Numerical simulation and fast method for the 0D-1D multi-scale coupled model and its application in ischemic brain tissue blood flow problems.

As living standards rise, more and more people are paying attention to their own health, especially issues such as cerebral thrombosis, cerebral infarction, and other cerebral blood flow problems. An accurate simulation of blood flow within cerebral vessels has emerged as a crucial area of research. In this study, we focus on microcirculatory blood flow in ischemic brain tissue and employ a 0D-1D geometric multi-scale coupled model to characterize this process. Given the intricate nature of human cerebral vessels, we apply a numerical method combining the finite element method and the third-order Runge-Kutta method to resolve the coupled model. To enhance computational efficiency, we introduce a fast method based on the reduced-order extrapolation algorithm. Our numerical example underscores the stability of the method and convergence accuracy to O h 3 + τ 3 , while significantly improving the accuracy and efficiency of blood flow simulation, making the mechanism analysis more accurate. Additionally, we present examples detailing variations and distribution of intracranial pressure and blood flow in ischemic brain tissue throughout a cardiac cycle. Both reduced vascular compliance and vascular stenosis can have adverse effects on intracranial cerebral pressure and blood flow, leading to insufficient local oxygen supply and negative effects on brain function. Meanwhile, there will also be corresponding changes in volume flow and pulsatile blood pressure.

Toxic effects of shale gas fracturing flowback fluid on microbial communities in polluted soil.

A large amount of shale gas fracturing flowback fluid (FFBF) from the process of shale gas exploitation causes obvious ecological harm to health of soil and water. However, biological hazard of soil microbial populations by fracturing flowback fluid remains rarely reported. In this study, the microbiological compositions were assessed via analyzing diversity of microbial populations. The results showed significant differences between polluted soil by fracturing flowback fluid and unpolluted soil in different pH and temperature conditions. And then, the microbe-index of biological integrity (M-IBI) was used to evaluate the toxicity of the fracturing flowback fluid based on analysis of microbial integrity. The results showed that polluted soil lacks key microbial species known to be beneficial to soil health, including denitrifying bacteria and cellulose-decomposing bacteria, and 35 °C is a critical value for estimating poor and sub-healthy level of damage to microbial integrity by fracturing flowback fluid. Our results provide a valuable reference for the evaluation of soil damage by fracturing flowback fluid.

Equivalent system for a multiple-rational-order fractional differential system.

The equivalent system for a multiple-rational-order (MRO) fractional differential system is studied, where the fractional derivative is in the sense of Caputo or Riemann-Liouville. With the relationship between the Caputo derivative and the generalized fractional derivative, we can change the MRO fractional differential system with a Caputo derivative into a higher-dimensional system with the same Caputo derivative order lying in (0,1). The stability of the zero solution to the original system is studied through the analysis of its equivalent system. For the Riemann-Liouville case, we transform the MRO fractional differential system into a new one with the same order lying in (0,1), where the properties of the Riemann-Liouville derivative operator and the fractional integral operator are used. The corresponding stability is also studied. Finally, several numerical examples are provided to illustrate the derived results.

[Seasonal variation of trophic states in backwater areas of tributaries in Three Gorges Reservoir].

After the Three Gorges Reservoir was storage water in June 2003, organic contamination, nutrient and biomass were determined in backwater areas of 13 tributaries in three seasons. Potassium permanganate index, chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4+ -N),total phosphorus (TP) and chlorophyll a (Chl-a) value are 0.20-9.61 mg x L(-1), 4.58-42.0 mg x L(-1), 0.601-10.1 mg x L(-1), 0.044-6.82 mg x L(-1), 0.011-0.756 mg x L(-1) and 2.0-161 mg x m(-3) respectively.The water body of tributaries is polluted at various levels. The concentration of TN is abundant.The rate of TN and TP showed that a part of tributaries eutrophication are limited by TP. Utilizing the method of between-subjects effects tests, it is indicated that spatial and seasonal distribution of nutrient factors is different in diverse seasons.Chl-a value of backwater areas of tributaries is usually beyond upstream and concentration of Ch1-a in flood season is higher than that in normal and dry season. There was a significant positive correlation between Chl-a, nutrient and organic contamination. Utilizing the method of integrated nutrition state index,it assessed the trophic states degree of the studied area. The integrated nutrition state index ranged 35-72.All of the studied tributaries are beyond mesotropher. The degree of eutrophication in flood season is higher than that in normal and dry season.The degree of eutrophication is more serious than that before the Three Gorges Reservoir impoundment. The problem of eutrophication in tributaries of Three Gorges Area should be noticed.

[Seasonal variation and output of nutrient in tributaries of Three Gorges Reservoir].

After the Three Gorges Reservoir was storage water in June 2003, organic contamination, nutrient and biomass were determined in 13 tributaries of Three Gorges Area in three seasons. Potassium permanganate index, chemical oxygen demand (COD), ammonia nitrogen (NH4+ -N), total nitrogen (TN), total phosphorus (TP) and chlorophyll a (Chl-a) value are 0.20-5.91 mg x L(-1), 4.06-30.2 mg x L(-1), 0.542-7.44 mg x L(-1), 0.034-2.83 mg x L(-1), 0.010-0.449 mg x L(-1) and 1.02-128 mg x m(-3) respectively. The water body of tributaries is polluted at various levels. The concentration of TN is abundant. The rate of TN and TP showed that a part of tributaries eutrophication are limited by TP. Low concentration of Chl-a was in tributaries water body except Zhuxi river. Trophic states of tributaries were oligotropher to mesotropher. Utilizing the method of between-subjects effects tests, it indicated that spatial and seasonal distribution of nutrient factors is different in diverse seasons. The correlation of nutrient, organic contamination and Chl-a were researched. It indicated there was a significant positive correlation among Chl-a, nutrient and organic contamination. Fluxes load of nutrient and organic contamination was calculated by discharge and concentration of each tributary. It indicated that flux load of nutrient and organic contamination was mainly controlled by discharge. The flux load in flood season is higher than normal and dry season. The nutrient fluxes load of COD, potassium permanganate index, NH4+ -N, TN and TP are 1172-6701 g x s(-1), 380-1 875 g x s(-1), 40.1-172 g x s(-1), 249-922 g x s(-1) and 9.97-50.5 g x s(-1) respectively. Pollution of tributaries in Three Gorges Area should be noticed.