76 research outputs found

    Mitigating Greenhouse Gas Emissions from Winter Production of Agricultural Greenhouses

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    Consuming conventional fossil fuel, such as coal, natural gas, and oil, to heat agricultural greenhouses has contributed to the climate change and air pollutions regionally and globally, so the clean energy sources have been increasingly applied to replace fossil energies in heating agricultural greenhouses, especially in urban area. To assess the environment performance (e.g., greenhouse gas (GHG) emissions) of the ground source heat pump system (GSHPs) for heating agricultural greenhouses in urban area, a GSHPs using the shallow geothermal energy (SGE) in groundwater was applied to heat a Chinese solar greenhouse (G1) and a multispan greenhouse (G2) in Beijing (latitude 39Β°40β€² N), the capital city of China. Emission rates of the GSHPs for heating the G1 and G2 were quantified to be 0.257–0.879 g CO2 eq. mβˆ’2 dayβˆ’1. The total GHG emissions from heating greenhouses in Beijing with the GSHPs were quantified as 1.7–2.9 Gt CO2 eq. yearβˆ’1 based on the electricity from the coal-fired power plant (CFPP) and the gas-fired power plant (GFPP). Among different stages of the SGE flow, the SGE promotion contributed most GHG emissions (66%) in total due to the higher consumption of electricity in compressors. The total GHG emissions from greenhouses heating with the coal-fired heating system (CFHs) and gas-fired heating system (GFHs) were quantified as 2.3–5.2 Gt CO2 eq. yearβˆ’1 in Beijing. Heating the G1 and G2 with the GSHPs powered by the electricity from the CFPP, the equivalent CO2 emissions were 43% and 44% lower than directly burning coal with the CFHs but were 46% and 44% higher than the GFHs that burn natural gas. However, when using the GFPP-generated electricity to run the GSHPs, the equivalent CO2 emissions would be 84% and 47% lower than the CFHs and the GFHs, respectively

    Three Dimensional Quantitative Structure-Activity Relationships of Sulfonamides Binding Monoclonal Antibody by Comparative Molecular Field Analysis

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    The three-dimensional quantitative structure-activity relationship (3D-QSAR) model of sulfonamide analogs binding a monoclonal antibody (MabSMR) produced against sulfamerazine, was carried out by comparative molecular field analysis (CoMFA). The affinities of MabSMR, expressed as Log10IC50, for 17 sulfonamide analogs were determined by competitive fluorescence polarization immunoassay (FPIA). Removal of two outliers from the initial set of 17 sulfonamide analogs improved the predictability of the models. The 3D-QSAR model of 15 sulfonamides resulted in q2cv values of 0.600, and r2 values of 0.995, respectively. This novel study combining FPIA with CoMFA demonstrates that multidisciplinary research can be used as a useful tool to investigate antigen-antibody interactions and provide information required for design of novel haptens, which may result in new antibodies with properties already optimized by an antibody-based immunoassay

    Association Between Pretreatment Serum Apolipoprotein A1 and Prognosis of Solid Tumors in Chinese Population: A Systematic Review and Meta-Analysis

