Gels That Serve as Mucus Simulants: A Review.

Mucus is a critical part of the human body's immune system that traps and carries away various particulates such as anthropogenic pollutants, pollen, viruses, etc. Various synthetic hydrogels have been developed to mimic mucus, using different polymers as their backbones. Common to these simulants is a three-dimensional gel network that is physically crosslinked and is capable of loosely entrapping water within. Two of the challenges in mimicking mucus using synthetic hydrogels include the need to mimic the rheological properties of the mucus and its ability to capture particulates (its adhesion mechanism). In this paper, we review the existing mucus simulants and discuss their rheological, adhesive, and tribological properties. We show that most, but not all, simulants indeed mimic the rheological properties of the mucus; like mucus, most hydrogel mucus simulants reviewed here demonstrated a higher storage modulus than its loss modulus, and their values are in the range of that found in mucus. However, only one mimics the adhesive properties of the mucus (which are critical for the ability of mucus to capture particulates), Polyvinyl alcohol-Borax hydrogel.

Troubleshooting dioxins stack emissions in an industrial waste gas incinerator.

An important source of dioxins and furans at present is waste incineration, utmost formed during combustion processes and emitted to the environment without being fully captured by waste-gas treatment equipment. In this study, monitoring campaign of International Toxic Equivalents for dioxins and furans (I-TEQDF), was carried out at pharmaceutical industrial waste incinerator to find a correlation between combustion parameters and feed composition with potential emission. Principal Component Analysis (PCA) shows that high values of dioxin emission correlate with short residence time of the flue gas in the furnace as well as low oxygen concentration. These operating conditions were further investigated, using COMSOL Computational Fluid Dynamics (CFD) simulation to calculate the temperature profiles along the furnace. The results suggest that the flame temperature profile is anticipated to exhibit cold areas (cold spots), which may be used as a proxy for dioxin formation due to incomplete combustion. Additionally, the calculated congeners furan to dioxin concentration ratio, points to their formation via de novo mechanism. SEM-EDS analysis preformed on the bag filter upstream the feed following its filtration, have shown large amount of iron, which may have served as a metal catalytic source for dioxin formation. The iron origin is most likely from corrosion of the feeding pipe, drifted with the waste gas and trapped on the bag filter. The results of this study provide a better understanding of the parameters controlling dioxin formation and emission from the plant and may assist a planning of process optimization in such a plant.

Demonstration of mucus simulant clearance in a Bench-Model using acoustic Field-Integrated Intrapulmonary Percussive ventilation.

Intrapulmonary Percussive Ventilation (IPV) is a high-frequency airway clearance technique used to help in mucus transport for mechanically ventilated and unventilated patients. Despite the many years of usage, this technique does not provide clear evidence of its intended efficacy. This is mainly attributable to the lack of in vitro observations that show "mucokinesis" towards the direction of the mouth. In the current manuscript, we demonstrate and subsequently propose a mechanism that details the movement of a mucus simulant in the proximal (towards the mouthpiece) direction. Towards this end, a novel method utilizing a high-frequency acoustic field in addition to the conventional air pulsations brought forth by traditional IPV is proposed. Under these conditions, at certain parameter settings, it is shown that the simulant is broken down into much smaller parts and subsequently pushed in the upstream direction gradually over a period of half-hour.

A novel Python module for statistical analysis of turbulence (P-SAT) in geophysical flows.

We present Python Statistical Analysis of Turbulence (P-SAT), a lightweight, Python framework that can automate the process of parsing, filtering, computation of various turbulent statistics, spectra computation for steady flows. P-SAT framework is capable to work with single as well as on batch inputs. The framework quickly filters the raw velocity data using various methods like velocity correlation, signal-to-noise ratio (SNR), and acceleration thresholding method in order to de-spike the velocity signal of steady flows. It is flexible enough to provide default threshold values in methods like correlation, SNR, acceleration thresholding and also provide the end user with an option to provide a user defined value. The framework generates a .csv file at the end of the execution, which contains various turbulent parameters mentioned earlier. The P-SAT framework can handle velocity time series of steady flows as well as unsteady flows. The P-SAT framework is capable to obtain mean velocities from instantaneous velocities of unsteady flows by using Fourier-component based averaging method. Since P-SAT framework is developed using Python, it can be deployed and executed across the widely used operating systems. The GitHub link for the P-SAT framework is: https://github.com/mayank265/flume.git .

Administration of aerosolized drugs to infants by a hood: a three-dimensional numerical study.

