Numerical investigation of the flow over a model transonic turbine blade tip

Direct numerical simulations (DNS) are used to investigate the unsteady flow over a model turbine blade tip at engine-scale Reynolds and Mach numbers. The DNS are performed with an in-house multiblock structured compressible Navier–Stokes solver. The particular case of a transonic tip flow is studied since previous work has suggested that compressibility has an important effect on the turbulent nature of the separation bubble at the inlet to the tip–casing gap and subsequent flow reattachment. The flow is simulated over an idealized tip geometry where the tip gap is represented by a constant-area channel with a sharp inlet corner to represent the pressure side edge of the turbine blade. The effects of free-stream disturbances, cross-flow and the pressure side boundary layer on the tip flow aerodynamics and heat transfer are studied. For ‘clean’ inflow cases we find that even at engine-scale Reynolds numbers the tip flow is intermittent in nature, i.e. neither laminar nor fully turbulent. The breakdown to turbulence occurs through the development of spanwise streaks with wavelengths of approximately 15 %–20 % of the gap height. Multidimensional linear stability analysis confirms the two-dimensional base state to be most unstable with respect to spanwise wavelengths of 25 % of the gap height. The linear stability analysis also shows that the addition of cross-flows with 25 % of the streamwise gap exit velocity increases the stability of the tip flow. This is confirmed by the DNS, which also show that the turbulence production is significantly reduced in the separation bubble. For the case when free-stream disturbances are added to the inlet flow, viscous dissipation and the rapid acceleration of the flow at the inlet to the tip–casing gap cause significant distortion of the vorticity field and reductions of turbulence intensity as the flow enters the tip gap. The DNS results also suggest that the assumption of the Reynolds analogy and a constant recovery factor are not accurate, in particular in regions where the skin friction approaches zero while significant temperature gradients remain, such as in the vicinity of flow reattachment.Computer time was provided by the UK turbulence consortium under EPSRC grant EP/L000261/1. This work was also supported by resources provided by The Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.This is the author accepted manuscript. The final version is available from Cambridge University Press via https://doi.org/10.1017/jfm.2016.47

Direct numerical simulations of a high-pressure turbine vane

In this paper, we establish a benchmark data set of a generic high-pressure (HP) turbine vane generated by direct numerical simulation (DNS) to resolve fully the flow. The test conditions for this case are a Reynolds number of 0.57 × 106 and an exit Mach number of 0.9, which is representative of a modern transonic HP turbine vane. In this study, we first compare the simulation results with previously published experimental data. We then investigate how turbulence affects the surface flow physics and heat transfer. An analysis of the development of loss through the vane passage is also performed. The results indicate that freestream turbulence tends to induce streaks within the near-wall flow, which augment the surface heat transfer. Turbulent breakdown is observed over the late suction surface, and this occurs via the growth of two-dimensional Kelvin–Helmholtz spanwise roll-ups, which then develop into lambda vortices creating large local peaks in the surface heat transfer. Turbulent dissipation is found to significantly increase losses within the trailing-edge region of the vane.Partnership for Advanced Computing in Europe (PRACE) and the UK Turbulence Consortium funded by the EPSRC under Grant No. EP/L000261/

Molecular imaging of glycan chains couples cell-wall polysaccharide architecture to bacterial cell

Biopolymer composite cell walls maintain cell shape and resist forces in plants, fungi and bacteria. Peptidoglycan, a crucial antibiotic target and immunomodulator, performs this role in bacteria. The textbook structural model of peptidoglycan is a highly ordered, crystalline material. Here we use atomic force microscopy (AFM) to image individual glycan chains in peptidoglycan from Escherichia coli in unprecedented detail. We quantify and map the extent to which chains are oriented in a similar direction (orientational order), showing it is much less ordered than previously depicted. Combining AFM with size exclusion chromatography, we reveal glycan chains up to 200 nm long. We show that altered cell shape is associated with substantial changes in peptidoglycan biophysical properties. Glycans from E. coli in its normal rod shape are long and circumferentially oriented, but when a spheroid shape is induced (chemically or genetically) glycans become short and disordered

