936 research outputs found

    Ramjet bypass duct and preburner configuration

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    A combined turbofan and ramjet aircraft engine includes a forward bypass duct which allows the engine to operate more efficiently during the turbofan mode of operation. By mounting a ramjet preburner in the forward duct and isolating this duct from the turbofan bypass air, a transition from turbofan operation to ramjet operation can take place at lower flight Mach numbers without incurring pressure losses or blockage in the turbofan bypass air

    Admission mixing duct assembly

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    A variable cycle jet engine is provided with a mixing duct assembly which mixes core engine exhaust gas with bypass air when the engine is operating in a turbofan mode and which blocks flow from the core engine and isolates the core engine from the bypass flow when the engine is operating as a ramjet

    Conventional and High Resolution Scanning Electron Microscopy and Cryofracture Techniques as Tools for Tracing Cerebellar Short Intracortical Circuits

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    The present paper shows the potential contribution of conventional and high resolution scanning electron microscopy (SEM) to trace short intracortical circuits in cryofractured fish, primate and human cerebelli. Conventional SEM slicing technique allowed us to identify afferent mossy and climbing fibers and their synaptic relationship in the granular layer. SEM freeze-fracture method exposed the mossy glomerular synapses and the axo-dendritic connections of climbing fibers. At the Purkinje cell layer, the cryofracture process removed the satellite Bergmann glial cell layer, displaying a partial view of the supra-and infra-ganglionic plexuses of Purkinje cells and the ascending pathways of climbing fibers. High resolution SEM (HRSEM) showed the specimen specific secondary electron (SE-I) image of axosomatic synapses on Golgi cell surface. At the molecular layer, the outer surface of parallel fiber synaptic varicosities were distinguished, establishing the cruciform en passant synaptic contact with the Purkinje cell dendritic spines. HRSEM showed the fractured parallel fiber synaptic varicosities containing spheroidal synaptic vesicles embedded in a high dense extravesicular material. Conventional SEM and gold-palladium coating are useful to trace intracortical circuits. With HRSEM and chromium coating, it is possible to study the outer and inner surfaces of synaptic connections

    The Fire INventory from NCAR (FINN): A High Resolution Global Model to Estimate the Emissions from Open Burning

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    The Fire INventory from NCAR version 1.0 (FINNv1) provides daily, 1 km resolution, global estimates of the trace gas and particle emissions from open burning of biomass, which includes wildfire, agricultural fires, and prescribed burning and does not include biofuel use and trash burning. Emission factors used in the calculations have been updated with recent data, particularly for the non-methane organic compounds (NMOC). The resulting global annual NMOC emission estimates are as much as a factor of 5 greater than some prior estimates. Chemical speciation profiles, necessary to allocate the total NMOC emission estimates to lumped species for use by chemical transport models, are provided for three widely used chemical mechanisms: SAPRC99, GEOS-CHEM, and MOZART-4. Using these profiles, FINNv1 also provides global estimates of key organic compounds, including formaldehyde and methanol. Uncertainties in the emissions estimates arise from several of the method steps. The use of fire hot spots, assumed area burned, land cover maps, biomass consumption estimates, and emission factors all introduce error into the model estimates. The uncertainty in the FINNv1 emission estimates are about a factor of two; but, the global estimates agree reasonably well with other global inventories of biomass burning emissions for CO, CO2, and other species with less variable emission factors. FINNv1 emission estimates have been developed specifically for modeling atmospheric chemistry and air quality in a consistent framework at scales from local to global. The product is unique because of the high temporal and spatial resolution, global coverage, and the number of species estimated. FINNv1 can be used for both hindcast and forecast or near-real time model applications and the results are being critically evaluated with models and observations whenever possible

    Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors

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    Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME- 4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography-time-offlight mass spectrometry (GC×GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was also deployed, as well as whole-air sampling (WAS) with onedimensional gas chromatography-mass spectrometry (GCMS) analysis. This combination of instruments provided an unprecedented level of detection and chemical speciation. The chemical composition and emission factors (EFs) determined by these four analytical techniques were compared for four representative fuels. The results demonstrate that the instruments are highly complementary, with each covering some unique and important ranges of compositional space, thus demonstrating the need for multi-instrument approaches to adequately characterize BB smoke emissions. Emission factors for overlapping compounds generally compared within experimental uncertainty, despite some outliers, including monoterpenes. Data from all measurements were synthesized into a single EF database that includes over 500 non-methane organic gases (NMOGs) to provide a comprehensive picture of speciated, gaseous BB emissions. The identified compounds were assessed as a function of volatility; 6-11% of the total NMOG EF was associated with intermediate-volatility organic compounds (IVOCs). These atmospherically relevant compounds historically have been unresolved in BB smoke measurements and thus are largely missing from emission inventories. Additionally, the identified compounds were screened for published secondary organic aerosol (SOA) yields. Of the total reactive carbon (defined as EF scaled by the OH rate constant and carbon number of each compound) in the BB emissions, 55-77% was associated with compounds for which SOA yields are unknown or understudied. The best candidates for future smog chamber experiments were identified based on the relative abundance and ubiquity of the understudied compounds, and they included furfural, 2-methyl furan, 2-furan methanol, and 1,3- cyclopentadiene. Laboratory study of these compounds will facilitate future modeling efforts

