Comparative and Exergetic Study of a Gas Turbine System with Inlet Air Cooling

The efficiency of the combined cycle is significantly influenced by the temperature, pressure and humidity of the ambient air. The aim of this study is to investigate the influence of the inlet air cooling system (fogging cooling system) on the gas turbine performance by energy and exergy analyses. Energy and exergy analysis was carried out for nine cases based on the operation data of a gas turbine. Performance parameters include fuel consumption, specific fuel consumption, thermal efficiency, net power output, exergetic efficiency and exergy destruction rates of the components for the cases. It is concluded that the net power output of the gas-turbine system increases at lower inlet air temperatures, and based on the mean values, exergetic efficiency and exergy destruction ratio were found as 37.35% and 33.02%, respectively

Theoretical Performance Analysis of an R1234yf Refrigeration Cycle Based on the Effectiveness of Internal Heat Exchanger

I n this paper, the effects of internal heat exchanger IHX effectiveness on the performance parameters of the refrigeration cycle with R1234yf were theoretically investigated. For this purpose, a mathematical model was developed based on the energy balance of the cycle. The analysis were performed between -20°C and 0°C evaporation and 40°C and 50°C condensation temperatures based on the effectiveness value of IHX. The cooling capacity, coefficient of performance COP , subcooling, superheat and compressor discharge temperature of the refrigeration cycle was examined. Finally, the performance results of the cycle with R1234yf were compared with the baseline cycle that utilizes with R134a. As a result, it was determined that the critical effectiveness to supply the same COP with R1234yf was determined 50% in comparison the baseline cycl

Comparison of R134a and R516A’s Performance at Different Air Velocities in Two Evaporator Ejector Cooling System

This study aims experimentally to investigate the performance parameters of R134a and the alternative R516A refrigerant in two evaporator ejector cooling system (DEES) at different air velocities of evaporator#1. Firstly, the tests were carried out with R134a refrigerant under steady-state conditions at different air velocities and then repeated with low GWP R516A refrigerant. As the tests were carried out with R134a, higher cooling capacity was achieved at different air velocity values. When the air velocity value was 1.1, 1.7, 2.2, and 2.7 m s-1, the COP value obtained from the tests with R134a was 1%, 2%, 5%, and 4% higher than R516A, respectively. Additionally, test results illustrate that the higher air velocity contributed to increasing performance parameters, however air velocity higher than 2.2 m s-1 had a slight effect. The study concluded that R516A performance values are slightly lower than R134a performance and can be alternatively used as a refrigerant in vapor compression refrigeration (VCR) systems

Adli Olgu Bildirimiyle İlgili İkilemlerde Hekimlerin Tutumları

Amaç: Yasalara göre adli olgu bildiriminde bulunulması gereken bazı durumlarda sağlık çalışanlarının çifte yükümlülükleri gündeme gelmektedir. Hekimler bu durumlarda ikilimler yaşayabilmekte ve yasalarla tıbbi etik ilkelerin çeliştiğini düşünebilmektedir. Bu çalışmada, XXX Hastanesi’nde görev yapan hekimlerin adli olgu bildirimi konusundaki haberlilikleri ve yasalarla tıbbi etik ilkelerin çeliştiğini düşündükleri durumlardaki tutum ve davranışların belirlenmesi amaçlanmıştır. Yöntem: 22 sorudan oluşan anket formları ile 106 hekime ulaşılmış; adli olgu tanımı, adli olgu bildirim yükümlülüğü, ilgili yasal ve etik düzenlemeler konusunda haberdarlık, yasa ve etik ilkelerin çeliştiği alanlarda hekimlerin tutum ve davranışları sorgulanmıştır. Bulgular: Hekimlerin ikilem yaşadığı durumlarla karşı karşıya kaldığında % 62 oranında yasalara, %35 oranındaysa etik ilkelere uygun hareket ettiği görülmüştür. Sonuç: İlgili yasalarla tıbbi etik ilkelerin birbiriyle çeliştiği ve desteklediği alanlar tartışılmış, tartışmanın ikilem yaratan durumlarda hekimlerin tutum davranış değişikliğine katkı sağlayacağı düşünülmüştür

