Effects of cavitation in common-rail diesel nozzles on the mixing process

[EN] A study to experimentally analyze the effect of cavitation on the mixing process in diesel nozzles was carried out. The mixing process was studied through the spray cone angle. It was characterized in two different scenarios: with the liquid length (nearly realistic conditions, that is, evaporative but non-reactive spray) and the heat release fraction (fully realistic conditions, that is, evaporative and reactive spray). In both studied scenarios, the increase in spray cone angle caused by the cavitation phenomenon, which leads to a better mixing process, has been confirmed. Nevertheless, when the variations of the effective injection velocity and the spray cone angle obtained by comparing a cylindrical nozzle (i.e. a nozzle that promotes the cavitation phenomenon) with a conical nozzle (i.e. a nozzle that inhibits this phenomenon) were analyzed together, it was found that, for the cases studied here, the mixing process worsens with the cylindrical nozzle.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors thank the FPU program of the Spanish Ministry of Education for supporting the PhD studies of Oscar A de la Garza (grant: AP2008-01913) and also thank the PSA Peugeot-Citroen, National Council of Science and Technology (CONACYT) of the Mexican Government (project: CB-239943) and the Royal Academy of Engineering, United Kingdom (project: NRCP/1415/238) for supporting this research.López, JJ.; De La Garza De Leon, O.; De La Morena, J.; Martínez Martínez, S. (2017). Effects of cavitation in common-rail diesel nozzles on the mixing process. International Journal of Engine Research. 18(10):1017-1034. https://doi.org/10.1177/1468087417697759S10171034181

La responsabilidad de los Prácticos del Canal de Panamá a partir del año 2000

El fin de este estudio es determinar cuál sería el mejor sistema de practicaje en el Canal de Panamá y en los puertos de Balboa y Cristóbal, a partir del año 2000. Hay dos sistemas de practicaje que se diferencian por el rol de sus dos figuras principales: el capitán del buque y el práctico. En el sistema de practicaje internacional, el capitán tiene la responsabilidad de la navegación de su buque, pero en el sistema de practicaje actual del Canal de Panamá, la tiene el práctico. Es importante anotar que quien lleva la responsabilidad de la navegación del buque también la tiene en caso de que ocurra un accidente. Para solucionar el dilema, el investigador entrevistó a los 33 expertos marítimos locales más calificados en la materia; en los que se incluyen a empleados de la Comisión del Canal, abogados marítimos, agentes navieros y a ejecutivos de la Autoridad Portuaria Nacional. En el caso del Canal de Panamá, el 79% de los expertos en asuntos marítimos y la mayoría de cada uno de los cuatro grupos, concluyeron que es preferible mantener el sistema de practicaje actual. No obstante, en los puertos de Balboa y Cristóbal, el 67% de los expertos y la mayoría de cada uno de los cuatro grupos, se decidieron por el sistema de practicaje internacional. En este estudio se recomienda mantener el sistema de practicaje actual en el Canal de Panamá, en el cual es el práctico el responsable de la navegación del buque, y cambiar en los Puertos de Balboa y Cristóbal, al sistema de practicaje internacional, donde el capitán es el responsable de la navegación de su buque

Biohydrogen production from diary processing wastewater by anaerobic biofilm reactors

Fermentative hydrogen production was studied in packed bed batch reactors to assess the influence of environmental factors over yield hydrogen production from dairy wastewater. Dried stems of Opuntia imbricata were used as substratum adding a pretreated mixed culture for biofilm formation. Experimental results showed that, yield hydrogen production was significantly affected by initial COD concentration, temperature and dairy wastewater pH. Maximum yield obtained was 12.73 mM H2/g CODc when initial COD concentration was 21.1 g COD, dairy wastewater pH with no adjustment (11.32) and room temperature of 16 ± 3°C. Methane production was completely inhibit at an initial pH of 4 at all temperature studied (final pH 4.06), meanwhile, with an initial pH of 11.32, with exception for 16°C, methanogenic activity was not completely inhibit when final pH was over 5, showing an increase in methane production of 0.35 to 0.75 g CH4/l for 35 to 55°C.Key words: Biofilm, dairy wastewater, hydrogen, Opuntia imbricat

Pilot Safety Evaluation of Varenicline for the Treatment of Methamphetamine Dependence.

