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Journal articles on the topic "PlGF ratio"
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Lévy, Pacifique, Safouane Hamdi, Jean Guiboudenche, Marie Clothilde Haguet, Sophie Bailleul, and Guillaume Lefèvre. "Applying the concept of uncertainty to the sFlt-1/PlGF cut-offs for diagnosis and prognosis of preeclampsia." Clinical Chemistry and Laboratory Medicine (CCLM) 59, no. 4 (February 23, 2021): 681–86. http://dx.doi.org/10.1515/cclm-2020-0477.
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Abstract Objectives Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) assays and the corresponding ratios (sFlt-1/PlGF) have been proposed to aid in the diagnosis by exclusion and/or prognosis of preeclampsia (PE). A method for evaluating ratio uncertainties (RUs), based on the theory of error propagation, was applied to the sFlt-1/PlGF ratio. Methods RUs were calculated using data derived from sFlt-1 and PlGF Internal Quality Control (IQC) results collected from four centers using Elecsys (Roche) or Kryptor (Thermo Fisher) sFlt-1 and PlGF assays. The corresponding ratio uncertainties were defined for each ratio value. Results The RUs increased linearly with the sFlt-1/PlGF ratio values. The Elecsys RUs were lower than the Kryptor RUs. Although RUs cannot eliminate differences in ratio values observed among various immunoassays, it can affect interpretation of the sFlt-1/PlGF ratio, especially when results are within the range of predefined PE diagnosis or prognosis cut-offs. Conclusions Since RUs are only a function of PlGF and sFlt-1 precision, they can be calculated for each assay from each laboratory to adjust the interpretation of sFlt-1/PlGF ratio results in the context of PE.
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Wulandari, Diah, Mohamad Sulchan, and Syarief Thaufik Hidayat. "Levels of molecular angiogenic and antiangiogenic in pregnant women with risk of preeclampsia." International Journal of Reproduction, Contraception, Obstetrics and Gynecology 8, no. 10 (September 26, 2019): 4034. http://dx.doi.org/10.18203/2320-1770.ijrcog20194376.
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Background: Angiogenic and antiangiogenic imbalances play a major role in the pathogenesis of preeclampsia. Increased production of sFlt-1 by the placenta causes free circulating PIGF and VEGF concentrations to lower because it is bound by sFlt-1. Measuring levels of angiogenic and antiangiogenic proteins as biomarkers indicates placental dysfunction and distinguishes preeclampsia from other disorders. This study aims to analyze the levels of angiogenic and antiangiogenic molecules in pregnant women at risk for preeclampsia.Methods: The study with a cross-sectional design was carried out in 11-15 weeks gestational age whom had a risk of preeclampsia with 30 samples in primary health care starting April-August 2018. Blood serum was measured by molecular levels of VEGF, PlGF, sFlt-1, and sFlt-1/PlGF ratio using the ELISA method. Data analysis used Pearson product moment test.Results: The mean of VEGF levels are 15.5±21.6, PlGF 89.7±55.5, sFlt-1 11519.4±5126.0 and the ratio sFlt-1/PlGF 166.7±102.1. Correlation value of risk factors for preeclampsia with molecular levels of VEGF r= -0.05; p = 0.76, PlGF r= -0.21; p = 0.26, sFlt r= 0.01; p =0.99 and ratio sFlt-1/PlGF r = 0.10; p = 0.58.Conclusions: The higher the total score of preeclampsia risk factor, the lower the molecular level of VEGF and PlGF is. Moreover, the higher the total score of preeclampsia risk factor, the higher the molecular level sFlt-1 and the sFlt-1/PlGF ratio is. There are no significant correlation between total score of preeclampsia risk factor and levels of molecule VEGF, PlGF, sFlt-1 and sFlt-1/PlGF ratio.
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Smeele, H. T., R. I. Neuman, A. H. J. Danser, R. Dolhain, and W. Visser. "POS0542 DISEASE ACTIVITY IN PREGNANT WOMEN WITH RHEUMATOID ARTHRITIS: IMPACT ON THE SOLUBLE FMS-LIKE TYROSINE KINASE-1 TO PLACENTAL GROWTH FACTOR RATIO." Annals of the Rheumatic Diseases 80, Suppl 1 (May 19, 2021): 505. http://dx.doi.org/10.1136/annrheumdis-2021-eular.2438.
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Background:An elevated sFlt-1 indicates soluble Fms-like tyrosine kinase-1 (sFlt-1)/ placental growth factor (PlGF) ratio has recently been validated as significant predictor of preeclampsia (PE)(1). However, raised sFlt-1 levels due to inflammation are observed in patients with rheumatoid arthritis (RA)(2). The use of the sFlt-1/PlGF ratio for the prediction of PE has not been evaluated in pregnant women with diseases that are characterized by high levels of inflammation, such as RAObjectives:We investigated whether sFlt-1 and/or PlGF are altered in pregnant women with RA according to disease activity, and evaluated whether a sFlt-1/PlGF ratio of ≤38 could be used to predict the absence of PE in pregnant RA-patients.Methods:This study was embedded in a nationwide, observational, prospective cohort study on pregnant women with RA (PARA-study). sFlt-1 and PlGF levels were measured, using automated analyzer (Cobas-6000, e-module; Roche-Diagnostics), in the third trimester of pregnancy.Results:A total of 221 women, aged 21–42 years, were included. Values of sFlt-1, PlGF and sFlt-1/PlGF ratio were not significantly correlated with the DAS28-CRP (Figure 1). CRP correlated weakly with PlGF (r=-0.14, p=0.03), while no correlation was found with sFlt-1 or the sFlt-1/PlGF ratio.Preeclampsia occurred in four out of 214 women with a ratio ≤38 (2%) in contrast to three out of seven women with a ratio >38 (43%), p<0.001 (Table 1). When stratified to a sFlt-1/PlGF ratio of ≤38 only 2% of women developed preeclampsia, compared to 43% of the women with a ratio >38. The observed sensitivity and specificity for a sFlt-1/PlGF ratio cut-off of ≤38 were 42.1% and 98.1%, respectively, with a negative predictive value (NPV) of 98%. All women that developed PE, developed PE >4 weeks after collecting of blood samples in the 3rd trimester, therefore the observed NPV could be even higher.Table 1.Pregnancy Outcome according to sFlt-1/PlGF ratio with a cut-off value of 38.ParameterRatio ≤38Ratio >38P-valueN2147GA at birth, weeks39 (38 - 40)37 (36 - 40)0.05<342 (1)0(0)1.0034 - 3718 (8)2 (29)0.12Male, n (%)113 (53)5 (71)0.45Birth weight, grams3420 (2998 - 3800)2620 (2360 - 2850)<0.01Maternal OutcomeGestational Hypertension15 (7)2 (29)0.09Preeclampsia4 (2)3 (43)<0.001Time to delivery, days66 (52 - 75)52 (44 - 66)0.08Fetal OutcomeBirth weight percentile <1033 (15)5 (71)<0.01Fetal/Neonatal Death1 (1)0 (0)1.00Data are reported as median (interquartile range) or number (percentage). sFlt-1 indicates soluble Fms-like tyrosine kinase-1; PlGF, placental growth factor; GA, gestational age. Time to delivery is defined as the amount of days between blood sampling and delivery.Conclusion:Our study shows that in pregnant women with RA, the sFlt-1/PlGF ratio is not altered due to disease activity, and a cut-off of ≤38 of this ratio can be used to exclude preeclampsia.References:[1]H. Zeisler et al. Predictive Value of the sFlt-1:PlGF Ratio in Women with Suspected Preeclampsia. N Engl J Med 2016; 374: 13-22. DOI 10.1056/NEJMoa1414838.