Effect of liquid volume fraction and shear rate on rheological properties and microstructure formation in ternary particle/oil/water dispersion systems under shear flow: two-dimensional direct numerical simulation.

We numerically studied the rheological properties and microstructure formation under shear flow in a ternary particle/oil/water dispersion system. Our numerical simulation method was based on a phase-field model for capturing a free interface, the discrete element method for tracking particle motion, the immersed boundary method for calculating fluid-particle interactions, and a wetting model that assigns an order parameter to the solid surface according to the wettability. The effects of the water-phase volume fraction and shear rate on the microstructure and apparent viscosity were investigated. When the water-phase volume fraction was low, a pendular state was formed, and with an increase in the water-phase volume fraction, the state transitioned into a co-continuous state and a Pickering emulsion. This change in the microstructure state is qualitatively consistent with the results of previous experimental studies. In the pendular state, the viscosity increased with an increase in the water-phase volume fraction. This was due to the development of a network structure connected by liquid bridges, and the increase in the coordination number was quantitatively confirmed. In the case of the pendular state, significant shear thinning was observed, but in the case of the Pickering emulsion, no significant shear thinning was observed. It is concluded that this is due to the difference in the manner in which the microstructure changes with the shear rate. This is the first study to numerically demonstrate the microstructure formation of a ternary dispersion under shear flow and its correlation with the apparent viscosity.

High-Resolution Numerical Simulation of Microfiltration of Oil-in-Water Emulsion Permeating through a Realistic Membrane Microporous Structure Generated by Focused Ion Beam Scanning Electron Microscopy Images.

Owing to the limitations of visualization techniques in experimental studies and low-resolution numerical models based on computational fluid dynamics (CFD), the detailed behavior of oil droplets during microfiltration is not well understood. Hence, a high-resolution CFD model based on an in-house direct numerical simulation (DNS) code was constructed in this study to analyze the detailed dynamics of an oil-in-water (O/W) emulsion using a microfiltration membrane. The realistic microporous structure of commercial ceramic microfiltration membranes (mullite and α-alumina membranes) was obtained using an image processing technique based on focused ion beam scanning electron microscopy (FIB-SEM). Numerical simulations of microfiltration of O/W emulsions on the membrane microstructure obtained by FIB-SEM were performed, and the effects of different parameters, including contact angle, transmembrane pressure, and membrane microporous structure, on filtration performance were studied. Droplet deformation had a strong impact on filtration behavior because coalesced droplets with diameters larger than the pore diameter permeated the membrane pores. The permeability, oil hold-up fraction inside the pores, and rejection were considerably influenced by the contact angle, while the transmembrane pressure had a little impact on the permeability and oil hold-up fraction. The membrane structure, especially the pore size distribution, also had a significant effect on the microfiltration behavior and performance.

CFD modeling of airborne pathogen transmission of COVID-19 in confined spaces under different ventilation strategies.

Airborne transmission is an important route of spread of viral diseases (e.g., COVID-19) inside the confined spaces. In this respect, computational fluid dynamics (CFD) emerged as a reliable and fast tool to understand the complex flow patterns in such spaces. Most of the recent studies, nonetheless, focused on the spatial distribution of airborne pathogens to identify the infection probability without considering the exposure time. This research proposes a framework to evaluate the infection probability related to both spatial and temporal parameters. A validated Eulerian-Lagrangian CFD model of exhaled droplets is first developed and then evaluated with an office case study impacted by different ventilation strategies (i.e., cross- (CV), single- (SV), mechanical- (MV) and no-ventilation (NV)). CFD results were analyzed in a bespoke code to calculate the tempo-spatial distribution of accumulated airborne pathogens. Furthermore, two indices of local and general infection risks were used to evaluate the infection probability of the ventilation scenarios. The results suggest that SV has the highest infection probability while SV and NO result in higher dispersions of airborne pathogens inside the room. Eventually, the time history of indices reveals that the efficiency of CV and MV can be poor in certain regions of the room.

Wind tunnel measurement dataset of 3D turbulent flow around a group of generic buildings with and without a high-rise building.

