COVID-19 airborne transmission: a new frontier of infection

COVID-19 has spread around the globe and infections are still rising despite the development of vaccinations and protocols. Various mutations of the SARS-CoV-2 virus have arisen with a greater rate of transmission and increased virulence. New found research has proven that the new strains of the virus are more virulent and use airborne aerosolized transmission to enable long range spread of the virus. By virtue of the fact that the virus spreads through such means, increases the risk of transmission and contamination highly as the virus can be transmitted via long range and through common ventilation and duct systems. In light of this it is now pertinent for legislation to support the use of personal protection equipment to safeguard the health of the public.

Hereditary leiomyomatosis and renal cell cancer presenting as urothelial carcinoma

Hereditary leiomyomatosis is a genetic disorder that follows an autosomal dominant pattern of inheritance. Along with a variety of leiomyomas, affected individuals are predisposed to developing an aggressive form of type 2 papillary renal malignancy known as Hereditary Leiomyomatosis Associated Renal Cell Carcinoma (HLRCC) that can occur in both the tubulo-papillary and collecting-duct systems. We present a rare case of HLRCC with components of urothelial carcinoma. The patient was treated with cisplatin-based neoadjuvant chemotherapy followed by left radical nephroureterectomy to achieve complete remission of disease.

Band structure and defect states in acoustic phononic crystals using expansion and micro-perforated chamber mufflers

The expansion and the micro-perforated chamber mufflers are acoustic silencers designed to attenuate the sound propagation at duct systems. These silencers can show interesting phononic crystals behavior when set periodically. The concept of phononic crystals still is an emerging topic in vibration and sound control. The periodic arrangement of acoustic silencers can provide a significant enhancement of the sound absorption due to the "wave filtering" property where the wave cannot propagate at certain frequency ranges, called stopbands or bandgaps. However, these properties may be affected by defects, like the break of the periodicity due to manufacturing errors. For the present work, the influence of some defects on the acoustic efficiency is investigated numerically for expansion and micro-perforated chamber mufflers. A direct and efficient approach is used to obtain the transfer and dynamic stiffness matrices. Simulated examples are used to calculate the forced response, transmission loss, and dispersion diagram, which are verified by other methods.

Numerical Prediction and Reduction of Pressure Loss of Air Flow Inside a Sharp 90˚ Elbow Using Turning Vanes

The aim of this study is to calculate the pressure loss and the effect of turning vanes on the pressure loss incurred by the flow in a duct with a 90˚ sharp elbow using numerical fluid mechanics. The main focus this study was to calculate the effects of the number of turning vanes and the length of the turning vanes on the pressure loss. Computational Fluid Dynamics calculations have been carried out using ANSYS Workbench software. Two turbulence models have been used in these calculations. They are the standard k- and the k- turbulence models. The number and length of the vanes were changed in the study to calculate their effects on pressure loss. The length of the vanes was varied from 0mm to 400mm in steps of 100mm on both sides of the bend and the number of vanes was changed from 0 to 3. It was found that a single curved turning vane can reduce the pressure loss significantly. The pressure loss does not reduce further when the length of the vanes was extended. As the number of turning vanes increased beyond one, the predicted pressure loss starts increasing. The turning vanes in duct systems can be used in industries and factories to reduce the pressure loss.

Performance Analysis of Smoke Control Systems for Elevators based on Pressurization Method

The pressurization of emergency or evacuation elevator shafts or duct systems during installation is used for smoke control. In this study, the performance of smoke control systems applied to emergency and evacuation elevators were compared and analyzed using the airflow network analysis program CONTAM 3.2. Under the stack effect condition (temperature difference of 30 ℃), the differential pressure formed in the vestibule was analyzed by adjusting the air volume by changing the value of the loss coefficient factor of the automatic pressure smoke damper. In the case of the duct pressurization method, the air flow in the lower floor was introduced to the elevator shaft owing to the duct pressure and the airflow in the upper floors was from the elevator shaft out to the elevator lobby. In the case of the elevator shaft pressurization method, the pressurized air passing through vestibule from the elevator shaft created a differential pressure at the fire door of vestibule. To maintain the differential pressure in the lower floor, relatively more relief dampers should be installed in the upper floors as compared to those in the duct pressurization method.

A study of aerodynamic noise in air duct systems with turning vanes

Noise is becoming one of the problems in many industrial applications. In this paper the aerodynamic noise in air duct system that arises from air flow passing over a surface of turning vanes is investigated. Based on Proudman's formula using Lighthill's acoustic analogy broadband acoustic noise model can be predicted. To model the turbulent flow in an air duct k - e turbulent model is used and required constants are obtained experimentally in a low speed wind tunnel followed by noise measurement in the vicinity of deflected airfoil. Several designs are investigated: Inner airfoil in the duct elbow, center positioned air foil, outer positioned and the overall combination of all previous cases. It was found that in order to satisfy all noise requirements and regulation, which are becoming more strict nowadays, the acoustic analysis and design must be performed in most industrial systems since the noise levels arising from the operating industrial equipment may represent occupational and health hazard.

Computational Analysis of the Dynamics Flow in the Duct System of an Continuous Positive Airways Pressure Device

In this paper, 3-D duct models of Continuous Positive Airway Pressure (CPAP) device are developed to investigate the internal airflow behaviours and to identify potential noise source locations. The Computational Aeroacoustics (CAA) with a hybrid approach is conducted in the ANSYS software environment. CFD simulations were used to investigate the internal flow behaviours of the duct systems. The predicted results have shown the internal flow characteristics as circulation and separation behaviours. Those behaviours were found at several locations such as 90-degree corners, restricted cross-sectional areas, etc. High levels of turbulent energy are also found in those locations indicated they are likely to have a high level of noise. Further investigation to predict the noise generated from the duct system to validate the findings in CFD simulations. The results showed that there is a high level of noise generated at the identified locations in the CFD simulations. The noise experiments were also conducted to compare with the predicted noise results. It was found the predicted models can be used to evaluate the flow behaviours inside the duct system. In summary, the CAA with a hybrid approach is used to investigate the internal flow behaviours and the potential noise source locations of the duct systems in the studied CPAP device. The predicted results have explained and identified some potential noise source locations. These findings will be used as guidelines to optimize the internal flow and therefore improve the noise generated from ducts. The broadband noise source models are potential tools that can be used to determine the loudness at the source locations in the early product development process for reducing noise level and better sound quality as well as a cost-effective tool for noise prediction.

3D kidney organoids for bench-to-bedside translation

The kidneys are essential organs that filter the blood, removing urinary waste while maintaining fluid and electrolyte homeostasis. Current conventional research models such as static cell cultures and animal models are insufficient to grasp the complex human in vivo situation or lack translational value. To accelerate kidney research, novel research tools are required. Recent developments have allowed the directed differentiation of induced pluripotent stem cells to generate kidney organoids. Kidney organoids resemble the human kidney in vitro and can be applied in regenerative medicine and as developmental, toxicity, and disease models. Although current studies have shown great promise, challenges remain including the immaturity, limited reproducibility, and lack of perfusable vascular and collecting duct systems. This review gives an overview of our current understanding of nephrogenesis that enabled the generation of kidney organoids. Next, the potential applications of kidney organoids are discussed followed by future perspectives. This review proposes that advancement in kidney organoid research will be facilitated through our increasing knowledge on nephrogenesis and combining promising techniques such as organ-on-a-chip models.