Hydrodynamic behavior and start-up performance of a periodic anaerobic baffled reactor in an "every second" switching manner treating traditional Chinese medicine wastewater.

Most studies focus on the "clockwise sequential" switching manner for a four-compartment periodic anaerobic baffled reactor (PABR), while the exploration of the "every second" option on the feasibility for real industrial wastewater treatment is rarely reported. Hence, a PABR-treating traditional Chinese medicine wastewater was run continuously in "every second" switching manner with both switching period T and hydraulic residence time of 48 h. Satisfactory start-up performance was achieved during the operation of a climbing average organic load rate at approximately 1, 2, 4, and 6 kg chemical oxygen demand (COD) m-3 d-1 for 12, 24, 24, and 6 days, respectively. The average COD removal was 87.20% after the second lifting of OLR and 89.98% after the third one. Denaturing gradient gel electrophoresis and its cluster analysis showed that the microbial communities in each compartment adapted their structure in response to the periodically changing micro-ecology conditions. Moreover, the residence time distribution test with tap water in the clean PABR was carried out in experiments and computational fluid dynamics (CFD) simulation, both of which were in good agreement. The CFD model output visualized the flow velocity field and hydrodynamic-mass transport inside the PABR. Optimization of operation pattern in PABR including switching manner and frequency depended on both the type of waste being treated and the flexibility of biomass to periodically changing micro-ecology conditions.

[Effect of nasal swell body on nasal airflow and Artemisia pollen deposition].

Objective:The nasal swell body（NSB） consists of the nasal septal cartilage, nasal bone, and swollen soft tissue, all of which are visible during endoscopic and imaging examinations. Although the function of the NSB remains uncertain, there is evidence to suggest that it plays a vital role in regulating nasal airflow and filtering inhaled air. Based on anatomical and histological evidence, it is hypothesized that the NSB is indispensable in these processes. This study aims to investigate the impact of NSB on nasal aerodynamics and the deposition of allergen particles under physiological conditions. Methods:The three-dimensional （3D） nasal models were reconstructed from computed tomography （CT） scans of the paranasal sinus and nasal cavity in 30 healthy adult volunteers from Northwest China, providing basis for the construction of models without NSB following virtual NSB-removal surgery. To analyze the distribution of airflow in the nasal cavity, nasal resistance, heating and humidification efficiency, and pollen particle deposition rate at various anatomical sites, we employed the computed fluid dynamics（CFD） method for numerical simulation and quantitative analysis. In addition, we created fully transparent segmented nasal cavity models through 3D printing, which were used to conduct bionic experiments to measure nasal resistance and allergen particle deposition. Results:①The average width and length of the NSB in healthy adults in Northwest China were （12.85±1.74） mm and （28.30±1.92） mm, respectively. ②After NSB removal, there was no significant change in total nasal resistance, and cross-sectional airflow velocity remained essentially unaltered except for a decrease in topical airflow velocity in the NSB plane. ③There was no discernible difference in the nasal heating and humidification function following the removal of the NSB; ④After NSB removal, the deposition fraction（DF） of Artemisia pollen in the nasal septum decreased, and the DFs post-and pre-NSB removal were（22.79±6.61）% vs （30.70±12.27）%, respectively; the DF in the lower airway increased, and the DFs post-and pre-NSB removal were（24.12±6.59）% vs （17.00±5.57）%, respectively. Conclusion:This study is the first to explore the effects of NSB on nasal airflow, heating and humidification, and allergen particle deposition in a healthy population. After NSB removal from the healthy nasal cavities: ①nasal airflow distribution was mildly altered while nasal resistance showed no significantly changed; ②nasal heating and humidification were not significantly changed; ③the nasal septum's ability to filter out Artemisia pollen was diminished, which could lead to increased deposition of Artemisia pollen in the lower airway.

Design Optimization of a Phototherapy Extracorporeal Membrane Oxygenator for Treating Carbon Monoxide Poisoning.

