97 research outputs found
Analysis of Heat Flux Distribution during Brush Seal Rubbing Using CFD with Porous Media Approach
This paper discusses the question of heat flux distribution between bristle package and rotor during a rubbing event. A three-dimensional Computational Fluid Dynamics (3D CFD) model of the brush seal test rig installed at the Institute of Thermal Turbomachinery (ITS) was created. The bristle package is modelled as a porous medium with local non-thermal equilibrium. The model is used to numerically recalculate experimentally conducted rub tests on the ITS test rig. The experimentally determined total frictional power loss serves as an input parameter to the numerical calculation. By means of statistical evaluation methods, the ma in influences on the heat flux distribution and the maximum temperature in the frictional contact are determined. The heat conductivity of the rotor material, the heat transfer coefficients at the bristles and the rubbing surface were identified as the dominant factors
Contamination of Brush Seals by Oil and Salt and Its Impact on Rubbing and Hysteresis Behaviour
The literature already contains some experimental, analytical and numerical investigations
on the rubbing and hysteresis behaviour of brush seals. What the investigations have in common
is that they were carried out with new and uncontaminated seals, or that such a condition was
assumed. The inïŹuence of contamination has not been explicitly investigated yet. Particularly in
stationary gas and steam turbines, foreign substances can accumulate on and in the bristle package
during steady-state operation. In the case of a rubbing event with a contaminated brush seal, e.g.,
during shutdown of the machine, the process is not expected to be comparable to that assumed
in the presence of a new, uncontaminated seal. The present paper is dedicated to the question of
the inïŹuence of contamination on the total frictional power loss generated during rubbing and the
distribution of heat ïŹuxes in friction contact. For this purpose, rub tests with two seals were carried
out on the brush seal test rig of the Institute of Thermal Turbomachinery (ITS) in new conditions.
Subsequently, the sealing packages were contaminated with oil or a salt mixture. After the treatment,
the rub tests were repeated and compared with the previous tests. In addition, stiffness measurements
were used to assess the degree of contamination. A strong inïŹuence on the rubbing behaviour by
the contamination was detected. Contamination causes the ïŹexibility of the bristle package to be
greatly reduced. As a result, especially at the beginning of the ïŹrst measurements, the total power
losses and rotor heat inputs are strongly increased. This ïŹexibility is partly regained in the course of
the measurements. As expected, contamination also inïŹuences the hysteresis behaviour of the seal.
A highly increased leakage rate after rubbing could be observed, because the bristles remained close
to their deïŹected positions. In the case of the salted seal, however, an improvement in the leakage
performance could be observed after several repeat tests
What are the Role and Capabilities of Fab Labs as a Contribution to a Resilient City? Insights from the Fab City Hamburg
Recent events such as the COVID-19 pandemic or the Ever-Given accident in the Suez Canal, which have led to local product shortages and negative social and environmental impacts, highlight the need to build resilience in areas that are highly affected by such events: in cities. One aspect of a multidisciplinary concept of resilient cities is the local manufacturing of physical products, which currently is mainly based on globally complex supply chains. The resilience of a city can be impaired if the supply of consumer goods can no longer be guaranteed, e.g., due to the fragility of supply chains. From this perspective, one of several pathways to a more resilient city is the emerging movement of open production sites (so called Fab Labs), where physical products can be produced or repaired in a distributed way by the consumers themselves. In metropolitan areas such as Hamburg, Fab Labs form networks including makerspaces, open workshops and educational institutions â so called Fab Cities. This article highlights the role of Fab Labs with regards to urban resilience and displays the capability of the Fab City Hamburg to contribute to the resilience of the city. To explore these capabilities, semi-structured interviews were conducted with makers and operators, and different Fab Labs were explored via participant observation. This article demonstrates that Fab Labs can contribute to a resilient city - especially from the perspective of manufacturing capability but also regarding the development of technical education. However, there are clear limitations with regards to the vertical range and manufacturing diversity
Effects of the Back Plate Inner Diameter on the Frictional Heat Input and General Performance of Brush Seals
