Effect of steam addition on the flow field and NOx emissions for Jet-A in an aircraft combustor

The steam injection technology for aircraft engines is gaining rising importance because of the strong limitations imposed by the legislation for NOx reduction in airports. In order to investigate the impact of steam addition on combustion and NOx emissions, an integrated performance-CFD-chemical reactor network (CRN) methodology was developed. The CFD results showed steam addition reduced the high temperature size and the radical pool moved downstream. Then different post-processing techniques are employed and CRN is generated to predict NOx emissions. This network consists of 14 chemical reactor elements and the results were in close agreement with the ICAO databank. The established CRN model was then used for steam addition study and the results showed under air/steam mixture atmosphere, high steam content could push the NOx formation region to the post-flame zone and a large amount of the NOx emission could be reduced when the steam mass fraction is quite high

Effect of steam addition on gas turbine combustor design and performance

Adding steam influences the combustion process inside the combustor, which should be taken into account during combustor design. The design of combustor has long been the most challenging process. This study integrated the gas turbine performance with the combustor design, and formulated a detailed procedure for single annular combustors with steam addition consideration in particular. To accomplish this, a computer code has been developed based on the design procedures. The design model could provide the combustor geometry and the combustor performance. The inlet parameters for combustor design are obtained and validated through the calculation of gas turbine engine performance provided by our own home code. The model predictions are compared with operational and configuration data from two real engines and show reasonably good accuracy. The influence of steam addition on combustor design is investigated and results showed the variation of geometrical size is highest for components where intense combustion takes place while the design is almost kept the same for components where only pure flow exists. After conforming the feasibility of the combustor design code, we investigated the effects of steam addition on combustor performance. It revealed that steam injection is an effective way to reduce the temperature in the burner while other performance like the total pressure loss would be slightly deteriorated

DCAF26, an Adaptor Protein of Cul4-Based E3, Is Essential for DNA Methylation in Neurospora crassa

DNA methylation is involved in gene silencing and genome stability in organisms from fungi to mammals. Genetic studies in Neurospora crassa previously showed that the CUL4-DDB1 E3 ubiquitin ligase regulates DNA methylation via histone H3K9 trimethylation. However, the substrate-specific adaptors of this ligase that are involved in the process were not known. Here, we show that, among the 16 DDB1- and Cul4-associated factors (DCAFs) encoded in the N. crassa genome, three interacted strongly with CUL4-DDB1 complexes. DNA methylation analyses of dcaf knockout mutants revealed that dcaf26 was required for all of the DNA methylation that we observed. In addition, histone H3K9 trimethylation was also eliminated in dcaf26KO mutants. Based on the finding that DCAF26 associates with DDB1 and the histone methyltransferase DIM-5, we propose that DCAF26 protein is the major adaptor subunit of the Cul4-DDB1-DCAF26 complex, which recruits DIM-5 to DNA regions to initiate H3K9 trimethylation and DNA methylation in N. crassa

Retinal Nerve Fiber Layer Thinning Is Associated With Brain Atrophy: A Longitudinal Study in Nondemented Older Adults

Backgrounds: Abnormal retinal nerve fiber layer (RNFL) thickness has been observed in patients with Alzheimer’s disease (AD) and therefore suggested to be a potential biomarker of AD. However, whether the changes in RNFL thickness are associated with the atrophy of brain structure volumes remains unknown. We, therefore, set out a prospective investigation to determine the association between longitudinal changes of RNFL thickness and brain atrophy in nondemented older participants over a period of 12 months.Materials and Methods: We measured the RNFL thickness using optical coherence tomography (OCT) and brain structure volumes by 3T magnetic resonance imaging (MRI) before and after 12 months. Cognitive function was assessed using the Chinese version of Mini-Mental State Examination (CMMSE) and Repeatable Battery for the Assessment of Neurological Status. Associations among the changes of RNFL, brain structures and cognitive function were analyzed with Spearman correlation and multiple linear regression models adjusting for the confounding factors.Results: Fifty old participants were screened and 40 participants (mean age 71.8 ± 3.9 years, 60% were male) were enrolled at baseline. Among them, 28 participants completed the follow-up assessments. The average reduction of RNFL thickness was inversely associated with the decrease of central cingulate cortex volume after the adjustment of age and total intracranial volume (β = −0.41, P = 0.039). Specifically, the reduction of RNFL thickness in the inferior, not other quadrants, was independently associated with the decline of central cingulate cortex volume after the adjustment (β = −0.52, P = 0.006). Moreover, RNFL thinning, central cingulate cortex atrophy and the aggregation of white matter hyperintensities (WMH) were found associated with episodic memory in these older adults with normal cognition.Conclusions: RNFL thinning was associated with cingulate cortex atrophy and episodic memory decline in old participants. The longitudinal changes of RNFL thickness are suggested to be a useful complementary index of neurocognitive aging or neurodegeneration

Simultaneous removal of SO2 and NOx by a new combined spray-and-scattered-bubble technology based on preozonation: from lab scale to pilot scale