We designed a photo-ECMO device to speed up the rate of carbon monoxide (CO) removal by using visible light to dissociate CO from hemoglobin (Hb). Using computational fluid dynamics, fillets of different radii (5 cm and 10 cm) were applied to the square shape of a photo-ECMO device to reduce stagnant blood flow regions and increase the treated blood volume while being constrained by full light penetration. The blood flow at different flow rates and the thermal load imposed by forty external light sources at 623 nm were modeled using the Navier-Stokes and convection-diffusion equations. The particle residence times were also analyzed to determine the time the blood remained in the device. There was a reduction in the blood flow stagnation as the fillet radii increased. The maximum temperature change for all the geometries was below 4 °C. The optimized device with a fillet radius of 5 cm and a blood priming volume of up to 208 cm3 should decrease the time needed to treat CO poisoning without exceeding the critical threshold for protein denaturation. This technology has the potential to decrease the time for CO removal when treating patients with CO poisoning and pulmonary gas exchange inhibition.

Application of HIPEC simulations for optimizing treatment delivery strategies.

INTRODUCTION: Hyperthermic IntraPEritoneal Chemotherapy (HIPEC) aims to treat microscopic disease left after CytoReductive Surgery (CRS). Thermal enhancement depends on the temperatures achieved. Since the location of microscopic disease is unknown, a homogeneous treatment is required to completely eradicate the disease while limiting side effects. To ensure homogeneous delivery, treatment planning software has been developed. This study compares simulation results with clinical data and evaluates the impact of nine treatment strategies on thermal and drug distributions. METHODS: For comparison with clinical data, three treatment strategies were simulated with different flow rates (1600-1800mL/min) and inflow temperatures (41.6-43.6 °C). Six additional treatment strategies were simulated, varying the number of inflow catheters, flow direction, and using step-up and step-down heating strategies. Thermal homogeneity and the risk of thermal injury were evaluated. RESULTS: Simulated temperature distributions, core body temperatures, and systemic chemotherapeutic concentrations compared well with literature values. Treatment strategy was found to have a strong influence on the distributions. Additional inflow catheters could improve thermal distributions, provided flow rates are kept sufficiently high (>500 mL/min) for each catheter. High flow rates (1800 mL/min) combined with high inflow temperatures (43.6 °C) could lead to thermal damage, with CEM4310 values of up to 27 min. Step-up and step-down heating strategies allow for high temperatures with reduced risk of thermal damage. CONCLUSION: The planning software provides valuable insight into the effects of different treatment strategies on peritoneal distributions. These strategies are designed to provide homogeneous treatment delivery while limiting thermal injury to normal tissue, thereby optimizing the effectiveness of HIPEC.

[Current research status and application prospect of numerical simulation in traditional Chinese medicine drying].

With the rapid development of computer technology, numerical simulation has gradually become an important method to study drying process and improve drying equipment. Using computer to simulate the drying process of traditional Chinese medicine(TCM) is characterized by intuitiveness, scientificity, and low cost, which serves as an auxiliary means for technical innovation in TCM drying. This paper summarizes the theories of different drying methods and the research status of numerical simulation in drying, introduces the modeling methods and software of numerical simulation, and expounds the significance of numerical simulation modeling in shortening the research and development cycle, improving drying equipment, and optimizing drying parameters. However, the current numerical simulation method for drying process has problems, such as low accuracy, lack of quantitative indicators for the control of simulation results on the process, and insufficient in-depth research on the mechanism of drug quality changes. Furthermore, this paper put forward the application prospect of numerical simulation in TCM drying, providing reference for the further study of numerical simulation in this field.

Therapeutic effects of curcumin liposomes and nanocrystals on inflammatory osteolysis: In vitro and in vivo comparative study.