Characterisation and expression of SPLUNC2, the human orthologue of rodent parotid secretory protein

We recently described the Palate Lung Nasal Clone (PLUNC) family of proteins as an extended group of proteins expressed in the upper airways, nose and mouth. Little is known about these proteins, but they are secreted into the airway and nasal lining fluids and saliva where, due to their structural similarity with lipopolysaccharide-binding protein and bactericidal/permeability-increasing protein, they may play a role in the innate immune defence. We now describe the generation and characterisation of novel affinity-purified antibodies to SPLUNC2, and use them to determine the expression of this, the major salivary gland PLUNC. Western blotting showed that the antibodies identified a number of distinct protein bands in saliva, whilst immunohistochemical analysis demonstrated protein expression in serous cells of the major salivary glands and in the ductal lumens as well as in cells of minor mucosal glands. Antibodies directed against distinct epitopes of the protein yielded different staining patterns in both minor and major salivary glands. Using RT-PCR of tissues from the oral cavity, coupled with EST analysis, we showed that the gene undergoes alternative splicing using two 5' non-coding exons, suggesting that the gene is regulated by alternative promoters. Comprehensive RACE analysis using salivary gland RNA as template failed to identify any additional exons. Analysis of saliva showed that SPLUNC2 is subject to N-glycosylation. Thus, our study shows that multiple SPLUNC2 isoforms are found in the oral cavity and suggest that these proteins may be differentially regulated in distinct tissues where they may function in the innate immune response

Effects of dapagliflozin on major adverse kidney and cardiovascular events in patients with diabetic and non-diabetic chronic kidney disease: a prespecified analysis from the DAPA-CKD trial

Background: Dapagliflozin reduces the risk of kidney failure and heart failure in patients with chronic kidney disease. We aimed to investigate the effects of dapagliflozin on kidney, cardiovascular, and mortality outcomes according to presence or absence of type 2 diabetes and according to underlying cause of chronic kidney disease, reported as diabetic nephropathy, chronic glomerulonephritides, ischaemic or hypertensive chronic kidney disease, or chronic kidney disease of other or unknown cause. Methods: DAPA-CKD was a multicentre, double-blind, placebo-controlled, randomised trial done at 386 study sites in 21 countries, in which participants with a urinary albumin-to-creatinine ratio of 200–5000 mg/g and an estimated glomerular filtration rate (eGFR) of 25–75 mL/min per 1·73m2 were randomly assigned (1:1) to dapagliflozin 10 mg once daily or matching placebo, as an adjunct to standard care. The primary outcome was a composite of sustained decline in eGFR of at least 50%, end-stage kidney disease, or kidney-related or cardiovascular death. Secondary efficacy outcomes were a kidney-specific composite (the same as the primary outcome but excluding cardiovascular death), a composite of cardiovascular death or hospital admission for heart failure, and all-cause mortality. In this study, we conducted a prespecified subgroup analysis of the DAPA-CKD primary and secondary endpoints by presence or absence of type 2 diabetes and by aetiology of chronic kidney disease. DAPA-CKD is registered with ClinicalTrials.gov, NCT03036150. Findings: The study took place between Feb 2, 2017, and June 12, 2020. 4304 participants were randomly assigned (2152 to dapagliflozin and 2152 to placebo) and were followed up for a median of 2·4 years (IQR 2·0–2·7). Overall, 2906 (68%) participants had a diagnosis of type 2 diabetes, of whom 396 (14%) had chronic kidney disease ascribed to causes other than diabetic nephropathy. The relative risk reduction for the primary composite outcome with dapagliflozin was consistent in participants with type 2 diabetes (hazard ratio [HR] 0·64, 95% CI 0·52–0·79) and those without diabetes (0·50, 0·35–0·72; pinteraction=0·24). Similar findings were seen for the secondary outcomes: kidney-specific composite outcome (0·57 [0·45–0·73] vs 0·51 [0·34–0·75]; Pinteraction=0·57), cardiovascular death or hospital admission for heart failure (0·70 [0·53–0·92] vs 0·79 [0·40–1·55]; Pinteraction=0·78), and all-cause mortality (0·74 [0·56–0·98] vs 0·52 [0·29–0·93]; Pinteraction=0·25). The effect of dapagliflozin on the primary outcome was also consistent among patients with diabetic nephropathy (n=2510; HR 0·63, 95% CI 0·51–0·78), glomerulonephritides (n=695; 0·43, 0·26–0·71), ischaemic or hypertensive chronic kidney disease (n=687; 0·75, 0·44–1·26), and chronic kidney disease of other or unknown cause (n=412; 0·58, 0·29–1·19; Pinteraction=0·53), with similar consistency seen across the secondary outcomes. The proportions of participants in the dapagliflozin and placebo groups who had serious adverse events or discontinued study drug due to adverse events did not vary between those with and those without type 2 diabetes. Interpretation: Dapagliflozin reduces the risks of major adverse kidney and cardiovascular events and all-cause mortality in patients with diabetic and non-diabetic chronic kidney disease

