Adaptación de un protocolo para la evaluación neuropsicológica de la relación entre imagenes internas y leguaje verbal en población persa

"La neuropsicología es una ciencia nueva que aborda la relación que existe entre el cerebro y la actividad consciente del ser humano. Para evaluar las actividades que realiza el cerebro siempre se necesita un instrumento, con el cual se podría saber si las partes distintas de este sistema son funcionales o no. El presente estudio revisa los pasos para lograr una adaptación de un protocolo para evaluar neuropsicológicamente a niños Persa de la República Islámica de Irán. El proceso para obtener un protocolo concreto con validez y confiablidad considera los aspectos culturales (religiosos), lingüísticos y de representación interna del mundo. Los datos estadísticos obtenidos permitieron identificar que las puntuaciones de cada niño, así como su promedio fueron relativamente diferentes. En la mayoría de las tareas y factores, el promedio aunque era diferente no era significativamente distante. Se concluye que el protocolo que se utilizó para evaluar a niños normo típicos de la República Islámica de Irán puede ser bastante sólido y representativo para ser empleado"

A novel stiffness scaling methodology for discrete element modelling of cohesive fine powders

The application of discrete element modelling (DEM) to cohesive fine powders in industrial processes, such as additive manufacturing, requires accurate and efficient calculations of van der Waals interaction forces. In DEM community, it is a general practice to reduce particle stiffness to accelerate the simulations; however, this study shows that, for cohesive particles, there are many cases where previously proposed scaling methodologies fail to preserve the original particle behaviour. The reason was attributed to underestimated sliding and rolling resistances and a poorly resolved non-contact cohesive interaction, thus limiting the applicability of these scaling approaches for contact-dominated systems. To address these significant issues, a new stiffness scaling methodology is proposed for the modelling of cohesive fine powders, which includes an established scaling law for contact adhesion, modified sliding and rolling resistances, and a new force-estimation scheme for the calculation of non-contact van der Waals interaction. The new approach was verified with a series of simple cases; stiffness independent results were demonstrated for head-on particle–particle collisions, particle–wall collisions, and particle-agglomerate collisions. The predictions of stop distance of a particle sliding and/or rolling over a flat surface was preserved when the stiffness was scaled down almost four orders of magnitude, which was not possible with previous scaling approaches. The new approach was further validated by packing of cohesive fine particles. This work confirmed that not only was the packing density insensitive to the particle stiffness, but the details of the packing structure (coordination number and packing density distribution) were also maintained when the original particle stiffness was scaled down by three orders of magnitude. Finally, the applicability of the new approach was explored by simulations of homogeneous simple shearing, which was found to be controlled by system cohesiveness and inertial number

Numerical Analysis of the Effect of Particle Shape and Adhesion on the Segregation of Powder Mixtures

Segregation of granules is an undesired phenomenon in which particles in a mixture separate from each other based on the differences in their physical and chemical properties. It is, therefore, crucial to control the homogeneity of the system by applying appropriate techniques. This requires a fundamental understanding of the underlying mechanisms. In this study, the effect of particle shape and cohesion has been analysed. As a model system prone to segregation, a ternary mixture of particles representing the common ingredients of home washing powders, namely, spray dried detergent powders, tetraacetylethylenediamine, and enzyme placebo (as the minor ingredient) during heap formation is modelled numerically by the Discrete Element Method (DEM) with an aim to investigate the effect of cohesion/adhesion of the minor components on segregation quality. Non-spherical particle shapes are created in DEM using the clumped-sphere method based on their X-ray tomograms. Experimentally, inter particle adhesion is generated by coating the minor ingredient (enzyme placebo) with Polyethylene Glycol 400 (PEG 400). The JKR theory is used to model the cohesion/adhesion of coated enzyme placebo particles in the simulation. Tests are carried out experimentally and simulated numerically by mixing the placebo particles (uncoated and coated) with the other ingredients and pouring them in a test box. The simulation and experimental results are compared qualitatively and quantitatively. It is found that coating the minor ingredient in the mixture reduces segregation significantly while the change in flowability of the system is negligible

