作者机构：
[Qian, Shengyou; Zou, Xiao; Chang, Shuai; Tian, Feng; Lei, Weirui; Qian, SY] Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Peoples R China.;[Hu, JW; Hu, Jiwen] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Hu, JW ] U;[Zou, X; Qian, SY ] H;Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Peoples R China.;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Blood–brain barrier;Drug delivery;Finite element method (FEM);Multiple bubbles
摘要：
Experimental studies have shown that ultrasonic cavitation can reversibly open the blood–brain barrier (BBB) to assist drug delivery. Nevertheless, the majority of the present study focused on experimental aspects of BBB opening. In this study, we developed a three-bubble-liquid-solid model to investigate the dynamic behavior of multiple bubbles within the blood vessels, and elucidate the physical mechanism of drug molecules through endothelial cells under ultrasonic cavitation excitation. The results showed that the large bubbles have a significant inhibitory effect on the movement of small bubbles, and the vibration morphology of intravascular microbubbles was affected by the acoustic parameters, microbubble size, and the distance between the microbubbles. The ultrasonic cavitation can significantly enhance the unidirectional flux of drug molecules, and the unidirectional flux growth rate of the wall can reach more than 5 %. Microjets and shock waves emitted from microbubbles generate different stress distribution patterns on the vascular wall, which in turn affects the pore size of the vessel wall and the permeability of drug molecules. The vibration morphology of microbubbles is related to the concentration, arrangement and scale of microbubbles, and the drug permeation impact can be enhanced by optimizing bubble size and acoustic parameters. The results offer an extensive depiction of the factors influencing the blood–brain barrier opening through ultrasonic cavitation, and the model may provide a potential technique to actively regulate the penetration capacity of drugs through endothelial layer of the neurovascular system by regulating BBB opening.
Experimental studies have shown that ultrasonic cavitation can reversibly open the blood–brain barrier (BBB) to assist drug delivery. Nevertheless, the majority of the present study focused on experimental aspects of BBB opening. In this study, we developed a three-bubble-liquid-solid model to investigate the dynamic behavior of multiple bubbles within the blood vessels, and elucidate the physical mechanism of drug molecules through endothelial cells under ultrasonic cavitation excitation. The results showed that the large bubbles have a significant inhibitory effect on the movement of small bubbles, and the vibration morphology of intravascular microbubbles was affected by the acoustic parameters, microbubble size, and the distance between the microbubbles. The ultrasonic cavitation can significantly enhance the unidirectional flux of drug molecules, and the unidirectional flux growth rate of the wall can reach more than 5 %. Microjets and shock waves emitted from microbubbles generate different stress distribution patterns on the vascular wall, which in turn affects the pore size of the vessel wall and the permeability of drug molecules. The vibration morphology of microbubbles is related to the concentration, arrangement and scale of microbubbles, and the drug permeation impact can be enhanced by optimizing bubble size and acoustic parameters. The results offer an extensive depiction of the factors influencing the blood–brain barrier opening through ultrasonic cavitation, and the model may provide a potential technique to actively regulate the penetration capacity of drugs through endothelial layer of the neurovascular system by regulating BBB opening.
作者：
Su, Chi;Hua, Yilong;Liu, Yi;Tao, Shu;Jia, Fei;...
期刊：
PLOS ONE,2024年19(3):e0300800 ISSN：1932-6203
通讯作者：
Lin, WY
作者机构：
[Hua, Yilong; Liu, Yi; Su, Chi; Zhao, Wenhui] Univ South China, Sch Resources Environm & Safety Engn, Hengyang 421001, Peoples R China.;[Tao, Shu] Univ South China, Sch Math & Phys, Hengyang, Peoples R China.;[Jia, Fei] Univ South China, Sch Civil Engn, Hengyang, Peoples R China.;[Zhao, Wenhui] Shanxi Prov Changzhi City Wuxiang Cty Jia Huo Town, Changzhi, Peoples R China.;[Lin, WY; Lin, Wangyang] Univ South China, Coll Mech Engn, Hengyang, Peoples R China.