[2]S. Ballara et al. Paleolog. Raised serum vascular endothelial growth factor levels are associated with destructive change in inflammatory arthritis. Arthritis Rheum 2001; 44: 2055-2064. DOI 10.1002/1529-0131(200109)44:9<2055::AID-ART355>3.0.CO;2-2.Figure 1.Correlations between sFlt-1, PlGF and sFlt-1/PlGF ratio with DAS28-CRP and CRP. Correlation coefficients for sFlt-1 (A-B), PlGF (C-D) and sFlt-1/PlGF ratio (E-F) with DAS28-CRP and CRP.Acknowledgements:The kits for measurement of sFlt-1/PlGF ratio were a kind gift from Roche Diagnostics, Germany. We thank all participants of the PARA study. Additionally, we extend our gratitude to the laboratory workers, in particular Nadine Davelaar and Priyanka Bangoer, and research assistants for their contribution to the data collection. We thank ReumaNederland (LLP project number: LLP-26) for their financial support.Disclosure of Interests:Hieronymus TW Smeele: None declared, R.I. Neuman: None declared, A.H.J. Danser: None declared, Radboud Dolhain Speakers bureau: Yes UCB, Roche, Abbvie, Genzyme, Novartis, Consultant of: Yes, Galapagos, Grant/research support from: Yes, UCB, W. Visser: None declared
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Hodel, Markus, Patricia R. Blank, Petra Marty, and Olav Lapaire. "sFlt-1/PlGF Ratio as a Predictive Marker in Women with Suspected Preeclampsia: An Economic Evaluation from a Swiss Perspective." Disease Markers 2019 (August 14, 2019): 1–10. http://dx.doi.org/10.1155/2019/4096847.
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In Switzerland, 2.3% of pregnant women develop preeclampsia. Quantification of the soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) ratio has shown a diagnostic value in the second and third trimesters of pregnancy, in particular in ruling out preeclampsia within one week. We estimated the economic impact of implementing sFlt-1/PlGF ratio evaluation, in addition to the standard of care (SOC), for women with suspected preeclampsia from a Swiss healthcare system’s perspective. A decision tree model was developed to estimate direct medical costs of diagnosis and management of a simulated cohort of Swiss pregnant women with suspected preeclampsia (median week of gestation: 32) until delivery. The model compared SOC vs. SOC plus sFlt-1/PlGF ratio, using clinical inputs from a large multicenter study (PROGNOSIS). Resource use data and unit costs were obtained from hospital records and public sources. The assumed cost for sFlt-1/PlGF evaluation was €141. Input parameters were validated by clinical experts in Switzerland. The model utilized a simulated cohort of 6084 pregnant women with suspected preeclampsia (representing 7% of all births in Switzerland in 2015, n=86,919). In a SOC scenario, 36% of women were hospitalized, of whom 27% developed preeclampsia and remained hospitalized until birth. In a sFlt-1/PlGF test scenario, 76% of women had a sFlt-1/PlGF ratio of ≤38 (2% hospitalized), 11% had a sFlt-1/PlGF ratio of >38-<85 (55% hospitalized), and 13% had a sFlt-1/PlGF ratio of ≥85 (65% hospitalized). Total average costs/pregnant woman (including birth) were €10,925 vs. €10,579 (sFlt-1/PlGF), and total costs were €66,469,362 vs. €64,363,060 (sFlt-1/PlGF). Implementation of sFlt-1/PlGF evaluation would potentially achieve annual savings of €2,105,064 (€346/patient), mainly due to reduction in unnecessary hospitalization. sFlt-1/PlGF evaluation appears economically promising in predicting short-term absence of preeclampsia in Swiss practice. Improved diagnostic accuracy and reduction in unnecessary hospitalization could lead to significant cost savings in the Swiss healthcare system.
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Hassan, Mahmoud Fathy, Nancy Mohamed Ali Rund, and Ahmed Husseiny Salama. "An Elevated Maternal Plasma Soluble fms-Like Tyrosine Kinase-1 to Placental Growth Factor Ratio at Midtrimester Is a Useful Predictor for Preeclampsia." Obstetrics and Gynecology International 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/202346.
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Background.To assess the ability of mid-trimester sFlt-1/PlGF ratio for prediction of preeclampsia in two different Arabic populations.Methods.This study measured levels of sFlt-1, PlGF, and sFlt-1/PlGF ratio at midtrimester in 83 patients who developed preeclampsia with contemporary 250 matched controls.Results.Women subsequently developed preeclampsia had significantly lower PlGF levels and higher sFlt-1 and sFlt-1/PlGF ratio levels than women with normal pregnancies (P<0.0001for all). Women who with preterm preeclampsia had significantly higher sFlt-1 and sFlt-1/PlGF ratio than term preeclamptic women (P=0.01, 0.003, resp.). A cutoff value of 3198 pg/mL for sFlt-1 was able to predict preeclampsia with sensitivity, specificity, and accuracy of 88%, 83.6%, and 84.7%, respectively, with odds ratio (OR) 37.2 [95% confidence interval (CI) 17.7–78.1]. PIGF at cutoff value of 138 pg/mL was able to predict preeclampsia with sensitivity, specificity, and accuracy of 85.5%, 77.2%, and 79.3%, respectively, with OR 20 [95% CI, 10.2–39.5]. The sFlt-1/PIGF ratio at cutoff value of 24.5 was able to predict preeclampsia with sensitivity, specificity, and accuracy of 91.6%, 86.4%, and 87.7%, respectively with OR 67 [95% CI, 29.3–162.1].Conclusion.Midtrimester sFlt-1/PlGF ratio displayed the highest sensitivity, specificity, accuracy, and OR for prediction of preeclampsia, demonstrating that it may stipulate more effective prediction of preeclampsia development than individual factor assay.
