170 research outputs found

    Barycentric rational interpolation method for solving time-dependent fractional convection-diffusion equation

    Get PDF
    The time-dependent fractional convection-diffusion (TFCD) equation is solved by the barycentric rational interpolation method (BRIM). Since the fractional derivative is the nonlocal operator, we develop a spectral method to solve the TFCD equation to get the coefficient matrix as a full matrix. First, the fractional derivative of the TFCD equation is changed to a nonsingular integral from the singular kernel to a density function. Second, efficient quadrature of the new Gauss formula are constructed to simply compute it. Third, matrix equation of discrete the TFCD equation is obtained by the unknown function replaced by a barycentric rational interpolation basis function. Then, the convergence rate of BRIM is proved. Finally, a numerical example is given to illustrate our result

    Using Clustering to Understand Intra-city Warming in Heatwaves: Insights into Paris, Montreal, and Zurich

    Full text link
    We introduce a novel methodological advancement by clustering paired near-surface air temperature with the planetary boundary layer height (PBLH) to characterize intra-city clusters for analytics. To illustrate this approach, we analyze three heatwaves (HW): the 2019 HW in Paris, the 2018 HW in Montreal, and the 2017 HW in Zurich. We assess cluster-based characteristics before, during, and after heatwave events. Using the objective hysteresis model, we determine the overall strength coefficient of the hysteresis loop between ground storage flux and all-wave downward radiative flux, ranging from 0.414 to 0.457 for urban clusters and from 0.126 to 0.157 for rural clusters during the heatwave periods. Across all cities, we observe a consistent refueling-restoration mode in the cumulative ground heat flux as the heatwaves progress. Future developments of this proposed two-component clustering approach, with the integration of more influential physics, will offer a more comprehensive characterization of cities for urban climate analytics

    Hot spots and flow structures around an isolated cuboid building subjected to surface warming: Large eddy simulations and wind tunnel measurements

    Full text link
    Urban warming is evident in numerous cities. On especially hot days, building surfaces warm up, leading to buoyancy-driven flows adjacent to these surfaces. The dynamics of the flow structures are largely influenced by the interplay between incoming wind and the buoyancy-driven flows. In this study, we used large eddy simulations and wind tunnel measurements to investigate the flow field around an isolated cubic building when different surfaces of the building are warmed. Under conditions of low wind speeds, ranging from 0.5 to 2 m/s, the surface temperatures of the scaled building were maintained between 20 and 95 {\deg}C. As the Richardson number (Ri) varied from 0 to 4.00, the flow, initially dominated by forced convection, shifted to being primarily steered by mixed convection. At low wind speeds and high Ri values, the thermal effect led to noticeable changes in the reattachment and recirculation region lengths, with reductions of up to 48.3% in some cases. At pedestrian levels, thermally induced airflows often created localized hot spots, particularly around building corners and wall sections. This study offers insights into architectural designs that can potentially enhance wind-thermal comfort and improve pollutant dispersion around buildings

    Molecular Cloning and Expression Analysis of a MADS-Box Gene (GbMADS2) from Ginkgo biloba

    Get PDF
    As a kind of transcription factors gene family, MADS-box genes play an important role in plant development processes. To find genes involved in the floral transition of Ginkgo biloba, a MADS-box gene, designated as GbMADS2, was cloned from G. biloba based on EST sequences by RT-PCR. Sequence analysis results showed that the cDNA sequence of GbMADS2 contained a 663 bp length ORF encoding 221 amino acids protein, which displayed typical structure of plant MADS-box protein including MADS, I, and K domains and C terminus. The sequence of GbMADS2 protein was highly homologous to those of MADS-box proteins from other plant species with the highest homologous to AGAMOUS (CyAG) from Cycas revoluta. The phylogenetic tree analysis revealed that GbMADS2 belonged to AGAMOUS clade genes. Real-time PCR analysis indicated that expression levels of GbMADS2 gene in female and male flower were significantly higher than those in root, stem, and leaves, and that GbMADS2 expression level increased along with time of flower development. The spatial and time-course expression profile of GbMADS2 implied that GbMADS2 might be involved in development of reproductive organs. The isolation and expression analysis of GbMADS2 provided basis for further studying the molecular mechanism of flower development in G. biloba