Despite the worldwide extent of methamphetamine dependence, no medication has been shown to effectively treat afflicted individuals. One relatively unexplored approach is modulation of cholinergic system function. Animal research suggests that enhancement of central cholinergic activity, possibly at nicotinic acetylcholine receptors (nAChRs), can reduce methamphetamine-related behaviors. Further, preliminary findings indicate that rivastigmine, a cholinesterase inhibitor, may reduce craving for methamphetamine after administration of the drug in human subjects. We therefore performed a double-blind, placebo-controlled, crossover pilot study of the safety and tolerability of varenicline in eight methamphetamine-dependent research subjects. Varenicline is used clinically to aid smoking cessation, and acts as a partial agonist at α4β2 nAChRs with full agonist properties at α7 nAChRs. Oral varenicline dose was titrated over 1 week to reach 1 mg bid, and then was co-administered with 30 mg methamphetamine, delivered in ten intravenous infusions of 3 mg each. Varenicline was found to be safe in combination with IV methamphetamine, producing no cardiac rhythm disturbances or alterations in vital sign parameters. No adverse neuropsychiatric sequelae were detected either during varenicline titration or following administration of methamphetamine. The results suggest that varenicline warrants further investigation as a potential treatment for methamphetamine dependence

Characterization of the pressure losses in a common rail diesel injector

A methodology to characterise the pressure losses in quasi-steady conditions (i.e. at full needle lift) of common rail diesel injectors was developed. The aim was to quantify the error when experimental results of nozzle internal flow are compared with CFD results, where pressure losses are usually neglected. The proposed methodology is based mainly on experimental tests that are complemented with some approximate calculations, based on the physics of the phenomenon, to take into account the effect of the needle deformation. The results obtained in the work lead to two important conclusions: on the one hand, that it is dangerous to extrapolate results relative to the injection (internal flow, spray atomization, spray penetration˙ ..) and combustion processes from low permeability nozzles (e.g. single-hole nozzles) to high permeability nozzles (e.g. multi-hole nozzles), and, on the other hand, that the comparison of these results between experiments and CFD simulations should be carried out carefully, because the pressure losses in the injector can be high under certain conditions. Finally, people working on the study of the injection and/or combustion processes, through experiments or simulations, will find here some interesting information to better know the actual injection pressure to be used in their analysis and/or simulations.The PhD studies of Oscar A. de la Garza were funded by the FPU program of the Ministerio de Educacion of Spain (grant no. AP2008-01913).López, JJ.; Salvador Rubio, FJ.; De La Garza De Leon, O.; Arregle, JJP. (2012). Characterization of the pressure losses in a common rail diesel injector. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 226(12):1697-1706. https://doi.org/10.1177/0954407012447020S169717062261

Celecoxib accelerates functional recovery after sciatic nerve crush in the rat

The inflammatory response appears to be essential in the modulation of the degeneration and regeneration process after peripheral nerve injury. In injured nerves, cyclooxygenase-2 (COX-2) is strongly upregulated around the injury site, possibly playing a role in the regulation of the inflammatory response. In this study we investigated the effect of celecoxib, a COX-2 inhibitor, on functional recovery after sciatic nerve crush in rats. Unilateral sciatic nerve crush injury was performed on 10 male Wistar rats. Animals on the experimental group (n = 5) received celecoxib (10 mg/kg ip) immediately before the crush injury and daily for 7 days after the injury. Control group (n = 5) received normal saline at equal regimen. A sham group (n = 5), where sciatic nerve was exposed but not crushed, was also evaluated. Functional recovery was then assessed by calculating the sciatic functional index (SFI) on days 0,1,7,14 and 21 in all groups, and registering the day of motor and walking onset. In comparison with control group, celecoxib treatment (experimental group) had significant beneficial effects on SFI, with a significantly better score on day 7. Anti-inflammatory drug celecoxib should be considered in the treatment of peripheral nerve injuries, but further studies are needed to explain the mechanism of its neuroprotective effects

Atypical Lemierre’s syndrome caused by Prevotella oris

Lemierre’s syndrome is a rare form of severe sepsis secondary to oropharyngeal infection characterized by septic thrombophlebitis of the internal jugular vein with disseminated infections, with the lungs being the most frequent target. We report the case of a previously healthy 15-year-old admitted to the intensive care unit because of septic shock, brain and lung abscesses, and a positive blood culture for Prevotella oris with a clinical presentation compatible with the diagnosis of Lemierre’s syndrome. Conclusion: This is an atypical presentation of Lemierre’s syndrome because of the isolated microorganism

Emphysema model in rats exposed to tobacco smoke. Morphometric and functional analysis

Several models of chronic obstructive pulmonary disease (COPD) in mice have been developed; the most similar to the habit of smoking is the inhalation of the smoke in mice. The objective was to develop and implement an experimental model of COPD in mice through the passive inhalation of smoke and demonstrate the physiological changes on ventilatory function and its correlation with 3 emphysema quantification methods. Materials and methods: Twenty Wistar mice were included in an experimental and control group. The experimental group was exposed to tobacco smoke, and we performed several pulmonary functional tests and imaging techniques. Results: Pulmonary function tests showed the volume expiration in the first second (VEF1) differs significantly between groups (p < 0.001). Pulmonary compliance was reduced in the experimental group by 50% in comparison to the control group (male vs control p < 0.001). Morphometric analysis: 17% reduction in lung volume with a destructive index (DI) of 45%. The intersection test had a DI of 43%. The free point test showed a DI of 44%. Conclusions: The implementation of our model generated the presence of emphysema and alterations in the lung physiology in the experimental group. We demonstrated evidence of 90% with emphysem