Curcumin could inhibit periprosthetic osteolysis induced by wear debris and adherent endotoxin, which commonly cause prosthesis loosening and negatively influence the long-term survival of joint arthroplasty. However, its limited water solubility and poor stability pose challenges for its further clinical application. To address these issues, we developed curcumin liposomes for intraarticular injection, as liposomes possess good lubricant capacity and pharmacological synergy with curcumin. Additionally, a nanocrystal dosage form was prepared to enable comparison with the liposomes based on their ability to disperse curcumin effectively. A microfluidic method was used for its controllability, repeatability, and scalability. The Box-Behnken Design was employed to screen the formulations and flow parameters, while computational fluid dynamics was used to simulate the mixing process and predict the formation of liposomes. The optimized curcumin liposomes (Cur-LPs) had a size of 132.9 nm and an encapsulation efficiency of 97.1%, whereas the curcumin nanocrystals (Cur-NCs) had a size of 172.3 nm. Both Cur-LPs and Cur-NCs inhibited LPS-induced pro-inflammatory polarization of macrophages and reduced the expression and secretion of inflammatory factors. The mouse air pouch model further demonstrated that both dosage forms attenuated inflammatory cell infiltration and inflammatory fibrosis in subcutaneous tissues. Interestingly, the anti-inflammatory effect of Cur-LPs was more potent than that of Cur-NCs, both in vitro and in vivo, although the cellular uptake of Cur-NCs was quicker. In conclusion, the results demonstrate that Cur-LPs have great potential for the clinical treatment of inflammatory osteolysis and that the therapeutic effect is closely related to the liposomal dosage form.

Current research status and application prospect of numerical simulation in traditional Chinese medicine drying / 中国中药杂志

With the rapid development of computer technology, numerical simulation has gradually become an important method to study drying process and improve drying equipment. Using computer to simulate the drying process of traditional Chinese medicine(TCM) is characterized by intuitiveness, scientificity, and low cost, which serves as an auxiliary means for technical innovation in TCM drying. This paper summarizes the theories of different drying methods and the research status of numerical simulation in drying, introduces the modeling methods and software of numerical simulation, and expounds the significance of numerical simulation modeling in shortening the research and development cycle, improving drying equipment, and optimizing drying parameters. However, the current numerical simulation method for drying process has problems, such as low accuracy, lack of quantitative indicators for the control of simulation results on the process, and insufficient in-depth research on the mechanism of drug quality changes. Furthermore, this paper put forward the application prospect of numerical simulation in TCM drying, providing reference for the further study of numerical simulation in this field.

Effect of nasal swell body on nasal airflow and Artemisia pollen deposition / 临床耳鼻咽喉头颈外科杂志

Objective:The nasal swell body（NSB） consists of the nasal septal cartilage, nasal bone, and swollen soft tissue, all of which are visible during endoscopic and imaging examinations. Although the function of the NSB remains uncertain, there is evidence to suggest that it plays a vital role in regulating nasal airflow and filtering inhaled air. Based on anatomical and histological evidence, it is hypothesized that the NSB is indispensable in these processes. This study aims to investigate the impact of NSB on nasal aerodynamics and the deposition of allergen particles under physiological conditions. Methods:The three-dimensional （3D） nasal models were reconstructed from computed tomography （CT） scans of the paranasal sinus and nasal cavity in 30 healthy adult volunteers from Northwest China, providing basis for the construction of models without NSB following virtual NSB-removal surgery. To analyze the distribution of airflow in the nasal cavity, nasal resistance, heating and humidification efficiency, and pollen particle deposition rate at various anatomical sites, we employed the computed fluid dynamics（CFD） method for numerical simulation and quantitative analysis. In addition, we created fully transparent segmented nasal cavity models through 3D printing, which were used to conduct bionic experiments to measure nasal resistance and allergen particle deposition. Results:①The average width and length of the NSB in healthy adults in Northwest China were （12.85±1.74） mm and （28.30±1.92） mm, respectively. ②After NSB removal, there was no significant change in total nasal resistance, and cross-sectional airflow velocity remained essentially unaltered except for a decrease in topical airflow velocity in the NSB plane. ③There was no discernible difference in the nasal heating and humidification function following the removal of the NSB; ④After NSB removal, the deposition fraction（DF） of Artemisia pollen in the nasal septum decreased, and the DFs post-and pre-NSB removal were（22.79±6.61）% vs （30.70±12.27）%, respectively; the DF in the lower airway increased, and the DFs post-and pre-NSB removal were（24.12±6.59）% vs （17.00±5.57）%, respectively. Conclusion:This study is the first to explore the effects of NSB on nasal airflow, heating and humidification, and allergen particle deposition in a healthy population. After NSB removal from the healthy nasal cavities: ①nasal airflow distribution was mildly altered while nasal resistance showed no significantly changed; ②nasal heating and humidification were not significantly changed; ③the nasal septum's ability to filter out Artemisia pollen was diminished, which could lead to increased deposition of Artemisia pollen in the lower airway.