    Effects of 5-aminolevulinic Acid on the Photosynthesis, Antioxidant System, and α-Bisabolol Content of Matricaria recutita

    Get PDF
    Matricaria recutita is a widely used medicinal plant with broad pharmacological effects, and α-bisabolol is the main active ingredient of this plant. To improve its α-bisabolol content, M. recutita was sprayed with different concentrations (1.0, 2.0,and 4.0 mmol.L−1) of 5-aminolevulinic acid (ALA) or with water as a control to study the effects of ALA treatment on the photosynthesis, antioxidant system, and α-bisabolol content of M. recutita. Results showed that the photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, soluble protein, total amino acids, soluble sugar, and α-bisabolol of M. recutita were significantly increased. Moreover, the activities of superoxide dismutase, peroxidase, and catalase of M. recutita were also enhanced by ALA treatment. Optimal results were obtained when the concentration of ALA was 2.0 mmol.L−1. Results showed that ALA treatment could improve the α-bisabolol content of M. recutita, and the underlying physiological mechanism was analyzed. ALA treatment was an effective measure for improving the medicinal value of M. recutita

    A Novel and Disposable Enzyme-Labeled Amperometric Immunosensor Based on MWCNT Fibers for Listeria monocytogenes

    Get PDF
    A sensitive and specific immunosensor was developed by immobilizing HRP-labeled antibody against Listeria monocytogenes onto the surface of the novel multiwalled carbon nanotube fibers. Firstly, the influence of immunoelectrode modification methods (chemical and physical method) on detection sensitivity and stability was studied. Next, immunosensor was developed, optimized, and applied for the detection of L. monocytogenes. The morphology was characterized by scanning electron microscopy (SEM), and electrochemical behaviors were by cyclic voltammetry. SEM image, relative response (%), and current data showed chemical modification for immunoelectrode was helpful to capture more target bacteria and obtain more stable current response, resulting in improving the detection sensitivity. The linear relationship between L. monocytogenes concentration and ΔIpc was from 102 to 105 cfu/mL (R2=0.993), and LOD was 1.07×102 cfu/mL. L. monocytogenes in mixed bacteria (1.51 × 103 cfu/mL) of milk sample (S/N > 14) were detected by developed immunosensor, showing good specificity. Good storage stability and reproducibility (RSD < 6.5%) also showed the potential application of immunosensor for the rapid detection of L. monocytogenes

    The effects of jobs, amenities, and locations on housing submarkets in Xiamen City, China

    Get PDF
    Numerous studies have found that jobs, amenities, and location influence housing prices in urban areas. However, there is still a lack of in-depth understanding of the impacts of these factors on various housing submarkets within a city. With the case study of Xiamen, this paper investigates the impacts of jobs, amenities, and location on four housing submarkets, classified by owner-occupied and rental housing, in inner and outer districts. The hedonic model, Chow test, and Tiao-Goldberger test are applied to analyze differentiation in the determinants of housing prices between four submarkets. The results show that all submarkets are influenced by blue-collar jobs (which have negative effects) and seascape (which has a positive impact). Besides, differentiated after submarkets show that school districts and public transportation have a greater influence on owner-occupied markets than on rental markets. A heterogeneity exists between inner-district and outer-district markets. For instance, bus rapid transit (BRT) has a positive effect on housing and rental prices in the outer districts but not in the inner districts. These differences are mainly caused by the disparities of spatial quality, economic development, and public facilities and amenities. The findings have profound implications for decision-making and planning practices

    Effects of Methotrexate on Plasma Cytokines and Cardiac Remodeling and Function in Postmyocarditis Rats

