Comparison of organic packing materials for toluene biofiltration

he paper focuses on the operation of a pilot plant with four biofilters operated in parallel for determining the suitability of coconut fiber, peat, compost from the digested sludge of a wastewater treatment plant and pine leaves as packing materials for biofiltration of toluene. Physical characteristics of packing materials such as specific surface area, density, pore size and elemental composition were determined for each packing material. Biological activity and packing capabilities related to toluene removal were determined during the startup and operation of the four biofilters under different conditions of nutrients, watering and inlet air relative humidity supply. Nutrient addition was key in improving removal efficiency (RE) and elimination capacity (EC) of biofilters. Feeding of medium with nutrients increased the RE and the EC by a factor of 2 to 4 than these found when supplying only tap water. Additionally, when extra nitrogen was supplied in the medium, RE and EC increased by a factor of 2. Nutrient addition also lead to a microbial population change from bacterial to fungal biofilters. It was denoted that watering control is necessary to improve fungal biofilters performance in terms of ensuring a proper washout of acidic by-products to avoid fungi inhibition and consequent lowered removal capacities.Peer ReviewedPostprint (published version

An Application of Cooperative Game Theory to Distributed Control

18th World CongressThe International Federation of Automatic ControlMilano (Italy) August 28 - September 2, 2011In this paper we propose to study the underlying properties of a given distributed control scheme in which a set of agents switch between different communication strategies that define which network links are used in order to regulate to the origin a set of unconstrained linear systems. The problems of how to decide the time-varying communication strategy, share the benefits/costs and detect which are the most critical links in the network are solved using tools from game theory. The proposed scheme is demonstrated through a simulation example

Magnification in apical surgerymusing the endoscope: a review

Objective: A review is made to determine whether the use of the endoscope in endodontic surgery offers advantages in clinical practice, and whether it improves the clinical and radiographic outcomes of the procedure. Material and methods: The main search terms used were: endodontic surgery, apicoectomy, apical surgery, endoscope, and magnification devices . The authors searched the Medline database for articles published up to 1 September 2010. The review included experimental studies comparing endoscopic microstructural findings with the findings of the naked eye or other magnification devices, as well as prospective clinical trials comparing endodontic surgery with or without the use of an endoscope, or comparing the endoscope with some other magnification device. Results: Two experimental studies on the capability of the endoscope to identify microstructures and three prospective clinical trials were included in the review. The experimental studies showed the endoscope to be highly precise in application to intraoperative diagnoses in periapical surgery. There were no significant differences in the prognosis of periapical surgery when performed with or without endoscopy. Likewise, there were no significant differences among the use of endoscopy, magnifying lenses or the microscope. Conclusion: Experimental studies have demonstrated the usefulness of the endoscope in identifying microstructures during periapical surgery. However, further randomized and controlled clinical trials are needed to determine whether these advantages in clinical practice imply improved outcomes for periapical surgery

Caracterización experimental en banda estrecha del canal vehicular V2V

[ES] La estimación de la cobertura en interiores a partir de medidas de drive test, presenta una nueva forma de calcular las pérdidas de propagación, esta propuesta basada en el desarrollo de un modelo de propagación outdoor to indoor (o2i) en frecuencias alrededor de 1800 MHz permite al operador mejorar la cobertura de su red en interiores con el fin de brindar un mejor servicio a sus clientes. Para comprobar la fiabilidad del modelo de propagacion o2i se realizo una comparacion entre las pérdidas ajustadas y las perdidas medidas con drive test; el modelo de propagacion o2i propuesto permite predecir las perdidas en el interior a partir de la potencia transmitida desde el exterior considerando los parámetros de diseño de los edificios.[EN] The estimation of indoor coverage from drive test measures presents a new way of calculating the propagation losses, this proposal based on the development of an outdoor to indoor (o2i) propagation model for the frequency band around 1800 MHz allows the operator to improve the indoor network coverage in order to provide better service to their subscribers. To demonstrate the reliability of o2i propagation model was made a comparison between the results (adjusted losses) and the losses measured through drive test measurements; the o2i propagation model developed in this work can predict indoor losses from the outdoor power transmitted considering the design parameters of buildings.Balaguer Maestre, D. (2012). Caracterización experimental en banda estrecha del canal vehicular V2V. http://hdl.handle.net/10251/27453.Archivo delegad