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Lafuente-Ganuza, Paula, Paloma Lequerica-Fernandez, Francisco Carretero, Ana I. Escudero, Eduardo Martinez-Morillo, Enric Sabria, Ignacio Herraiz, et al. "A more accurate prediction to rule in and rule out pre-eclampsia using the sFlt-1/PlGF ratio and NT-proBNP as biomarkers." Clinical Chemistry and Laboratory Medicine (CCLM) 58, no. 3 (February 25, 2020): 399–407. http://dx.doi.org/10.1515/cclm-2019-0939.
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AbstractBackgroundThe management of potential pre-eclamptic patients using the soluble FMS-like tyrosine kinase 1 (sFlt-1)/ placental growth factor (PlGF) ratio is characterised by frequent false-positive results.MethodsA retrospective cohort study was conducted to identify and validate cut-off values, obtained using a machine learning model, for the sFlt-1/PlGF ratio and NT-proBNP that would be predictive of the absence or presence of early-onset pre-eclampsia (PE) in singleton pregnancies presenting at 24 to 33 + 6 weeks of gestation.ResultsFor the development cohort, we defined two sFlt-1/PlGF ratio cut-off values of 23 and 45 to rule out and rule in early-onset PE at any time between 24 and 33 + 6 weeks of gestation. Using an sFlt-1/PlGF ratio cut-off value of 23, the negative predictive value (NPV) for the development of early-onset PE was 100% (95% confidence interval [CI]: 99.5–100). The positive predictive value (PPV) of an sFlt-1/PlGF ratio >45 for a diagnosis of early-onset PE was 49.5% (95% CI: 45.8–55.6). When an NT-proBNP value >174 was combined with an sFlt-1/PlGF ratio >45, the PPV was 86% (95% CI: 79.2–92.6). In the validation cohort, the negative and positive values were very similar to those found for the development cohort.ConclusionsAn sFlt-1/PlGF ratio <23 rules out early-onset PE between 24 and 33 + 6 weeks of gestation at any time, with an NPV of 100%. An sFlt-1/PlGF ratio >45 with an NT-proBNP value >174 significantly enhances the probability of developing early-onset PE.
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Binder, Julia, Pilar Palmrich, Petra Pateisky, Erkan Kalafat, Lorenz Kuessel, Harald Zeisler, March Munkhbaatar, Karin Windsperger, Basky Thilaganathan, and Asma Khalil. "The Prognostic Value of Angiogenic Markers in Twin Pregnancies to Predict Delivery Due to Maternal Complications of Preeclampsia." Hypertension 76, no. 1 (July 2020): 176–83. http://dx.doi.org/10.1161/hypertensionaha.120.14957.
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The sFlt-1 (soluble fms-like tyrosine kinase-1), PlGF (placental growth factor), and their ratio are useful for predicting delivery because of preeclampsia in singleton pregnancies. Evidence on the utility of sFlt-1/PlGF ratio in twin pregnancies is lacking. We aimed to evaluate the predictive value of sFlt-1/PlGF ratio for delivery because of preeclampsia in twins. A retrospective data analysis of 164 twin pregnancies with suspected preeclampsia was performed. The sFlt-1/PlGF ratio, which was known to clinicians, was significantly higher in women who delivered within 1 and 2 weeks compared with those who did not (median: 98.9 and 84.2 versus 23.5 pg/mL, respectively; P <0.001). The area under the curve values sFlt-1/PlGF ratio levels were 0.88 (95% CI, 0.83–0.84) and 0.88 (95% CI, 0.83–0.93) for predicting delivery because of preeclampsia within 1 and 2 weeks of blood sampling, respectively. The predictive accuracy of sFlt-1/PlGF was independent of gestational age at sampling and chorionicity ( P >0.100 for interaction). The area under the curve values of sFlt-1/PlGF were significantly higher than for PlGF alone (mean 0.88 and 0.88 versus 0.81 and 0.80) for predicting delivery because of preeclampsia within 1 and 2 weeks of blood sampling ( P =0.055 and 0.001, respectively). sFlt-1/PlGF ratio lower than 38 was able to rule-out delivery within 1 and 2 weeks with a negative predictive value of 98.8% and 96.4% for delivery because of preeclampsia within 1 and 2 weeks, respectively. A cutoff of 38 is applicable for ruling out delivery because of preeclampsia in twin pregnancies.
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Mayer-Pickel, Karoline, Vassiliki Kolovetsiou-Kreiner, Christina Stern, Julia Münzker, Katharina Eberhard, Slave Trajanoski, Ioana-Claudia Lakovschek, et al. "Effect of Low-Dose Aspirin on Soluble FMS-Like Tyrosine Kinase 1/Placental Growth Factor (sFlt-1/PlGF Ratio) in Pregnancies at High Risk for the Development of Preeclampsia." Journal of Clinical Medicine 8, no. 9 (September 10, 2019): 1429. http://dx.doi.org/10.3390/jcm8091429.
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Background: Soluble FMS-like Tyrosine Kinase 1 (sFlt-1) and placental growth factor (PlGF) have been reported to be highly predictive several weeks before the onset of preeclampsia. Objective: To investigate longitudinal changes of serum levels sFlt-1 and PlGF in pregnant women at high risk for the development of preeclampsia and to reveal an impact of aspirin on maternal serum concentrations of sFlt-1 and PlGF. Methods: This was a prospective longitudinal study in 394 women with various risk factors for the development of preeclampsia (chronic hypertension, antiphospholipid syndrome/APS or systemic lupus erythematosus/SLE, thrombophilia, women with a history of preeclampsia, pathologic first trimester screening for preeclampsia) and 68 healthy women. Serum levels of sFlt-1 and PlGF were measured prospectively at 4-week intervals (from gestational weeks 12 until postpartum). Results: The sFlt-1/PlGF ratio was significantly higher in women with an adverse obstetric outcome compared to women with a normal pregnancy, starting between 20 and 24 weeks of gestation. There was no effect of aspirin on sFlt-1/PlGF ratio in women with chronic hypertension, APS/SLE, thrombophilia and controls. The use of aspirin showed a trend towards an improvement of the sFlt-1/PlGF ratio in women with preeclampsia in a previous pregnancy and a significant effect on the sFlt-1/PlGF ratio in women with a pathologic first trimester screening for preeclampsia. Conclusions: Our findings reveal an impact of aspirin on sFlt-1/PlGF ratio in women with a pathologic first trimester screening for preeclampsia, strongly supporting its prophylactic use.