    Get PDF
    Excessive immune activation and inflammatory mediators may play a critical role in the pathogenesis of chronic heart failure. Methotrexate is a commonly used anti-inflammatory and immunosuppressive drug. In this study, we used a rat model of cardiac myosin-induced experimental autoimmune myocarditis to investigate the effects of low-dose methotrexate (0.1 mg/kg/d for 30 d) on the plasma level of cytokines and cardiac remodeling and function. Our study showed that levels of tumor necrosis factor-(TNF-)alpha and interleukin-6 (IL-6) are significantly increased in postmyocarditis rats, compared with the control rats. Methotrexate treatment reduced the plasma levels of TNF-alpha and IL-6 and increased IL-10 level, compared to saline treatment. In addition, postmyocarditis rats showed significant cardiac fibrosis characterized by increased myocardial collagen volume fraction, perivascular collagen area, and the ratio of collagen type I to type III, compared with the control rats. However, MTX treatment not only markedly attenuated cardiac fibrosis, diminished the left ventricular end-diastolic dimension, but also increased the left ventricular ejection fraction and fractional shortening. Collectively, these results suggest that low-dose methotrexate has ability to regulate inflammatory responses and improves cardiac function and hence contributes to prevent the development of postmyocarditis dilated cardiomyopathy

    Isolation and extraction of glansreginin A from walnut meal and its effect on the proliferation of 3T3-L1 cells

    Get PDF
    Abstract Glansreginin A is an indicative component in walnut and is abundant in walnut meal. The aim of this study was to isolate and purify glansreginin A from the walnut meal, and to investigate the weight loss and lipid-lowering potential of glansreginin A by studying the effect of glansregin A on the proliferation of 3T3-L1 preadipocytes. Firstly, the response surface methodology was used to effectively improve the extraction yield of glansreginin A. The maximum extraction rate of glansreginin A was 0.363%, and the optimal extraction process conditions were determined. In addition, the lipid-lowering activity of glansreginin A was investigated by cell experiments. The results showed that glansreginin A could inhibit the proliferation of 3T3-L1 preadipocytes in a dose-dependent manner. And cell cycle of different groups of cells treated with glansreginin A was also measured using flow cytometry. The results showed most of the cells were blocked in G0/G1 phase and significantly decreased in S phase. These results suggest that glansreginin A could inhibit the proliferation of 3T3-L1 preadipocytes by causing cell cycle arrest. These findings provided a theoretical basis for the future research of glansreginin A and the development of slimming and fat-reducing foods

    Relating three-decade surge in space cooling demand to urban warming

    Get PDF
    Rising demand for space cooling has been placing enormous strain on various technological, environmental, and societal dimensions, resulting in issues related to energy consumption, environmental sustainability, health and well-being, affordability, and equity. Holistic approaches that combine energy efficiency optimization, policy-making, and societal adaptation must be rapidly promoted as viable and timely solutions. We interpret the 30-year climatic-induced upward trend and spikes in urban space cooling demand from the perspective of climate change, urbanization, and background climates, through the lens of five major populated cities: Hong Kong, Sydney, Montreal, Zurich, and London. An unequivocal, worrying upward trend in cooling demand is observed in meteorological data, using cooling degree hours (CDH) as a city-scale climatic-induced metric. The surge in cooling energy demand can be largely attributed to climate warming and urban heat islands, with the most abrupt spikes associated with intensified extreme heat events. Further, our quantification of the impact of the base temperature, in relation to the historical CDH, reveals that a 20% energy saving could be achieved instantly within a rather broad range of air temperature and relative humidity by increasing the setpoint temperature by one degree. With the rise in background temperatures due to climate change, the potential for energy saving diminishes for the same level of increase in setpoint temperature. For instance, an increase from 26 °C to 27 °C results in about 10% energy savings, while an increase from 22 °C to 23 °C could yield over 20% in energy savings. To reduce cooling energy demand rapidly in a warming climate, we highlight the necessity of promoting hard and soft behavioral adaptation along with regulatory intervention for the operation of space cooling systems
    corecore