: Stage 1: Dissection and three-dimensional analysis of the tendon, Step 2: Application of tools bioengineering to determine the causes of rupture of the tibial tendon: Stage 3: Evaluation of 24 patients with flatfoot disease valgus for describe the deformity.

La insuficiencia del tendón del tibial posterior es la causa adquirida de dolor más común relacionada con la deformidad de pie plano valgo en adultos. El pie plano adquirido por el adulto es una deformidad sintomática muy dolorosa que resulta de un estiramiento gradual (atenuación) del tendón del tibial posterior, así como de los ligamentos que sostienen el arco de la planta del pie. El dolor progresivo en el pie plano adquirido por el adulto afecta cuatro veces más a las mujeres que a los hombres. Algunos factores que contribuyen a incrementar el riesgo del pie plano adquirido en el adulto son la diabetes, la hipertensión y la obesidad. Se piensa que la combinación de los eventos siguientes es la causa del pie plano adquirido por el adulto. La clasificación de Johnson Strom modificada por Mayerson lo evalúa en cuatro estadios. Este estudio se dividió en tres etapas: etapa 1: disección y análisis tridimensional del tendón, etapa 2: aplicación de herramientas de bioingeniería para determinar las causas de ruptura del tendón del tibial posterior y etapa 3: evaluación de 24 pacientes con enfermedad de pie plano valgo para describir la deformidad.

Análisis biomecánico a través de simulación numérica de la ruptura del tendón del tibial posterior en el pie plano valgo: estudio en cadáver / Biomechanical analysis through numerical simulation of rupture of the tibial posterior tendon in valgus flat foot: a cadeveric study

Resumen: La insuficiencia del tendón del tibial posterior es la causa adquirida de dolor más común relacionada con la deformidad de pie plano valgo en adultos. El pie plano adquirido por el adulto es una deformidad sintomática muy dolorosa que resulta de un estiramiento gradual (atenuación) del tendón del tibial posterior, así como de los ligamentos que sostienen el arco de la planta del pie. El dolor progresivo en el pie plano adquirido por el adulto afecta cuatro veces más a las mujeres que a los hombres. Algunos factores que contribuyen a incrementar el riesgo del pie plano adquirido en el adulto son la diabetes, la hipertensión y la obesidad. Se piensa que la combinación de los eventos siguientes es la causa del pie plano adquirido por el adulto. La clasificación de Johnson Strom modificada por Mayerson lo evalúa en cuatro estadios. Este estudio se dividió en tres etapas: etapa 1: disección y análisis tridimensional del tendón, etapa 2: aplicación de herramientas de bioingeniería para determinar las causas de ruptura del tendón del tibial posterior y etapa 3: evaluación de 24 pacientes con enfermedad de pie plano valgo para describir la deformidad.

Abstract: The insufficiency of the posterior tibial tendon is the most common acquired cause of pain related to valgus flatfoot deformity in adults. The acquired flatfoot adult is a very painful symptomatic deformity resulting from a gradual stretching (attenuation) of the posterior tibial tendon and ligaments that support the arch of the foot. The progressive pain acquired flatfoot adult affects four times more women than men. Some factors that contribute to increased risk of acquired flatfoot in adults, are diabetes, hypertension and obesity. It is thought that the combination of the following events is the cause of acquired flatfoot adult. Johnson Strom classification modified by Mayerson evaluates in 4 stages. This study was divided into 3 stages: Stage 1: Dissection and three-dimensional analysis of the tendon, Step 2: Application of tools bioengineering to determine the causes of rupture of the tibial tendon: Stage 3: Evaluation of 24 patients with flatfoot disease valgus for describe the deformity.

Análise teórico-experimental da dispersão de poluentes líquidos em solos / Theoretical-experimental analysis of liquid pollutant dispersion in soils

Acidentes envolvendo o contato de substâncias químicas tóxicas com o meio ambiente são muito freqüentes. Exemplos são derramamentos acidentais de combustíveis e solventes industriais. Seria interessante predizer a distribuição da substância no solo em função do tempo de contato. Isso possibilitaria prever a extensão do impacto ambiental causado por algum acidente e auxiliar na aplicação de técnicas de remediação. Sendo assim, desenvolveu-se um código computacional para simular a dispersão de poluentes líquidos em solos, a partir de um modelo matemático baseado nos princípios de conservação de massa e transporte de poluentes em meios porosos. Resultados obtidos em simulações foram comparados com experimentos realizados em pequena escala, apresentando uma boa concordância.

Accidents which result in the contact of hazardous chemical substances with the environment are frequent. Typical examples are solvents accidental spills and inadequate waste disposal. Therefore, it would be interesting to predict the distribution of the substance throughout the soil as a function of contact time, in order to foresee the environmental impact and help in the application of remediation techniques. It has been developed a computational code to simulate the dispersion of pollutants in soils, by solving a mathematical model based on the mass conservation and on the transport rate of pollutants in porous media. Numerical results were compared with experimental data, showing a good agreement.