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Lou, Wei-zhen, Fang Jiang, Jing Hu, Xiao-xu Chen, Ying-na Song, Xi-ya Zhou, Jun-tao Liu, Xu-ming Bian, and Jin-song Gao. "Maternal Serum Angiogenic Factor sFlt-1 to PlGF Ratio in Preeclampsia: A Useful Marker for Differential Diagnosis and Prognosis Evaluation in Chinese Women." Disease Markers 2019 (July 16, 2019): 1–7. http://dx.doi.org/10.1155/2019/6270187.
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The ratio of soluble fms-like tyrosine kinase-1 to placental growth factor (sFlt-1/PlGF) is elevated and proved to be useful in preeclampsia (PE) diagnosis. Its value in differential diagnosis with other pregnancy complications and prediction of pregnancy duration has yet to be clarified in Chinese population. We retrospectively analyzed 118 singleton pregnancies with suspected or diagnosed PE at the Peking Union Medical College Hospital (PUMCH) in China. Among these, 62 pregnancies were diagnosed as PE (48 early onsets and 14 late onsets, with 39 and 5 severe PE, respectively), 12 gestational hypertension (GH), 15 chronic hypertension (chrHTN), 16 autoimmune diseases, and 13 pregnancies with uncomplicated proteinuria. And 76 normal pregnancies were included as control. The results showed (1) the sFlt-1/PlGF ratio in early onset PE subgroup was significantly higher than that in GH, chrHTN, and control groups; the sFlt-1/PlGF ratio in late onset PE subgroup was significantly higher than that in chrHTN and control groups, but similar as GH group; the sFlt-1/PlGF ratio was similar among GH, chrHTN, and control groups. (2) The sFlt-1/PlGF ratio was significantly increased in the PE group compared with autoimmune disease and uncomplicated proteinuria pregnancies. (3) By ROC curve analysis, the cutoff value of the sFlt-1/PlGF ratio was less than 21.5 to rule out PE and higher than 97.2 to confirm the diagnosis of PE. (4) The sFlt-1/PlGF ratio was higher in PE pregnancies delivering within 7 days than those more than 7 days, either in early onset PE or severe PE. In conclusion, we show that maternal sFlt-1/PlGF ratio is an efficient biomarker in the diagnosis and differential diagnosis of PE. This ratio can be used to predict the timing of delivery for PE pregnancies.
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Ohkuchi, Akihide, Chikako Hirashima, Shigeki Matsubara, Hirotada Suzuki, Kayo Takahashi, Rie Usui, and Mitsuaki Suzuki. "Serum sFlt1:PlGF Ratio, PlGF, and Soluble Endoglin Levels in Gestational Proteinuria." Hypertension in Pregnancy 28, no. 1 (January 2009): 95–108. http://dx.doi.org/10.1080/10641950802419895.
Full textDissertations / Theses on the topic "PlGF ratio"
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Tauscher, Anne. "Zusammenhang zwischen angiogenen Faktoren (sFlt-1/PlGF-Ratio) und klinischen Parametern des Schwangerschaftsausgangs bei manifesten hypertensiven Schwangerschaftserkrankungen." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-106852.
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Die Bedeutung der angiogenen Faktoren „soluble fms-like tyrosine kinase-1“ (sFlt-1) und „placental growth factor“ (PIGF) in der Pathogenese der Präeklampsie (PE) ist in den letzten Jahren hinreichend belegt worden. Bei Patienten mit manifester PE lassen sich dramatisch hohe sFlt-1- bzw. sehr niedrige PlGF-Werte nachweisen. Mittlerweile konnte in Studien die sFlt-1/PlGF-Ratio als sensitiver Parameter ermittelt werden. Ziel der vorliegenden Arbeit ist es, die Zusammenhänge zwischen klinischen Parametern der manifesten Präeklampsie und der sFlt-1/PlGF-Ratio zu spezifizieren. Dabei soll geprüft werden, ob bei manifester PE die Höhe der sFlt-1/PlGF-Ratio vor Entbindung klinische Bedeutung hat und mit Parametern des Schwangerschaftsausgangs in Beziehung steht.
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Husse, Sorina Ines. "Die Wertigkeit des sFlt-1/PlGF-Quotienten als Prädiktionsmarker bei Schwangeren mit erhöhtem Präeklampsierisiko." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-160542.
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Einleitung: Die Dysbalance proangiogener (Placental Growth Factor = PlGF) und antiangiogener Faktoren (soluble fms-like tyrosine kinase 1 = sFlt-1) gilt heute als pathophysiologische Grundlage bei der Entstehung einer Präeklampsie (PE), eines HELLP-Syndroms (Haemolysis, Elevated Liver enzymes, Low Platelets) oder einer intrauterinen Wachstumsretardierung (IUGR). Der sFlt1/PlGF-Quotient, ein sensitiver und robuster diagnostischer Marker, ist bereits Wochen vor der Krankheitsmanifestation erhöht. Ziel dieser Studie war es, die Wertigkeit des sFlt1/PlGFQuotienten als prädiktiven Faktor bei Risikopatientinnen zu untersuchen. Patienten und Methode: In diese prospektive Studie wurden 68 Patientinnen mit einer Einlingsschwangerschaft und mindestens einem Risikofaktor für das Auftreten einer PE, eines HELLP-Syndrom oder einer IUGR im Schwangerschaftsverlauf eingeschlossen. Die Patientinnen wurden je nach Verlauf der Schwangerschaft in eine Gruppe mit Symptomen (Fallgruppe) und eine Gruppe ohne Symptome (Kontrollgruppe) für eine der oben genannten Erkrankungen unterteilt. Der sFlt1/PlGF-Quotient wurde bei der Aufnahme in die Studie und im weiteren Schwangerschaftsverlauf bestimmt. Ergebnisse: Eine PE, ein HELLP-Syndrom oder eine IUGR trat bei 41 % der Risikopatientinnen auf… Der absolute Wert des sFlt-1/PlGF-Quotienten war nur bei der Gruppe mit Symptomen auf ≥ 85 erhöht und zeigte sich in der 25 + 0-31 + 0 SSW (p = 0,005) und ab der 35 + 0 SSW (p = 0,044) als prädiktiver Faktor für eine PE, ein HELLP-Syndrom oder eine IUGR. Ab 7–10 Wochen vor der Entbindung war, in der Fallgruppe stärker als in der Kontrollgruppe, ein Anstieg des sFlt1/PlGFQuotienten zu beobachten. Dieser war 0–2 