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    Background/Aims: Serum apolipoprotein A1 (apoA1) has been reported to be abnormally expressed in several malignancies. However, the prognostic role of apoA1 in solid tumors is still controversial. We conducted this meta-analysis to obtain a more accurate evaluation of prognostic significance of apoA1 in Chinese patients with solid tumors. Methods: A comprehensive literature search of electronic databases was carried out up to August 2018. We included studies investigating the association between pretreatment serum apoA1 level and clinicopathological features, including survival outcomes, in solid tumors. Hazard ratios (HRs) and odds ratio (ORs) with 95% confidence intervals (CIs) were applied as effect size estimates. Results: A total of 13 studies and 8052 patients were included in our meta-analysis. Elevated level of pretreatment serum apoA1 was markedly associated with an improved OS (pooled HR = 0.608, 95% CI = 0.557 – 0.665, P < 0.001). The statistical significances were observed in all cancer types, including digestive system malignancies (pooled HR = 0.633; 95% CI = 0.550–0.727; P < 0.001), urinary system cancers (pooled HR = 0.471; 95% CI = 0.352–0.630; P < 0.001), nasopharyngeal cancer (pooled HR = 0.642; 95% CI = 0.538–0.766; P < 0.001) and non-small cell lung cancer (pooled HR = 0.526; 95% CI = 0.329–0.841; P = 0.007), but not in breast cancer (pooled HR = 0.573; 95% CI = 0.266–1.246; P = 0.155). Meanwhile, cancer patients with a low level of serum apoA1 suffered an unfavorable DFS (pooled HR = 0.714, 95% CI = 0.603 – 0.845, P < 0.001). Moreover, abnormal serum apoA1 was significantly correlated to tumor size (pooled OR = 0.640, 95% CI = 0.475 – 0.863, P = 0.003), tumor differentiation (pooled HR = 0.724, 95% CI = 0.565 – 0.929, P = 0.011), and tumor stage (pooled HR = 0.493, 95% CI = 0.384 – 0.633, P < 0.001). Conclusion: Elevated level of pretreatment serum apoA1 was significantly associated with longer survival in patients with solid tumors. Pretreatment serum apoA1 could serve as a novel positive factor for malignant patient prognosis in Chinese population

    ConceptMath: A Bilingual Concept-wise Benchmark for Measuring Mathematical Reasoning of Large Language Models

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    This paper introduces ConceptMath, a bilingual (English and Chinese), fine-grained benchmark that evaluates concept-wise mathematical reasoning of Large Language Models (LLMs). Unlike traditional benchmarks that evaluate general mathematical reasoning with an average accuracy, ConceptMath systematically organizes math problems under a hierarchy of math concepts, so that mathematical reasoning can be evaluated at different granularity with concept-wise accuracies. Based on our ConcepthMath, we evaluate a broad range of LLMs, and we observe existing LLMs, though achieving high average accuracies on traditional benchmarks, exhibit significant performance variations across different math concepts and may even fail catastrophically on the most basic ones. Besides, we also introduce an efficient fine-tuning strategy to enhance the weaknesses of existing LLMs. Finally, we hope ConceptMath could guide the developers to understand the fine-grained mathematical abilities of their models and facilitate the growth of foundation models.Comment: The benchmark dataset will be released soo

    TencentPretrain: A Scalable and Flexible Toolkit for Pre-training Models of Different Modalities

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    Recently, the success of pre-training in text domain has been fully extended to vision, audio, and cross-modal scenarios. The proposed pre-training models of different modalities are showing a rising trend of homogeneity in their model structures, which brings the opportunity to implement different pre-training models within a uniform framework. In this paper, we present TencentPretrain, a toolkit supporting pre-training models of different modalities. The core feature of TencentPretrain is the modular design. The toolkit uniformly divides pre-training models into 5 components: embedding, encoder, target embedding, decoder, and target. As almost all of common modules are provided in each component, users can choose the desired modules from different components to build a complete pre-training model. The modular design enables users to efficiently reproduce existing pre-training models or build brand-new one. We test the toolkit on text, vision, and audio benchmarks and show that it can match the performance of the original implementations

    Selection of Anti-Sulfadimidine Specific ScFvs from a Hybridoma Cell by Eukaryotic Ribosome Display

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    BACKGROUND:Ribosome display technology has provided an alternative platform technology for the development of novel low-cost antibody based on evaluating antibiotics derived residues in food matrixes. METHODOLOGY/PRINCIPAL FINDINGS:In our current studies, the single chain variable fragments (scFvs) were selected from hybridoma cell lines against sulfadimidine (SM(2)) by using a ribosome library technology. A DNA library of scFv antibody fragments was constructed for ribosome display, and then mRNA-ribosome-antibody (MRA) complexes were produced by a rabbit reticulocyte lysate system. The synthetic sulfadimidine-ovalbumin (SM(2)-OVA) was used as an antigen to pan MRA complexes and putative scFv-encoding genes were recovered by RT-PCR in situ following each panning. After four rounds of ribosome display, the expression vector pCANTAB5E containing the selected specific scFv DNA was constructed and transformed into Escherichia coli HB2151. Three positive clones (SAS14, SAS68 and SAS71) were screened from 100 clones and had higher antibody activity and specificity to SM(2) by indirect ELISA. The three specific soluble scFvs were identified to be the same molecular weight (approximately 30 kDa) by Western-blotting analysis using anti-E tag antibodies, but they had different amino acids sequence by sequence analysis. CONCLUSIONS/SIGNIFICANCE:The selection of anti-SM(2) specific scFv by in vitro ribosome display technology will have an important significance for the development of novel immunodetection strategies for residual veterinary drugs