Fabrication and in vitro evaluation of 3D printed porous silicate substituted calcium phosphate scaffolds for bone tissue engineering.

Silicate-substituted calcium phosphate (Si-CaP) ceramics, alternative materials for autogenous bone grafting, exhibit excellent osteoinductivity, osteoconductivity, biocompatibility, and biodegradability; thus, they have been widely used for treating bone defects. However, the limited control over the spatial structure and weak mechanical properties of conventional Si-CaP ceramics hinder their wide application. Here, we used digital light processing (DLP) printing technology to fabricate a novel porous 3D printed Si-CaP scaffold to enhance the scaffold properties. Scanning electron microscopy, compression tests, and computational fluid dynamics simulations of the 3D printed Si-CaP scaffolds revealed a uniform spatial structure, appropriate mechanical properties, and effective interior permeability. Furthermore, compared to Si-CaP groups, 3D printed Si-CaP groups exhibited sustained release of silicon (Si), calcium (Ca), and phosphorus (P) ions. Furthermore, 3D printed Si-CaP groups had more comprehensive and persistent osteogenic effects due to increased osteogenic factor expression and calcium deposition. Our results show that the 3D printed Si-CaP scaffold successfully improved bone marrow mesenchymal stem cells (BMSCs) adhesion, proliferation, and osteogenic differentiation and possessed a distinct apatite mineralization ability. Overall, with the help of DLP printing technology, Si-CaP ceramic materials facilitate the fabrication of ideal bone tissue engineering scaffolds with essential elements, providing a promising approach for bone regeneration.

The face behind the Covid-19 mask - A comprehensive review.

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

Molybdenum Disulphide Precipitation in Jet Reactors: Introduction of Kinetics Model for Computational Fluid Dynamics Calculations.

In our previous work, we used the population balance method to develop a molybdenum disulphide kinetics model consisting of a set of differential equations and constants formulated to express the kinetics of complex chemical reactions leading to molybdenum disulphide precipitation. The purpose of the study is to improved the model to describe the occurring phenomena more thoroughly and have introduced computational fluid dynamics (CFD) modelling to conduct calculations for various reactor geometries. CFD simulations supplemented with our nucleation and growth kinetics model can predict the impact of mixing conditions on particle size with good accuracy. This introduces another engineering tool for designing efficient chemical reactors.

Planktos: An Agent-Based Modeling Framework for Small Organism Movement and Dispersal in a Fluid Environment with Immersed Structures.

Multiscale modeling of marine and aerial plankton has traditionally been difficult to address holistically due to the challenge of resolving individual locomotion dynamics while being carried with larger-scale flows. However, such problems are of paramount importance, e.g., dispersal of marine larval plankton is critical for the health of coral reefs, and aerial plankton (tiny arthropods) can be used as effective agricultural biocontrol agents. Here we introduce the open-source, agent-based modeling software Planktos targeted at 2D and 3D fluid environments in Python. Agents in this modeling framework are relatively tiny organisms in sufficiently low densities that their effect on the surrounding fluid motion can be considered negligible. This library can be used for scientific exploration and quantification of collective and emergent behavior, including interaction with immersed structures. In this paper, we detail the implementation and functionality of the library along with some illustrative examples. Functionality includes arbitrary agent behavior obeying either ordinary differential equations, stochastic differential equations, or coded movement algorithms, all under the influence of time-dependent fluid velocity fields generated by computational fluid dynamics, experiments, or analytical models in domains with static immersed mesh structures with sliding or sticky collisions. In addition, data visualization tools provide images or animations with kernel density estimation and velocity field analysis with respect to deterministic agent behavior via the finite-time Lyapunov exponent.

