Oxidative potential of logwood and pellet burning particles assessed by a novel profluorescent nitroxide probe

This study reports the potential toxicological impact of particles produced during biomass combustion by an automatic pellet boiler and a traditional logwood stove under various combustion conditions using a novel profluorescent nitroxide probe BPEAnit. This probe is weakly fluorescent, but yields strong fluorescence emission upon radical trapping or redox activity. Samples were collected by bubbling aerosol through an impinger containing BPEAnit solution, followed by fluorescence measurement. The fluorescence of BPEAnit was measured for particles produced during various combustion phases, at the beginning of burning (cold start), stable combustion after refilling with the fuel (warm start) and poor burning conditions. For particles produced by the logwood stove under cold-start conditions significantly higher amounts of reactive species per unit of particulate mass were observed compared to emissions produced during a warm start. In addition, sampling of logwood burning emissions after passing through a thermodenuder at 250oC resulted in an 80-100% reduction of the fluorescence signal of BPEAnit probe, indicating that the majority of reactive species were semivolatile. Moreover, the amount of reactive species showed a strong correlation with the amount of particulate organic material. This indicates the importance of semivolatile organics in particle-related toxicity. Particle emissions from the pellet boiler, although of similar mass concentration, were not observed to lead to an increase in fluorescence signal during any of the combustion phases.

The interplay between chondrocyte redifferentiation pellet size and oxygen concentration

Chondrocytes dedifferentiate during ex vivo expansion on 2-dimensional surfaces. Aggregation of the expanded cells into 3-dimensional pellets, in the presence of induction factors, facilitates their redifferentiation and restoration of the chondrogenic phenotype. Typically 1×105–5×105 chondrocytes are aggregated, resulting in “macro” pellets having diameters ranging from 1–2 mm. These macropellets are commonly used to study redifferentiation, and recently macropellets of autologous chondrocytes have been implanted directly into articular cartilage defects to facilitate their repair. However, diffusion of metabolites over the 1–2 mm pellet length-scales is inefficient, resulting in radial tissue heterogeneity. Herein we demonstrate that the aggregation of 2×105 human chondrocytes into micropellets of 166 cells each, rather than into larger single macropellets, enhances chondrogenic redifferentiation. In this study, we describe the development of a cost effective fabrication strategy to manufacture a microwell surface for the large-scale production of micropellets. The thousands of micropellets were manufactured using the microwell platform, which is an array of 360×360 µm microwells cast into polydimethylsiloxane (PDMS), that has been surface modified with an electrostatic multilayer of hyaluronic acid and chitosan to enhance micropellet formation. Such surface modification was essential to prevent chondrocyte spreading on the PDMS. Sulfated glycosaminoglycan (sGAG) production and collagen II gene expression in chondrocyte micropellets increased significantly relative to macropellet controls, and redifferentiation was enhanced in both macro and micropellets with the provision of a hypoxic atmosphere (2% O2). Once micropellet formation had been optimized, we demonstrated that micropellets could be assembled into larger cartilage tissues. Our results indicate that micropellet amalgamation efficiency is inversely related to the time cultured as discreet microtissues. In summary, we describe a micropellet production platform that represents an efficient tool for studying chondrocyte redifferentiation and demonstrate that the micropellets could be assembled into larger tissues, potentially useful in cartilage defect repair.

Production of cast aluminium-graphite particle composites using a pellet method

Copper- and nickel-coated graphite particles can be successfully introduced into aluminium-base alloy melts as pellets to produce cast aluminium-graphite particle composites. The pellets were made by pressing mixtures of nickel- or copper-coated graphite particles and aluminium powders together at pressures varying between 2 and 20 kg mm–2. These pellets were dispersed in aluminium alloy melts by plunging and holding them in the melts using a refractory coated mild steel cone, until the pellets disintegrated and the powders were dispersed. The optimum pressure for the preparation of pellets was 2 to 5 kg mm–2 and the optimum size and percentage of aluminium powder were 400 to 1000mgrm and 35 wt% respectively. Under optimum conditions the recovery of the graphite particles in the castings was as high as 96%, these particles being pushed into the last freezing interdendritic regions. The tensile strength and the hardness of the graphite aluminium alloys made using the pellet method are comparable to those of similar composites made using gas injection or the vortex method. The pellet method however has the advantage of greater reproducibility and flexibility. Dispersion of graphite particles in the matrix of cast aluminium alloys using the pellet method increases their resistance to wear.

Behavior of Ca(OH)2/CaO pellet under dehydration and hydration

With construction of a thermochemical energy conversion prototype system to store solar heat, thermal dissociation of pellets of Ca(OH)2 and hydration of CaO have been investigated in some detail for its application to the system. The inorganic substance is very attractive as a material for long term heat storage, but molar density changes associated with the reaction are fairly large. Therefore, this factor has been taken into account in the kinetic equation. The importance of additives and pellet size has been discussed considering reactivity and strength of pellets. An analysis has been attempted when chemical reaction is important. The deformation of pellets was observed during hydration.

