24,316 research outputs found
Withdrawal of statins leads to an attenuation of endothelial function and an increase in redox-mediated signalling and gene expression
No full textLarge-eddy simulation of kerosene spray combustion in a model scramjet chamber
No full textLarge-eddy simulation (LES) of kerosene spray combustion in a model supersonic combustor with cavity flame holder is carried out. Kerosene is injected through the ceiling of the cavity. The subgrid-scale (SGS) turbulence stress ensor is closed via the Smagorinsky’s eddyviscosity model, chemical source terms are modelled by a finite rate chemistry (FRC) model, and a four-step reduced kerosene combustion kinetic mechanism is adopted. The chamber wallpressure predicted from the LES is validated by experimental data reported in literature. The test case has a cavity length of 77mm and a depth of 8mm. After liquid kerosene is injected through the orifice, most of the droplets are loaded with recirculation fluid momentum inside the cavity. Due to lower velocity of the carrier fluid inside the cavity, sufficient atomization and evaporation take place during the process of droplet transportation, resulting in a rich fuel mixture of kerosene vapour accumulating inside the cavity. These rich fuel mixtures are mixed with fresh air by the approachmixing layer at the front of the cavity and are thus involved in burning accompanied with the approach boundary layer separation extending towards upstream. The combustion flame in the downstream impinges onto the rear wall of the cavity and is then reflected back to the front of the cavity. During the recirculation of hot flow, heat is compensated for evaporation of droplets. The circulation processes mentioned above provide an efficient flame-holdingmechanism to stabilize the flame.Comparisons with results froma shorter length of cavity (cavity length of 45mm) show that, due to insufficient atomization and evaporation of the droplets in the short distance inside the cavity, parts of the droplets are carried out of the cavity through theboundary layer fluctuation and evaporated in the hot flame layer, thus resulting in incomplete air fuel mixing and worse combustion performance. The flow structures inside the cavity play an important role in the spray istribution, thus determining the combustion performance
Tangle-bearing neurons survive despite disruption of membrane integrity in a mouse model of tauopathy
No full textNeurofibrillary tangles (NFTs) are associated with neuronal loss and correlate with cognitive impairment in Alzheimer disease, but how NFTs relate to neuronal death is not clear. We studied cell death in Tg4510 mice that reversibly express P301L mutant human tau and accumulate NFTs using in vivo multiphoton imaging of neurofibrillary pathology, propidium iodide (PI) incorporation into cells, caspase activation, and DNA labeling. We first observed that in live mice, a minority of neurons were labeled with the caspase probe or with PI fluorescence. These markers of cell stress were localized in the same cells and appeared specifically within NFT-bearing neurons. Contrary to expectations, the PI-stained neurons did not die during a day of observation; the presence of Hoechst-positive nuclei in them on the subsequent day indicated that the NFT-associated membrane disruption, as suggested by PI staining, and caspase activation do not lead to immediate death of neurons in this tauopathy model. This unique combination of in vivo multiphoton imaging with markers of cell death and pathological alteration is a powerful tool for investigating neuronal damage associated with neurofibrillary pathology
“Bring in the Graduates” – alumni contributions to HE T&L - Blog post
No full textBlog post on Teaching-focused in HE: THE GEES network. A teaching-focused network for Geography, Earth and Environmental Science academic
Turbine blade tip heat transfer in low speed and high speed flows
No full textIn this paper, high and low speed tip flows are investigated for a high-pressure turbine blade. Previous experimental data are used to validate a CFD code, which is then used to study the tip heat transfer in high and low speed cascades. The results show that at engine representative Mach numbers the tip flow is predominantly transonic. Thus, compared to the low speed tip flow, the heat transfer is affected by reductions in both the heat transfer coefficient and the recovery temperature. The high Mach numbers in the tip region (M>1.5) lead to large local variations in recovery temperature. Significant changes in the heat transfer coefficient are also observed. These are due to changes in the structure of the tip flow at high speed. At high speeds, the pressure side corner separation bubble reattachment occurs through supersonic acceleration which halves the length of the bubble when the tip gap exit Mach number is increased from 0.1 to 1.0. In addition, shock/boundary-layer interactions within the tip gap lead to large changes in the tip boundary-layer thickness. These effects give rise to significant differences in the heat-transfer coefficient within the tip region compared to the low-speed tip flow. Compared to the low speed tip flow, the high speed tip flow is much less dominated by turbulent dissipation and is thus less sensitive to the choice of turbulence model. These results clearly demonstrate that blade tip heat transfer is a strong function of Mach number, an important implication when considering the use of low speed experimental testing and associated CFD validation in engine blade tip desig
