Effect of Viscous Dissipation (Φ) on Temperature Distribution of Blood Plasma in Presence of a Magnetic Field

Applications of heat transfer show the variations in temperature of the body which is helpful for the purpose of thermal therapy in the treatment of tumor glands. This study considered theoretical approaches in analyzing the effect of viscous dissipation on temperature distribution on the flow of blood plasma through an asymmetric arterial segment. The plasma was considered to be unsteady, laminar and an incompressible fluid through non-uniform arterial segment in a two-dimensional flow. Numerical schemes developed for the coupled partial differential equations governing blood plasma were solved using Finite Difference scheme (FDS). With the aid of the finite difference approach and the related boundary conditions, results for temperature profiles were obtained. The study determined the effect of viscous dissipation on temperature of blood plasma in arteries. The equations were solved using MATLAB softwares and results were presented graphically and in tables. The increase in viscous dissipation tends to decrease blood plasma heat distribution. This study will find important application in hospitals.

Stationary Flow of Blood in a Rigid Vessel in the Presence of an External Magnetic Field: Considerations about the Forces and Wall Shear Stresses

The magnetohydrodynamics laws govern the motion of a conducting fluid, such as blood, in an externally applied static magnetic field B0. When an artery is exposed to a magnetic field, the blood charged particles are deviated by the Lorentz force thus inducing electrical currents and voltages along the vessel walls and in the neighboring tissues. Such a situation may occur in several biomedical applications: magnetic resonance imaging (MRI), magnetic drug transport and targeting, tissue engineering… In this paper, we consider the steady unidirectional blood flow in a straight circular rigid vessel with non-conducting walls, in the presence of an exterior static magnetic field. The exact solution of Gold (1962) (with the induced fields not neglected) is revisited. It is shown that the integration over a cross section of the vessel of the longitudinal projection of the Lorentz force is zero, and that this result is related to the existence of current return paths, whose contributions compensate each other over the section. It is also demonstrated that the classical definition of the shear stresses cannot apply in this situation of magnetohydrodynamic flow, because, due to the existence of the Lorentz force, the axisymmetry is broken.

Impact of an External Magnetic Field on the Shear Stresses Exerted by Blood Flowing in a Large Vessel

The aim of this paper is to provide an advanced analysis of the shear stresses exerted on vessel walls by the flowing blood, when a limb or the whole body, or a vessel prosthesis, a scaffold… is placed in an external static magnetic field B0. This type of situation could occur in several biomedical applications, such as magnetic resonance imaging (MRI), magnetic drug transport and targeting, tissue engineering, mechanotransduction studies… Since blood is a conducting fluid, its charged particles are deviated by the Hall effect, and the equations of motion include the Lorentz force. Consequently, the velocity profile is no longer axisymmetric, and the velocity gradients at the wall vary all around the vessel. To illustrate this idea, we expand the exact solution given by Gold (1962) for the stationary flow of blood in a rigid vessel with an insulating wall in the presence of an external static magnetic field: the analytical expressions for the velocity gradients are provided and evaluated near the wall. We demonstrate that the derivative of the longitudinal velocity with respect to the radial coordinate is preponderant when compared to the θ-derivative, and that elevated values of B0 would be required to induce some noteworthy influence on the shear stresses at the vessel wall.

Mathematical Model of Blood Flow in Small Blood Vessel in the Presence of Magnetic Field

A mathematical model for blood flow in the small blood vessel in the presence of magnetic field is presented in this paper. We have modeled the two phase model for the blood flow consists of a central core of suspended erythrocytes and cell-free layer surrounding the core. The system of differential equations has been solved analytically. We have obtained the result for velocity, flow rate and effective viscosity in presence of peripheral layer and magnetic field .All the result has been obtained and discussed through graphs.