A novel design of in-line static mixer for permanganate/bisulfite process: Numerical simulations and pilot-scale testing.

An increasing number of chemical technologies to wipe out contaminants within an incredibly short period of time have been developed recently, while their application was always hindered by the inefficient or improper mixing of reactants. To address this issue, the present work proposed a new static mixer named Tai-Chi which consists of blade, fin, and spoiler elements. Tai-Chi mixer can slice and divert the solutions inside and generate high shear flow to promote mixing process. Numerical simulations helped to determine the optimal operating conditions for Tai-Chi mixer, including laying its components anterior to the injection nozzles and keeping the velocity rate ratio of main pipe to branch pipe within the range of 0.5 to 1. Numerical simulations further proved that Tai-Chi mixer could strike a great balance between mixing performance (coefficient of variation [CoV] reaches 0.1 within 5 to 7 pipe diameters downstream) and head loss (nearly a half of other high shear static mixer in the market). Data of pilot-scale testing by Tai-Chi mixer confirm that 80% sulfamethoxazole could be eliminated in permanganate/bisulfite process within 8 pipe diameters, as well as showed the superiority of Tai-Chi's mixing performance in early stage compared with other static mixers in the market. PRACTITIONER POINTS: A Tai-Chi static mixer with blade, fin, and spoiler elements is devised. The optimal condition of flow rate and installment of Tai-Chi mixer is determined. Ultra-fast mixing is achieved by Tai-Chi (CoV < 0.1 within 5-7 pipe diameters). Pilot-scale test verifies the mixing efficiency of Tai-Chi mixer.

Computational fluid dynamics analysis of Trichosporon fermentans flocculation in refined soybean oil wastewater and flocculation rate prediction method.

Trichosporon fermentans can be used to treat refined soybean oil wastewater (RSOW) and produce microbial lipids. Bioflocculation is an effective method to recover Trichosporon fermentans which accumulates intracellular oils from wastewater. During the flocculation, the hydrodynamic distribution and parameters in the reactor are important limiting factors of yeast flocculation performance. In a 0.25 L flocculation device, it was found that the appropriate range of turbulence kinetic energy was within 0.00065-0.00073 m2/s2, the dissipation rate was within 0.119-0.317 m2/s3, and the shear force was less than 0.433 Pa by computational fluid dynamics. In this case, the flocculation rate (Fr) of Trichosporon fermentans could reach more than 90%. The empirical formula associated Fr of Trichosporon fermentans with hydrodynamic parameters was obtained by Matlab, and improved in the enlargement of flocculation device, displaying an error of less than 3.03%. A conical draft tube airlift circulating reactor for flocculation was designed based on the empirical formula, and the Fr reached 91.3%. The study shows that it is feasible to predict Fr of Trichosporon fermentans according to hydrodynamic parameters by numerical simulation, and design the industrial reactor for flocculation harvesting yeasts. It is also helpful for large-scale treatment of RSOW in a safe environment.