Wochen vor der Entbindung bei beiden Gruppen (Kontrollgruppe (MW ± SA 66,9 ± 134) vs. Fallgruppe (MW ± SA 393,3 ± 147,4, p = 0,021) am ,stärksten und zeigte sich ebenfalls als prädiktiver Faktor für eine der genannten Schwangerschaftserkrankungen (p = 0,025). Schlussfolgerung: Bei Risikoschwangeren kann der sFlt1/ PlGF-Quotient für die Einschätzung des individuellen Risikos für eine PE, ein HELLP-Syndrom oder eine IUGR im Schwangerschaftsverlauf genutzt werden. Wiederholte Messungen des Quotienten versprechen eine risikoangepasste Betreuung dieser PatientinnenBackground: A dysbalance of proangiogenic [placental growth factor (PlGF)] and antiangiogenic [soluble fms-like tyrosine kinase 1 (sFlt-1)] proteins is known to cause the symptoms of preeclampsia (PE), HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) or intrauterine growth restriction (IUGR). An increased sFlt-1/ PlGF ratio ≥ 85 is considered a reliable diagnostic marker. Altered sFlt1 and PlGF concentrations can be detected several weeks prior to the onset of clinical symptoms. In this study we analysed the role of the sFlt1/PlGF ratio as a predictive marker for preeclampsia in a high-risk patient group. Patients and materials: We prospectively included 68 singleton pregnancies with at least one risk factor for PE, HELLP syndrome or IUGR. During the study the patients were divided into one group with symptoms (patient group) and one group without symptoms (control group) for the above-mentioned diseases. The sFlt1/PlGF ratios were measured on admission and during the course of pregnancy. Results: During pregnancy 41 % of patients developed PE, HELLP syndrome or IUGR. An increase of the absolute value of the sFlt1/PlGF ratio ≥ 85 was only observed in the patient group and was found to be a predictive factor for PE, HELLP syndrome or IUGR at 25 + 0 to 31 + 0 weeks of gestation (p = 0.005) and after 35 + 0 weeks of gestation (p = 0.044). Alterations of the sFlt1/PlGF ratio were observed in all patients but were higher in the patient group from 7–10 weeks prior to delivery and with the highest peak 0–2 weeks prior to delivery. Compared to the control group (mean ± SD 66.9 ± 134) absolute values of sFlt1/PlGF ratio were signifi cantly (p = 0.021) increased 0–2 weeks prior to delivery in the patient group (mean ± SD 393.3 ± 147.4). An increase of the sFlt1/PlGF ratio ≥ 85 0–2 weeks before delivery has shown to be predictive for one of the mentioned diseases (p = 0.025).Conclusions: In high-risk patients the sFlt1/PlGF ratio can be used for an individual risk assessment with regard to PE, HELLP syndrome or IUGR. Serial measurements permit a risk-adapted prenatal care of these patients
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Tauscher, Anne [Verfasser], Holger [Akademischer Betreuer] Stepan, Wolfgang [Gutachter] Henrich, and Dietmar [Gutachter] Schlembach. "Zusammenhang zwischen angiogenen Faktoren (sFlt-1/PlGF-Ratio) und klinischen Parametern des Schwangerschaftsausgangs bei manifesten hypertensiven Schwangerschaftserkrankungen / Anne Tauscher ; Gutachter: Wolfgang Henrich, Dietmar Schlembach ; Betreuer: Holger Stepan." Leipzig : Universitätsbibliothek Leipzig, 2013. http://d-nb.info/1238365965/34.
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Tauscher, Anne. "Zusammenhang zwischen angiogenen Faktoren (sFlt-1/PlGF-Ratio) und klinischen Parametern des Schwangerschaftsausgangs bei manifesten hypertensiven Schwangerschaftserkrankungen." Doctoral thesis, 2012. https://ul.qucosa.de/id/qucosa%3A11849.
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Die Bedeutung der angiogenen Faktoren „soluble fms-like tyrosine kinase-1“ (sFlt-1) und „placental growth factor“ (PIGF) in der Pathogenese der Präeklampsie (PE) ist in den letzten Jahren hinreichend belegt worden. Bei Patienten mit manifester PE lassen sich dramatisch hohe sFlt-1- bzw. sehr niedrige PlGF-Werte nachweisen. Mittlerweile konnte in Studien die sFlt-1/PlGF-Ratio als sensitiver Parameter ermittelt werden. Ziel der vorliegenden Arbeit ist es, die Zusammenhänge zwischen klinischen Parametern der manifesten Präeklampsie und der sFlt-1/PlGF-Ratio zu spezifizieren. Dabei soll geprüft werden, ob bei manifester PE die Höhe der sFlt-1/PlGF-Ratio vor Entbindung klinische Bedeutung hat und mit Parametern des Schwangerschaftsausgangs in Beziehung steht.
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Husse, Sorina Ines. "Die Wertigkeit des sFlt-1/PlGF-Quotienten als Prädiktionsmarker bei Schwangeren mit erhöhtem Präeklampsierisiko." Doctoral thesis, 2014. https://ul.qucosa.de/id/qucosa%3A13146.
Full textAbstract:
Einleitung: Die Dysbalance proangiogener (Placental
Growth Factor = PlGF) und antiangiogener
Faktoren (soluble fms-like tyrosine kinase
1 = sFlt-1) gilt heute als pathophysiologische
Grundlage bei der Entstehung einer Präeklampsie
(PE), eines HELLP-Syndroms (Haemolysis, Elevated
Liver enzymes, Low Platelets) oder einer
intrauterinen Wachstumsretardierung (IUGR).
Der sFlt1/PlGF-Quotient, ein sensitiver und robuster
diagnostischer Marker, ist bereits Wochen
vor der Krankheitsmanifestation erhöht. Ziel dieser
Studie war es, die Wertigkeit des sFlt1/PlGFQuotienten
als prädiktiven Faktor bei Risikopatientinnen
zu untersuchen.
Patienten und Methode: In diese prospektive
Studie wurden 68 Patientinnen mit einer Einlingsschwangerschaft
und mindestens einem Risikofaktor
für das Auftreten einer PE, eines
HELLP-Syndrom oder einer IUGR im Schwangerschaftsverlauf
eingeschlossen. Die Patientinnen
wurden je nach Verlauf der Schwangerschaft in
eine Gruppe mit Symptomen (Fallgruppe) und
eine Gruppe ohne Symptome (Kontrollgruppe)
für eine der oben genannten Erkrankungen unterteilt.
Der sFlt1/PlGF-Quotient wurde bei der
Aufnahme in die Studie und im weiteren Schwangerschaftsverlauf
bestimmt.
