Based on detailed in situ attenuated total‐reflection–surface‐enhanced IR reflection absorption spectroscopy (ATR‐SEIRAS) studies of the methanol oxidation reaction (MOR) on Ru/Pt thin film and ...commercial Johnson–Matthey PtRu/C, a revised MOR enhancement mechanism is proposed in which CO on Pt sites is irrelevant but instead Pt‐Ru boundary sites catalyze the oxygen insertion reaction that leads to the formation of formate and enhances the direct reaction pathway.
The methanol oxidation reaction (MOR) on Ru/Pt thin film and commercial PtRu/C was studied by in situ attenuated total‐reflection–surface‐enhanced IR reflection absorption spectroscopy. A revised MOR enhancement mechanism is proposed in which CO on Pt sites is irrelevant but instead Pt–Ru boundary sites catalyze the oxygen insertion reaction that leads to the formation of bidentate formate (indicated as OOCH) and enhances the direct reaction pathway.
•In-situ treatment of site soil using DJM technique and SPC binder is presented.•Solidified/stabilized soil exhibits satisfactory long-term performance after 326 days.•Leached concentrations of heavy ...metals and COD in soil are considerably reduced.•Soil resistance and acid neutralization capacity are remarkably improved.•In-situ field trial coincides well with lab study in strength/leaching properties.
In this study, in-situ treatment using dry jet mixing construction method and SPC (single superphosphate and calcium oxide) new binder are used to solidify/stabilize a heavy metal contaminated site soil with relatively high content of organic matters. Time-dependent field performance of the soils at 41 and 326 days after treatment is evaluated, which includes electrical conductivity (EC), leachability of heavy metals and chemical oxygen demand (COD), soil penetration resistance, acid neutralization capacity (ANC), and chemical speciation of heavy metals. The results indicate that the stabilized soils exhibit satisfactory performance which is comparable with the laboratory study. In-situ SPC treatment significantly decreases EC values and increases penetration resistance values of the soils. Leachability of lead, zinc, cadmium and COD decreases with increasing SPC content or curing time. Large percentages of heave metals in the soils are transformed from exchangeable fractions to residual fractions after treatment. These, coupled with the improved ANC, result in low heavy metal leachability in stabilized soils.
This paper presents the simulation of the condensation of water vapour in the presence of non-condensable gas using computational fluid dynamics (CFD) for turbulent flows in a vertical cylindrical ...condenser tube. The simulation accounts for the turbulent flow of the gas mixture, the condenser wall and the turbulent flow of the coolant in the annular channel with no assumptions of constant wall temperature or heat flux. The condensate film is assumed to occupy a negligible volume and its effect on the condensation of the water vapour has been taken into account by imposing a set of boundary conditions. A new strategy is used to overcome the limitation of the currently available commercial CFD package to solve the simultaneous simulation of flows involving multispecies and fluids of gas and liquid in separate channels. The results from the CFD simulations are compared with the experimental results from the literature for the condensation of water vapour with air as the non-condensable gas and for inlet mass fraction of the water vapour from 0.66 to 0.98. The CFD simulation results in general agree well with the directly measured quantities and it is found that the variation of heat flux in the condenser tube is more complex than a simple polynomial curve fit. The CFD results also show that, at least for flows involving high water vapour content, the axial velocity of the gas mixture at the interface between the gas mixture and the condensate film is in general not small and cannot be neglected.
Additive manufacturing has entered the phase of industrial adoption, for which its quality repeatability is of vital importance to industries where functional parts with consistent mechanical ...properties are desired. This concern will manifest with large scale implementation of such technology, affecting not only the reliability of products but the reputation and profitability of a business. The root cause to this problem is obscure demanding a systematic approach to identify potential influencing parameters for better process control. In this article, the quality repeatability of laser powder bed fusion (L-PBF) technology, in terms of static mechanical properties of printed parts, was quantified using relative standard deviation, and a machine learning approach for root cause analysis was demonstrated. While most of the prior work focused on the effect of laser-related process parameters to part properties, this research emphasises on the downstream production parameters while keeping laser-related parameters fixed. It was found that the combinational effect of part location and post-chamber pressure drop heavily influences the quality of printed parts. A follow-up experiment with the new process control was able to produce parts with improved quality repeatability. This proves the effectiveness of the proposed approach for process control of L-PBF at large scale implementation.
