Abstract Exposure to polychlorinated biphenyls (PCBs) during pregnancy and lactation leads to cognitive impairment and motor disorders in children by mechanisms which remain unknown. It also remains ...unclear whether different non-dioxin-like PCBs have similar or different mechanisms of neurotoxicity. The main aims of this work were: (1) to assess whether developmental exposure to non-dioxin-like-PCBs 52, 138 or 180 affect cognitive function or motor coordination in 3–4 months-old rats; (2) to shed light on the underlying mechanisms. Female rats were treated with PCBs (1 mg/kg day) in food from gestational-day 7 to postnatal-day 21. The ability to learn a Y maze conditional discrimination task was reduced in rats exposed to PCBs 138 or 180, but not in rats exposed to PCB52. The function of the glutamate–nitric oxide–cGMP pathway (NMDA-induced increase in extracellular cGMP) in cerebellum in vivo was reduced by 33–59% in rats exposed to PCBs 138 or 180, but not by PCB52. The amount of NR1 subunit of NMDA receptors was reduced by 41–49% in rats exposed to PCBs 138 or 180, but not by PCB 52. PCB52 but not 138 or 180 increases extracellular GABA in cerebellum and impairs motor coordination. The effects were similar in males and females. Developmental exposure to different non-dioxin-like PCBs induces different behavioural alterations by different mechanisms. PCB52 impairs motor coordination but not learning while PCB138 or 180 impair learning but not motor coordination. These data are consistent with the following possible mechanisms: (1) developmental exposure to PCBs 138 or 180 reduces the amount of NMDA receptors in cerebellum, which would contribute to reduced function of the glutamate–NO–cGMP pathway, which, in turn, would be a main contributor to the impairment of the ability to learn the Y maze task. (2) Developmental exposure to PCB52 increases extracellular GABA in cerebellum, which would contribute to motor coordination impairment.
This work describes a combined experimental-numerical study to characterize fine spray-dried powder used in the ceramic tile pressing process. A DEM-based granular assembly is endowed with a new set ...of scaling laws that allows for simulating reliably industrial processes using a much lower number of granules. To do it, a calibration strategy relying on three experimental setups is proposed; (i) compression test of bulk for granule stiffness, (ii) dynamic angle of repose and (iii) image analysis of the powder motion in a rotating drum for the intergranular and granular-boundary sliding and rolling friction coefficients. In order to evaluate the powder motion in a rotating drum, a robust method relying on a direct image analysis is proposed. This methodology makes it possible to quantitatively assess the frictional properties of the powder in contact with different surface materials.
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•A novel methodology to calibrate DEM simulations is proposed.•The methodology is focused on systems with low particle size (Φ < 1 mm).•Scaling laws required to reduce the number of particles to simulate are shown.•Spray-dried powder behaviour with several surfaces is investigated.
The lack of orthogonality in the ceramic tiles is a common problem associated with the mould filling process during its manufacturing process. Unfortunately, the existing mould filling equipment have ...not undergone significant changes over the years. This paper studies alternatives to the traditional powder filling systems used in the ceramic tile manufacture industry. The new proposals are analysed via virtual prototyping using a simulation framework based on the Discrete Element Method (DEM). These new systems aim at improving the product quality and process sustainability and efficiency demanded by the ceramic industrial sector. The demanded requirements involve: (i) assessment of average powder compactness in the mould, (ii) quantification of the powder heterogeneity in the mould as a function of the filling system, (iii) characterization of the filling dynamics and (iv) evaluation of the powder wasted during the filling process. Compared to the traditional systems, the new designs substantially simplify the mould filling by using a single or double hopper. The results obtained with a single hopper system generates the highest and the most homogeneous powder mould filling. A double hopper system, which yielded similar mould compactness, revealed less sustainable compared to other systems due to wasted powder mass to complete a filling cycle, reaching up to 25%. DEM-based virtual prototyping proves to be a powerful tool to develop new equipment giving insightful information and helping to substantially reduce the high costs of physical prototypes construction and instrumentation.
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•New feeding prototypes as an alternative to the traditional feeder grids are proposed.•Assessment of average powder compactness in the mould is performed.•Filling dynamics and powder wasted during the filling process is evaluated.•A simple feeder hopper generates the best powder distribution in the mould.•A double feeder hopper wastes up to 25% of the initial powder.
This is the third and final paper in a series presenting a DEM-based modelling framework for simulating the spray-dried powder rheology in ceramic tiles industry. Part I described the ...characterization of the spray-dried powder. Part II detailed the implementation of a new dedicated solver for simulating demanding scenarios. In this part, the validation procedure of the framework is presented through 2 validation series: a partial mould filling and a complete mould filling equivalent to industrial filling. A pilot-scale powder feeder was built expressly for this purpose. Powder dynamics was accurately reproduced in series 1, with a maximum relative error of 10%. Surface density in the mould was adequately reproduced in series 2 (maximum absolute error < 4 kg/m2). The formation of defects is accurately predicted. Some discrepancies in the surface density values are observed. The DEM-based modelling framework proves as a valid tool to design and optimize spray-dried powder handling equipment.