A Mathematical Model for Pulsating Flow of Ionic Fluid under an Axial Electric Field： EMF Effect on Blood Flow

The present work introduces a mathematical model for ionic fluid that flows under the effect of both pulsating pressure and axial electromagnetic field. The fluid is treated as a Newtonian fluid applying Navier-Stokes equation. The fluid is considered as a neutral mixture of positive and negative ions. The effect of axial electric field is investigated to determine velocity profiles. Hydroelectric equation of the flow is deduced under dc and ac external electric field. Hence the effect of applied frequency （0-1 GHz） and amplitude （10-350 V/m） is illustrated. The ultimate goal is to approach the problem of EMF field interaction with blood flow. The applied pressure waveform is represented as such to simulate the systolic-diastolic behavior. Simulation was carried out using Maple software using blood plasma parameters; hence velocity profiles under various conditions are reported.

Effect Of Pulsatile Electromagnetic Fields On Blood Viscosity And Coagulation

We studied the effect of extremely low frequency (ELF) pulsatileelectromagnetics fields on blood apparent viscosity and coagulation. With irradiationof ELF electromagnetics fields, the amount of chage at the surface of erythrocyteincreases, the apparent viscosity of blood and the maximum shear stress of sludgedblood decrease (P＜0.01). Compared among treatment groups, the pulsatile magneticfield was better influence on blood.

一种基于线性零磁场的动脉血管扫描成像方法仿真

基于磁电耦合效应的血流检测及血管成像是实现心血管疾病早期诊疗的有效方法之一。该文基于磁场与血流耦合电效应,设计一种用于动脉血管扫描成像的组合线圈结构,产生带有零磁场线(FFL)区域的线性梯度磁场;在此结构的基础上,通过控制激励电流驱动FFL实现成像区域双向扫描;结合卷积神经网络(CNN)实现磁电耦合信号与血管信息的非线性映射,进而提出一种基于线性零磁场的动脉血管扫描成像新方法。采用多物理场仿真软件COMSOL对基于线性零磁场的血管扫描成像方法进行建模,求解磁电耦合信号,验证了所提出方法的合理性和有效性。结果表明,线性梯度磁场模式下的磁电耦合信号含有血管位置、半径等信息;CNN重建血管位置误差平均值为1.5694 mm,重建血管半径的方均误差(MSE)和相关系数(CC)平均值分别为0.0548和0.9870。研究结果可用于血管成像装置设计及后续相关临床应用提供研究支撑。

基于FPCB绕组的导管泵用电动机设计及损耗分析

基于无槽无刷直流电动机具有体积小、功率密度高、无齿槽转矩的特点,采用柔性印刷电路板(FPCB)技术设计了一种导管泵用无槽无刷微型直流电动机,提出了基于3D多物理场耦合模型分析方法,对导管泵用无槽无刷微型直流电动机进行了损耗分析和优化设计.结果表明:导管泵用无槽无刷微型直流电动机的铜损占整个电动机损耗的88%左右,是导致电动机发热的主要原因;在温度场仿真中,温度变化会改变电动机损耗,影响电动机输出转矩;在流场仿真模型中,电动机温度会使人体血液温度升高,影响血液相容性;流动的血液会带走部分热量,降低电动机温度;绕组优化后的导管泵用电动机输出转矩得到提高,损耗得以降低.

响应面法优化冷冻鸡血豆腐的制备工艺

为使肉鸡副产物之一鸡血高效利用。以新鲜鸡血为主要原料,采用低场核磁不易流动水峰面积为评价标准,通过添加不同品种与浓度的抗冻改良剂对冷冻鸡血豆腐中不易流动水峰面积影响的单因素实验,再结合响应面设计优化冷冻鸡血豆腐的制备工艺。进一步以失水率、质构、色泽指标对优化的冷冻鸡血豆腐的品质进行分析,为开发冷冻鸡血豆腐产品提供科学依据。结果表明,冷冻鸡血豆腐优化制备工艺为:添加脂酰乳酸钠0.1%,海藻酸钾0.1%,木薯变性淀粉2%。在此工艺条件下,冷冻鸡血豆腐的低场核磁不易流动水峰面积为2143,与空白组和其他优化组相比不易流动水峰面积最大,故保水效果最好。优化制备的冷冻鸡血豆腐的硬度、咀嚼性、凝胶性以及亮度都显著(P<0.05)高于空白组(其中硬度是空白组的17倍,亮度的是空白组的1.13倍)。因此,冷冻鸡血豆腐的制备工艺可显著提高解冻后鸡血豆腐的品质,可促进肉鸡副产物高值化产品的开发。

