İçerisinde dairesel halkalar bulunan bir boruda nanoakışkanların pulsatif akışının ısı transferine etkisinin parametrik incelenmesi

WOS: 000441810300005In this study, the heat transfer characteristics and friction factor of nanofluids under laminar pulsating inlet flow conditions in a tube with circular rings are investigated numerically. In investigations, the governing equations are solved with FLUENT ANSYS 15.0 package program, along with boundary conditions using the finite volume approach (FVM) by SIMPLE algorithm. Firstly, the effects on heat transfer of different nanofluid types with varying particle volume fractions and Reynolds numbers under steady flow conditions are analyzed. Then, these nanofluids parameters are kept constant and the effects on heat transfer under pulsating flow conditions of nanofluids are investigated. The average Nusselt number and friction factor are calculated for different pulsating parameters. The numerical results indicate that the heat transfer performance enhances with increase in particle volume fraction and Reynolds number in steady regime. It is observed that the heat transfer performance increases with increasing pulsating amplitude in pulsating nanofluid flow, and there is a slightly increase in pressure drop. The computed results reveal that there is a good potential in promoting the heat transfer enhancement by using the nanoparticles under pulsating flow in a tube with circular rings

Heat transfer in a triangular wavy channel with CuO-water nanofluids under pulsating flow

In this paper, heat transfer and pressure drop characteristics of CuO-water nanofluid flow in a isothermally heated triangular-wavy channel under pulsating inlet conditions are numerically investigated. A numerical simulation is conducted by solving the governing continuity, momentum, and energy equations for laminar flow using the finite volume approach. In the studies, the main parameters including the Reynolds number, pulsating amplitude and frequency, are changed while the nanoparticle volume fraction and the other parameters are kept constant for all cases. Numerical results are compared with the steady flow conditions, which showed that heat transfer performance significantly increases due to improve thermal conductivity and the use of nanoparticles in the pulsating flow conditions. The results indicate that there is a high potential for promoting the thermal performance enhancement by using nanoparticles under pulsating flow in wavy channels. It is found that the heat transfer enhancement increases with increasing pulsating amplitude and Reynolds number, and there is a slight increase in pressure drop. The obtained results are given as a function of dimensionless parameters

A National Registry of Thalassemia in Turkey: Demographic and Disease Characteristics of Patients, Achievements, and Challenges in Prevention

WOS: 000426572200002PubMed ID: 28404539Objective: The Turkish Society of Pediatric Hematology set up a National Hemoglobinopathy Registry to demonstrate the demographic and disease characteristics of patients and assess the efficacy of a hemoglobinopathy control program (HCP) over 10 years in Turkey. Materials and Methods: A total of 2046 patients from 27 thalassemia centers were registered, of which 1988 were eligible for analysis. This cohort mainly comprised patients with beta-thalassemia major (n = 1658, 83.4%) and intermedia (n = 215, 10.8%). Results: The majority of patients were from the coastal areas of Turkey. The high number of patients in Southeastern Anatolia was due to that area having the highest rates of consanguineous marriage and fertility. The most common 11 mutations represented 90% of all beta-thalassemia alleles and 47% of those were IVS1-110(G->A) mutations. The probability of undergoing splenectomy within the first 10 years of life was 20%, a rate unchanged since the 1980s. Iron chelators were administered as monotherapy regimens in 95% of patients and deferasirox was prescribed in 81.3% of those cases. Deferasirox administration was the highest (93.6%) in patients aged <10 years. Of the thalassemia major patients, 5.8% had match-related hemopoietic stem cell transplantation with a success rate of 77%. Cardiac disease was detected as a major cause of death and did not show a decreasing trend in 5-year cohorts since 1999. Conclusion: While the HCP has been implemented since 2003, the affected births have shown a consistent decrease only after 2009, being at lowest 34 cases per year. This program failure resulted from a lack of premarital screening in the majority of cases. Additional problems were unawareness of the risk and misinformation of the at-risk couples. In addition, prenatal diagnosis was either not offered to or was not accepted by the at-risk families. This study indicated that a continuous effort is needed for optimizing the management of thalassemia and the development of strategies is essential for further achievements in the HCP in Turkey.Ege Children's Foundation; Novartis Pharmaceuticals CorporationNovartisThe authors thank Caglar Serdar, Aylin Gokduman, and Tolga Turgay of Plexus Information Technologies for their website support. The current study and the work presented here are from an Investigator Initiated Trial, which was sponsored by the Ege Children's Foundation and funded by Novartis Pharmaceuticals Corporation

Inborn errors of OAS–RNase L in SARS-CoV-2–related multisystem inflammatory syndrome in children

International audienceMultisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1 , OAS2 , or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)–sensing OAS1 and OAS2 generate 2′-5′-linked oligoadenylates (2-5A) that activate the single-stranded RNA–degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L–deficient cells. Cytokine production in RNase L–deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS–RNase L deficiencies in these patients unleash the production of SARS-CoV-2–triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C