Cathodoluminescence of defects in sintered tin oxide

Cathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the luminescence mechanisms in tin oxide. Sintered material prepared from high purity powder has been found to show a strong dependence of the CL emission on the thermal treatments applied during sample preparation. SEM images show the presence of nano and microcrystalline grains. The correlation of the grain size and morphology with the optical emission is analyzed by CL microscopy and spectroscopy. The main emission bands appear centered at about 2.58, 2.25, and 1.94 eV depending on the sintering treatment. CL images reveal that the 2.25 and the 2.58 eV bands are associated at specific crystal faces. The evolution of the luminescence bands with mechanical milling shows a complex evolution of the 1.94 and 2.58 eV emissions which is explained by formation and recovery of defects during milling

Study of NH3 removal by gas-phase biofiltration: effects of shock loads and watering rate on biofilter performance

[Abstract] Ammonia biofiltration performance under shock loads episodes was studied in a reactor packed with coconut fiber as carrier material. Periodical gas and leachate samplings were analyzed and used to characterize the biofilter performance in terms of removal efficiency (RE) and elimination capacity (EC). Nitrogen fractions in the leachate were quantified to identify the experimental rates of nitritation and nitratation.. In a primary experiment a sudden increment of ammonia load was applied for 1 day by changing the ammonia inlet load from 5.2 to 29.1 g N.m-3.h-1. Even though stable operation was obtained (RE of 99.9%), a notable accumulation of nitrite was verified in the leachate. Experimental rates showed that nitritation increased at the same the same ratio that ammonia load was varied. However the nitratation seemed to be largely affected by high ammonia and nitrite concentration. In a subsequent experiment varying the inlet ammonia load, the system was rapidly recovered by increasing the watering rate. Since ammonia was partially removed by physicochemical process as observed in previous experiments, a final experimental was conducted to improve the nitritation capacity. The addition of inorganic carbon source demonstrated to enhance the capacity of the biofilter to degrade a higher amount of ammonia

Cathodoluminescence and REBIC study of defects in tin oxide

Cathodoluminescence (CL) and remote electron beam induced current (REBIC) in the scanning electron microscope (SEM) has been used to investigate the electron recombination mechanisms in tin oxide. Sintered material prepared from high purity powder has been found to show a strong dependence of the CL emission on the thermal treatments applied during sample preparation. SEM images show the presence of nano and microcrystalline grains. The correlation of the grain size and morphology with the optical emission is analysed by CL microscopy and spectroscopy. The evolution of the luminescence bands with mechanical milling shows a complex evolution of the 1.94 eV and 2.58 eV emissions which is explained by formation and recovery of defects during milling. REBIC measurements and imaging are used to characterize the formation of a potential barrier at the grain boundaries

Virtual articulator for the analysis of dental occlusion : an update

The future of dental practice is closely linked to the utilization of computer-based technology, specifically virtual reality, which allows the dental surgeon to simulate true life situations in patients. The virtual articulator has been designed for the exhaustive analysis of static and dynamic occlusion, with the purpose of substituting mechanical articulators and avoiding their errors. These tools will help both odontologists and dental prosthetists to provide the best individualized treatment for each patient. The present review analyzes the studies published in the literature on the design, functioning and applications of virtual articulators. A Medline-PubMed search was made of dental journals, with the identification of 137 articles, of which 16 were finally selected. The virtual articulator can simulate the specific masticatory movement of the patient. During mandibular animation, the program calculates the sites where the opposing teeth come into contact. The studies made to assess the reliability of the virtual articulator show good correspondence in visualization of the number and position of the dynamic contacts. The virtual articulator is a precise tool for the full analysis of occlusion in a real patient. © Medicina Oral S. L