Review on the possible tool materials for friction stir welding of steel plates

The friction stir welding (FSW) process is mainly used in industrial applications for joining low melting temperature materials such as aluminium and magnesium. FSW has many advantages in comparison with conventional fusion arc welding. Therefore the interest to use this technique for joining steel plates has grown. However such usage is still limited because of the lack of adequate tool materials. This review gives an overview of possible tool materials for FSW of steels focussing on tungsten, tungsten carbide, pcBN and a few ultra-high temperature ceramics

Shape dependence of two-cylinder Renyi entropies for free bosons on a lattice

Universal scaling terms occurring in Renyi entanglement entropies have the potential to bring new understanding to quantum critical points in free and interacting systems. Quantitative comparisons between analytical continuum theories and numerical calculations on lattice models play a crucial role in advancing such studies. In this paper, we exactly calculate the universal two-cylinder shape dependence of entanglement entropies for free bosons on finite-size square lattices, and compare to approximate functions derived in the continuum using several different ansatzes. Although none of these ansatzes are exact in the thermodynamic limit, we find that numerical fits are in good agreement with continuum functions derived using the AdS/CFT correspondence, an extensive mutual information model, and a quantum Lifshitz model. We use fits of our lattice data to these functions to calculate universal scalars defined in the thin-cylinder limit, and compare to values previously obtained for the free boson field theory in the continuum.Comment: 7 pages, 5 figures, 1 tabl

Achievements and state of the art of hydrogen fuelled IC engines after twenty years of research at Ghent University

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Hydrogen could be “the” fuel for the future, not only for fuel cells but certainly for internal combustion engines. The research on hydrogen started at Ghent University in 1990 with the adaptation of a Valmet diesel engine to hydrogen operation (atmospheric, carbureted version) to prove the capability of hydrogen as a fuel for IC engines. Since then several engines were modified for hydrogen use with the state of the art technologies (sequential injection, electronic management units). With European (Craft, Brite) and Belgian grants three buses demonstrated on several levels the application of hydrogen IC engines. At the moment the laboratory test proves an operation with a power output higher than the gasoline engine, with an equal efficiency of the diesel engine and with very low emissions (NOx less than 100 ppm). The interests of the research group of Ghent University was not only for the experimental work, but also the combustion process is simulated (GUEST code). The estimated formula of the laminar flame speed of hydrogen by Verhelst is worldwide used in other research studies. At the moment a doctoral study examines the heat transfer in hydrogen engines, which is so different from the already not very accurate heat transfer models in gasoline and diesel engines. In our laboratory tests, the hydrogen engine is ready for mass production (backfire safe, high power output, high efficiency, very low emissions). But storage on the vehicle recently and infrastructure of the fuel delivery are the bottle-necks for a real implementation of the hydrogen economy. From hydrogen, methanol can be produced on a sustainable way. Methanol is a liquid (no storage problem on het vehicle) and with minor modifications the same infrastructure can be used as for gasoline. Methanol has very good engine characteristics. Will methanol based on hydrogen be then “the” fuel of the future?mp201

Rise time evaluation of the heat flux microsensor (HFM) on a hot-air-gun test rig

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Investigating the heat transfer inside internal combustion engines is key in the search for higher efficiency, higher power output and lower emissions. To understand the process and to validate model predictions, heat flux measurements inside an engine have to be conducted. In previous works, we have always used a commercially available thermopile to measure the heat transfer in a hydrogen combustion engine, but its large dimensions pose concerns about the sensor’s response time. Therefore, measurements have been done on a calibration rig with a hot air flow as heat source. This paper presents a comparison of the rise time of the thermopile with that of an alternative sensor developed for heat transfer measurements in gas turbines. The papers results in an increased confidence in the thermopile sensor, because its response time is at least as good as that of the alternative sensor. The results do show that the reproducibility of the test rig can be improved. Moreover, due to fluctuations in the heat flux level generated by the source, only the order of magnitude of the measured heat flux of two different experiments was comparable. Therefore, a new calibration rig will be developed to improve the reproducibility and to increase stability of the heat flux level of the heat source.mp201

Association of 11β-hydroxysteroid dehydrogenase type I expression and activity with estrogen receptor β in adipose tissue from postmenopausal women