通讯机构：
[Lin, WY ] U;Univ South China, Coll Mech Engn, Hengyang, Peoples R China.
摘要：
Mining wastewater with heavy metals poses a serious threat to the ecological environment. However, the acute single and combined ecological effects of heavy metals, such as chromium (Cr) and nickel (Ni), on freshwater ostracods, and the development of relevant prediction models, remain poorly understood. In this study, Heterocypris sp. was chosen to investigate the single and combined acute toxicity of Cr and Ni. Then, the quantitative structure-activity relationship (QSAR) model was used to predict the combined toxicity of Cr and Ni. The single acute toxicity experiments revealed high toxicity for both Cr and Ni. In addition, Cr exhibited greater toxicity compared to Ni, as evidenced by its lower 96-hour half-lethal concentration (LC50) of 1.07 mg/L compared to 4.7 mg/L for Ni. Furthermore, the combined acute toxicity experiments showed that the toxicity of Cr-Ni was higher than Ni but lower than Cr. Compared with the concentration addition (CA) and independent action (IA) models, the predicted results of the QSAR model were more consistent with the experimental results for the Cr-Ni combined acute toxicity. So, the high accuracy of QSAR model identified its feasibility to predict the toxicity of heavy metal pollutants in mining wastewater.
期刊：
Journal of Environmental Radioactivity,2024年278:107469 ISSN：0265-931X
通讯作者：
Xu, ZH
作者机构：
[Liu, Kai] Univ South China, Sch Resources Environm & Safety Engn, Hengyang 421001, Hunan, Peoples R China.;[Liu, Yong] Shenzhen Univ, Coll Phys & Optoelect Engn, Shenzhen 518060, Guangdong, Peoples R China.;[Hong, Changshou; Xu, Zhenghua] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Xu, ZH ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
Crack;Laterite layer;Radon;Uranium tailing pond;Wet and dry cycles
摘要：
Compacted soil layers effectively prevent the migration of radon gas from uranium tailings impoundments to the nearby environment. However, surface damage caused by wet and dry cycles (WDCs) weakens this phenomenon.In order to study the effect of crack network on radon exhalation under WDCs, a homemade uranium tailing pond model was developed to carry out radon exhalation tests under five WDCs. Based on image processing and morphological methods, the area, length, mean width and fractal dimension of the drying cracks were quantitatively analyzed, and multiple linear regression was used to establish the relationship between the geometric characteristics of the cracks and the radon exhalation rate under multiple WDCs. The results suggested that the radon release rate and crack network of the uranium tailings pond gradually stabilized as the water content decreased, following rapid development in a single WDC process. The radon release rate increased continuously after each cycle, with a cumulative increase of 25.9% over 5 cycles. The radon release rate and average crack width remained consistent in size, and a binary linear regression considering width and fractal dimension could explain the changes in radon release rate after multiple WDCs.
Compacted soil layers effectively prevent the migration of radon gas from uranium tailings impoundments to the nearby environment. However, surface damage caused by wet and dry cycles (WDCs) weakens this phenomenon.In order to study the effect of crack network on radon exhalation under WDCs, a homemade uranium tailing pond model was developed to carry out radon exhalation tests under five WDCs. Based on image processing and morphological methods, the area, length, mean width and fractal dimension of the drying cracks were quantitatively analyzed, and multiple linear regression was used to establish the relationship between the geometric characteristics of the cracks and the radon exhalation rate under multiple WDCs. The results suggested that the radon release rate and crack network of the uranium tailings pond gradually stabilized as the water content decreased, following rapid development in a single WDC process. The radon release rate increased continuously after each cycle, with a cumulative increase of 25.9% over 5 cycles. The radon release rate and average crack width remained consistent in size, and a binary linear regression considering width and fractal dimension could explain the changes in radon release rate after multiple WDCs.