泵机一体化的轴流式血泵模拟优化

针对现有的轴流式血泵存在一定的结构缺陷,导致性能不足和血液相容性差等问题,提出以一种泵机一体化的轴流式血泵为研究对象,利用计算流体力学方法,对其几何结构进行优化改进。同时研究不同运行参数对该血泵性能的影响,并与实验的数据进行比较,确定最佳的运行参数。本研究对该血泵的流场特性进行全面的分析,进一步揭示其内部的流动规律,并采用DPM方法模拟血液中红细胞的流动行为及其受剪切应力的情况,完成对该血泵的血液相容性的评估。研究表明,新型的血泵在扬程方面表现出良好的性能。在转速为9000r/min、流量为6.24L/min的最佳工况下,血泵的扬程比原结构提升16%,效率达到25%,能够满足大部分人的生理需求。此外血泵内大部分区域的压力梯度和速度梯度都比较均匀,内部流场情况比较稳定,能够有效避免溶血现象的发生。本研究优化改进的血泵能在确保高性能和良好的流场特性的同时具备较好的血液相容性,可为轴流式血泵的结构优化和改进提供重要的参考依据。

益气养阴化瘀法对糖尿病视网膜病变患者微血管功能、动脉血流、微视野及血清Vaspin和SCUBE2水平的影响

目的:观察益气养阴化瘀法对糖尿病视网膜病变患者微血管功能、动脉血流、微视野及血清脂肪特异性丝氨酸蛋白酶抑制剂(Vaspin)和骨形态发生蛋白1-表皮生长样结构域蛋白2(SCUBE2)水平的影响。方法:选择2021年1月至2022年12月于该院治疗的糖尿病视网膜病变患者102例,以随机数字表法分组。对照组50例患者给予常规西医治疗,观察组52例患者在对照组的基础上给予益气养阴化瘀方治疗。比较两组患者的临床疗效、治疗前后的中医证候评分,检测视野平均敏感度、视力、收缩期血流速度峰值、眼动脉阻力指数(RI)和舒张期血流速度峰值,检测患者Vaspin、低氧诱导因子-1(HIF-1)、可溶性细胞黏附分子(sICAM-1)、SCUBE2、外周血内皮细胞(CEC)和循环祖细胞(CPC)水平。结果:观察组患者总有效率为98.08%(51/52),高于对照组的84.00%(42/50),差异有统计学意义(P<0.05)。治疗后,观察组患者的中医证候评分较对照组降低,差异有统计学意义(P<0.05)。治疗后,观察组患者的RI低于对照组,收缩期血流速度峰值、舒张期血流速度峰值、视野平均敏感度和最佳矫正视力高于对照组,差异均有统计学意义(P<0.05)。治疗后,观察组患者的CPC水平较对照组升高,CEC水平较对照组降低,Vaspin、HIF-1、sICAM-1和SCUBE2水平较对照组降低,差异均有统计学意义(P<0.05)。结论:益气养阴化瘀法治疗糖尿病视网膜病变,可改善患者微血管功能、动脉血流、微视野和视力,提高临床疗效。

基于二维卷积的连续血压预测系统

针对生命体征信号数字化采集和连续血压预测等需求,设计并实现了一种基于二维卷积的连续血压预测系统。在系统硬件部分使用ESP32模组、AD8232模块和PulseSensor传感器,采集获得的人体心电图(ECG)和光电容积脉搏波(PPG)信号数据并通过MQTT协议传输至服务端处理。本文算法部分使用格拉米角差场(GADF)、二维卷积和模型剪枝技术,设计并训练了使用ECG和PPG信号预测人体连续血压的神经网络模型,并分别在开源数据集和自制数据集中测试了连续血压预测模型的性能。本文系统为重要体征信号采集和连续血压预测提供了一个有效的参考方案。

