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Taha Toros Arşivi, Dosya No: 491-Tango-CazUnutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

Arjantin topraklarında sosyal bir olgu haline gelen coşkuyu yansıtan müzik ve dans, kıtaları atladı:tango, Avrupa'da romantik havaya girdi

Taha Toros Arşivi, Dosya No: 134-Fehmi Eg

EFFECT OF PARTICLE-SIZE ON THE SPONTANEOUS HEATING OF A COAL STOCKPILE

A large-scale apparatus has been used to evaluate the effect of particle size on the spontaneous heating of a coal stockpile. To accomplish this, coal with various ranges of particle size (between 2 and 50 mm in diameter) was oxidized in a cylinder of 3-m length and 0.3-m diameter. A critical range of particle size was observed, below which spontaneous heating leads to flaming combustion. From the results of the oxygen consumption and the temperature of the coal bed, the influence of particle size on the oxidation rate has been analyzed in greater depth. The oxygen conservation equation, in which the oxygen consumption rate is first order in oxygen concentration and obeys the Arrhenius equation, allows the determination of apparent activation energies and preexponential factors. Calculated values of these parameters, by fitting the experimental data to the integrated form of the oxygen conservation equation, have been used to evaluate the effect of particle size. It was of particular interest to determine the operating regime for coal-oxygen reaction and this was achieved by defining an empirical exponent for the particle diameter in the rate equation. This exponent indicated the oxidation regime for a change from chemical to pore diffusion control at successively higher temperatures

Application of response surface methodology to optimize and investigate the effects of operating conditions on the performance of DMFC

In this study, the response surface methodology (RSM) has been applied to optimize the operating conditions of direct methanol fuel cell (DMFC). A quadratic model was developed through RSM in terms of related independent variable to describe the current as the response. The input data required in this model has been obtained experimentally. For this purpose, an experimental set up for testing of direct methanol fuel cell has been established to investigate the effects of temperature and flow rate parameters on the cell performance. Two different analyses for operating conditions were performed applying the response surface method to obtain the maximum power. These analyses were based on the unlimited and minimum methanol consumptions. Methanol flow rate, oxygen flow rate, methanol temperature, humidification temperature and cell temperature were the main parameters considered that they were varied between 2 and 50 ml/min, 100-1000 ml/min, 30-70 degrees C, 30 70 degrees C and 30-80 degrees C in the analyses respectively. The maximum current under the unlimited and minimum methanol consumptions was found as 1230 mA and 582 mA based on the contour plots and variance analysis. (C) 2010 Elsevier Ltd. All rights reserved.https://doi.org/10.1016/j.energy.2010.11.03

Dexmedetomidine As A Substitute For Remifentanil In Ambulatory Gynecologic Laparoscopic Surgery

Objectives: To compare dexmedetomidine with remifentanil in desflurane based ambulatory gynecologic laparoscopic surgery, in respect to its effects on orientation, discharge time, nausea-vomiting, and postoperative analgesic need. Methods: Sixty 20-40 year old ASA I-II patients undergoing gynecologic laparoscopic surgery were randomized into 2 groups. This study was performed in the operating theaters of the Hacettepe University Faculty of Medicine, Hacettepe, Turkey in 2004 as a prospective, randomized, and double blinded study. The remifentanil group (group R), and dexmedetomidine group (group D) received a bolus of 1 mu g/kg over 10 minutes, followed by 0.2 mu g/kg/minute peroperative infusion of remifentanil, and 0.4 mu g/kg/hour of dexmedetomidine. Hemodynamic parameters, time to extubation, and to orientation to person, Place, and date, postoperative nausea, vomiting, pain, analgesic requirement at home, and satisfaction with anesthesia were recorded. Results: Demographic, hemodynamic data, postoperative pain scores, and discharge time were similar in both groups. Time to extubation, to orientation to person, to place and date were shorter in group R. Postoperative nausea, vomiting, and analgesic requirements at home were less in group D. Conclusion: This study demonstrated that dexmedetomidine infusion causes a relatively slow recovery with reduced postoperative nausea, vomiting, and analgesic requirements, and similar hemodynamics compared to remifentanil in ambulatory laparoscopic surgeries. It may be an alternative to remifentanil in ambulatory anesthesia.Wo

Low levels of 1.25-dihydroxy vitamin d is associated with all-cause mortality in prevalent hemodialysis patients

It has been suggested that vitamin D contributes not only to bone mineral metabolism but also to important other physiological processes. Vitamin D levels have been associated with increased mortality in predialysis and incident HD patients, but no data is available on the association between vitamin D levels and survival in prevalant hemodialysis (HD) patients. Five hundred and forty five prevalent hemodialysis patients were recruited. Time averaged laboratory values throughout the two years and base line serum 25-OH vitamin D and 1.25-OH vitamin D levels were determined. All-cause mortality was prospectively evaluated after 2-year follow-up period. 25- OH vitamin D levels were significantly lower in females and in patients with diabetes. 1.25-OH2 vitamin D level was significantly lower in diabetics. After two years of follow-up period, in crude analysis low serum 25-OH and 1.25 OH2 vitamin D levels were associated with all cause mortality. In adjusted Cox-regression analysis, 1.25-OH2 vitamin D level, but not 25-OH, was found as an independent predictor for all-cause mortality. Low 1.25-OH2 vitamin D level was also found as an independent predictor for all-cause mortality in non-diabetic study group even after inclusion of time averaged vitamin Dtherapy dosage. Serum 1.25-OH vitamin D level is associated with all cause mortality in prevalant hemodialysis patients.Vitamin D, kemik mineral metabolizması dışında da bir çok önemli fizyolojik süreçte rol oynamaktadır. İnsidan hemodiyaliz ve prediyaliz dönem hastalarda vitamin D düzeyi ile mortalite ilişkisi gösterilmiştir. Ancak prevelan hemodiyaliz hastalarında serum vitamin D düzeyi ile mortalite ilişkisi hakkında çok az veri vardır. Bu çalışmaya 545 prevelan hemodiyaliz hastası alındı. Hastaların bazal serum 25-Hidroksi ve 1,25- Dihidroksi vitamin D düzeyleri ve 2 yıl boyunca zamansal ortalamalı laboratuvar verileri belirlendi. Tüm nedenli mortalite, prospektif olarak bu 2 yıl sonunda incelendi. 25-Hidroksi vitamin D kadınlarda ve diyabetiklerde anlamlı olarak daha düşük saptandı. 1,25-Dihidroksi vitamin D de aynı şekilde diyabetiklerde anlamlı daha düşük saptandı. İki yıl sonunda, 25-Hidroksi ve 1,25-Dihidroksi vitamin D düzeyleri, prevelan hemoidiyaliz hastalarında tüm nedenli mortalite öngörücüsü olarak saptandı. Cox regresyon analizinde 1,25-Dihidroksi vitamin D düzeyi bağımsız tüm nedenli mortalite öngörücüsü olarak saptandı. Diyabetik olmayan prevelan hemodiyaliz hastalarında aktif vitamin D tedavisi modele eklendiğinde bile 1,25-Dihidroksi vitamin D düzeyi bağımsız tüm nedenli mortalite öngörücüsü idi. Serum 1,25-Dihidroksi vitamin D düzeyi prevelan hemodiyaliz hastalarında tüm nedenli mortalite öngörücüsüdür