Spray Drying in Research of Traditional Chinese Medicine Powders： A Review / 中国实验方剂学杂志

After more than 100 years of development， spray drying technology has become more mature and widely used， and it is of great importance in the field of traditional Chinese medicine （TCM）. TCM powders prepared by spray drying is the raw material of dispensing granules， and the powder properties have an important influence on subsequent molding process and product quality. As a new form of TCM， dispensing granules have been included in the management category of TCM decoction pieces， indicating a broader application market， and a consensus has also been reached on the importance of TCM powder research. Based on this， the author summarized the application progress of spray drying in the study of TCM powders， including the factors affecting spray drying process， such as liquid properties， process parameters and equipment factors， as well as the application of computational fluid dynamics （CFD） and thermodynamic model in spray drying process simulation. Moreover， some commonly used pharmaceutical excipients for the modification of TCM powders were also introduced such as maltodextrin， microcrystalline cellulose and povidone. In addition， spray drying technology can also be used as a preparation technology for new drug delivery systems such as microcapsules and solid dispersions. Through the summary of this paper， the author suggests that the future research direction of spray drying of TCM can be carried out from the aspects of application rule of the coprocessing auxiliary materials based on the "unification of medicines and excipients"， the "structure-property" relationship of spray-dried powders and the application of computer simulation and design， so as to further enrich the application of spray drying in the field of TCM powders.

Exploring the sensitivity in jellyfish locomotion under variations in scale, frequency, and duty cycle.

Jellyfish have been called one of the most energy-efficient animals in the world due to the ease in which they move through their fluid environment, by product of their bell kinematics coupled with their morphological, muscular, material properties. We investigated jellyfish locomotion by conducting in silico comparative studies and explored swimming performance across different fluid scales (i.e., Reynolds Number), bell contraction frequencies, and contraction phase kinematics (duty cycle) for a jellyfish with a fineness ratio of 1 (ratio of bell height to bell diameter). To study these relationships, an open source implementation of the immersed boundary method was used (IB2d) to solve the fully coupled fluid-structure interaction problem of a flexible jellyfish bell in a viscous fluid. Thorough 2D parameter subspace explorations illustrated optimal parameter combinations in which give rise to enhanced swimming performance. All performance metrics indicated a higher sensitivity to bell actuation frequency than fluid scale or duty cycle, via Sobol sensitivity analysis, on a higher performance parameter subspace. Moreover, Pareto-like fronts were identified in the overall performance space involving the cost of transport and forward swimming speed. Patterns emerged within these performance spaces when highlighting different parameter regions, which complemented the global sensitivity results. Lastly, an open source computational model for jellyfish locomotion is offered to the science community that can be used as a starting place for future numerical experimentation.

Inhalation and deposition of spherical and pollen particles after middle turbinate resection in a human nasal cavity.

Middle turbinate resection significantly alters the anatomy and redistributes the inhaled air. The superior half of the main nasal cavity is opened up, increasing accessibility to the region. This is expected to increase inhalation dosimetry to the region during exposure to airborne particles. This study investigated the influence of middle turbinate resection on the deposition of inhaled pollutants that cover spherical and non-spherical particles (e.g. pollen). A computational model of the nasal cavity from CT scans, and its corresponding post-operative model with virtual surgery performed was created. Two constant flow rates of 5 L/min, and 15 L/min were simulated under a laminar flow field. Inhaled particles including pollen (non-spherical), and a spherical particle with reference density of 1000 kg/m3 were introduced in the surrounding atmosphere. The effect of surgery was most prominent in the less patent cavity side, since the change in anatomy was proportionally greater relative to the original airway space. The left cavity produced an increase in particle deposition at a flow rate of 15 L/min. The main particle deposition mechanisms were inertial impaction, and to a lesser degree gravitational sedimentation. The results are expected to provide insight into inhalation efficiency of different aerosol types, and the likelihood of deposition in different nasal cavity surfaces.

A novel rotating wide gap annular bioreactor (Taylor-Couette type flow) for polyhydroxybutyrate production by Ralstonia eutropha using carob pod extract.