This paper presents a high tempo-spatial resolution dataset of the three-dimensional (3D) turbulent flow over a group of generic buildings with and without a high-rise building measured in an atmospheric boundary layer wind tunnel. This dataset is the basis of the study reported in the research article entitled "Wind tunnel measurement of three-dimensional turbulent flow structures around a building group: Impact of high-rise buildings on pedestrian wind environment" by Tominaga and Shirzadi (2021), which investigates the effect of a high-rise building on the pedestrian wind environment formed around the surrounding buildings and its interaction mechanism with the street flow at the pedestrian height. The instantaneous velocity vectors over a vertical central plane and a horizontal plane and the time-averaged surface pressure over the central building were measured for two cases consisting of a low-rise (Case 1H) and high-rise (Case 3H) buildings, which are in the center of a group of eight low-rise cubic buildings at a regular arrangement with an urban planar area density of 0.25. Data acquisition procedure and measurements details are explained in this paper. Time-averaged values of three velocity components and surface pressure coefficients, and turbulent statistics, i.e. turbulent kinetic energy and normal component of the Reynolds stresses are presented. Furthermore, the time-averaged two-dimensional (2D) velocity magnitude over the pedestrian height are presented for evaluating the gust factor. The presented database is useful for the validation of computational fluid dynamics (CFD) models and turbulent model developments for urban and building-related studies.

Seroconversion after three doses of intramuscular rabies vaccine as a post-exposure treatment.

Rabies is still threatening half of the world's population with the global burden of canine rabies being estimated as 59,000 human deaths, annually. With no cure existing for clinical rabies, post-exposure prophylaxis (PEP) is the only certain means to save lives of the exposed people. In Iran, bite incidences exceed 180,000 per year, where all victims receive 5 vaccine doses for PEP, conforming to the Essen regimen. More than two-thirds of the exposed individuals stop receiving treatments after day 7, for the reason of being exposed to a non-rabid dog or cat. According to the national standard protocols, these individuals should re-start a complete 5-dose PEP course upon the re-exposure. New WHO recommendations based on scientific data is encouraging revisions to the existing prophylaxis programs. In order to know if an incomplete Essen regimen can provide adequate immunity, in the present study, 5 groups of individuals who had only received 3 first doses of the Essen regimen within the previous 1, 3, 6, 12 and 24 months were examined for immunity against rabies. Our results indicated sufficient anti-rabies neutralizing antibody in all individuals, before and after receiving two standard booster doses (i.e. days 0 and 3). This might also suggest the adequacy of the 3 first doses of vaccination, as a one-week long post-exposure vaccination program.

Incidence and Disability-Adjusted Life Years (Dalys) Attributable to Leishmaniasis In Iran, 2013.

BACKGROUND: Leishmaniasis covers a range of clinical manifestations. Estimation of the burden of leishmaniasis may help guide healthcare management personnel and policy-makers in applying effective interventions. The present study aimed to calculate the incidence and burden of cutaneous and visceral leishmaniasis in Iran in 2013. METHODS: To evaluate the epidemiological aspects of the disease in Iran, published studies over the past 20 years were searched and the viewpoints of relevant specialists in Iran were obtained. Data were collected from the Ministry of Health and from the Tehran University of Medical Sciences. To calculate years of life lost due to premature death, standard expected years of life lost was used. Standard life table of Global Burden of Disease (GBD) 2010 with the life expectancy of 86.02 years for both sexes was used to calculate the remaining potential years of life at any age from death. RESULTS: The overall incidence of cutaneous and visceral leishmaniasis was calculated as 22 and 0.092 per 100000 population of Iran, respectively. The burden of leishmaniasis was 99.5 years: 95.34 and 4.16 years for cutaneous and visceral, respectively. Sensitivity was analyzed and deaths predicted by the Institute of Health Metrics and Evaluation added, the burden of visceral leishmaniasis was 726 years. CONCLUSION: The share of leishmaniasis burden in Iran is lower than the global burden of the disease. GBD 2010 standard method is recommended to calculate the burden of leishmaniasis in different countries and set local priorities on the basis of these measures.