Reducing losses in the secondary air system of gas and steam turbines can significantly increase the efficiency of such machines. Meanwhile, brush seals are a widely used alternative to labyrinth seals. Their most valuable advantage over other sealing concepts is the very small gap between the sealing package and the rotor and thus reduced leakage mass flow. This small gap can be achieved due to the great radial flexibility without running the risk of severe detrimental deterioration in case of rubbing. Rubbing between rotor and seal during operation might occur as a result of e.g., an unequal thermal expansion of the rotor and stator or a rotor elongation due to centrifugal forces or manoeuvre forces. Thanks to the flexible structure of the brush seal, the contact forces during a rubbing event are reduced; however, the frictional heat input can still be considerable. Particularly in aircraft engines with their thin and lightweight rotor structures, the permissible material stresses can easily be exceeded by an increased heat input and thus harm the engineâs integrity. The geometry of the seal has a decisive influence on the resulting contact forces and consequently the heat input. This paper is a contribution to further understand the influence of the geometrical parameters of the brush seal on the heat input and the leakage during the rubbing of the seal on the rotor. In this paper, a total of three seals with varied back plate inner diameter are examined in more detail. The experimental tests were carried out on the brush seal test rig of the Institute of Thermal Turbomachinery (ITS) under machine-relevant conditions. These are represented by pressure differences of 1 to 7, surface speeds of 30 to 180 m / s and radial interferences of 0.1 to 0.4mm . For a better interpretation, the results were compared with those obtained at the static test rig of the Institute of Jet Propulsion and Turbomachinery (IFAS) at the Technical University of Braunschweig. The stiffness, the blow-down and the axial behaviour of the seals as a function of the differential pressure can be examined at this test rig. It could be shown that the back plate inner diameter has a decisive influence on the overall operating behaviour of a brush seal
A big data approach to metagenomics for all-food-sequencing
Background
All-Food-Sequencing (AFS) is an untargeted metagenomic sequencing method that allows for the detection and quantification of food ingredients including animals, plants, and microbiota. While this approach avoids some of the shortcomings of targeted PCR-based methods, it requires the comparison of sequence reads to large collections of reference genomes. The steadily increasing amount of available reference genomes establishes the need for efficient big data approaches.
Results
We introduce an alignment-free k-mer based method for detection and quantification of species composition in food and other complex biological matters. It is orders-of-magnitude faster than our previous alignment-based AFS pipeline. In comparison to the established tools CLARK, Kraken2, and Kraken2+Bracken it is superior in terms of false-positive rate and quantification accuracy. Furthermore, the usage of an efficient database partitioning scheme allows for the processing of massive collections of reference genomes with reduced memory requirements on a workstation (AFS-MetaCache) or on a Spark-based compute cluster (MetaCacheSpark).
Conclusions
We present a fast yet accurate screening method for whole genome shotgun sequencing-based biosurveillance applications such as food testing. By relying on a big data approach it can scale efficiently towards large-scale collections of complex eukaryotic and bacterial reference genomes. AFS-MetaCache and MetaCacheSpark are suitable tools for broad-scale metagenomic screening applications. They are available at https://muellan.github.io/metacache/afs.html (C++ version for a workstation) and https://github.com/jmabuin/MetaCacheSpark (Spark version for big data clusters).This work was partially supported by the Deutsche Forschungsgemeinschaft (DFG), Project HySim, the MINECO under award RTI2018-093336-B-C21, Xunta de Galicia under awards ED481B 2018/013 and ED431C 2018/19, the European Regional Development Fund, and by the Federal Office for Agriculture and FoodS
Bacterial symbiont subpopulations have different roles in a deep-sea symbiosis
© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hinzke, T., Kleiner, M., Meister, M., Schlueter, R., Hentschker, C., Pane-Farre, J., Hildebrandt, P., Felbeck, H., Sievert, S. M., Bonn, F., Voelker, U., Becher, D., Schweder, T., & Markert, S. Bacterial symbiont subpopulations have different roles in a deep-sea symbiosis. Elife, 10, (2021): e58371, https://doi.org/10.7554/eLife.58371.The hydrothermal vent tubeworm Riftia pachyptila hosts a single 16S rRNA phylotype of intracellular sulfur-oxidizing symbionts, which vary considerably in cell morphology and exhibit a remarkable degree of physiological diversity and redundancy, even in the same host. To elucidate whether multiple metabolic routes are employed in the same cells or rather in distinct symbiont subpopulations, we enriched symbionts according to cell size by density gradient centrifugation. Metaproteomic analysis, microscopy, and flow cytometry strongly suggest that Riftia symbiont cells of different sizes represent metabolically dissimilar stages of a physiological differentiation process: While small symbionts actively divide and may establish cellular symbiont-host interaction, large symbionts apparently do not divide, but still replicate DNA, leading to DNA endoreduplication. Moreover, in large symbionts, carbon fixation and biomass production seem to be metabolic priorities. We propose that this division of labor between smaller and larger symbionts benefits the productivity of the symbiosis as a whole.This work was supported by the German Research Foundation DFG (grant MA 6346/2â1 to SM), fellowships of the Institute of Marine Biotechnology Greifswald (TH, MM), a German Academic Exchange Service (DAAD) grant (TH), the NC State Chancellorâs Faculty Excellence Program Cluster on Microbiomes and Complex Microbial Communities (MK), the USDA National Institute of Food and Agriculture, Hatch project 1014212 (MK), the U.S. National Science Foundation (grants OCE-1131095 and OCE-1559198 to SMS), and The WHOI Investment in Science Fund (to SMS). We furthermore acknowledge support for article processing charges from the DFG (Grant 393148499) and the Open Access Publication Fund of the University of Greifswald
A multi-stage genome-wide association study of bladder cancer identifies multiple susceptibility loci.
