Thermal performance comparison between microchannel and round tube heat exchangers

Alternative round tube profiles to straight microchannel (SMC) tube geometry was explored by gradually applying the microchannel features to fin and tube type heat exchangers. First, previous experimental and computational works related to design and heat transfer analysis of microchannel heat exchanger tubes and testing was reviewed and then a numerical CFD model in FLUENT solver was developed, which was experimentally validated within an error range of 0.1 to 7.8 % based on available data in literature. Single phase, water to water, laminar, counter fluid flow of tube in shell calorimeter heat transfer experiments were numerically simulated to analyze the refrigerant side heat transfer enhancement if round microchannel tubes are used as outdoor coil. According to numerical results, the refrigerant side heat transfer capacity of round tubes of 10.3mm outer diameter with 42 microports of about 0.6 mm port diameter distributed around the tube perimeter (round tube microchannel) was estimated to be about 24% higher than conventional round tube (with no microchannel ports in them) and about 15% lower than conventional straight microchannel tube heat exchangers used in outdoor evaporators. In addition to refrigerant side, parametric studies were performed to investigate the heat transfer effectiveness of 10.3 mm and 5.15 mm outer diameter round (microchannel) tubes (multi port and annular) under cross flow configuration with dry air streams and results were compared with straight microchannel tubes in terms of tube diameter tube spacing effect. It was obtained that the round tube design of 5.15 mm outer diameter having an annular port of 1.6mm hydraulic diameter within 11mm edge to edge tube spacing of vertically parallel fin and tube coil configuration can provide similar air side heat transfer capacity of straight microchannel coil based on its secondary heat transfer area. Additionally, this configuration can provide 50 % better pressure drop performance compared to conventional straight microchannel tube coil.Mechanical & Aerospace Engineerin

Relationship between seizures and metabolic acidosis: a prospective observational study

Objective: To assess changes in blood gas parameters, such as pH, partial carbon dioxide pressure (PaCO2), bicarbonate (HCO3), base deficit, and lactate values, in patients who present to the emergency care unit after aseizure. Methods: This is a prospective study on patients who suffered a generalized tonic-clonic seizure. The demographic and biochemical data of the patients and their blood gas parameters were recorded both at the time of presentation to the emergency department and during the follow-up examination. Results: A total of 68 patients were included in the study. Among the patients, 60.3% (41) were male. The median age of the patients was 43 years (IQR: 29-65.25). The median initial lactate value was 5.7 mmol/L (25th and 75th percentiles: 3.5–8.5 mmol/L). The median follow-up lactate value was 1.8 mmol/L (25th and 75th percentiles: 1.1–2.8 mmol/L). The statistical analysis of the blood gas parameters revealed a statistically significant difference in the pH, PaCO2, base deficit, and lactate values between the initial and follow-up evaluations (P<0.001). Conclusion: The results of our study suggest that metabolic acidosis with high anion gap may develop due to the increase in the lactate levels as a result of a tonic-clonic seizur

99mTc-exendin-4: Radiolabeling and quality control studies of glucagon-like peptide analog

Aim: Exendin-4 is a type 2 diabetes antidiabetic drug that is a peptide agonist of the glucagon-like peptide 1 receptor (GLP-1R). Up to date, different exendin-4 compounds have been radiolabeled with many radioisotopes such as 68Ga, 18F, 64Cu and 99mTc for various purposes like study of over expression of GLP-1R in insulinoma. The purpose of this study is to radiolabel exendin-4 with 99mTc under appropriate conditions. Methods: In this study, exendin-4 was labeled with 99mTc, and quality control tests of 99mTc-exendin-4 were done using ascending radioactive thin layer chromatography (RTLC). Also, the effects of important parameters such as the amount of reducing agent, pH value, incubation time, and radiation dose on the labeling efficiency were investigated. Then, the stability of 99mTc-exendin-4 was assessed. Results: According to the results, 99mTc-exendin-4 was prepared with over 95 percent labeling efficiency by a novel, easy, and quick direct method with 30-min incubation time at pH 6.6. To achieve the best radiolabeling condition; 10 µg of exendin-4, 50 µg of stannous chloride (reducing agent) and 37 MBq 99mTc was used. The RTLC studies indicated that 99mTc-exendin-4 is stable up to 6 h in room temperature. Conclusion: The obtained results demonstrated that radiolabeled exendin-4 may be a promising agent for GLP-1R imaging studies. Further studies are in progress in order to evaluate receptor binding capacity and biodistribution of the complex in experimental animals

Total and partial ear epithesis : two case reports with review of literature.

Auricular defects may be congenitally or occur secondary to trauma or surgical removal of a neoplasm. Treatment options for the reconstruction of the ear may include either plastic surgery or provision of an auricular prosthesis.The requirements of prosthesis are esthetics, retention and stability, alignment and positioning, biocompatibility, and longevity. In the present study we present  2 patients (a partial and a total auricular defects) were rehabilitated with epistheses that were constructed on endosteal titanium implants of the ITI system with magnetive anchors in mastoid process. The success of both 2 epithesis compared in terms of function, aesthetics and psychological activity

Does Unemployment Invariance Hypothesis Hold for Canada?

This article explores the long-run relationship between unemployment rate and labor force participation rate in Canada. The cointegration analysis vindicates the existence of a long-run relationship between these two variables. This finding leads us to doubt the pertinence of the unemployment invariance hypothesis for Canada. This is consistent with the empirical studies for Japan, Sweden and the United States, but contradicts the empirical studies for Australia, Romania and Turkey. There are contradictory studies for the United Kingdom

Does Unemployment Invariance Hypothesis Hold for Canada?

This article explores the long-run relationship between unemployment rate and labor force participation rate in Canada. The cointegration analysis vindicates the existence of a long-run relationship between these two variables. This finding leads us to doubt the pertinence of the unemployment invariance hypothesis for Canada. This is consistent with the empirical studies for Japan, Sweden and the United States, but contradicts the empirical studies for Australia, Romania and Turkey. There are contradictory studies for the United Kingdom

Unemployment and Labor Force Participation in Turkey

This paper investigates the relationship between labor force participation rate and unemployment rate in Turkey a developing country. Cointegration analysis is carried out for the aggregate and gender and age specific series. The findings indicate that there is no long-run relationship between labor force participation and unemployment rates in Turkey. Thus, unlike in the case of the developed countries the unemployment invariance hypothesis is supported in Turkey

Unemployment and Labor Force Participation in Turkey

This paper investigates the relationship between labor force participation rate and unemployment rate in Turkey a developing country. Cointegration analysis is carried out for the aggregate and gender and age specific series. The findings indicate that there is no long-run relationship between labor force participation and unemployment rates in Turkey. Thus, unlike in the case of the developed countries the unemployment invariance hypothesis is supported in Turkey