A new technology (called here, spray-and-scattered-bubble technology) based on preozonation was designed and tested for simultaneous removal of SO2 and NOx from power plant flue gas. It combines the advantages of the common spray tower and the jet bubble reactor, in which the flue gas experiences an initial SO2/NOx removal in the spray zone and then undergoes further removal in the bubble zone. Factors that affect the simultaneous removal of SO2/NOx were investigated through lab-scale experiments, by varying the O3/NO molar ratio, liquid/gas ratio and the immersion depth. The results showed the removal of SO2 and NOx can be significantly improved as compared to a separate spray column or bubble reactor, by as much as 17%, for the spray column and 18% for the bubble reactor for NOx and 11% for the spray column, and 13% for the bubble reactor for SO2, for liquid/gas ratio of 4 dm3/m3 or immersion depth of 100 mm. The O3/NO molar ratio had little effect on the SO2 removal, but it strongly affected the removal efficiency of NOx especially when it was less than 1.0. Both the liquid/gas ratio and immersion depth demonstrated a positive correlation with the removal efficiency. However, a balance must be maintained between efficiency and economics, since the liquid/gas ratio directly influences the performance and number of the circulating pumps, and the depth is closely related to the flue gas pressure drop, and both factors affect energy requirements. To further confirm its industrial feasibility, a 30 h test using real coal-fired flue gas was conducted in a pilot-scale experimental facility (flue gas volume of 5000 Nm3/h). Increasing SO2 concentration in flue gas can promote the removal efficiency of NOx, but the SO2 removal was almost complete under all conditions tested. Finally, taking a 300 MW unit as an example,- the total energy cost of this new technology is estimated as being 10% lower than that of the common spray tower technology, based on an analysis using Aspen Plus™, with the largest difference reflected in the energy requirements of the circulating pumps and the ozonizer. Over all, the new technology offers the joint advantages of reducing emissions and saving energy

Differentiation potential of STRO-1+ dental pulp stem cells changes during cell passaging

<p>Abstract</p> <p>Background</p> <p>Dental pulp stem cells (DPSCs) can be driven into odontoblast, osteoblast, and chondrocyte lineages in different inductive media. However, the differentiation potential of naive DPSCs after serial passaging in the routine culture system has not been fully elucidated.</p> <p>Results</p> <p>DPSCs were isolated from human/rat dental pulps by the magnetic activated cell sorting based on STRO-1 expression, cultured and passaged in the conventional culture media. The biological features of STRO-1⁺DPSCs at the 1^stand 9^thpassages were investigated. During the long-term passage, the proliferation ability of human STRO-1⁺DPSCs was downregulated as indicated by the growth kinetics. When compared with STRO-1⁺DPSCs at the 1^stpassage (DPSC-P1), the expression of mature osteoblast-specific genes/proteins (alkaline phosphatase, bone sialoprotein, osterix, and osteopontin), odontoblast-specific gene/protein (dentin sialophosphoprotein and dentin sialoprotein), and chondrocyte-specific gene/protein (type II collagen) was significantly upregulated in human STRO-1⁺DPSCs at the 9^thpassage (DPSC-P9). Furthermore, human DPSC-P9 cells in the mineralization-inducing media presented higher levels of alkaline phosphatase at day 3 and day 7 respectively, and produced more mineralized matrix than DPSC-P9 cells at day 14. <it>In vivo </it>transplantation results showed that rat DPSC-P1 cell pellets developed into dentin, bone and cartilage structures respectively, while DPSC-P9 cells can only generate bone tissues.</p> <p>Conclusions</p> <p>These findings suggest that STRO-1⁺DPSCs consist of several interrelated subpopulations which can spontaneously differentiate into odontoblasts, osteoblasts, and chondrocytes. The differentiation capacity of these DPSCs changes during cell passaging, and DPSCs at the 9^thpassage restrict their differentiation potential to the osteoblast lineage <it>in vivo</it>.</p

Taking the pulse of COVID-19: A spatiotemporal perspective

The sudden outbreak of the Coronavirus disease (COVID-19) swept across the world in early 2020, triggering the lockdowns of several billion people across many countries, including China, Spain, India, the U.K., Italy, France, Germany, and most states of the U.S. The transmission of the virus accelerated rapidly with the most confirmed cases in the U.S., and New York City became an epicenter of the pandemic by the end of March. In response to this national and global emergency, the NSF Spatiotemporal Innovation Center brought together a taskforce of international researchers and assembled implemented strategies to rapidly respond to this crisis, for supporting research, saving lives, and protecting the health of global citizens. This perspective paper presents our collective view on the global health emergency and our effort in collecting, analyzing, and sharing relevant data on global policy and government responses, geospatial indicators of the outbreak and evolving forecasts; in developing research capabilities and mitigation measures with global scientists, promoting collaborative research on outbreak dynamics, and reflecting on the dynamic responses from human societies.Comment: 27 pages, 18 figures. International Journal of Digital Earth (2020

AXL targeting restores PD-1 blockade sensitivity of STK11/LKB1 mutant NSCLC through expansion of TCF1+ CD8 T cells

Mutations in STK11/LKB1 in non-small cell lung cancer (NSCLC) are associated with poor patient responses to immune checkpoint blockade (ICB), and introduction of a Stk11/Lkb1 (L) mutation into murine lung adenocarcinomas driven by mutant Kras and Trp53 loss (KP) resulted in an ICB refractory syngeneic KPL tumor. Mechanistically this occurred because KPL mutant NSCLCs lacked TCF1-expressing CD8 T cells, a phenotype recapitulated in human STK11/LKB1 mutant NSCLCs. Systemic inhibition of Axl results in increased type I interferon secretion from dendritic cells that expanded tumor-associated TCF1+PD-1+CD8 T cells, restoring therapeutic response to PD-1 ICB in KPL tumors. This was observed in syngeneic immunocompetent mouse models and in humanized mice bearing STK11/LKB1 mutant NSCLC human tumor xenografts. NSCLC-affected individuals with identified STK11/LKB1 mutations receiving bemcentinib and pembrolizumab demonstrated objective clinical response to combination therapy. We conclude that AXL is a critical targetable driver of immune suppression in STK11/LKB1 mutant NSCLC.publishedVersio