OBJECTIVE: 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) regenerates active cortisol from inert cortisone in adipose tissue. Elevated adipose tissue 11βHSD1 activity is observed in obese humans and rodents where it is linked to obesity and its metabolic consequences. Menopause is also associated with increased abdominal fat accumulation suggesting that estrogen is also important in adipose tissue metabolism. The purpose of this current study was to establish whether estrogen signalling through estrogen receptors-α and -β (ERα and ERβ) can influence 11βHSD1 in premenopausal and postmenopausal adipose tissue. METHODS: 19 premenopausal (aged 26±5, BMI 23.6±1.6) and 23 postmenopausal healthy women (aged 63±4, BMI 23.4±1.9) were studied. Subcutaneous adipose tissue biopsies and fasting venous blood samples were taken. Body composition was measured by bio-electrical impedance analysis. Human SGBS adipocyte cells were treated with ERα and ERβ-specific agonists for 24h. Basic anthropometric data, Serum 17β-estradiol and progesterone concentrations, ERα and ERβ mRNA levels and 11βHSD1 mRNA, protein and activity levels were assessed. RESULTS: ERβ and 11βHSD1, but not ERα mRNA was significantly increased in adipose tissue from postmenopausal women compared to premenopausal women. ERβ had a significant positive correlation with the mRNA level of 11βHSD1 in adipose tissue from pre- and postmenopausal women. This association between ERβ and 11βHSD1 was greatest in adipose tissue from postmenopausal women. In human SGBS adipocytes, diarylpropiolnitrile (DPN), a selective ERβ agonist increased 11βHSD1 mRNA, protein and activity levels. CONCLUSIONS: We conclude that in adipose tissue, ERβ-mediated estrogen-signalling can upregulate 11βHSD1 and that this may be of particular importance in postmenopausal women

Role of maternal diet in the risk of childhood acute leukemia: a systematic review and meta-analysis

Many studies have investigated the etiology of acute leukemia, one of the most common types of cancer in children; however, there is a lack of clarity regarding preventable risk factors. This systematic review and meta-analysis aimed to summarize the current evidence regarding the role of maternal dietary factors in the development of childhood leukemia. All epidemiological studies published until July 2022 that evaluated maternal dietary risk factors for childhood acute leukemia were identified in two electronic databases (PubMed and Web of Science) without limits of publication year or language. A total of 38 studies (1 prospective cohort study, 34 case-control studies and 3 studies with pooled analysis) were included. The published risk estimates were combined into a meta-analysis, using the Generic Inverse Variance method. The maternal consumption of fruits (two or more daily servings vs. less) was inversely associated with acute lymphoblastic leukemia (odds ratio = 0.71; 95% CI, 0.59–0.86), whereas maternal coffee intake (higher than two cups per day vs. no consumption) was associated with an increased risk of acute lymphoblastic leukemia (odds ratio = 1.45; 95% CI, 1.12–1.89). Despite these findings, more high-quality research from cohort studies and the identification of causal factors are needed to develop evidence-based and cost-effective prevention strategies applicable at the population level. Review Registration: PROSPERO registration no. CRD42019128937

Early Life Nutrition Factors and Risk of Acute Leukemia in Children: Systematic Review and Meta-Analysis

Acute leukemia commonly occurs in young children with peak incidence at the age of 2–5 years. However, the etiology is still unclear and many preventable risk factors still deserve to be reviewed. The focus of this systematic review and meta-analysis is to summarize the evidence concerning early life nourishment (breastfeeding, early life diet), neonatal vitamin K administration and the risk of acute leukemia. All epidemiological studies published up to June 2023 and assessing diet-related risk factors for childhood acute leukemia were identified in two electronic databases (PubMed and Web of Science), with no limits on publication year or language. A total of 38 studies (37 case–control studies and 1 study with pooled analysis) were included. The published risk estimates were combined into a meta-analysis using the Generic Inverse Variance method. The current evidence shows that breastfeeding (yes vs. no) has a protective effect against acute lymphoblastic leukemia (odds ratio = 0.85; 95% CI, 0.76–0.94). Evidence related to the role of other studied factors (foods and supplements) is inconclusive. Further research into the potential role of diet in early life and the risk of acute leukemia is needed to develop prevention strategies at population level. Review Registration: PROSPERO registration no. CRD42019128937

‘We Learn Together’—Translanguaging within a Holistic Approach towards Multilingualism in Education

Within two multilingual education projects in the north of the Netherlands a holistic model for multilingualism in education is being tested. This is done through design-based interventions in which in- and pre-service teachers, teacher trainers and researchers co-develop and evaluate multilingual activities for different school types. Results show that through experimenting in a safe environment teachers gradually embraced their pupils’ multilingualism. This contradicts earlier findings on teachers strongly favouring monolingual instruction and viewing migrant languages as a deficit.<br/

Motivated learning with digital learning tasks: what about autonomy and structure?

Article about Motivated learning with digital learning tasks: what about autonomy and structure