摘要：
This study addresses the preassigned-time synchronization for complex-valued memristive neural networks with reaction–diffusion terms and Markov parameters. Employing a preassigned-time stable control strategy, two distinct controllers with varying power exponent parameters are designed to ensure that synchronization can be achieved within a predefined time frame. Unlike existing finite/fixed-time results, a priori specification of the settling time is addressed. Furthermore, Green’s formula and boundary conditions are efficiently applied to overcome potential symmetry loss. Additionally, the activation function’s constraint range is more lenient compared to existing constraints. Finally, the effectiveness of the presented methods are demonstrated through two examples.
This study addresses the preassigned-time synchronization for complex-valued memristive neural networks with reaction–diffusion terms and Markov parameters. Employing a preassigned-time stable control strategy, two distinct controllers with varying power exponent parameters are designed to ensure that synchronization can be achieved within a predefined time frame. Unlike existing finite/fixed-time results, a priori specification of the settling time is addressed. Furthermore, Green’s formula and boundary conditions are efficiently applied to overcome potential symmetry loss. Additionally, the activation function’s constraint range is more lenient compared to existing constraints. Finally, the effectiveness of the presented methods are demonstrated through two examples.
期刊：
Journal of Biological Dynamics,2022年16(1):354-372 ISSN：1751-3758
通讯作者：
Zhu, X.
作者机构：
[Zhu, Xiaoxiao; Ouyang, Zigen; Wang, Huilan] Univ South China, Sch Math & Phys, Hengyang, Peoples R China.
通讯机构：
[Xiaoxiao Zhu; Huilan Wang; Zigen Ouyang] S;School of Mathematics and Physics, University of South China, Hengyang, People's Republic of China<&wdkj&>School of Mathematics and Physics, University of South China, Hengyang, People's Republic of China<&wdkj&>School of Mathematics and Physics, University of South China, Hengyang, People's Republic of China
关键词：
34A37;34C25;37N25;Poincaré map;State-dependent impulse;order-1 periodic solution;predator–prey model;successor function
摘要：
The control problem in ultrasound therapy is to destroy the tumor tissue while not harming the intervening healthy tissue with a desired temperature elevation. The objective of this research is to present a robust and feasible method to control the temperature distribution and the temperature elevation in treatment region within the prescribed time, which can improve the curative effect and decrease the treatment time for heating large tumor (>= 2.0 cm in diameter). An adaptive self-tuning-regulator (STR) controller has been introduced into this control method by adding a time factor with a recursive algorithm, and the speed of sound and absorption coefficient of the medium is considered as a function of temperature during heating. The presented control method is tested for a self-focused concave spherical transducer (0.5 MHz, 9 cm aperture, 8.0 cm focal length) through numerical simulations with three control temperatures of 43 degrees C, 50 degrees C and 55 degrees C. The results suggest that this control system has adaptive ability for variable parameters and has a rapid response to the temperature and acoustic power output in the prescribed time for the hyperthermia interest. There is no overshoot during temperature elevation and no oscillation after reaching the desired temperatures. It is found that the same results can be obtained for different frequencies and temperature elevations. This method can obtain an ellipsoid-shaped ablation region, which is meaningful for the treatment of large tumor. (C) 2012 Elsevier B.V. All rights reserved.