Effect of dapagliflozin on urinary albumin excretion in patients with chronic kidney disease with and without type 2 diabetes: a prespecified analysis from the DAPA-CKD trial

BACKGROUND: Reductions in albuminuria are associated with a subsequent lower risk of kidney failure in patients with chronic kidney disease. The SGLT2 inhibitor dapagliflozin significantly reduced albuminuria in patients with type 2 diabetes and normal or near-normal kidney function. Whether this effect persists in patients with chronic kidney disease with and without type 2 diabetes is unknown. We assessed the effects of dapagliflozin on albuminuria in patients with chronic kidney disease with and without type 2 diabetes in the dapagliflozin and prevention of adverse outcomes in chronic kidney disease (DAPA-CKD) trial. METHODS: DAPA-CKD was a multicentre, double-blind, placebo-controlled, randomised trial done at 386 sites in 21 countries. Patients were eligible for the trial if they had chronic kidney disease, defined as an estimated glomerular filtration rate (eGFR) between 25 mL/min per 1·73 m2 and 75 mL/min per 1·73 m2 and a urinary albumin-to-creatinine ratio (UACR) between 200 mg/g and 5000 mg/g (22·6 to 565·6 mg/mmol). Participants were randomly assigned to dapagliflozin 10 mg (AstraZeneca; Gothenburg, Sweden) once daily or matching placebo, in accordance with the sequestered, fixed randomisation schedule, using balanced blocks to ensure an approximate 1:1 ratio. Change in albuminuria was a pre-specified exploratory outcome of DAPA-CKD. Regression in UACR stage, defined as a transition from macroalbuminuria (≥300 mg/g) to microalbuminuria or normoalbuminuria (<300 mg/g), and progression in UACR stage, defined as a transition from less than 3000 mg/g to 3000 mg/g or greater, were additional discrete endpoints. The trial is registered with ClinicalTrials.gov, NCT03036150. FINDINGS: Between Feb 2, 2017, and April 3, 2020, 4304 patients were recruited and randomly assigned to either dapagliflozin (n=2152) or placebo (n=2152). Median UACR was 949 mg/g (IQR 477 to 1885). Overall, compared with placebo, dapagliflozin reduced geometric mean UACR by 29·3% (95% CI -33·1 to -25·2; p<0·0001); relative to placebo, treatment with dapagliflozin resulted in a geometric mean percentage change of -35·1% (95% CI -39·4 to -30·6; p<0·0001) in patients with type 2 diabetes and -14·8% (-22·9 to -5·9; p=0·0016) in patients without type 2 diabetes over the follow-up visits (pinteraction<0·0001) Among 3860 patients with UACR of 300 mg/g or greater at baseline, dapagliflozin increased the likelihood of regression in UACR stage (hazard ratio 1·81, 95% CI 1·60 to 2·05). Among 3820 patients with UACR less than 3000 mg/g at baseline, dapagliflozin decreased the risk of progression in UACR stage (0·41, 0·32 to 0·52). Larger reductions in UACR at day 14 during dapagliflozin treatment were significantly associated with attenuated eGFR decline during subsequent follow-up (β per log unit UACR change -3·06, 95% CI -5·20 to -0·90; p=0·0056). INTERPRETATION: In patients with chronic kidney disease with and without type 2 diabetes, dapagliflozin significantly reduced albuminuria, with a larger relative reduction in patients with type 2 diabetes. The similar effects of dapagliflozin on clinical outcomes in patients with or without type 2 diabetes, but different effects on UACR, suggest that part of the protective effect of dapagliflozin in patients with chronic kidney disease might be mediated through pathways unrelated to reduction in albuminuria. FUNDING: AstraZeneca