We conducted a multi-stage, genome-wide association study of bladder cancer with a primary scan of 591,637 SNPs in 3,532 affected individuals (cases) and 5,120 controls of European descent from five studies followed by a replication strategy, which included 8,382 cases and 48,275 controls from 16 studies. In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1: rs1014971, (P = 8 Ă 10â»ÂčÂČ) maps to a non-genic region of chromosome 22q13.1, rs8102137 (P = 2 Ă 10â»ÂčÂč) on 19q12 maps to CCNE1 and rs11892031 (P = 1 Ă 10â»â·) maps to the UGT1A cluster on 2q37.1. We confirmed four previously identified genome-wide associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P = 4 Ă 10â»ÂčÂč) and a tag SNP for NAT2 acetylation status (P = 4 Ă 10â»ÂčÂč), and found interactions with smoking in both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into the mechanisms of carcinogenesis
A multi-stage genome-wide association study of bladder cancer identifies multiple susceptibility loci.
We conducted a multi-stage, genome-wide association study of bladder cancer with a primary scan of 591,637 SNPs in 3,532 affected individuals (cases) and 5,120 controls of European descent from five studies followed by a replication strategy, which included 8,382 cases and 48,275 controls from 16 studies. In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1: rs1014971, (P = 8 Ă 10â»ÂčÂČ) maps to a non-genic region of chromosome 22q13.1, rs8102137 (P = 2 Ă 10â»ÂčÂč) on 19q12 maps to CCNE1 and rs11892031 (P = 1 Ă 10â»â·) maps to the UGT1A cluster on 2q37.1. We confirmed four previously identified genome-wide associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P = 4 Ă 10â»ÂčÂč) and a tag SNP for NAT2 acetylation status (P = 4 Ă 10â»ÂčÂč), and found interactions with smoking in both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into the mechanisms of carcinogenesis
Variability of NT-proBNP and Its Relationship with Inflammatory Status in Patients with Stable Essential Hypertension: A 2-Year Follow-Up Study
The variability of NT-proBNP levels has been studied in heart failure, yet no data exist on these changes over time in hypertensive patients. Furthermore, studies on the relationship between natriuretic peptides and inflammatory status are limited.220 clinically and functionally asymptomatic stable patients (age 59 ± 13, 120 male) out of 252 patients with essential hypertension were followed up, and NT-proBNP was measured at baseline, 12 and 24 months. No differences in NT-proBNP were found with respect to the basal stage in the hypertrophic group, but significant changes were found in non-hypertrophic subjects. The reproducibility of NT-proBNP measurements was better in patients with hypertrophy than in the non-hypertrophic group for the three intervals (stage I-basal; stage II-stage I; stage II-basal) with a reference change value of 34%, 35% and 41%, respectively, in the hypertrophic group. A more elevated coefficient of correlation was obtained in the hypertrophic group than in patients without hypertrophy: basal versus stage I (r = 0.79, p < 0.0001 and r = 0.59, p < 0.0001) and stage I versus stage II (r = 0.86, p < 0.0001 and r = 0.56, p < 0.0001). Finally, levels of NT-proBNP significantly correlated with sTNF-R1 (p < 0.0001) and IL-6 (p < 0.01) during follow-up. A multivariate linear regression analysis showed that sTNF-R1 is an independent factor of NT-proBNP.This work shows that there is good stability in NT-proBNP levels in a follow-up study of asymptomatic patients with stable hypertension and left ventricular hypertrophy. As a consequence, assessment of NT-proBNP concentrations may be a useful tool for monitoring the follow-up of hypertensive patients with hypertrophy. Measured variations in peptide levels, exceeding 35% in a 12-month follow-up and 41% in a 24-month follow-up, may indicate an increase in cardiovascular risk, and therefore implies adjustment in the medical treatment. In addition, this study shows a link between neurohormonal and inflammatory activation in these patients