Ergebnisse: Eine PE, ein HELLP-Syndrom oder
eine IUGR trat bei 41 % der Risikopatientinnen
auf… Der absolute Wert des sFlt-1/PlGF-Quotienten
war nur bei der Gruppe mit Symptomen
auf ≥ 85 erhöht und zeigte sich in der 25 + 0-31 + 0
SSW (p = 0,005) und ab der 35 + 0 SSW (p = 0,044)
als prädiktiver Faktor für eine PE, ein HELLP-Syndrom
oder eine IUGR. Ab 7–10 Wochen vor der
Entbindung war, in der Fallgruppe stärker als in
der Kontrollgruppe, ein Anstieg des sFlt1/PlGFQuotienten
zu beobachten. Dieser war 0–2 Wochen
vor der Entbindung bei beiden Gruppen
(Kontrollgruppe (MW ± SA 66,9 ± 134) vs. Fallgruppe
(MW ± SA 393,3 ± 147,4, p = 0,021) am
,stärksten und zeigte sich ebenfalls als prädiktiver Faktor für eine
der genannten Schwangerschaftserkrankungen (p = 0,025).
Schlussfolgerung: Bei Risikoschwangeren kann der sFlt1/
PlGF-Quotient für die Einschätzung des individuellen Risikos für
eine PE, ein HELLP-Syndrom oder eine IUGR im Schwangerschaftsverlauf
genutzt werden. Wiederholte Messungen des
Quotienten versprechen eine risikoangepasste Betreuung dieser
Patientinnen.:1. BIBLIOGRAFISCHE BESCHREIBUNG 2
2. EINFÜHRUNG 3
2.1. Allgemeines 3
2.2. Klassifikationen 3
2.3. Risikofaktoren 5
2.4. Neue molekulare Erkenntnisse: angiogene Faktoren 6
2.5. Klinische Studien 7
2.6. Differentialdiagnostik anhand angiogener Faktoren 11
2.7. Die Methode für die automatisierte Messung 12
2.8. Die Bedeutung der Dopplersonografie 12
2.9. Weitere Marker und First-Trimester-Screening 13
2.10. Prävention 14
3. PUBLIKATIONSMANUSKRIPT
Die Wertigkeit des sFlt-1/PlGF-Quotienten als Prädiktionsparameter bei
Schwangeren mit erhöhtem Präeklamsierisiko......................................................15
4. ZUSAMMENFASSUNG DER ARBEIT 22
5. ANLAGEN 27
5.1. Literaturverzeichnis 27
5.2. Erklärung über die eigenständige Abfassung der Arbeit 332
5.3. Lebenslauf 33
5.4. Danksagung 35Background: A dysbalance of proangiogenic [placental growth factor (PlGF)] and antiangiogenic [soluble fms-like tyrosine kinase 1 (sFlt-1)] proteins is known to cause the symptoms of preeclampsia (PE), HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) or intrauterine growth restriction (IUGR). An increased sFlt-1/ PlGF ratio ≥ 85 is considered a reliable diagnostic marker. Altered sFlt1 and PlGF concentrations can be detected several weeks prior to the onset of clinical symptoms. In this study we analysed the role of the sFlt1/PlGF ratio as a predictive marker for preeclampsia in a high-risk patient group. Patients and materials: We prospectively included 68 singleton pregnancies with at least one risk factor for PE, HELLP syndrome or IUGR. During the study the patients were divided into one group with symptoms (patient group) and one group without symptoms (control group) for the above-mentioned diseases. The sFlt1/PlGF ratios were measured on admission and during the course of pregnancy. Results: During pregnancy 41 % of patients developed PE, HELLP syndrome or IUGR. An increase of the absolute value of the sFlt1/PlGF ratio ≥ 85 was only observed in the patient group and was found to be a predictive factor for PE, HELLP syndrome or IUGR at 25 + 0 to 31 + 0 weeks of gestation (p = 0.005) and after 35 + 0 weeks of gestation (p = 0.044). Alterations of the sFlt1/PlGF ratio were observed in all patients but were higher in the patient group from 7–10 weeks prior to delivery and with the highest peak 0–2 weeks prior to delivery. Compared to the control group (mean ± SD 66.9 ± 134) absolute values of sFlt1/PlGF ratio were signifi cantly (p = 0.021) increased 0–2 weeks prior to delivery in the patient group (mean ± SD 393.3 ± 147.4). An increase of the sFlt1/PlGF ratio ≥ 85 0–2 weeks before delivery has shown to be predictive for one of the mentioned diseases (p = 0.025).Conclusions: In high-risk patients the sFlt1/PlGF ratio can be used for an individual risk assessment with regard to PE, HELLP syndrome or IUGR. Serial measurements permit a risk-adapted prenatal care of these patients.:1. BIBLIOGRAFISCHE BESCHREIBUNG 2 2. EINFÜHRUNG 3 2.1. Allgemeines 3 2.2. Klassifikationen 3 2.3. Risikofaktoren 5 2.4. Neue molekulare Erkenntnisse: angiogene Faktoren 6 2.5. Klinische Studien 7 2.6. Differentialdiagnostik anhand angiogener Faktoren 11 2.7. Die Methode für die automatisierte Messung 12 2.8. Die Bedeutung der Dopplersonografie 12 2.9. Weitere Marker und First-Trimester-Screening 13 2.10. Prävention 14 3. PUBLIKATIONSMANUSKRIPT Die Wertigkeit des sFlt-1/PlGF-Quotienten als Prädiktionsparameter bei Schwangeren mit erhöhtem Präeklamsierisiko......................................................15 4. ZUSAMMENFASSUNG DER ARBEIT 22 5. ANLAGEN 27 5.1. Literaturverzeichnis 27 5.2. Erklärung über die eigenständige Abfassung der Arbeit 332 5.3. Lebenslauf 33 5.4. Danksagung 35
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Soleimani, nia Majid. "Experimental investigation of multi-component jets issuing from model pipeline geometries with application to hydrogen safety." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10451.
Full textAbstract:
Development of modern safety standards for hydrogen storage infrastructure requires fundamental insight into the physics of buoyant gas dispersion into ambient air. Also, from a practical engineering stand-point, flow patterns and dispersion of gas originating from orifices in the side wall of circular pipe or storage tank need to be studied. In this thesis, novel configurations were considered to investigate the evolution of turbulent jets issuing from realistic pipeline geometries. First, the effect of jet densities and Reynolds numbers on vertical jets were investigated, as they emerged from the side wall of a circular pipe, through a round orifice. The resulting jet flow was thus issued through a curved surface from a source whose original velocity components were nearly perpendicular to the direction of the ensuing jets. Particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques were employed simultaneously to provide instantaneous and time-averaged flow fields of velocity and concentration. The realistic flow arrangement resulted in an asymmetric flow pattern and a significant deflection from the vertical axis of jets. The deflection was influenced by buoyancy, where heavier gases deflected more than lighter gases. These realistic jets experienced faster velocity decay, and asymmetric jet spreading compared to round jets due to significant turbulent mixing in their near field.