Effect of dapagliflozin on the rate of decline in kidney function in patients with chronic kidney disease with and without type 2 diabetes: a prespecified analysis from the DAPA-CKD trial

BACKGROUND: Dapagliflozin reduced the risk of kidney failure in patients with chronic kidney disease with and without type 2 diabetes in the DAPA-CKD trial. In this pre-specified analysis, we assessed the effect of dapagliflozin on the rate of change in estimated glomerular filtration rate (eGFR)-ie, the eGFR slope. METHODS: DAPA-CKD was a randomised controlled trial that enrolled participants aged 18 years or older, with or without type 2 diabetes, with a urinary albumin-to-creatinine ratio (UACR) of 200-5000 mg/g, and an eGFR of 25-75 mL/min per 1·73m2. Participants were randomly assigned (1:1) to oral dapagliflozin 10 mg once daily or placebo, added to standard care. In this pre-specified analysis, we analysed eGFR slope using mixed-effect models with different slopes from baseline to week 2 (acute eGFR decline), week 2 to end of treatment (chronic eGFR slope), and baseline to end of treatment (total eGFR slope). DAPA-CKD is registered with ClinicalTrials.gov, NCT03036150, and is now complete. FINDINGS: Between Feb 2, 2017, and April 3, 2020, 4304 participants were recruited, of whom 2152 (50%) were assigned to dapagliflozin and 2152 (50%) were assigned to placebo. At baseline, the mean age was 62 years (SD 12), 1425 (33·1%) participants were women, 2906 (67·5%) participants had type 2 diabetes. The median on-treatment follow-up was 2·3 years (IQR 1·8-2·6). From baseline to the end of treatment, dapagliflozin compared with placebo slowed eGFR decline by 0·95 mL/min per 1·73 m2 per year (95% CI 0·63 to 1·27) in the overall cohort. Between baseline and week 2, dapagliflozin compared with placebo resulted in an acute eGFR decline of 2·61 mL/min per 1·73 m2 (2·16 to 3·06) in patients with type 2 diabetes and 2·01 mL/min per 1·73 m2 (1·36 to 2·66) in those without type 2 diabetes. Between week 2 and end of treatment, dapagliflozin compared with placebo reduced the mean rate of eGFR decline by a greater amount in patients with type 2 diabetes (mean difference in chronic eGFR slope 2·26 mL/min per 1·73 m2 per year [1·88 to 2·64]) than in those without type 2 diabetes (1·29 mL/min per 1·73 m2 per year [0·73 to 1·85]; pinteraction=0·0049). Between baseline and end of treatment, the effect of dapagliflozin compared with placebo on the decline of total eGFR slope in patients with type 2 diabetes was 1·18 mL/min per 1·73 m2 per year (0·79 to 1·56) and without type 2 diabetes was 0·46 mL/min per 1·73 m2 per year (-0·10 to 1·03; pinteraction=0·040). The total eGFR slope was steeper in patients with higher baseline HbA1c and UACR; the effect of dapagliflozin on eGFR slope was also more pronounced in patients with higher baseline HbA1c and UACR. INTERPRETATION: Dapagliflozin significantly slowed long-term eGFR decline in patients with chronic kidney disease compared with placebo. The mean difference in eGFR slope between patients treated with dapagliflozin versus placebo was greater in patients with type 2 diabetes, higher HbA1c, and higher UACR. FUNDING: AstraZeneca

Effects of dapagliflozin on mortality in patients with chronic kidney disease: a pre-specified analysis from the DAPA-CKD randomized controlled trial