Polymorphisms within autophagy-related genes as susceptibility biomarkers for multiple myeloma: a meta-analysis of three large cohorts and functional characterization
Functional data used in this project have been meticulously catalogued and archived in the BBMRI-NL data infrastructure (https://hfgp.bbmri.nl/, accessed on 12 February 2020) using the MOLGENIS open-source platform for scientific data.Multiple myeloma (MM) arises following malignant proliferation of plasma cells in the
bone marrow, that secrete high amounts of specific monoclonal immunoglobulins or light chains,
resulting in the massive production of unfolded or misfolded proteins. Autophagy can have a
dual role in tumorigenesis, by eliminating these abnormal proteins to avoid cancer development,
but also ensuring MM cell survival and promoting resistance to treatments. To date no studies
have determined the impact of genetic variation in autophagy-related genes on MM risk. We
performed meta-analysis of germline genetic data on 234 autophagy-related genes from three independent study populations including 13,387 subjects of European ancestry (6863 MM patients and
6524 controls) and examined correlations of statistically significant single nucleotide polymorphisms
(SNPs; p < 1 Ă 10â9) with immune responses in whole blood, peripheral blood mononuclear
cells (PBMCs), and monocyte-derived macrophages (MDM) from a large population of healthy
donors from the Human Functional Genomic Project (HFGP). We identified SNPs in six loci, CD46,
IKBKE, PARK2, ULK4, ATG5, and CDKN2A associated with MM risk (p = 4.47 Ă 10â4â5.79 Ă 10â14).
Mechanistically, we found that the ULK4rs6599175 SNP correlated with circulating concentrations
of vitamin D3 (p = 4.0 Ă 10â4), whereas the IKBKErs17433804 SNP correlated with the number of
transitional CD24+CD38+ B cells (p = 4.8 Ă 10â4) and circulating serum concentrations of Monocyte
hemoattractant Protein (MCP)-2 (p = 3.6 Ă 10â4). We also found that the CD46rs1142469 SNP corre lated with numbers of CD19+ B cells, CD19+CD3â B cells, CD5+ IgDâ cells, IgMâ cells, IgDâIgMâ
cells, and CD4âCD8â PBMCs (p = 4.9 Ă 10â4â8.6 Ă 10â4
) and circulating concentrations of interleukin (IL)-20 (p = 0.00082). Finally, we observed that the CDKN2Ars2811710 SNP correlated with levels
of CD4+EMCD45RO+CD27â cells (p = 9.3 Ă 10â4
). These results suggest that genetic variants within
these six loci influence MM risk through the modulation of specific subsets of immune cells, as well
as vitamin D3â, MCP-2â, and IL20-dependent pathways.This work was supported by the European Unionâs Horizon 2020 research and innovation program, N° 856620 and by grants from the Instituto de Salud Carlos III and FEDER (Madrid, Spain; PI17/02256 and PI20/01845), ConsejerĂa de TransformaciĂłn EconĂłmica, Industria, Conocimiento y Universidades and FEDER (PY20/01282), from the CRIS foundation against cancer, from the Cancer Network of Excellence (RD12/10 Red de CĂĄncer), from the Dietmar Hopp Foundation and the German Ministry of Education and Science (BMBF: CLIOMMICS [01ZX1309]), and from National Cancer Institute of the National Institutes of Health under award numbers: R01CA186646, U01CA249955 (EEB).This work was also funded d by Portuguese National funds, through the Foundation for Science and Technology (FCT)âproject UIDB/50026/2020 and UIDP/50026/2020 and by the project NORTE-01-0145-FEDER-000055, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)
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