Re-examining the characteristics of pediatric multiple sclerosis in the era of antibody-associated demyelinating syndromes

Background: The discovery of anti-myelin oligodendrocyte glycoprotein (MOG)-IgG and anti-aquaporin 4 (AQP4)-IgG and the observation on certain patients previously diagnosed with multiple sclerosis (MS) actually have an antibody-mediated disease mandated re-evaluation of pediatric MS series. Aim: To describe the characteristics of recent pediatric MS cases by age groups and compare with the cohort established before 2015. Method: Data of pediatric MS patients diagnosed between 2015 and 2021 were collected from 44 pediatric neurology centers across Turkiye. Clinical and paraclinical features were compared between patients with dis-ease onset before 12 years (earlier onset) and >= 12 years (later onset) as well as between our current (2015-2021) and previous (< 2015) cohorts. Results: A total of 634 children (456 girls) were enrolled, 89 (14%) were of earlier onset. The earlier-onset group had lower female/male ratio, more frequent initial diagnosis of acute disseminated encephalomyelitis (ADEM), more frequent brainstem symptoms, longer interval between the first two attacks, less frequent spinal cord involvement on magnetic resonance imaging (MRI), and lower prevalence of cerebrospinal fluid (CSF)-restricted oligoclonal bands (OCBs). The earlier-onset group was less likely to respond to initial disease-modifying treatments. Compared to our previous cohort, the current series had fewer patients with onset < 12 years, initial presentation with ADEM-like features, brainstem or cerebellar symptoms, seizures, and spinal lesions on MRI. The female/male ratio, the frequency of sensorial symptoms, and CSF-restricted OCBs were higher than reported in our previous cohort. Conclusion: Pediatric MS starting before 12 years was less common than reported previously, likely due to exclusion of patients with antibody-mediated diseases. The results underline the importance of antibody testing and indicate pediatric MS may be a more homogeneous disorder and more similar to adult-onset MS than previously thought

Broad-spectrum XX and XY gonadal dysgenesis in patients with a homozygous L193S variant in PPP2R3C

Context Homozygous and heterozygous variants in PPP2R3C are associated with syndromic 46,XY complete gonadal dysgenesis (Myo-Ectodermo-Gonadal Dysgenesis (MEGD) syndrome), and impaired spermatogenesis, respectively. This study expands the role of PPP2R3C in the aetiology of gonadal dysgenesis (GD). Method We sequenced the PPP2R3C gene in four new patients from three unrelated families. The clinical, laboratory, and molecular characteristics were investigated. We have also determined the requirement for Ppp2r3c in mice (C57BL6/N) using CRISPR/Cas9 genome editing. Results A homozygous c.578T>C (p.L193S) PPP2R3C variant was identified in one 46,XX girl with primary gonadal insufficiency, two girls with 46,XY complete GD, and one undervirilised boy with 46,XY partial GD. The patients with complete GD had low gonadal and adrenal androgens, low anti-Mullerian hormone, and high follicle-stimulating hormone and luteinizing hormone concentrations. All patients manifested characteristic features of MEGD syndrome. Heterozygous Ppp2r3c knockout mice appeared overtly normal and fertile. Inspection of homozygous embryos at 14.5, 9.5, and 8.5 days post coitum(dpc) revealed evidence of dead embryos. We conclude that loss of function of Ppp2r3c is not compatible with viability in mice and results in embryonic death from 7.5 dpc or earlier. Conclusion Our data indicate the essential roles for PPP2R3C in mouse and human development. Germline homozygous variants in human PPP2R3C are associated with distinctive syndromic GD of varying severity in both 46,XY and 46,XX individuals