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•Two mould filling series are proposed to perform the validation.•A pilot-scale powder feeder is designed and constructed to validate the framework.•Powder dynamics during the mould filling is accurately reproduced (error < 10%).•Surface density of the powder bed is adequately reproduced (absolute error < 4 kg/m2).•Modelling framework developed is valid for use in ceramic tile manufacturing.
In the preceding Part I, a combined experimental-numerical study to characterize fine spray-dried powder used in the ceramic tile pressing process was presented. In the present Part II, the algorithm ...proposed by (Mazhar, 2011) to solve the numerical simulation of powder dynamics through the Discrete Element Method (DEM) was extended. In this paper, the original algorithm was adapted for efficient use on multi-core CPUs and a single GPU. In both cases, history-dependent contact models were considered. The efficiency of the algorithms was compared among them and with LIGGGHTS, a reference software package for particle simulation using DEM. The results demonstrated a higher performance of the codes developed compared to LIGGGHTS, particularly in demanding scenarios with a large number of particles (more than 1 million) of small size (median diameter in volume less than 1 mm). In particular, the CPU-based algorithm was suitable for simulating the mould filling in ceramic tiles industry.
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•A novel GPU and CPU-based DEM algorithm is developed.•Any general-purpose contact model can be used without restrictions in the contact searching.•The developed algorithms are fairly compared with LIGGGHTS.•Developed CPU-based DEM algorithm outperforms LIGGGHTS in demanding filling scenarios.•GPU-based DEM algorithm executed on a single GPU does not enhance the CPU-based algorithm.
ProtoDUNE-DP is a <inline-formula> <tex-math notation="LaTeX">6\times 6\times 6\,\,\text{m}^{3} </tex-math></inline-formula> liquid argon time-projection-chamber operated at the CERN Neutrino ...Platform in 2019-2020 as a prototype of the dual phase concept for the Deep Underground Neutrino Experiment (DUNE) far detector. The photon detection system (PDS) is based on 36 8-in photomultiplier tubes (PMTs) and allows triggering on the scintillation light signals produced by cosmic rays and other charged particles traversing the detector. The acquisition and calibration software specifically developed for the ProtoDUNE-DP PDS is described in this article. This software controls the high-voltage power supplies, the calibration system, and the PDS DAQ. It has been developed with Qt Creator and features different operation modes and a graphical user interface. This software has already been validated and used during the ProtoDUNE-DP operation.
An upgrade of the Near Detector of the T2K long baseline neutrino oscillation experiment, ND280, has been proposed. This upgrade will include two new Time Projection Chambers, each equipped with 16 ...resistive Micromegas modules for gas amplification. A first prototype of resistive Micromegas has been designed, built, installed in the HARP field cage, and exposed to a beam of charged particles at CERN. The data have been used to characterize the performances of the resistive Micromegas module. A spatial resolution of 300 μm and a deposited energy resolution of 9% were observed for horizontal electrons crossing the TPCs at 30 cm from the anode. Such performances fully satisfy the requirements for the upgrade of the ND280 TPC.
El objetivo del estudio fue realizar la clasificación sistemática de grupos afines y con base a semejanzas morfológicas de 19 razas de gallinas del grupo mediterráneo. Estas fueron 15 españolas ...(Alicantina, Andaluza Azul, Cara Blanca, Castellana Negra, Empordanesa, Flor d’Ametller, Mallorquina, Menorquina, Murciana, Pairal, Penedesenca, Prat, Sobrarbe, Utrerana y Valenciana de Chulilla) y cuatro italianas (Italiana, Livorno, Mericanel della Brianza y Paduana) a partir de 17 características morfológicas cualitativas. Se evaluaron con base al principio de parsimonia usando el método de Fitch. El filograma resultante, interpretado como un árbol de grupos concernientes a las relaciones morfológicas entre las razas estudiadas y no como un árbol filogenético, ya que no permite la agrupación de las razas en función de su origen o aptitud. Ello, junto con los índices obtenidos de sinapomorfia –caracteres homólogos compartidos– y homoplasia –cambios paralelos adquiridos independientemente–, más elevado en el primero, permite suponer que, aunque en el proceso de diversificación de la gallina se hayan podido dar fenómenos de convergencia de caracteres morfológicos, han sido mayores los fenómenos de conservación de caracteres morfológicos ya existentes. Es decir, que se han dado cambios en los modelos morfológicos en el proceso de formación de las razas, independientes de su origen y aptitud.
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