137 research outputs found
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 ātheā 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 ātheā 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 sensorās 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 11Ī²-hydroxysteroid dehydrogenase type I expression and activity with estrogen receptor Ī² in adipose tissue from postmenopausal women
OBJECTIVE: 11Ī²-hydroxysteroid dehydrogenase type 1 (11Ī²HSD1) regenerates active cortisol from inert cortisone in adipose tissue. Elevated adipose tissue 11Ī²HSD1 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-Ī± and -Ī² (ERĪ± and ERĪ²) can influence 11Ī²HSD1 in premenopausal and postmenopausal adipose tissue. METHODS: 19 premenopausal (aged 26Ā±5, BMI 23.6Ā±1.6) and 23 postmenopausal healthy women (aged 63Ā±4, BMI 23.4Ā±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 ERĪ± and ERĪ²-specific agonists for 24h. Basic anthropometric data, Serum 17Ī²-estradiol and progesterone concentrations, ERĪ± and ERĪ² mRNA levels and 11Ī²HSD1 mRNA, protein and activity levels were assessed. RESULTS: ERĪ² and 11Ī²HSD1, but not ERĪ± mRNA was significantly increased in adipose tissue from postmenopausal women compared to premenopausal women. ERĪ² had a significant positive correlation with the mRNA level of 11Ī²HSD1 in adipose tissue from pre- and postmenopausal women. This association between ERĪ² and 11Ī²HSD1 was greatest in adipose tissue from postmenopausal women. In human SGBS adipocytes, diarylpropiolnitrile (DPN), a selective ERĪ² agonist increased 11Ī²HSD1 mRNA, protein and activity levels. CONCLUSIONS: We conclude that in adipose tissue, ERĪ²-mediated estrogen-signalling can upregulate 11Ī²HSD1 and that this may be of particular importance in postmenopausal women
Oestrogen receptor Ī² and neoadjuvant therapy with tamoxifen: prediction of response and effects of treatment
In order to elucidate the relative importance of oestrogen receptor (ER)Ī±, ERĪ² and an ERĪ² variant (ERĪ²2/Ī²cx) in the response of breast cancers to tamoxifen, tumour levels of each receptor were assessed in 36 patients before and after 3 months of neoadjuvant treatment with tamoxifen (20āmg daily). All patients were postmenopausal women presenting with large ERĪ±-positive breast cancers. Clinical response to treatment was assessed by tumour volume changes as determined from sequential ultrasounds and pathological response by comparison of the tumour morphology before and after treatment. Of 33 cases, 23 (70%) were classified as having a clinical response and 16 (48%) as having a response pathologically. All tumours stained positively for ERĪ± and ERĪ² and 15 out of 33 (45%) for ERĪ²2/Ī²cx. There were no significant differences in quantitative expression of any receptor between tumours that subsequently responded and that did not, whether response was assessed clinically or pathologically. Tamoxifen treatment was associated with a decrease in ERĪ±, but an increase was the most frequent change (17 out of 33) in ERĪ², and no consistent change was evident in staining of the ERĪ²2/Ī²cx variant. In summary, ERĪ²1 and ERĪ²2/Ī²cx variant protein are detected in ERĪ±-positive breast tumours but their expression is not associated with a response to tamoxifen. Differential changes in ERĪ± and ERĪ² were seen with treatment
āWe Learn TogetherāāTranslanguaging 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 pupilsā 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
Soy isoflavones and their relationship with microflora: beneficial effects on human health in equol producers
The bioavailability of soy isoflavones depends on the composition of the microflora for each subject. Bacteria act on different isoflavones with increased or reduced absorption and cause biotransformation of these compounds into metabolites with higher biological activity. S-equol is the most important metabolite and only 25ā65 % of the population have the microflora that produces this compound. The presence of equol-producing bacteria in soy product consumers means that the consumption of such products for prolonged periods leads to lower cardiovascular
risk, reduced incidence of prostate and breast cancer, and greater relief from symptoms related to the menopause such as hot flushes and osteoporosis
Expression of oestrogen receptors, ERĪ±, ERĪ², and ERĪ² variants, in endometrial cancers and evidence that prostaglandin F may play a role in regulating expression of ERĪ±
<p>Abstract</p> <p>Background</p> <p>Endometrial cancer is the most common gynaecological malignancy; risk factors include exposure to oestrogens and high body mass index. Expression of enzymes involved in biosynthesis of oestrogens and prostaglandins (PG) is often higher in endometrial cancers when compared with levels detected in normal endometrium. Oestrogens bind one of two receptors (ERĪ± and ERĪ²) encoded by separate genes. The full-length receptors function as ligand-activated transcription factors; splice variant isoforms of ERĪ² lacking a ligand-binding domain have also been described. PGs act in an autocrine or paracrine manner by binding to specific G-protein coupled receptors.</p> <p>Methods</p> <p>We compared expression of ERs, progesterone receptor (PR) and cyclooxygenase-2 (COX-2) in stage 1 endometrial adenocarcinomas graded as well (G1), moderately (G2) or poorly (G3) differentiated (n ā„ 10 each group) using qRTPCR, single and double immunohistochemistry. We used endometrial adenocarcinoma cell lines to investigate the impact of PGF2Ī± on expression of ERs and PR.</p> <p>Results</p> <p>Full length ERĪ² (ERĪ²1) and two ERĪ² variants (ERĪ²2, ERĪ²5) were expressed in endometrial cancers regardless of grade and the proteins were immunolocalised to the nuclei of cells in both epithelial and stromal compartments. Immunoexpression of COX-2 was most intense in cells that were ERĪ±<sup>neg/low</sup>. Expression of PR in endometrial adenocarcinoma (Ishikawa) cell lines and tissues broadly paralleled that of ERĪ±. Treatment of adenocarcinoma cells with PGF2Ī± reduced expression of ERĪ± but had no impact on ERĪ²1. Cells incubated with PGF2Ī± were unable to increase expression of PR mRNA when they were incubated with E2.</p> <p>Conclusion</p> <p>We have demonstrated that ERĪ²5 protein is expressed in stage 1 endometrial adenocarcinomas. Expression of three ERĪ² variants, including the full-length protein is not grade-dependent and most cells in poorly differentiated cancers are ERĪ²<sup>pos</sup>/ERĪ±<sup>neg</sup>. We found evidence of a link between COX-2, its product PGF2Ī±, and expression of ERĪ± and PR that sheds new light on the cross talk between steroid and PG signalling pathways in this disease.</p
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