Using a hood for aerosol delivery to infants was found to be effective and user-friendly compared to the commonly used face mask. The currently available hood design has an even greater potential in terms of efficiency, and a numerical simulation can serve as a tool for its optimization. The present study describes the development and utilization of a numerical simulation for studying the transport and fate of the aerosol particles and the carrier gas within a three-dimensional realistic representation of the hood and the infant's head. The study further incorporates realistic breathing patterns, with a longer expiration phase than an inspiration phase. Both nose and mouth breathing are simulated. While the base case assumes that the funnel that delivers the aerosol within the hood is perpendicular to the infant's face, more realistic scenarios include a funnel that is slanted with respect to the infant face, the infant's head taking a general position with respect to the funnel, and the funnel and the head being both tilted. A good agreement is found between computation and experimental results. As expected, the most efficient drug delivery, 18%, is achieved when the funnel is normal to the infant's face. The quantitative evaluation of different scenarios presented in this work increases the knowledge of physicians, nurses, and parents regarding the efficacy of the treatment, in terms of the actual amount of drug inhaled under various modes of function of the device.

Numerical simulation of air flow and medical-aerosol distribution in an innovative nebulizer hood.

The use of a hood to administer therapeutic aerosols to wheezy infants has many advantages and was found as efficient as administration using a mask. The aim of the present study is to investigate numerically the airflow induced drug dispersion inside the hood. Drug droplet dispersion is examined with respect to three breathing phases: inspiration, expiration, and apnea. The governing equations describing the airflow and the trajectories of drug droplets were solved using the FLUENT 6.1 Computational Fluid Dynamics (CFD) software package. The geometry and mesh were generated with the GAMBIT package. The velocity field of the air and the trajectories of drug droplets inside the funnel--the tube that delivers the drug from the nebulizer to the infant's mouth--and close to its exit are robust and do not show any appreciable differences among the three breathing phases studied. However, in other parts of the hood, air velocity, and particle motion largely depend on the infant's breathing and physiological state. The efficiency of drug delivery to the mouth during inspiration is found to be as high as 84%, whereas it is much smaller in the other two (common) breathing phases examined. Our results may be utilized to improve the hood design and to increase its efficacy for administration of aerosolized medications to infants.

A computerized tank system for studying the effect of temperature on calcification of reef organisms.

Mediated by algal symbionts, calcification in reef building corals is one of the important processes, which enable coral's growth. In the present study, we used a buoyant weighing technique to study calcification of two coralline species, Stylophora pistillata and the hydrocoral Millepora dichotoma. The colonies were grown in a tank system, in which light, nutrition and water motion were kept constant and temperature was elevated by means of a computerized controlled apparatus. An almost constant rate of calcification was observed in the two species at 22-28 degrees C. Elevation of the temperature above this range to 29-31 degrees C caused a slow down in calcification in both species. A grater number of S. pistillata colonies became bleached at temperatures of >or=29 degrees C, whereas M. dichotoma colonies suffered from bleaching only after three days at 31 degrees C. For both species, control groups, remained viable during the experimental period. The differences in responses to changes in temperature of the two species may be as a consequence of different adaptive mechanisms or to different susceptibilities of the corals to elevated temperatures. We have shown that elevating temperatures above annual maximal ranges have a significant effect on coral calcification. We also demonstrated that sessile calcified marine organisms having ecological and biomedical significance could be cultured and manipulated under laboratory conditions.

Numerical investigation of aerosol deposition at the eyes when using a hood inhaler for infants--a 3D simulation.

A numerical investigation of a hood inhaler is presented, aiming at the assessment of the amount of aerosol that reaches the eyes of the patient when administering medications with such a device. Using a hood for aerosol therapy for infants was already found to be effective and friendly to handle over the commonly used face mask. Using a hood device may adversely deliver unwanted medications to the eyes of the infant. The current study addresses the extent of aerosol deposition at the infant's eye zone. We describe the development and utilization of a numerical simulation for studying the transport and fate of the aerosol particles within a 3D realistic representation of the hood and the infant's head, with a focus on the eye zone. The governing equations were solved using the commercial software, FLUENT 6.1, which is based on the finite volume method. The computational domain was created using the GAMBIT package. The computational geometry was built separately for each configuration of the hood and the infant. It is shown that under optimal working conditions (i.e., when the infant's head is aligned to the funnel) the percentage of aerosol reaching the eye zone is 0.48%. However, when the funnel is tilted toward the eyes the amount of aerosol reaching the eyes zone is predicted to be 4.7%. In general, the results obtained in this study are in good agreement with available in vitro data. It can be concluded that using the hood for aerosol therapy results in minimal deposition at the infant's eye area.