    Proteomic Analysis of the Acidocalcisome, an Organelle Conserved from Bacteria to Human Cells

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    Acidocalcisomes are acidic organelles present in a diverse range of organisms from bacteria to human cells. In this study acidocalcisomes were purified from the model organism Trypanosoma brucei, and their protein composition was determined by mass spectrometry. The results, along with those that we previously reported, show that acidocalcisomes are rich in pumps and transporters, involved in phosphate and cation homeostasis, and calcium signaling. We validated the acidocalcisome localization of seven new, putative, acidocalcisome proteins (phosphate transporter, vacuolar H+-ATPase subunits a and d, vacuolar iron transporter, zinc transporter, polyamine transporter, and acid phosphatase), confirmed the presence of six previously characterized acidocalcisome proteins, and validated the localization of five novel proteins to different subcellular compartments by expressing them fused to epitope tags in their endogenous loci or by immunofluorescence microscopy with specific antibodies. Knockdown of several newly identified acidocalcisome proteins by RNA interference (RNAi) revealed that they are essential for the survival of the parasites. These results provide a comprehensive insight into the unique composition of acidocalcisomes of T. brucei, an important eukaryotic pathogen, and direct evidence that acidocalcisomes are especially adapted for the accumulation of polyphosphate

    Progression of the FIB-4 index among patients with chronic HCV infection and early liver disease

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    Background and aims:Historical paired liver biopsy studies are likely to underestimate current progression of disease in patients with chronic hepatitis C virus (HCV) infection. We aimed to assess liver disease progression according to the non-invasive Fibrosis-4 (FIB-4) index in patients with chronic HCV and early disease. Methods and results:Patients diagnosed with chronic HCV and FIB-4 &lt;3.25 from four international liver clinics were included in a retrospective cohort study. Follow-up ended at start of antiviral therapy resulting in sustained virological response, at time of liver transplantation or death. Primary outcome of advanced liver disease was defined as FIB-4 &gt;3.25 during follow-up. Survival analyses were used to assess time to FIB-4 &gt;3.25. In total, 4286 patients were followed for a median of 5.0 (IQR 1.7-9.4) years, during which 41 071 FIB-4 measurements were collected. At baseline, median age was 47 (IQR 39-55) years, 2529 (59.0%) were male, and 2787 (65.0%) patients had a FIB-4 &lt;1.45. Advanced liver disease developed in 821 patients. Overall, 10-year cumulative incidence of advanced disease was 32.1% (95% CI 29.9% to 34.3%). Patients who developed advanced disease showed an exponential FIB-4 increase. Among patients with a presumed date of HCV infection, cumulative incidence of advanced disease increased 7.7-fold from 20 to 40 years as opposed to the first 20 years after HCV infection. Conclusions:The rate of advanced liver disease is high among chronic HCV-infected patients with early disease at time of diagnosis, among whom liver disease progression accelerated over time. These results emphasise the need to overcome any limitations with respect to diagnosing and treating all patients with chronic HCV across the globe.</p

    Simultaneous Isolation of Circulating Nucleic Acids and EV-Associated Protein Biomarkers From Unprocessed Plasma Using an AC Electrokinetics-Based Platform.

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    The power of personalized medicine is based on a deep understanding of cellular and molecular processes underlying disease pathogenesis. Accurately characterizing and analyzing connections between these processes is dependent on our ability to access multiple classes of biomarkers (DNA, RNA, and proteins)-ideally, in a minimally processed state. Here, we characterize a biomarker isolation platform that enables simultaneous isolation and on-chip detection of cell-free DNA (cfDNA), extracellular vesicle RNA (EV-RNA), and EV-associated proteins in unprocessed biological fluids using AC Electrokinetics (ACE). Human biofluid samples were flowed over the ACE microelectrode array (ACE chip) on the Verita platform while an electrical signal was applied, inducing a field that reversibly captured biomarkers onto the microelectrode array. Isolated cfDNA, EV-RNA, and EV-associated proteins were visualized directly on the chip using DNA and RNA specific dyes or antigen-specific, directly conjugated antibodies (CD63, TSG101, PD-L1, GPC-1), respectively. Isolated material was also eluted off the chip and analyzed downstream by multiple methods, including PCR, RT-PCR, next-generation sequencing (NGS), capillary electrophoresis, and nanoparticle size characterization. The detection workflow confirmed the capture of cfDNA, EV-RNA, and EV-associated proteins from human biofluids on the ACE chip. Tumor specific variants and the mRNAs of housekeeping gene PGK1 were detected in cfDNA and RNA isolated directly from chips in PCR, NGS, and RT-PCR assays, demonstrating that high-quality material can be isolated from donor samples using the isolation workflow. Detection of the luminal membrane protein TSG101 with antibodies depended on membrane permeabilization, consistent with the presence of vesicles on the chip. Protein, morphological, and size characterization revealed that these vesicles had the characteristics of EVs. The results demonstrated that unprocessed cfDNA, EV-RNA, and EV-associated proteins can be isolated and simultaneously fluorescently analyzed on the ACE chip. The compatibility with established downstream technologies may also allow the use of the platform as a sample preparation method for workflows that could benefit from access to unprocessed exosomal, genomic, and proteomic biomarkers
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