AIMS : Mortality rates from chronic kidney disease (CKD) have increased in the last decade. In this pre-specified analysis of the DAPA-CKD trial, we determined the effects of dapagliflozin on cardiovascular and non-cardiovascular causes of death. METHODS AND RESULTS : DAPA-CKD was an international, randomized, placebo-controlled trial with a median of 2.4 years of follow-up. Eligible participants were adult patients with CKD, defined as a urinary albumin-to-creatinine ratio (UACR) 200-5000 mg/g and an estimated glomerular filtration rate (eGFR) 25-75 mL/min/1.73 m2. All-cause mortality was a key secondary endpoint. Cardiovascular and non-cardiovascular death was adjudicated by an independent clinical events committee. The DAPA-CKD trial randomized participants to dapagliflozin 10 mg/day (n = 2152) or placebo (n = 2152). The mean age was 62 years, 33% were women, the mean eGFR was 43.1 mL/min/1.73 m2, and the median UACR was 949 mg/g. During follow-up, 247 (5.7%) patients died, of whom 91 (36.8%) died due to cardiovascular causes, 102 (41.3%) due to non-cardiovascular causes, and in 54 (21.9%) patients, the cause of death was undetermined. The relative risk reduction for all-cause mortality with dapagliflozin (31%, hazard ratio [HR] [95% confidence interval (CI)] 0.69 [0.53, 0.88]; P = 0.003) was consistent across pre-specified subgroups. The effect on all-cause mortality was driven largely by a 46% relative risk reduction of non-cardiovascular death (HR [95% CI] 0.54 [0.36, 0.82]). Deaths due to infections and malignancies were the most frequently occurring causes of non-cardiovascular deaths and were reduced with dapagliflozin vs. placebo. CONCLUSION : In patients with CKD, dapagliflozin prolonged survival irrespective of baseline patient characteristics. The benefits were driven largely by reductions in non-cardiovascular death

Efficacy and Safety of Dapagliflozin by Baseline Glycemic Status: A Prespecified Analysis From the DAPA-CKD Trial.

OBJECTIVE: The Dapagliflozin and Prevention of Adverse outcomes in Chronic Kidney Disease (DAPA-CKD) study demonstrated risk reduction for kidney and cardiovascular outcomes with dapagliflozin versus placebo in participants with chronic kidney disease (CKD) with and without diabetes. We compared outcomes according to baseline glycemic status. RESEARCH DESIGN AND METHODS: We enrolled participants with CKD, estimated glomerular filtration rate (eGFR) 25-75 mL/min/1.73m2, and urinary albumin-to-creatinine ratio 200-5,000 mg/g. The primary composite end point was sustained eGFR decline ≥50%, end-stage kidney disease, or kidney or cardiovascular death. RESULTS: Of 4,304 participants, 738 had normoglycemia, 660 had prediabetes, and 2,906 had type 2 diabetes. The effect of dapagliflozin on the primary outcome was consistent (P for interaction = 0.19) in normoglycemia (hazard ratio [HR] 0.62 [95% CI 0.39, 1.01]), prediabetes (HR 0.37 [0.21, 0.66]), and type 2 diabetes (HR 0.64 [0.52, 0.79]). We found no evidence for effect modification on any outcome. Adverse events were similar, with no major hypoglycemia or ketoacidosis in participants with normoglycemia or prediabetes. CONCLUSIONS: Dapagliflozin safely reduced kidney and cardiovascular events independent of baseline glycemic status

Integrating sequence and structural biology with DAS.

BACKGROUND: The Distributed Annotation System (DAS) is a network protocol for exchanging biological data. It is frequently used to share annotations of genomes and protein sequence. RESULTS: Here we present several extensions to the current DAS 1.5 protocol. These provide new commands to share alignments, three dimensional molecular structure data, add the possibility for registration and discovery of DAS servers, and provide a convention how to provide different types of data plots. We present examples of web sites and applications that use the new extensions. We operate a public registry of DAS sources, which now includes entries for more than 250 distinct sources. CONCLUSION: Our DAS extensions are essential for the management of the growing number of services and exchange of diverse biological data sets. In addition the extensions allow new types of applications to be developed and scientific questions to be addressed. The registry of DAS sources is available at http://www.dasregistry.org.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are