改良侧卧位固定在食管癌手术患者中的应用效果

目的:观察改良侧卧位固定在食管癌手术患者中的应用效果。方法:选取2020年11月至2022年10月该院收治的86例食管癌患者进行前瞻性研究,采用抽签法将其分为对照组和观察组各43例。对照组术中予以传统侧卧位固定,观察组术中予以改良侧卧位固定,比较两组术中视野暴露评分、手术时间、体位安置时间、不良事件发生率,体位安置前、安置3 min后舒张压(DBP)和收缩压(SBP)水平,以及医师满意度。结果:观察组术中视野暴露评分高于对照组,体位安置时间和手术时间均短于对照组,差异有统计学意义(P<0.05);观察组不良事件发生率为0,低于对照组的13.95%(6/43),差异有统计学意义(P<0.05);体位安置3 min后,两组DBP、SBP水平均高于体位安置前,但观察组低于对照组,差异有统计学意义(P<0.05);观察组医师满意度为97.67%(42/43),高于对照组的81.40%(35/43),差异有统计学意义(P<0.05)。结论:改良侧卧位固定应用于食管癌手术患者可提高术中视野暴露评分和医师满意度,缩短体位安置时间和手术时间,降低体位安置3 min后DBP、SBP水平和不良事件发生率,效果优于传统侧卧位固定。

Cytogenetic Effects of Pulsing Electromagnetic Field on Domestic Pig Lymphocytes in Vitro

The effects of pulsing electromagnetic fields(PEMFs)on cells are very important subjects in the field of bioelectromagnetics.In this experiment,the cytogenetic effects of PEMF on domestic pig lymphocytes were tested in vitro.Pig lymphocytes in RPMI 1640 medium were exposed to PEMFs of 100 kHz and 200 kHz for 12,24 and 48 hours.Chromosomal aberrations(aneuploidy,breaks,gaps,et al)were significantly increased in exposed cultures,and of these aberrations,56%chromosomal or chromatid breaks and 42%gaps induced by PEMFs were the points of pig chromosomal fragile sites.The baseline frequency of sister chromatid exchange(SCE)increased after exposing lymphocytes continuously to PEMFs of 100 kHz and 200 kHz for 48 hours.These results suggested that the exposure to PEMFs might induce a type of DNA lesion and chromosomal aberrations.

Efficacy of static magnetic field for pain of adjuvant arthritis rats

Rats suffering from adjuvant arthritis (AA) were used to examine the effect of a static magnetic field (SMF) upon pain relief. Rats were divided into SMF- treated AA rats, non-SMF treated AA rats and control rats. Following SMF stimulation, we measured blood flow volume in the paw and then reactive speed response to thermal stimulation. The AA groups exhibited significantly lower blood volume and reactivity to thermal stimulation compared to the control group. Compared to non-SMF, SMF exhibited increased blood flow volume in both the tail and paw, along with an increased reactive speed response to thermal stimulation. Our findings suggest that an improved of blood flow and reactive speed response, induced by SMF, appears to be effective for the relief of pain induced by chronic inflammation.

Mathematical Analysis of Unsteady MHD Blood Flow through Parallel Plate Channel with Heat Source

In the present study, a mathematical model of unsteady blood flow through parallel plate channel under the action of an applied constant transverse magnetic field is proposed. The model is subjected to heat source. Analytical expressions are obtained by choosing the axial velocity;temperature distribution and the normal velocity of the blood depend on y and t only to convert the system of partial differential equations into system of ordinary differential equations under the conditions defined in our model. The model has been analyzed to find the effects of various parameters such as, Hartmann number, heat source parameter and Prandtl number on the axial velocity, temperature distribution and the normal velocity. The numerical solutions of axial velocity, temperature distributions and normal velocity are shown graphically for better understanding of the problem. Hence, the present mathematical model gives a simple form of axial velocity, temperature distribution and normal velocity of the blood flow so that it will help not only people working in the field of Physiological fluid dynamics but also to the medical practitioners.