In addition to that, horizontal multi-component jets issuing from a round orifice on the side wall of a circular tube were also investigated experimentally by the means of simultaneous velocity and concentration measurements. A range of Reynolds numbers and gas densities were considered to study the effects of buoyancy and asymmetry on the resulting flow structure. The realistic pipeline jets were always exhibited an asymmetry structure and found to deflect about the jet's streamwise axis in the near field. In the far field, the buoyancy dominated much closer to the orifice than expected in the axisymmetric round jet due to the realistic leak geometry along with the pipeline orientation considered in this study. In general, significant differences were found between the centreline trajectory, spreading rate, and velocity decay of conventional horizontal round axisymmetric jets issuing through flat plates and the pipeline leak-representative jets considered in the present study.
Finally, the dispersion of turbulent multi-component jets issuing from high-aspect-ratio slots on the side wall of a circular tube were studies experimentally by employing simultaneous PIV and PLIF techniques. Two transversal & longitudinal oblong geometries in respect to the longitudinal axes of the tube , and with an aspect ratio of 10 were considered in this study. Both horizontal and vertical orientations along with broad range of Reynolds numbers and gas densities were considered to investigate the effects of buoyancy and asymmetry on the resulting flow structure. The ensuing jets were found to deflect along the jet streamwise axis, once more, due to the realistic pipeline leak-representative configuration. It was also found that increases in aspect ratio of these realistic jets caused a reduction in the angle of deflection, jet centreline decay rates and the width growth on both velocity and scalar fields compared to their round jets counterparts, most notably in the far field.
These findings indicate that conventional jets (those that are issuing through flat surfaces) assumptions are inadequate to predict gas concentration, entrainment rates and, consequently, the extent of the flammability envelope of realistic gas leaks. Thus, extreme caution is required when using conventional jet assumptions to describe the physics of a buoyant jet emitted from realistic geometries.Graduate
Book chapters on the topic "PlGF ratio"
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Black, Carin, and Fabricio da Silva Costa. "Biomarker Immunoassays in the Diagnosis of Preeclampsia: Calculating the sFlt1/PlGF Ratio Using the Cobas®e 411 Analyser." In Preeclampsia, 9–26. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7498-6_2.
Full textConference papers on the topic "PlGF ratio"
1
Enengl, S., P. Trautner, OJ Shebl, P. Oppelt, P. Le Renard, and RB Mayer. "The sFlt-1/PlGF ratio and its predictive value concerning time to delivery in patients with preeclampsia – Preliminary Data." In Jahrestagung der Österreichischen Gesellschaft für Gynäkologie und Geburtshilfe – OEGGG. Georg Thieme Verlag KG, 2018. http://dx.doi.org/10.1055/s-0038-1648257.
Full text
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Enengl, S., P. Trautner, O. Shebl, P. Oppelt, PE Le Renard, and RB Mayer. "The sFlt-1/PlGF ratio and its predictive value concerning time to delivery in patients with preeclampsia – preliminary data." In 62. Kongress der Deutschen Gesellschaft für Gynäkologie und Geburtshilfe – DGGG'18. Georg Thieme Verlag KG, 2018. http://dx.doi.org/10.1055/s-0038-1671477.
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Andraczek, T., J. Hoffmann, and H. Stepan. "Die Beziehung zwischen der sFlt-1/PlGF-Ratio und der klinischen Entscheidungsfindung bei Schwangerschaften mit Plazentapathologie – eine „real world“-Analyse." In 62. Kongress der Deutschen Gesellschaft für Gynäkologie und Geburtshilfe – DGGG'18. Georg Thieme Verlag KG, 2018. http://dx.doi.org/10.1055/s-0038-1671456.
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Meyer, Terrence R., Sukesh Roy, Sivaram P. Gogineni, Vincent M. Belovich, Edwin Corporan, and James R. Gord. "OH PLIF and Soot Volume Fraction Imaging in the Reaction Zone of a Liquid-Fueled Model Gas-Turbine Combustor." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54318.
Full textAbstract:
Simultaneous measurements of OH planar laser-induced fluorescence (PLIF) and laser-induced incandescence (LII) are used to characterize the flame structure and soot formation process in the reaction zone of a swirl-stabilized, JP-8-fueled model gas-turbine combustor. Studies are performed at atmospheric pressure with heated inlet air and primary-zone equivalence ratios from 0.55 to 1.3. At low equivalence ratios (φ < 0.9), large-scale structures entrain rich pockets of fuel and air deep into the flame layer; at higher equivalence ratios, these pockets grow in size and prominence, escape the OH-oxidation zone, and serve as sites for soot inception. Data are used to visualize soot development as well as to qualitatively track changes in overall soot volume fraction as a function of fuel-air ratio and fuel composition. The utility of the OH-PLIF and LII measurement system for test rig diagnostics is further demonstrated for the study of soot-mitigating additives.
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Estefanos, Wessam, Umesh Bhayaraju, Mahmoud Hamza, and San-Mou Jeng. "Evaluation of Two Measurement Techniques to Quantify Fuel-Air Mixing of a Gas Turbine Pre-Mixer at Atmospheric Conditions." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42747.
Full textAbstract:
In the present study, two measurement techniques are adopted to evaluate the fuel-air mixing under atmospheric conditions using an industrial fuel-air pre-mixer. These techniques are CO2 mixing and Planar Laser Induced Fluorescence (PLIF) in water. In these techniques, CO2 and fluorescent dye are injected as fuel simulants. CO2 measurements are used to validate PLIF in water. In the CO2 technique, CO2 concentrations are converted to fuel mass fractions whereas, in the PLIF technique, a modified post processing method is used to convert the LIF signal into fuel mass fraction. The experiments are conducted at the same Reynolds number and momentum flux ratio for two injection strategies. To study the effect of the flow aerodynamics on the mixing results, high speed PIV measurements are conducted in water at the same Reynolds number. A comparison of fuel concentrations measured with the CO2 and PLIF techniques shows good quantitative agreement at all momentum flux ratios. However, deviations between the two techniques are observed at high fuel concentration gradients. The unsteady mixing is evaluated using PLIF technique with high temporal resolution. Analysis of PIV and PLIF data shows that unsteady mixing is lower at regions of high fluctuations in velocity. Moreover, it is found that there is high unsteady mixing at locations where there is high concentration gradient.
