ABSTRACT
Research on the deposition of inhaled particles in human pulmonary acinus region is important to the pathogenesis investigation, prevention and treatment of lung diseases. Most of the current research focus on the final deposition fraction of inhaled particles in human acinar region, but little is involved in their dynamic deposition characteristics. In this paper, five multi-alveolar models, G3-G7, were built. The evaluation parameter 1/4 deposition time was introduced to study the particle deposition speed. The deposition characteristics of particles in the diameter ranging 0.1-5 μm were numerically simulated and summarized under the influence of factors such as the generation and structure of model, particle diameter and respiratory mode, shedding some new light on the further research of transport of inhaled particles. The results showed that the generation and structure of model had a significance effect on the deposition of particles. 0.1 μm particles were dominated by Brownian diffusion, which experienced a high deposition fraction, a fast deposition speed and a logarithmic deposition curve, while 5 μm particles were dominated by gravitational sedimentation, with a high deposition fraction, a fast deposition speed and an S-shaped deposition curve. The deposition of 0.3-1 μm particles were influenced greatly by convention and varied with the change of respiratory mode. The research methods and results in this paper can provide theoretical basis and data support for the further exploration of the mechanism, prevention and treatment of lung diseases.
Subject(s)
Humans , Aerosols , Computer Simulation , Lung , Models, Biological , Particle SizeABSTRACT
The inhalation and deposition of particles in human pulmonary acinus region can cause lung diseases. Numerical simulation of the deposition of inhaled particles in the pulmonary acinus region has offered an effective gateway to the prevention and clinical treatment of these diseases. Based on some important affecting factors such as pulmonary acinar models, model motion, breathing patterns, particulate characteristics, lung diseases and ages, the present research results of numerical simulation in human pulmonary acinus region were summarized and analyzed, and the future development directions were put forward in this paper, providing new insights into the further research and application of the numerical simulation in the pulmonary acinus region.
Subject(s)
Humans , Aerosols , Computer Simulation , Lung , Physiology , Models, Biological , Particle Size , Pulmonary Alveoli , PhysiologyABSTRACT
Research on the deposition of inhalable particles in the alveoli of the lungs is important to the causes, development for common respiratory diseases such as emphysema, and even the optimization of clinical treatment and prevention programs of them. In this paper, an experimental model was established to simulate the deposition of terminal bronchioles and pulmonary acinus particles. The deposition rate of inhalable particles with different particle sizes in the pulmonary acinus was studied under different functional residual capacity. The results showed that the particle diameter was an important factor affecting the deposition of particles in the lung alveoli. Particles with 1 μm diameter had the highest deposition rate. With the functional residual capacity increasing, particulate deposition rate significantly reduced. The results of this study may provide data support and optimization strategy for target inhalation therapy of respiratory diseases such as emphysema and pneumoconiosis. The established model may also provide a feasible experimental model for studying the deposition of inhalable particles in the pulmonary alveoli.
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Objective To investigate the transportation of chemico-biological particles(CBP) through the micropassage inside the human body in order to improve chemico-biological protection.Methods Dissipative particle dynamics (DPD) method was used to study CBP transportation through micropassages inside the human body.Results The Poiseuille flow could be ensured by imposing boundary conditions including pressure gradient and no-slip.The axial velocity between fluid particles and CBPs was well matched except the area close to the passage wall.However, CBPs tended to accumulate and the density of CBPs slightly increased, leading to the jam effect and producing particle accumulation.Conclusion The characteristic of CBP transportation is better understood,which can help develop some chemico-biological protection devices according to movement of CBPs and improve the performance of CBPs during chemico-biological protection.
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The research on cycle change form of the pressure and the wall shear in human upper respiratory tract can strengthen understanding of the characteristics of the airflow in the place and provide us with a scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol there. In our study, we used large eddy simulation to emulate the pressure and wall shear in human upper respiratory tract in conditions of the low intensive respiratory patterns, and discussed the distributing disciplinarian of the pressure and wall shear in mouth-throat model and trachea-triple bifurcation. The results showed that the pressure gradient variation in human upper respiratory tract was mainly fastened from root of epiglottis to trachea. The minimum pressure at the interim of inspiration was a duplication of the interim of expiration, and located on the posterior wall of the glottis. The pressure gradient variation was evident on trachea and its fork. The wall shear changed with the velocity of the air flow, and its direction changed periodically with breath cycle.
