The creep-ageing behaviour of a peak-aged aluminium alloy 7050 was investigated under different stress levels at 174 ∘C for up to 8 h. Interrupted creep tests and tensile tests were performed to ...investigate the influences of creep-ageing time and applied stress on yield strength. The mechanical testing results indicate that the material exhibits an over-ageing behaviour which increases with the applied stress level during creep-ageing. As creep-ageing time approaches 8 h, the material's yield strength under different stress levels gradually converge, which suggests that the difference in mechanical properties under different stress conditions can be minimised. This feature can be advantageous in creep-age forming to the formed components such that uniformed mechanical properties across part area can be achieved. A set of constitutive equations was calibrated using the mechanical test results and the alloy-specific material constants were obtained. A good agreement is observed between the experimental and calibrated results.
Our ALMA observations of HCO+ and HCN show such redshifted absorption toward an isolated core, BHR 71. Both lines show a similar redshifted absorption profile. We also found emissions of complex ...organic molecules (COMs) around 345 GHz from a compact region centered on the continuum source, which is barely resolved with a beam of 0″27, corresponding to ∼50 AU.
Creep-ageing behaviour of aluminium alloy 7B04-T651 at 115 °C under a range of tensile stress levels has been experimentally investigated and numerically modelled for creep-age forming (CAF) ...applications. Creep strain, yield strength evolution and precipitate growth of creep-aged specimens were investigated. The alloy was modelled using a set of unified constitutive equations, which captures its creep deformation and takes into account yield strength contributions from three creep-age hardening mechanisms. Applications of the present work are demonstrated by implementing the determined material model into a commercial finite element analysis solver to analyse CAF operations carried out in a novel flexible CAF tool. Stress relaxation, yield strength, precipitate size and springback were predicted for the creep-age formed plates. The predicted springback were further quantified and compared with experimental measurements and a good agreement of 2.5% deviation was achieved. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.
This paper presents a study on the creep-ageing behaviour of a peak-aged aluminium alloy 7B04 under different tensile loads at 115oC and subsequently modelling it for creep-age forming (CAF) ...applications. Mechanical properties and microstructural evolutions of creep-aged specimens were investigated. The material was modelled using a set of unified constitutive equations, which not only captures the material's creep deformation but also takes into account yield strength contributions from solid solution hardening, age hardening and dislocation hardening during creep-ageing. A possible application of the present work is demonstrated by implementing the determined material model into a commercial finite element analysis solver via a user-defined subroutine for springback prediction of creep-age formed plates. A good agreement is observed between the simulated springback values and experimental results. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.
Deregulation of polycomb group complexes polycomb repressive complex 1 (PRC1) and 2 (PRC2) is associated with human cancers. Although inactivating mutations in PRC2-encoding genes EZH2, EED, and ...SUZ12 are present in T-cell acute lymphoblastic leukemia and in myeloid malignancies, gain-of-function mutations in EZH2 are frequently observed in B-cell lymphoma, implying disease-dependent effects of individual mutations. We show that, in contrast to PRC1, PRC2 is a tumor suppressor in Eµ-myc lymphomagenesis, because disease onset was accelerated by heterozygosity for Suz12 or by short hairpin RNA–mediated knockdown of Suz12 or Ezh2. Accelerated lymphomagenesis was associated with increased accumulation of B-lymphoid cells in the absence of effects on apoptosis or cell cycling. However, Suz12-deficient B-lymphoid progenitors exhibit enhanced serial clonogenicity. Thus, PRC2 normally restricts the self-renewal of B-lymphoid progenitors, the disruption of which contributes to lymphomagenesis. This finding provides new insight regarding the functional contribution of mutations in PRC2 in a range of leukemias.
•PRC1 and PRC2 have opposing activity in Eμ-myc lymphoma.•Inhibition of PRC2 leads to increased self-renewal in B-cell progenitors.
Door-to-balloon (DTB) time is critical to ST elevation myocardial infarction (STEMI) patients' survival. Although DTB time is reduced with direct cardiovascular laboratory (CVL) activation by ...emergency physicians, concerns regarding false-positive activation remain. We evaluate false-positive rates before and after direct CVL activation and factors associated with false-positive activations.
This is a retrospective single centre study of all emergency CVL activation 3 years before and after introduction of direct activation in July 2007. False-positive activation is defined as either: 1) absence of culprit vessel with coronary artery thrombus or ulceration, or 2) presence of chronic total occlusion of culprit vessel, with no cardiac biomarker elevations and no regional wall abnormalities. All false-positive cases were verified by reviewing their coronary angiograms and patient records.
A total of 1809 subjects were recruited; 84 (4.64%) identified as false-positives. Incidence of false-positive before and after direct activation was 4.1% and 5.1% respectively, which was not significant (P = 0.315). In multivariate logistic regression analysis, factors associated with false-positive were: female (odds ratio (OR): 2.104 1.247-3.548, P = 0.005), absence of chest pain (OR: 5.369 3.024-9.531, P <0.0001) and presence of only left bundle branch block (LBBB) as indication for activation (OR: 65.691 19.870-217.179, P <0.0001).
Improvement in DTB time with direct CVL activation by emergency physicians is not associated with increased false-positive activations. Factors associated with false-positive, especially lack of chest pain or LBBB, can be taken into account to optimise STEMI management.
In both humans and mice, a deficiency of surfactant protein B (SP-B) is associated with a decreased concentration of mature SP-C and accumulation of a larger SP-C peptide, denoted SP-Ci, which is not ...observed under normal conditions. Isolation of hydrophobic polypeptides from the lungs of children who died with two different SP-B mutations yielded pure SP-Ci and showed only trace amounts of mature SP-C. Determination of the SP-Ci covalent structure revealed a 12-residue N-terminal peptide segment, followed by a 35-residue segment that is identical to mature SP-C. The SP-Ci structure determined herein is similar to that of a proposed late intermediate in the processing of proSP-C, suggesting that SP-Ci is the immediate precursor of SP-C. In bronchoalveolar lavage fluid from transgenic mice with a focal deficiency of SP-B, SP-Ci was detected in the biophysically active, large aggregate fraction and was associated with membrane structures that are typical for a large aggregate surfactant. However, unlike SP-C, SP-Ci exhibited a very poor ability to promote phospholipid adsorption, gave high surface tension during cyclic film compression, and did not bind lipopolysaccharide in vitro. SP-Ci is thus capable of associating with surfactant lipids, but its N-terminal dodecapeptide segment must be proteolytically removed to generate a biologically functional peptide. The results of this study indicate that the early postnatal fatal respiratory distress seen in SP-B-deficient children is combined with the near absence of active variants of SP-C.
A method based on liquid chromatography (LC) in combination with mass spectrometry (MS) for the analysis of alachlor (ALA) and its metabolites, 2-chloro-
N-2,6-diethylphenylacetamide (CDEPA) and ...2,6-diethylaniline (DEA), in rat plasma and urine has been developed.
13C-labeled ALA was used as the internal standard for quantitation. The analyte in plasma or urine was isolated using a Waters Oasis HLB extraction plate. The mass spectrometer was operated in the ESI MS-SIM mode with a programming procedure. The retention times for ALA, CDEPA and DEA were 1.84, 3.11 and 4.12 min, respectively. The limits of quantification (LOQ) for ALA, CDEPA and DEA were 2.3, 0.8 and 0.8 ng per injection, respectively. The linear fit of analyte to mass response had an
R
2 of 0.99. Reproducibility of the sample handling and LC–MS analysis had a RSD of ≤10%. The average recoveries for these analytes in rat plasma were better than 90%. Similar results were obtained with rat urine.
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