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Grisch, Frederic, Mikael Orain, Eric Jourdanneau, and Christian Guin. "Simultaneous Equivalence Ratio and Flame Structure Measurements in Multipoint Injectors Using PLIF." In 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-4868.
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Jayasuriya, A. Champa, Elisabeth Michels, and Nabil A. Ebraheim. "Demineralized Bone Matrix Incorporated PLGA Matrices." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14796.
Full textAbstract:
Poly(lactic-co-glycolic acid)-PLGA (85:15) films incorporated with demineralized bone matrix (DBM) powder with the weight ratio of polymer: DBM (75:25) were investigated for release of agents including osteoinductive (OI) factors during the 80 day period exposing to Phosphate Buffered Saline (PBS) at 37 °C. The release amount of agents including OI factors from DBM/PLGA matrices were more than 2-fold higher at 70 days than at 10 days, respectively. This result demonstrated that controlled release of OI factors can be achieved for extended time period at target site using PLGA as a carrier for DBM powder. Murine Bone Marrow Stromal Cell (BMSC) attachment was studied with different time points at 30 min, 1 h, 2 h, 4 h, 6 h and 24 h for DBM/PLGA and PLGA control matrices. Significantly higher number of BMSCs was attached to the DBM/PLGA matrices at each time points compared with controls. This result suggests that BMSCs favor to attach the surfaces having OI properties. If DBM is incorporated into biodegradable 3-D polymer scaffolds and culture with BMSCs, those scaffolds could be potentially used for bone tissue engineering applications.
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Chandh, Aravind, Shivam Patel, Oleksandr Bibik, Subodh Adhikari, David Wu, Reza Rezvani, Dustin Davis, Tim Lieuwen, and Benjamin Emerson. "High Speed OH PLIF Measurements of Combustor Effusion Films in a High Pressure, Liquid Fueled Combustor." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59306.
Full textAbstract:
Abstract This paper presents measurements of 10 kHz OH planar laser induced fluorescence (PLIF) with an objective to study the interaction of effusion cooling with the flame and hot combustion products in the liquid fueled combustor. The combustor rig is a single sector representation a rich-burn/quick-quench/lean-burn (RQL) configuration. It consists of a swirl nozzle, dilution, and effusion jets. The rig is operated under realistic aircraft conditions, including elevated combustor inlet temperature, and elevated pressure. The PLIF laser sheet was arranged perpendicular and parallel to the liner at distinct liner locations. Parametric variations of important parameters, namely equivalence ratio, and effusion cooling air blowing ratio are conducted to investigate their effect on flame-effusion jet interactions. The PLIF images were analyzed using several data reduction techniques to de-noise the images and identify patterns in the effusion jet-flame interactions. Results show that the effusion jets are highly unsteady, interacting strongly with the turbulent flame from the swirl nozzle and the dilution jets. This work is an extension of recent effusion film mixing studies that were performed with acetone PLIF under non-reacting conditions.
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Subash, Arman Ahamed, Ronald Whiddon, Robert Collin, Marcus Aldén, Atanu Kundu, and Jens Klingmann. "Flame Investigation of a Gas Turbine Central Pilot Body Burner at Atmospheric Pressure Conditions Using OH PLIF and High-Speed Flame Chemiluminescence Imaging." In ASME 2015 Gas Turbine India Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gtindia2015-1212.
Full textAbstract:
Experiments were performed on the central pilot body (RPL-rich-pilot-lean) of Siemens prototype 4th generation DLE burner to investigate the flame behavior at atmospheric pressure condition when varying equivalence ratio, residence time and co-flow temperature. The flame at the RPL burner exit was investigated applying OH planar laser-induced fluorescence (PLIF) and high-speed chemiluminescence imaging. The results from chemiluminescence imaging and OH PLIF show that the size and shape of the flame are clearly affected by the variation in operating conditions. For both preheated and non-preheated co-flow cases, at lean equivalence ratios combustion starts early inside the burner and primary combustion comes to near completion inside the burner if residence time permits. For rich conditions, the unburnt fuel escapes out through the burner exit along with primary combustion products and combustion subsequently restarts downstream the burner at leaner condition and in a diffuse-like manner. For preheated co-flow, most of the operating conditions yield similar OH PLIF distributions and the flame is stabilizing at approximately the same spatial positions. It reveals the importance of the preheating co-flow for flame stabilization. Flame instabilities were observed and Proper Orthogonal Decomposition (POD) is applied to time resolved chemiluminescence data to demonstrate how the flame is oscillating. Preheating has strong influence on the oscillation frequency. Additionally, combustion emissions were analyzed to observe the effect on NOX level for variation in operating conditions.
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Balakrishnan, Arun, Ramkumar N. Parthasarathy, and Subramanyam R. Gollahalli. "Concentration Measurements of OH and CH Radicals in Laminar Partially Premixed and Prevaporized Jet A / Palm Methyl Ester Blend Flames." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50541.
Full textAbstract:
Palm methyl ester (PME) is an attractive alternate fuel that is becoming popular in Asia and has the potential for a wider application. In this study, the near-burner flame characteristics in the laminar partially premixed flames of Jet A, PME and their blends (25%, 50% and 75% by volume) were investigated. Planar laser-induced fluorescence (PLIF) technique was used to determine the relative concentration of OH and CH radicals in the near-burner region of the flames. The fuel was prevaporized by injecting into a hot air stream and passed through a 9.5 mm stainless steel tube which served as the injector. The burner exit equivalence ratios of 2, 3 and 7, were selected to simulate a wide range of (high to low) partially premixed modes of combustion that exist in practical combustors. The PLIF measurements indicated that the OH and CH concentrations closely followed the temperature profiles at the equivalence ratio of 2. The blend-fuel flames had higher OH and CH concentrations than the neat fuel flames at equivalence ratios of 2 and 3. At the equivalence ratio of 7, a significant reduction in OH concentration was observed in the near-burner region of the flames having biofuel content, and the CH concentration was comparatively higher than OH concentration of corresponding flames. The presence of high CH concentration in the region of peak NO concentration indicated that the NO formation at this condition was likely through the Fenimore mechanism. The concentration measurements of OH and CH radicals revealed a non-monotonic variation with the proportion of biofuel in the fuel blend and suggested a complex competition between the growth and oxidation of poly aromatic hydrocarbons (PAH) and soot particles, and the formation of combustion products.