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•Relative standard deviation was found to be the most suitable metric for quality repeatability evaluation after comparison•The effects of downstream production parameters were studied simultaneously in a machine learning approach•A combinational effect from part location and post-chamber pressure drop was found to affect quality repeatability of parts•Quality repeatability was significantly improved with the new process control implementation based on findings from this work
The immunosuppressive microenvironment that is shaped by hepatic metastatic pancreatic ductal adenocarcinoma (PDAC) is essential for tumor cell evasion of immune destruction. Neutrophils are ...important components of the metastatic tumor microenvironment and exhibit heterogeneity. However, the specific phenotypes, functions and regulatory mechanisms of neutrophils in PDAC liver metastases remain unknown. Here, we show that a subset of P2RX1-negative neutrophils accumulate in clinical and murine PDAC liver metastases. RNA sequencing of murine PDAC liver metastasis-infiltrated neutrophils show that P2RX1-deficient neutrophils express increased levels of immunosuppressive molecules, including PD-L1, and have enhanced mitochondrial metabolism. Mechanistically, the transcription factor Nrf2 is upregulated in P2RX1-deficient neutrophils and associated with PD-L1 expression and metabolic reprogramming. An anti-PD-1 neutralizing antibody is sufficient to compromise the immunosuppressive effects of P2RX1-deficient neutrophils on OVA-activated OT1 CD8+ T cells. Therefore, our study uncovers a mechanism by which metastatic PDAC tumors evade antitumor immunity by accumulating a subset of immunosuppressive P2RX1-negative neutrophils.
Much theoretical and empirical research has verified the non-linear and uncertain relationships between carbon emissions and economic growth. To forecast the carbon emissions from fossil energy ...consumption, this paper introduces the power exponential term of the relevant variables as exogenous variables into a multivariable grey model. Under the target of minimisation of the mean absolute percentage error, two non-linear programming models are constructed to solve the unknown parameters of the non-linear grey multivariable model. In addition, to enhance the adaptability of the grey model to large sample sizes, we divide the data of Chinese gross domestic product and carbon emissions from fossil energy consumption of 1953–2013 into 15 stages. The empirical results show that the non-linear grey multivariable model can reflect the mechanism of the non-linear effects of gross domestic product on carbon emissions from fossil energy consumption, and has higher forecast accuracy than the traditional grey model and the autoregressive integrated moving average models. In three schemes – economic growth at low, medium, and high, speeds – we use the non-linear grey model to quantify future Chinese carbon emissions from fossil energy consumption from 2014 to 2020, and the predicted results can provide the basis for energy planning and the formulation of environmental policy.
•A non-linear grey multivariable model is presented.•The non-linear effect of economic growth on carbon emissions is measured.•Chinese carbon emissions from fossil energy consumption are predicted in three schemes.