Subject(s)
Humans , Biomechanical Phenomena , Bronchi , Physiology , Computer Simulation , Epiglottis , Physiology , Mouth , Physiology , Nose , Physiology , Pharynx , Physiology , Pressure , Pulmonary Ventilation , Physiology , Respiratory Mechanics , Physiology , Respiratory Physiological Phenomena , Respiratory System , Shear Strength , Stress, Mechanical , Trachea , PhysiologyABSTRACT
With the development of technology and the deterioration of environment,more and more attention was attracted to the research on fluid dynamics in human upper respiratory tract.In this paper,the methods of research on fluid dynamics in human upper respiratory tract were introduced,and the mechanical models of human upper respiratory tract which were constructed by the scholars in the resent years were summarized.In addition,the current status of research on the airflow movements,the transportation and deposition of the particles in human upper respiratory tract was analyzed.The developing trend of this field was prospected as well.
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Obiective To study the compartment environmental quality of ambulance against biological contamination for safe and comfortable transportation and treatment of patients. Methods The experimental research and numerical simulation were carried to master the state of compartment environmental quality, Results Compartment environment indexes excel technology demands, such as overpressure/negative-pressure, temperature, biological contamination, vibration and shock as well as noise and luminance, Conclusion The compartment environmental quality of this ambulance is in a good state.
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The technology of info-visualization is recommended.The main research of info-visualization system of medical equipment is proposed and the key technologies involved in that system are discussed.
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Based on the structure characteristics of the stretcher base of WCY2000field ambulance,this paper sets up a finite element analysis model with twotypes of beam elements.The accuracies under twotypes of elements are discussed and model method of the same structure is presented.
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S95-100field mobile medical system is a field mobile hospital composed of such function cells as medical shelters,tents,special vehicles and transportable containers.Several logistic functions of the cells are introduced including patients checking and sorting,surgery,pre-operation preparation,emergency,clinical laboratory,medical supply,X-ray diagnosis,sterilization,medical command and communication,patient holding ward,logistic technical support and connection.The whole system assignments by different modules clipping and transformations,the application tests and widen tryouts in the army are alsopresented.
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Objective To design and produce a kind of NBC filtration and ventilation unit with the function of filtering biological aerosols and chemical poisonous gas and so on in the air,providing new clean air for the medical shelter.Methods The filtration unit and ventilation unit were united in principle of manipulability and repairability by modularization method.Results Structural dimensions and vibrational noises of the unit were reduced,and manipulability and repairability were improved.Conclusion The unit can meet the demands of biological and chemical protection for the medical shelters,and the structural design of fast fitting and so on can meet the requirements of fast responses.
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To fulfill the plane-beam junction, this paper applies the simplified finite element modeling to the plane-beam composite structures. The finite element modeling of the teleconsulting vehicle compartment and its model analysis are performed. The results show that the finite element model can improve the design of the compartment and lays a foundation for the realization of the engineerization and sequencing of compartment dynamic strength design.
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Objective Mobile operating compartment with overpressure protection can provide a safety environment for the patients and the surgical team by minimizing the risk of biochemical contamination through appropriate air filtration, steady overpressure foundation and air distribution scheme. Methods The air movement and the temperature distribution inside the mobile operating compartment with the overpressure protection performance were simulated by the technique of computational fluid dynamics(CFD), the air pattern and the temperature distribution were analyzed. Results The air velocity was under 0.5m/s in the most zone of person activity and the air velocity were distributed uniformly in the mobile operating compartment under the condition of the overpressure protection system. The obvious temperature gradient didn't exist in the vertical plane of the mobile operating compartment. The temperature distribution in the mobile operating compartment was quite uniform and the temperature was almost at 27℃ with the temperature difference of almost 2℃. Conclusion The human thermal comfort is good in the mobile operating compartment and the environment in the mobile operating compartment can satisfy requirements of the operation.
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The domestic and foreign research status related to thermal environment in the cabin(room) is reviewed.Parameters which affect thermal environment and the index limits in the standards of the different cabin(room) are narrated overall.Measuring methods pertinent to parameters of thermal environment are introduced.Finally,the comprehensive evaluation indices of thermal comfort in the cabin(room) and their using fields are analyzed emphatically.It's essential to study thermal environment and it can establish theory foundation for research on thermal environment index system inside mobile medical equipments.
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The compartment temperature- environment of mobile medical equipment is simulated by using computational fluid dynamics (CFD) and finite element method (FEM). Simulation results indicate that the airflow shape is reasonable and the compartment temperature can be kept at (25?3)℃, and that the velocity of airflow is less than 0.5m/s. The collective overpressure protection system is established according to the following 5 procedures, including alarming, controlling, filtering toxin, establishing overpressure and overpressure monitoring. It's proved that the protection system can form the overpressure not less than 300 pascal and make the compartment free of the air containing biological toxin, noxious chemical fumes and radioactive dust. The contamination process of the compartment is simulated in case of some toxic and noxious contaminant flowing into the compartment. The results are obtained that concentration distribution of contaminant attenuates rapidly from 5,000ppmv to 10ppmv during 130 seconds.