Human unrestricted somatic stem cells ameliorate sepsis-related acute lung injury in mice

Background Aims: Sepsis and related disorders, especially acute lung injury (ALI), are the most challenging life-threatening diseases in the hospital intensive care unit. Complex pathophysiology, unbalanced immune condition, and high rate of mortality complicate the treatment of sepsis. Recently, cell therapy has been introduced as a promising option to recover the sepsis symptoms. The aim of this study was to investigate the therapeutic potential of human unrestricted somatic stem cells (USSCs) isolated from human umbilical cord blood in the mouse model of ALI. USSCs significantly enhanced the survival rate of mice suffering from ALI and suppressed concentrations of proinflammatory mediators TNF-α, and interleukin (IL)-6, and the level of anti-inflammatory cytokine IL-10. ALI mice injected by USSCs showed notable reduction in lung and liver injury, pulmonary edema, and hepatic enzymes, compared with the control group. These results determined the in vivo immunomodulatory effect of USSCs for recovery of immune balance and reduction of tissue injury in the mouse model of ALI. Therefore, USSCs can be a suitable therapeutic approach to manage sepsis disease through the anti-inflammatory potentia

Numerical Simulation of Segregation of Formulated Powder Mixtures

Granular segregation is a common and costly challenge among industries dealing with particulate materials. Controlling segregation requires a deep understanding of its underlying mechanisms. Gaining this understanding, experimentally, is challenging especially for polydisperse systems, where at least one of the main ingredients is in low-level content and highly prone to segregation. In this regard validated numerical simulations could overcome the limitations of the experimental techniques in analysing the segregation and its root causes. A relevant example is the segregation of enzyme granules with low-level content (less than 2% by weight) in laundry detergent powders which has cost and health issues for the production as well as consumers. This study focuses on predicting, analysing, and controlling the segregation tendency of minor active ingredients in polydisperse formulated powder mixtures, using high-fidelity numerical simulations. An extensive literature review is carried out on the capabilities and shortcomings of the available numerical methods; where the Discrete Element Method (DEM) is found to be the most suitable tool for mimicking the segregation phenomenon in this research project. The segregation of the main ingredients of the conventional home washing powders (i.e. Blown powder (BP), tetraacetylethylenediamine (TAED), and enzyme granules) during the heap formation and vibration processes is investigated using DEM modelling. The particles properties including size, density, shape, and surface properties are measured experimentally, where possible, and the values are calibrated for the DEM simulations. The results are validated against experiments, where the Enzyme Placebo granules (EP) are used instead of the real enzyme for the health and safety reasons. As a part of this study, the significance of using particle shape in simulations instead of employing spheres with calibrated rolling friction is investigated. To simulate shape in DEM, particles are scanned using X-Ray Tomography technique (XRT) and their shapes are approximated by the clumped-sphere method. The results reveal that considering the particle shape in simulations is a necessity, as the clumped-sphere approach reliably predicts the segregation during the heap formation; whereas, the rolling friction approach underestimates the particles segregation tendency. In the second part of this study, a special attention is paid to minimising the segregation of the minor ingredient, i.e. EP granules, which constitutes less than 2% of the weight of the mixture and is highly prone to segregation. This is investigated through 1) making the EP granules cohesive by tackifying agents as well as 2) manipulating their shapes. For the DEM simulation of the multi-component system with the cohesive EP granules, the interfacial energies of the components are inferred by matching the experimental and simulated repose angles. In addition, a dimensionless Cohesion number is introduced, based on the ratio of the particles cohesion energy and gravitational potential energy, to scale the interfacial energy when reducing Young’s modulus or changing the particle size for minimising the computation time. As a result of implementing a careful calibration methodology, a good match between the numerical and experimental analyses of the segregation of minor ingredient is observed. The results show that before coating, the EP granules easily penetrate into the top moving layers of the powder mixture during the heap formation, and therefore, segregate to the central area of the heap. This occurs due to their high density and round shape (push-away effect), leaving the corners and side walls with a lower mass concentration. However, both approaches of coating EP granules and making their shapes irregular reduce their ability to penetrate the powder bed, and hence, they are well distributed over the entire heap. It is observed via DEM simulations that manipulating shapes of minor ingredients in a mixture is a possible alternative to the coating approach. Less compromise in flowability of powder mixture and less exposure to variation in surface properties through time are two main advantages of the shape manipulation. Nevertheless, manufacturing particles which have a designed shape is more complex and costly compared to the coating approach. It is concluded that securing a reliable and predictive DEM simulation of segregation of formulated powder mixtures is possible only if the DEM input parameters are 1) justifiably selected and 2) precisely calibrated