Background & Aims Desmoplasia and poor vascularity cause severe metabolic stress in pancreatic ductal adenocarcinomas (PDACs). Serotonin (5-HT) is a neuromodulator with neurotransmitter and ...neuroendocrine functions that contributes to tumorigenesis. We investigated the role of 5-HT signaling in the growth of pancreatic tumors. Methods We measured the levels of proteins that regulate 5-HT synthesis, packaging, and degradation in pancreata from KrasG12D/+ /Trp53R172H/+ /Pdx1-Cre (KPC) mice, which develop pancreatic tumors, as well as in PDAC cell lines and a tissue microarray containing 81 human PDAC samples. We also analyzed expression levels of proteins involved in 5-HT synthesis and degradation by immunohistochemical analysis of a tissue microarray containing 311 PDAC specimens, and associated expression levels with patient survival times. 5-HT level in 14 matched PDAC tumor and non-tumor tissues were analyzed by ELISA. PDAC cell lines were incubated with 5-HT and cell survival and apoptosis were measured. We analyzed expression of the 5-HT receptor HTR2B in PDAC cells and effects of receptor agonists and antagonists, as well as HTR2B knockdown with small hairpin RNAs. We determined the effects of 5-HT stimulation on gene expression profiles of BxPC-3 cells. Regulation of glycolysis by 5-HT signaling via HTR2B was assessed by immunofluorescence and immunoprecipitation analyses, as well as by determination of the extracellular acid ratio, glucose consumption, and lactate production. Primary PDACs, with or without exposure to SB204741 (a selective antagonist of HTR2B), were grown as xenograft tumors in mice, and SB204741 was administered to tumor-bearing KPC mice; tumor growth and metabolism were measured by imaging analyses. Results In immunohistochemical analysis of a tissue microarray of PDAC specimens, increased levels of TPH1 and decreased level of MAOA, which regulate 5-HT synthesis and degradation, correlated with stage and size of PDACs and shorter patient survival time. We found levels of 5-HT to be increased in human PDAC tissues compared with non-tumor pancreatic tissues, and PDAC cell lines compared with non-transformed pancreatic cells. Incubation of PDAC cell lines with 5-HT increased proliferation and prevented apoptosis. Agonists of HTR2B, but not other 5-HT receptors, promoted proliferation and prevented apoptosis of PDAC cells. Knockdown of HTR2B in PDAC cells, or incubation of cells with HTR2B inhibitors, reduced their growth as xenograft tumors in mice. We observed a correlation between 5-HT and glycolytic flux in PDAC cells; levels of metabolic enzymes involved in glycolysis, the phosphate pentose pathway, and hexosamine biosynthesis pathway increased significantly in PDAC cells following 5-HT stimulation. 5-HT stimulation led to formation of the HTR2B–LYN–p85 complex, which increased PI3K–Akt–mTOR signaling and the Warburg effect by increasing protein levels of MYC and HIF1A. Administration of SB204741 to KPC mice slowed growth and metabolism of established pancreatic tumors and prolonged survival of the mice. Conclusions Human PDACs have increased levels of 5-HT, and PDAC cells increase expression of its receptor, HTR2B. These increases allow for tumor glycolysis under metabolic stress and promote growth of pancreatic tumors and PDAC xenograft tumors in mice.
•Our first-principles calculations and thermodynamics formalism predict 15 quaternary high-entropy metal carbides (HEMCs) of group IVB and VB metals.•A three-dimensional phase diagram of the 15 HEMCs ...in terms of thermodynamic and structural parameters is obtained.•We find that all the 15 HEMCs exhibit the unusual property of both high hardness and high fracture toughness, as well as ultra-high melting points.•The methodology we have developed for this work may be generalized for predicting the single-phase stability of other potential high-entropy ceramics.
With a combination of first-principles calculations and thermodynamics formalism of configurational mixing entropy, we have constructed three-dimensional phase diagram in terms of thermodynamic and structural parameters including the configurational mixing entropy and enthalpy, the temperature of the melting point, and the lattice constant difference of the constitute carbides for fifteen equiatomic quaternary high-entropy metal carbide (HEMC) ceramics of group IVB and VB refractory metals (RM = Ti, Zr, Hf, V, Nb, and Ta). We further predicted nine new HEMCs and provided an explanation for the existence of six experimentally realized quaternary HEMCs. In addition, our calculations of the melting points and mechanical properties show that the HEMCs have the unique properties of high hardness, high fracture toughness, and ultrahigh melting points. The computational procedure involved in this work may be used to design new high-entropy ceramics for specific applications.
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