Evaluación del efecto del Zeranol implante Ralgro (pellet) vs. Zeranol tixotrópico (en solución) como promotores de crecimiento en novillos de finalización del Centro Integral de Investigación, Innovación, Producción, Extensión y Enseñanza Agropecuaria, Las Lomas durante el período de Abril a Julio 2014

El presente estudio se realizó con el objetivo de generar información útil sobre las diferencias obtenidas en las ganancias de peso como en utilidades generadas por los tratamientos. Utilizando anabólicos con el mismo principio activo (zeranol), pero con distintas presentación comercial como lo es el zeranol Implante Ralgro: pellets y el zeranol Tixotropico: en solución. El estudio fue experimental, utilizando 2 tratamientos y un grupo control. De manera que el tratamiento 1: Zeranol Implante Ralgro y el tratamiento 2: Zeranol Tixotropi co, al seleccionar los novillos se realizo de un grupo de 250 animales, de los cuales se seleccionaron 27 novillos con pesos similares de aproximadamente 350 kg, características raciales de cruces como brahmán con pardo y brahmán con holstien. El diseño que se utilizó fue completamente aleatorio, para separar los novillos en los grupos experimentales se dividieron 9 novillos por cada grupo, estos en 3 unidades experimentales de 3 animales cada una, luego de ser seleccionados y divididos en sus grupos se les aplico los debido tratamientos a evaluar, a partir de ese momento se inició a realizar pesajes cada 15 días hasta cumplir los 90 días que es el periodo de retiro de los tratamientos; obteniendo así una GMD con el tratamiento 1: zeranol implante 0.76 kg /día/animal, con el tratamiento 2: zeranol Tixotropico 0.71 kg/día/animal y con el grupo control: 0.67 kg/día/a nimal. En la relación beneficio/ costo, se obtuvo con el tratamiento1: zeranol implante 1.27 tratamiento 2: zeranol tixotrópico 1.26 y grupo control: 1.25 teniendo mejores utilidades el tratamiento1. Zeranol implante que por cada córdoba invertido obtuvo 0.27 córdobas de ganancia (utilidades).

Ablation of hydrogen isotopic spherical pellet due to the impact of energetic ions of the respective isotopes

The ablation rate of a hydrogen isotopic spherical pellet G(is) due to the impact of energetic ions of the respective isotopes and its scaling law are obtained using the transsonic neutral-shielding model, where subscript s might refer to either hydrogen or deuterium. Numerical results show that if E0s/E0e2 greater-than-or-equal-to 1.5, G(is)/G(es) greater-than-or-equal-to 20%, where E0s and E0e are the energy of undisturbed ion and electron, respectively, and G(es) is the ablation rate of a pellet due to the impact of electrons. Hence, under the NBI heating, the effect of the impact of energetic ions on the pellet ablation should be taken into consideration. This result also gives an explanation of the observed enhancement of pellet ablation during NBIH.

Optimization of 2-stage gas gun for fusion refueling pellet injection with consideration of real effects

Analytic expression of pellet acceleration by constant base pressure with consideration of gas-wall friction, heat transfer and viscous dissipation that important for high speed injection is obtained. The process of compression stage is formulated by a set of governing equations and can be numerically integrated. Excellent confirmation with experiments is obtained and the ways to optimum match the compression stage with the launch stage are suggested.

Speed of the internal pellet target in CSRm

Pellet target is one of the main candidate targets in CSRm (cooler storage ring’s main ring) for hadron physics studies. Pellet speed is an important physical parameter for the target. Larger pellet speed could shorten the interacting time interval between the pellet and the cyclotron beam, and thus results in a small temperature variation for the pellet. This could make the pellet facility work in a stable condition. A fluid dynamic simulation was carried out for the pellet speed, and it was found that the maximum speed for the target pellet may be restricted to about 100 m/s even if all working parameters were set to their optimal values.

Speed of the internal pellet target in CSRm

Pellet target is one of the main candidate targets in CSRm (cooler storage ring’s main ring) for hadron physics studies. Pellet speed is an important physical parameter for the target. Larger pellet speed could shorten the interacting time interval between the pellet and the cyclotron beam, and thus results in a small temperature variation for the pellet. This could make the pellet facility work in a stable con-dition. A fluid dynamic simulation was carried out for the pellet speed, and it was found that the maxi-mum speed for the target pellet may be restricted to about 100 m/s even if all working parameters were set to their optimal values.

Optimizing the operation of straight-grate iron-ore pellet induration systems using process models

Mathematical models of straight-grate pellet induration processes have been developed and carefully validated by a number of workers over the past two decades. However, the subsequent exploitation of these models in process optimization is less clear, but obviously requires a sound understanding of how the key factors control the operation. In this article, we show how a thermokinetic model of pellet induration, validated against operating data from one of the Iron Ore Company of Canada (IOCC) lines in Canada, can be exploited in process optimization from the perspective of fuel efficiency, production rate, and product quality. Most existing processes are restricted in the options available for process optimization. Here, we review the role of each of the drying (D), preheating (PH), firing (F), after-firing (AF), and cooling (C) phases of the induration process. We then use the induration process model to evaluate whether the first drying zone is best to use on the up- or down-draft gas-flow stream, and we optimize the on-gas temperature profile in the hood of the PH, F, and AF zones, to reduce the burner fuel by at least 10 pct over the long term. Finally, we consider how efficient and flexible the process could be if some of the structural constraints were removed (i.e., addressed at the design stage). The analysis suggests it should be possible to reduce the burner fuel lead by 35 pct, easily increase production by 5+ pct, and improve pellet quality.