S.L.I.M., a small linear interdependent model of eight EU-member states, the USA and Japan
No full textInternational Economics;EU
Effects of shot peening on short crack growth rate and resulting low cycle fatigue behaviour in low pressure turbine blade material
No full textThe effect of shot peening on subsequent low cycle fatigue behaviour of a representative low pressure steam turbine blade material has been investigated in bend test samples. An analysis of the short fatigue crack growth behaviour has been conducted. For samples with no stress concentration feature, shot peening was found to have a more evident beneficial effect at lower strain levels than at higher strain levels, whereas for samples with a stress concentration feature, the beneficial effect was retained even at higher strain levels. Preexisting cracks were observed on the shot peened surface, which started to grow at 10–25% of fatigue life in the low cycle fatigue regime. The crack propagation rate was slower than that observed in the ground sample, suggesting that the shot peening process delayed crack propagation. This improvement in fatigue life has been attributed to the significant slowing of small cracks while growing through surface regions of significant compressive residual stresses and local work hardening developed by the shot peening process. Once cracks in the notch root have penetrated this region in the depth direction, faster crack growth rates, similar to those observed in the ground case, were seen
Anteon biprocessum Xu & He 1997
No full text13. Anteon biprocessum Xu & He, 1997 (Plate 19C) Anteon biprocessum Xu & He 1997b: 107; He & Xu 2002: 206. Description of Male. Fully winged; length 2.7 mm. Head black, except mandible testaceous; antenna black-brown except segment 1 testaceous; mesosoma and metasoma black; legs testaceous, except basal half of metacoxa brown. Antenna filiform; antennal segments in following proportions: 5.5:3.5:5.5:6:5.5:5.5:5.5:5:5:6.8. Head finely punctate, unsculptured among punctures; frontal line absent; POL = 2.3; OL = 1.3; OOL = 3.2; OPL = TL = 2.4; greatest breadth of posterior ocelli shorter than POL (1.4:2.3); occipital carina complete. Scutum partly punctate and unsculptured among punctures, partly unsculptured. Notauli incomplete, reaching about length of scutum. Scutellum and metanotum smooth. Propodeum reticulate rugose, with strong transverse between dorsal and posterior surface; posterior surface reticulate rugose, with two longitudinal keels, lateral reticulate rugose and median area smooth. Fore wing hyaline, without dark transverse bands; distal part of vein shorter than proximal part (3.5:6.5). Paramere (Plate 19C) with distal inner process. Tibial spurs 1/1/2. , blackshiny, 1.8; shiny, 0.7 keel areas stigmal leg.). Female. Unknown. Material examined. Type: holotype ♂: CHINA: Guizhou, Mt. Fanjingshan, 11.VII.1993, Songlin Yao (ZJUC). Other material. CHINA: Yunnan, Baoshan, Tengchong, Jietou, 13.V.2009, Jie Zeng leg., 2♂ (SCAU Hosts. Unknown. Distribution. China (Guizhou, Yunnan).Published as part of Xu, Zaifu, Olmi, Massimo & He, Junhua, 2013, Dryinidae of the Oriental region (Hymenoptera: Chrysidoidea), pp. 1-460 in Zootaxa 3614 (1) on page 78, DOI: 10.11646/zootaxa.3614.1.1, http://zenodo.org/record/527837
Dryinus maculipennis He & Xu 2002
No full text1. Dryinus maculipennis He & Xu, 2002 (Plate 88E, F) Dryinus maculipennis He & Xu 2002: 282. Description of Male. Fully winged; length 4.3 mm. Head black, except mandible testaceous; antenna testaceous; mesosoma and metasoma black; legs yellow. Antenna filiform; antennal segments in following proportions: 3.5:2.5:10.3:7.0:6.3:6.0:6.0:5.3:4.3:6.0. Head dull, granulated and irregularly rugose; occipital carina complete, laterally not reaching eyes; frontal line very slender, complete; POL = 4; OL = 1.5; OOL= 5; OPL = 0.5; TL = 1.5; greatest breadth of posterior ocelli longer than OPL (4:0.5). Scutum dull, as sculptured as head. Notauli complete, posteriorly separated; minimum distance between notauli longer than POL (6:4). Scutellum shiny, with anterior third granulated and rest of surface unsculptured. Metanotum unsculptured, with anterior third reticulate rugose. Propodeum reticulate rugose, without transverse or longitudinal keels. Fore wing hyaline, with distal half darkened (Plate 88E); distal part of stigmal vein longer than proximal part (15:13); marginal cell open. Genitalia in plate 88F. Tibial spurs 1/1/2. Female. Unknown. Material examined. Type: holotype ♂: CHINA: Fujian, Mt. Meihuashan, 22.VII.1988, Junhua He leg. (ZJUC). Hosts. Unknown. Distribution. China (Fujian).Published as part of Xu, Zaifu, Olmi, Massimo & He, Junhua, 2013, Dryinidae of the Oriental region (Hymenoptera: Chrysidoidea), pp. 1-460 in Zootaxa 3614 (1) on page 308, DOI: 10.11646/zootaxa.3614.1.1, http://zenodo.org/record/527837
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