    Effect of Droplet Impingement on the Weld Profile and Grain Morphology in the Welding of Aluminum Alloys

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    To achieve a better understanding of the effect of droplet impingement on the weld profile and grain morphology, welding with vertical and inclined torches in the double pulsed-gas metal arc welding of aluminum alloy were compared. When using vertical welding, the grains along the wall of the finger-like penetration (FLP) were refined by a more violent flow driven by droplet impingement running in the confined space created by FLP. When using inclined welding, the sharp inflection point disappeared and the curved columnar grains emerged on the non-impact action side, which was attributed to the gradually weakened impingement at that location. Moreover, when the penetration became shallower due to a low mean current, the droplets impinged alternately along split trajectories, causing significant changes in the grain morphology, such as creating grains which were sharply shortened by the direct impact of droplet impingement at impact point. The change of trajectory was ascribed to the variation of the width/depth ratio of FLP, which changed the magnitude of the contradiction between the room required by the fluid flow driven by droplet impingement and the space supplied for that by FLP

    High-Speed Welding of Stainless Steel with Additional Compensatory Gas Jet Blow Molten Pool

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    To avoid humping bead defects in high-speed welding, this paper proposes the method of an additional and compensatory gas jet blow molten pool. A pulsed metal inert gas high-speed welding test platform was constructed for compensatory gas jet blow molten pool. A total of 304 stainless steel sheets were used as the welding workpieces under equal heat inputs. Two high-speed butt welding processes were conducted and compared, in which the workpieces were welded with and without compensatory gas jets at 154 cm/min and 167 cm/min, respectively. After high-speed welding with compensatory gas jet blow, the weld appearance was straight, uniform, and high-quality, with no humping bead or undercut defects. The macroscopic morphologies and microstructures of cross-sections of the weld at the toe, near the surface, the middle, and the bottom portion all showed the stirring effect of the gas jet on the molten pool and improved grain refinement degrees. Hardness was enhanced in the weld center and the heat-affected zone. At welding speeds of 154 cm/min and 167 cm/min, the fracture load capacities of the welds were increased by 24.9 and 10.4%, respectively

    Stability and Heat Input Controllability of Two Different Modulations for Double-Pulse MIG Welding

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    Aluminum alloy welding frequently experiences difficulties such as heat input control, poor weld formation, and susceptibility to pore generation. We compared the use of two different modulations for double-pulse metal inert gas (MIG) welding to reduce the heat input required to generate oscillations in the weld pool. The stabilities of rectangular wave-modulated and trapezoidal wave-modulated double-pulse MIG welding (DP-MIG and TP-MIG) were analyzed by examining their welding processes and weld profiles. We found that the transitional pulse in TP-MIG welding results in smoother current transitions, softer welding arc sounds, and a highly uniform fish-scale pattern. Therefore, TP-MIG welding is more stable than DP-MIG welding. The effects of these double-pulse modulation schemes on welding input energy are presented. We propose methods for reducing welding input energy by varying the number of pulses or the pulse base time of low-energy pulse train while keeping the welding current and welding arc stable and unchanged. Compared to DP-MIG welding, TP-MIG welding reduces the input energy by 12% and produces finer grain sizes, which increases weld hardness. Therefore, TP-MIG welding offers a new approach for heat input control in DP-MIG welding of aluminum alloys. The results of this work are significant for aluminum alloy welding
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