Modelling of friction stir welding of DH36 steel

A 3-D computational fluid dynamics (CFD) model was developed to simulate the friction stir welding of 6-mm plates of DH36 steel in an Eulerian steady-state framework. The viscosity of steel plate was represented as a non- Newtonian fluid using a flow stress function. The PCBN-WRe hybrid tool was modelled in a fully sticking condition with the cooling system effectively represented as a negative heat flux. The model predicted the temperature distribution in the stirred zone (SZ) for six welding speeds including low, intermediate and high welding speeds. The results showed higher asymmetry in temperature for high welding speeds. Thermocouple data for the high welding speed sample showed good agreement with the CFD model result. The CFD model results were also validated and compared against previous work carried out on the same steel grade. The CFD model also predicted defects such as wormholes and voids which occurred mainly on the advancing side and are originated due to the local pressure distribution between the advancing and retreating sides. These defects were found to be mainly coming from the lack in material flow which resulted from a stagnant zone formation especially at high tra- verse speeds. Shear stress on the tool surface was found to in- crease with increasing tool traverse speed. To produce a “sound” weld, the model showed that the welding speed should remain between 100 and 350 mm/min. Moreover, to prevent local melt- ing, the maximum tool’s rotational speed should not exceed 550 RPM

P–232 A trophectoderm morphology can predict a live birth rate and gender imbalance

Abstract Study question Which morphology parameter is the most predictable in the live birth rate and can affect the sex ratio? Summary answer The trophectoderm grade (TE) can predict the live birth rate and skewed to male gender after single vitrified-warmed blastocyst transfers (SVBT). What is known already The Gardner and Schoolcraft grading system of blastocyst evaluation with morphology is the major predictor of the clinical outcome in ART. Inner cell mass (ICM) and trophectoderm (TE) morphology are strongly correlated between clinical pregnancy, live birth, and miscarriage. A greater degree of expansion of the transferred blastocysts showed a higher implantation rate. Therefore, it is essential to clarify which parameter is more predictable in clinical outcome during elective SVBT. However, SVBT has some potential limitations, including adverse effects such as a male-biased imbalance in the sex ratio. Study design, size, duration The retrospective analysis used 1138 cycles of SVBT in the Ojinmed IVF center, Mongolia, between May 2015 to January 2019. The morphology grade and blastocyst inner diameter compared with clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage. The sex ratio was estimated for all patients, excluding those who underwent PGT-A, donor oocytes, and monozygotic twins. Blastocyst quality was evaluated with Gardner and Schoolcraft grading system and measured inner diameter of the blastocyst. Participants/materials, setting, methods All patients underwent a clomiphene-based minimal ovarian stimulation protocol or drug-free natural cycle IVF treatment. On day 5 to 6, blastocysts that reached an inner diameter &amp;gt;160μm were immediately vitrified. Blastocyst morphology evaluated by ICM and TE grade. The CPR (with a confirmed gestational sac at 6–7 weeks of pregnancy) and the LBR (live birth at 22 weeks of pregnancy over) were estimated per embryo transfer procedure, followed by miscarriage rate. Main results and the role of chance The CPR was 44.69%, 38.97%, and 25.91% for A, B, C grades of ICM, respectively. And the LBR was 39.82%, 34.62%, and 19.1% for A, B, C grades of ICM, respectively. TE was strongly related to CPR (aOR=2.47, 95% CI 1.71–3.58, p &amp;lt; 0.01) and LBR (aOR=1.77, 95% CI 1.06–2.96, p = 0.028) in univariate and multivariable logistic regression analysis (A grade vs C grade). Also, CPR and LBR were increased with blastocyst inner diameter, proportionally. The A and B grade ICM blastocysts showed 2.8 - 2.9 times less miscarriage rate than the C grade of ICM in the univariate logistic regression analysis. The result of multivariable logistic regression analysis showed B grade of ICM had 2.3 times less than C grade of ICM (aOR 2.36, CI 95% 1.20–4.61, p = 0.012) and TE, patient age and blastocyst inner diameter were not significantly associated with miscarriage rate. The gender ratio was 56.8% (204/359) for male. The result of multivariable logistic regression analysis showed that A grade TE had a 2.3 times higher probability of male than C grade (aOR 2.31, CI 95% 1.22–4.37, p = 0.01). Neither fertilization method, ICM, expiation grade, nor fertility case was significantly associated with the sex ratio. Limitations, reasons for caution The result of the current retrospective study is limited to data from a single IVF center. Wider implications of the findings: Our study suggests that TE grade is the most predictable and ICM grade was associated with miscarriage. The high grade such as A-grade TE blastocyst transfer has more live birth rate, whereas it can affects at sex ratio in favor of male embryos after SVBT. Trial registration number Not applicable </jats:sec

Left Ventricular Noncompaction Cardiomyopathy in Children: A Focus on Genetic and Molecular Mechanisms

Left ventricular noncompaction (LVNC), also called noncompaction cardiomyopathy (NCM), is a myocardial disease that affects children and adults. Morphological features of LVNC include a noncompacted spongiform myocardium due to the presence of excessive trabeculations and deep recesses between prominent trabeculae. Incidence and prevalence rates of this disease remain contentious due to varying clinical phenotypes, ranging from an asymptomatic phenotype to fulminant heart failure, cardiac dysrhythmias, and sudden death. There is a strong genetic component associated with LVNC, and nearly half of pediatric LVNC patients harbor an identifiable genetic mutation. Recent studies have identified LVNC-associated mutations in genes involved in intercellular trafficking and cytoskeletal integrity, in addition to well-known mutations causing abnormal cardiac embryogenesis. Currently, the diagnosis is based on symptoms, as well as various diagnostic criteria, including echocardiography, electrocardiograms, and cardiac magnetic resonance imaging. Meanwhile, clinical management is primarily focused on the prevention of complications, such as heart failure, thromboembolic events, life-threatening arrhythmias, and stroke. Continued research is focusing on the genetic etiology, the development of gold-standard diagnostic criteria, and evidence-based treatment guidelines across all age groups. This review article will highlight the genotype–phenotype relationship within pediatric LVNC patients and assess the latest discoveries in genetic and molecular research aimed at improving their diagnostic and therapeutic management