3D CFD Simulation of Pulsatile Blood Flow in the Human Aorta

A three-dimensional computational fluid dynamics (CFD) simulation of the physiological pulsatile blood flow in the human aortic arch and its three branches has been conducted by using commercial software StarCD. The blood flow, of a peak Reynolds number of 3289 and a Womersley parameter of 16.44, was simulated in a rigid aorta geometry that was built by computer aided design (CAD) reconstruction method based on autopsy data of a female adult. The purpose of this work is to further the understanding of the complex nature of aorta flow, therefore it mainly focuses on analysis of the spatial and temporal distributions of velocities and wall shear stresses. The results, illustrated by 3D visualization pictures and 2D graphs of the primary velocity profiles, wall shear stress and pressure distributions, as well as the secondary flow patterns, are in good agreement with those of other experimental and computational works. The distributions of pressure and wall shear stress support the correlation between high and low shear stresses and pressures and the atherosclerotic lesions.

A Review of Some Reference Analytic Solutions for the Magnetohydrodynamic Flow of Blood

A short review of some reference solutions for the magnetohydrodynamic flow of blood is proposed in this paper. We present in details the solutions of Hartmann (1937), of Vardanyan (1973) and of Sud et al. (1974). In each case, a comparison is provided with the corresponding solution for the flow without any external magnetic field, namely Poiseuille (plane or cylindrical) and Womersley. We also present a synopsis of some other solutions for people who would like to go further in this topic. The interest in MHD flow of blood may be motivated by many reasons, such as Magnetic Resonance Imaging (MRI), Pulse Wave Velocity measurement, magnetic drug targeting, tissue engineering, mechanotransduction studies, and blood pulse energy harvesting… These fundamental solutions should also be used as particular limiting cases to validate any proposed more elaborated solutions or to validate computer codes.

Electrical fields and the promotion of endogenous angiogenesis in a rat spinal cord injury model

BACKGROUND： Previous studies have shown that direct current electrical fields affect development and growth of human microvascular endothelial cells, but the role of electrical fields on promoting angiogenesis in tissues following spinal cord injury remains poorly understood. OBJECTIVE： To determine the effects of electrical fields on angiogenesis and spinal cord repair following traumatic spinal cord injury in rats. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Chongqing Key Laboratory of Neurology, Affiliated Hospital of Chongqing Medical University, China from September 2007 to August 2008. MATERIALS： Hydrogen blood flow detector （Soochow University Medical Instrument, China）, Power Lab System （AD Instruments, Colorado Springs, CO, USA） and mouse anti-vascular endothelial growth factor （VEGF） monoclonal antibody （Sigma-Aldrich, St. Louis, MO, USA） were used in this study. METHODS： A total of 60 healthy, adult, Sprague Dawley rats were equally and randomly assigned to sham-surgery, model, and electrical field groups. The Allen＇s weight-drop method was used to induce complete spinal cord injury in the model and electrical field groups. Rats in the electrical field group were implanted with silver needles and electrical fields （350 V/m） were applied following traumatic injury. MAIN OUTCOME MEASURES： Latency of somatosensory-evoked potential was detected and spinal cord blood flow was measured by hydrogen blood flow detector. Microvascular density was determined by histological analysis. VEGF expression in the spinal cord was observed by immunohistochemical staining. RESULTS： Recovery of spinal cord blood flow was significantly increased in the electrical field group （at 1, 2, 4, 8, and 24 days after injury） compared with the model group （P 〈 0.05 or P 〈 0.01）. Latency of P1 waves in somatosensory-evoked potential of electrical field group （at 1,2, 4, 8, and 24 days after injury） was significantly shorter than the model group （P 〈 0.05 or P 〈 0.01）. Microvascular density and VEGF expression were greater in the electrical field group compared with the model group at 24 days after injury （P 〈 0.01）. CONCLUSION： Electrical fields （350 V/m） promoted angiogenesis within injured rat tissue following spinal cord injury and improved spinal cord function. Electrical fields could help to ameliorate spinal cord injury. The mechanisms of action could be related to increased VEGF expression.