An annular bioreactor (ABR) with wide gap was used for PHB production from Ralstonia eutropha. Hydrodynamic studies demonstrated the uniform distribution of fluid in the ABR due to the Taylor-Couette flow. Thereafter, the ABR was operated at different agitation and sparging rates to study its effect on R. eutropha growth and PHB production. The ABR operated at 500 rpm with air sparge rate of 0.8 vvm yielded a maximum PHB concentration of 14.89 g/L, which was nearly 1.4 times that obtained using a conventional stirred-tank bioreactor (STBR). Furthermore, performances of the bioreactors were compared by operating the reactors under fed-batch mode. At the end of 90 h of operation, the ABR resulted in a very high PHB production of 70.8 g/L. But STBR resulted in a low PHB concentration of 44.2 g/L. The superior performance was due to enhanced oxygen and nutrient mass transfer in the ABR.

Airway resistance variation correlates with prognosis of critically ill COVID-19 patients: A computational fluid dynamics study.

OBJECTIVE: To evaluate the quantitative changes of respiratory functions for critically ill COVID-19 patients with mechanical ventilation, computational fluid dynamics (CFD) analysis was performed based on patient-specific three-dimensional airway geometry. METHODS: 37 cases of critically ill patients with COVID-19 admitted to the ICU of Huangshi Traditional Chinese Medicine Hospital from February 1st to March 20th, 2020 were retrospectively analyzed. 5 patients whose clinical data met the specific criteria were finally cataloged into death group (2 patients) and survival group (3 patients). The patient-specific three-dimensional airways were reconstructed from the central airways down to the 4th-5th bifurcation of the tracheobronchial tree. The volume changes of bronchi were calculated during the disease progression according to the comparison of two CT scans. Additionally, the changes of air flow resistance were analyzed using numerical simulation of CFD. RESULTS: Pearson correlation analysis demonstrated that there was negative correlation between the change of volume (ΔV) and the change of resistance (ΔR) for all COVID-19 patients (r=-0.7025). For total airway volume, an average decrease of -11.41±15.71% was observed in death group compared to an average increase of 1.86±10.80% in survival group (p=0.0232). For air flow through airways in lower lobe, the resistance increases for death group by 10.97±77.66% and decreases for survival group by -45.49±42.04% (p=0.0246). CONCLUSION: The variation of flow resistance in the airway could be used as a non-invasive functional evaluation for the prognosis and outcome of critically ill patients with COVID-19. The 'virtual' pulmonary function test by integrating follow-up CT scans with patient-derived CFD analysis could be a potentially powerful way in improving the efficiency of treatment for critically ill patients with COVID-19.

Demonstration of treatment planning software for hyperthermic intraperitoneal chemotherapy in a rat model.

BACKGROUND: Hyperthermic intraperitoneal chemotherapy (HIPEC) is administered to treat residual microscopic disease after cytoreductive surgery (CRS). During HIPEC, fluid (41-43 °C) is administered and drained through a limited number of catheters, risking thermal and drug heterogeneities within the abdominal cavity that might reduce effectiveness. Treatment planning software provides a unique tool for optimizing treatment delivery. This study aimed to investigate the influence of treatment-specific parameters on the thermal and drug homogeneity in the peritoneal cavity in a computed tomography based rat model. METHOD: We developed computational fluid dynamics (CFD) software simulating the dynamic flow, temperature and drug distribution during oxaliplatin based HIPEC. The influence of location and number of catheters, flow alternations and flow rates on peritoneal temperature and drug distribution were determined. The software was validated using data from experimental rat HIPEC studies. RESULTS: The predicted core temperature and systemic oxaliplatin concentration were comparable to the values found in literature. Adequate placement of catheters, additional inflow catheters and higher flow rates reduced intraperitoneal temperature spatial variation by -1.4 °C, -2.3 °C and -1.2 °C, respectively. Flow alternations resulted in higher temperatures (up to +1.5 °C) over the peritoneal surface. Higher flow rates also reduced the spatial variation of chemotherapy concentration over the peritoneal surface resulting in a more homogeneous effective treatment dose. CONCLUSION: The presented treatment planning software provides unique insights in the dynamics during HIPEC, which enables optimization of treatment-specific parameters and provides an excellent basis for HIPEC treatment planning in human applications.