作者机构：
[Xiong Ping; Zhang Jing] Univ S China, Sch Med, Dept Forens Med, Hengyang 421001, Peoples R China.;[Guo Ping] Univ S China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Guo Ping] U;Univ S China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
显微拉曼光谱;DNA降解;死亡时间间隔(PMI);相对峰强
摘要：
为了给死亡时间推断的研究提供新的途径与数据, 探讨了人死亡后组织细胞DNA含量变化与死后时间间隔关系。 将离体肾、 肝组织置于特定环境中,在不同时间点提取离体组织, 利用激光共焦显微拉曼光谱技术和统计学方法, 在拉曼位移测试范围内, 对死后不同时间肾、 肝组织DNA含量变化进行拉曼光谱检测与统计学分析。 结果显示: 人死亡后48～72 h, 随着死亡时间的推移, 肾、 肝组织Raman光谱的主要散射峰峰位没有明显变化, 而其峰高有明显差异； 所测组织的激光拉曼光谱特征峰的相对峰强值(I1 094/I2 923)随死亡时间的推移而减小。 因此可以得出结论: 人死亡后肾、 肝组织细胞DNA含量随死亡时间延长呈下降趋势, 两者之间存在线性关系。 The present work is to study the relationship between DNA degradation in tissue cells and estimation of postmortem interval, and to provide a new way for the estimation of postmortem interval(PMI). The tissue cells of kidney and liver in vitro obtained at different time points were kept in a controlled environment. The kidney tissue and liver tissue were taken out every 4 h， during 48-72 h after death at 25 ℃. The DNA content in different tissue cells was examined by means of confocal Raman micro spectroscopy with an excitation wavelength of 532 nm. Results show that the relative peak intensities (I1 094/I2 923) of confocal Raman microscopy for the tissue cells decreased gradually with the prolongation of postmortem interval from 48 to 72 h after death, while the peak intensity at 1 094 cm-1 was reduced obviously; and the peak intensity at 1 454 and 2 923 cm-1 did not change significantly. It is concluded that the DNA content in tissue cells decreased gradually with the prolongation of postmortem interval from 48 to 72 h after death. There is a linear relationship between the degradation rate of DNA in the tissue cells and postmortem interval. This investigation shows that Raman micro spectroscopy is useful to the estimation of postmortem interval (PMI)．
期刊：
Journal of Chemical Information and Modeling,2002年42(3):524-528 ISSN：1549-9596
通讯作者：
Liu, YC
作者机构：
[Liu, YC] Nanhua Univ Hengyang, Dept Math & Phys Sci, Hunan 421001, Peoples R China.;Huazhong Univ Sci & Technol, Dept Control Sci & Engn, Wuhan 430074, Peoples R China.
通讯机构：
[Liu, YC] N;Nanhua Univ Hengyang, Dept Math & Phys Sci, Hunan 421001, Peoples R China.
摘要：
The graph-theoretic parameter that bas probably received the most attention over the years is the chromatic number. As is well-Known, the coloring problem is an NP-Complete problem. In this paper, it has been solved by means of molecular biology techniques. The algorithm is highly parallel and has satisfactory fidelity. This work shows further evidence for the ability of DNA computing to solve NP-Complete problems.
期刊：
Journal of Chemical Information and Modeling,2002年42(3):529-533 ISSN：1549-9596
通讯作者：
Liu, YC
作者机构：
[Liu, YC] Nanhua Univ, Inst Engn & Technol, Dept Math & Phys Sci, Hengyang 421001, Hunan, Peoples R China.;Xinjiang Univ, Inst Math & Phys, Urumqi 830046, Xinjiang, Peoples R China.;Huazhong Univ Sci & Technol, Dept Control Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
通讯机构：
[Liu, YC] N;Nanhua Univ, Inst Engn & Technol, Dept Math & Phys Sci, Hengyang 421001, Hunan, Peoples R China.
关键词：
Graphical representations;Graphic methods;Mathematical models;Nucleic acids;Vectors;DNA sequences;DNA;article;chemistry;DNA sequence;DNA;Sequence Analysis, DNA
摘要：
Some 2-D and 3-D graphical representations of DNA sequences have been given by Nandy, Leong and Mogenthaler, and Randic et al., which give visual characterizations of DNA sequences. In this paper, we presented a novel graphical representation of DNA sequences by taking four special vectors in 2-D Cartesian coordinate system to represent the four nucleic acid bases in DNA sequences, so that a DNA sequence is denoted on a plane by a directed walk. It is shown that the new graphical representation of DNA sequences has lower or nondegeneracy.