Utilisation du foin et de l'ensilage du colza pour l'engraissement des agneaux

International audienc

An investigation on process of seeded granulation in a continuous drum granulator using DEM

Numerical simulation of wet granulation in a continuous granulator is carried out using Discrete Element Method (DEM) to discover the possibility of formation of seeded granules in a continuous process with the aim of reducing number of experimental trials and means of process control. Simple and scooped drum granulators are utilized to attain homogenous seeded granules in which the effects of drum rotational speed, particles surface energy, and particles size ratio are investigated. To reduce the simulation time a scale-up scheme is designed in which a dimensionless number (Cohesion number) is defined based on the work of cohesion and gravitational potential energy of the particles. Also a mathematical/numerical method along with a MATLAB code is developed by which the percentage of surface coverage of each granule is predicted precisely. The results show that use of continuous granulator is promising provided that a high level of shear is considered in the granulator design, e.g. it is observed that using baffles inside the drum granulators is essential for producing seeded granules. It is observed, moreover, that the optimum surface energy for scooped granulator with rotational speed of 50 rpm is 3 J/m2 which is close to the number predicted by Cohesion number. It is also shown that increasing the seed/fine size ratio enhances the seeded granulation both quantitatively (60% increase in seeds surface coverage) and qualitatively (more homogeneous granules)

Assessment of blending performance of pharmaceutical powder mixtures in a continuous mixer using Discrete Element Method (DEM)

This study proposes a new sample-independent mixing index, termed the Coefficient of Blending Performance (CBP), for monitoring the formation of undesired API (Active Pharmaceutical Ingredient) agglomerates in continuous mixing processes. The proposed index is examined for the blending of pharmaceutical powders in a simulated twin-screw mixer using Discrete Element Method (DEM). Model excipient and API particles with physical and mechanical properties within the typical range of pharmaceutical powders are used in simulations. Results suggest that the CBP is an effective index for monitoring the formation of API agglomerates in the mixer. Using this index, DEM results suggest a high possibility of formation of API agglomerates during the first stage of twin screw mixing. The results show that adding a kneading zone to the twin screw mixer enhances the blending quality by breaking the API agglomerates, making the mixture ready for the next operating unit

Tailoring particle shape for enhancing the homogeneity of powder mixtures: Experimental study and DEM modelling

The effect of particle shape modification on the segregation reduction of enzyme granules in laundry detergent powder mixtures was investigated, both experimentally and computationally using Deseret Element Method (DEM). The shape of modified enzyme particles was in such a way that the large and dense enzyme particles were layered by other fine particles in the detergent powder, by means of a process known in the literature as “seeded granulation”. It is found that the homogeneity of modified enzyme particles could be improved significantly comparing to the original spherical enzyme particles in powder mixtures. Overall, the results of this research demonstrated that the segregation-induced properties of the dense/spherical enzyme particles could be lowered by altering their shape, which could enable the enzyme particles to behave almost similar to other ingredients during the pile formation process