RESUMEN
The effect of temperature on the service life of stranded carbon fiber composite core conductors was studied based on the kinetic theory of material pyrolysis. The thermal decomposition activation energy calculation for stranded carbon fiber composite cores was carried out by thermogravimetric analysis (TGA). The activation energy E of stranded carbon fiber composites was calculated according to the Flynn-Wall-Ozawa, Kissinger, and Coast-Redfern methods, which were 168.76 kJ/mol, 166.79 kJ/mol, and 160.35 kJ/mol, respectively. The results from these different treatments were within 10% or less, and thus the thermochemical reactions of stranded carbon fiber composite cores were considered to be effective. The life prediction model of the carbon fiber composite core was developed based on the kinetic equation of thermal decomposition. The service life is related to the reaction mechanism function G(α) and the reaction rate parameter k(t). The reaction mechanism function G(α) = ((1 - α)-3.3 - 1)/3.3 and the reaction rate parameter k(t) = 2.14 × 1012exp(E/RT) were obtained by fitting the thermal weight loss data of stranded carbon fiber composite cores. Based on the 5% mass loss criterion for the end of life of stranded carbon fiber composites, the service life of the carbon fiber composite core is given at various operating temperatures.
RESUMEN
Restoring the compromised neurogenesis has been served as a potential strategy to rescue cognitive dysfunction of Alzheimer's disease (AD). In this study, we explored whether icarisid II (ICS II), a natural product possessing powerful neuroprotection, could recover the neurogenesis dysfunction of APP/PS1 mice, and investigated its underlying mechanisms. Our results showed that oral administration of ICS II could alleviate cognitive injuries of APP/PS1 mice, promote hippocampal neurogenesis, as well as stimulate Wnt/ß-catenin signal pathway confirmed by upregulated Wnt-3a, phosphorylated glycogen synthase kinase-3ß (p-GSK-3ß), and ß-catenin. ICS II also depressed mitochondrial fission evidenced by upregulated Mitofusin 1 (Mfn 1) and Mitofusin 2 (Mfn 2), and downregulated mitochondrial fission 1 protein (Fis 1), mitochondrial fission factor (Mff), and phosphorylated dynamin-related protein 1 (p-Drp 1). However, these effects of ICS II were blunted by XAV-939, an inhibitor of Wnt/ß-catenin signaling pathway. In summary, our findings revealed that ICS II could improve neurogenesis and inhibit mitochondrial fission via activation of the Wnt/ß-catenin signaling pathway, which contributed to cognitive function restoration of APP/PS1 mice. This study discovered a novel mechanism involving neurogenesis regulation underlying the therapeutic effects of ICS II against AD.
Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Disfunción Cognitiva/tratamiento farmacológico , Flavonoides , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Hipocampo , Ratones , Ratones Transgénicos , Neurogénesis , Oligopéptidos/metabolismo , Vía de Señalización Wnt , beta Catenina/metabolismoRESUMEN
In economics, a demand curve is almost always downward-sloping, reflecting the willingness of consumers to purchase more of the commodity at lower price levels. In addition, the demand for seasonal products (such as fashion apparels, beverages etc.) or perishable goods (such as meat and seafood, dairy products, fruit and vegetables, pharmaceutical products, and chemicals) decreases over time. Hence, demand is a function of price and stock-age. With large business transactions, a seller usually demands a down payment (i.e., an advance payment) to ensure that the buyer is making a serious offer. Conversely, a buyer frequently requests to hold a fraction of total purchase cost until the business transaction is completed and satisfactory (i.e., a credit payment). As a result, a combination of advance, cash, and credit (ACC) payments is commonly used in business transactions. This paper develops a supplier-retailer-customer chain in which the retailer receives an upstream ACC payment from the supplier while in return offers a down-stream cash-credit (some in cash and the remainder in credit) payment to customers, the demand is influenced by the combined effect of selling price and stock age, and the deterioration rate is time-varying. The retailer must determine optimal unit price and replenishment time to maximize the present value of total profit, which is strictly concave in selling price and strictly pseudo-concave in replenishment time. Finally, a sensitivity analysis is performed, and several managerial insights are obtained. For instance, an increase in the fraction of advance payment forces the retailer to raise selling price.
RESUMEN
In this paper, multiwall carbon nanotubes (MWCNTs) were modified by Polyethylenimine of different molecular weight of 1800 (MWCNTs-18) and 7000 (MWCNTs-70). The structure and morphology of the functionalized MWCNTs were characterized by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The curve of TGA showed that the mass loss of MWCNTs-18 and MWCNTs-70 were 46.5% and 51.9% respectively, which was remarkably different with pristine MWCNTs. The XRD demonstrated that the structure of the pristine MWCNTs and functionalized MWCNTs were similar. In addition, the experiment of the removal of chromate from water solution using functionalized MWCNTs was also conducted. The experimental conditions such as concentration of chromate, temperature, pH were studied. The maximum uptake capacities for chromate anions were obtained at the concentration of 0.4 mmol·L-1. The solution pH showed a significant effect on chromate removal over a pH range from 4.0 to 9.0. Besides, the uptake capacities for chromate anions on MWCNTs-18 and MWCNTs-70 increased as the temperature increase within the range from 30 to 60 °C. Under the experimental conditions, the maximum uptake capacities of MWCNTs-18 and MWCNTs-70 for chromate anions were 0.27 and 0.33 mmol·g-1 respectively. The thermodynamic parameters of the uptake process were calculated, and the results showed that the process of uptake chromate was spontaneous.