Performance Optimization of an Air-Standard Irreversible Dual-Atkinson Cycle Engine Based on the Ecological Coefficient of Performance Criterion

This paper presents an ecological performance analysis and optimization for an air-standard irreversible Dual-Atkinson cycle (DAC) based on the ecological coefficient of performance (ECOP) criterion which includes internal irreversibilities, heat leak, and finite-rate of heat transfer. A comprehensive numerical analysis has been realized so as to investigate the global and optimal performances of the cycle. The results obtained based on the ECOP criterion are compared with a different ecological function which is named as the ecologic objective-function and with the maximum power output conditions. The results have been attained introducing the compression ratio, cut-off ratio, pressure ratio, Atkinson cycle ratio, source temperature ratio, and internal irreversibility parameter. The change of cycle performance with respect to these parameters is investigated and graphically presented

Examination of gutta-percha cones for microbial contamination during chemical use

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 µL of saline. The tubes were vortexed, serially diluted and samples of 250 µL were cultured on agar plates. The plates were incubated at 37ºC for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p >; 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p >; 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals

Adolescents with unexplained chest pain reported depression and impaired emotional and social functioning

AimChest pain is common in adolescence, but there are no established criteria for managing this problem, which is rarely associated with cardiac disease. This study addressed the gaps in the literature by evaluating psychosocial factors that could be associated with medically unexplained chest pain.MethodsWe consecutively selected 100 patients (68% girls) aged 13‐18 who were diagnosed with unexplained chest pain when they presented to the cardiology outpatient clinics of Tepecik Research Hospital, İzmir, Turkey, between 30 September 2015 and 30 June 2018. The controls were 76 age‐ and sex‐matched adolescents (69% girls) aged 13‐18 who were undergoing routine cardiology assessments before joining sports clubs. We assessed their health‐related quality of life and any depression and physical symptoms.ResultsRegression analysis showed some adolescents were a number of times more likely to report chest pain. These included those who reported boredom (4.1 times), felt stressed or anxious (2.2) and those who experienced sleep disturbance (2.6), co‐morbid headaches (2.0), back pain (3.1) and impaired social functioning (1.2).ConclusionThe results indicated a significant association between unexplained chest pain and physical symptoms, depression and impaired emotional and social functioning. These factors warrant further evaluation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156129/2/apa15144.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156129/1/apa15144_am.pd

Simulation of performance and nitrogen oxide formation of a hydrogen-enriched diesel engine with the steam injection method

In the present study, steam injection method (SIM) is implemented to a hydrogen-enriched diesel engine in order to improve the levels of performance and NO emissions. As hydrogen enrichment method increases effective efficiency, NO emissions could be increased. However, the SIM is used to control NO emissions and improve the engine performance. Due to these positive effects, hydrogen enrichment and the SIM)are applied into a diesel engine by using a two-zone combustion model for30% hydrogen enrichment of the fuel volume and 20% steam ratio of the fuel mass at full load conditions. The results obtained are compared with conventional diesel engine (D), steam injected diesel engine (D+S20), hydrogen-enriched diesel engine (D+H30) and hydrogen-enriched diesel engine with steam injection (D+H30+S20) in terms of performance and NO emissions. In the results, the effective efficiency and effective power improve up to 22.8% and %3.1, as NO emissions decrease up to 22.1%. Hence, the hydrogen enrichment with steam injection method is more environmentally friendly with better performance

A study on the effects of seat belt posters on drivers

2nd World Conference on Educational Sciences (WCES-2010) -- FEB 04-08, 2010 -- Bahceschir Univ, Istanbul, TURKEYWOS: 000282002800136The primary aim of this study was to identify the effects of several posters designed to encourage the use of seat belts on drivers. Discovering the seat belt use habits of drivers and their reasons for failing to use them constitute the secondary aims of the study. In order to fulfill these aims, four different posters appealing to drivers' safety and normative motivations were designed. The drivers were then asked to choose the poster that impressed them most. Half of the drivers chose the first poster, which drew a parallelism between the casualites of terrorism, earthquake and traffic, as most impressive. The second most impressive poster was the fourth one, which emphasized the link between traffic rules and morality. Female drivers found this poster with a moral message more impressive than males. Another finding of the study was that primary school and university graduates were more impressed by the posters appealing to normative motivation. (C) 2010 Elsevier Ltd. All rights reserved