ABSTRACT
Existing indoor closed ultraviolet-C (UVC) air purifiers (UVC in a box) have faced technological challenges during the COVID-19 breakout, owing to demands of low energy consumption, high flow rates, and high kill rates at the same time. A new conceptual design of a novel UVC-LED (light-emitting diode) air purifier for a low-cost solution to mitigate airborne diseases is proposed. The concept focuses on performance and robustness. It contains a dust-filter assembly, an innovative UVC chamber, and a fan. The low-cost dust filter aims to suppress dust accumulation in the UVC chamber to ensure durability and is conceptually shown to be easily replaced while mitigating any possible contamination. The chamber includes novel turbulence-generating grids and a novel LED arrangement. The turbulent generator promotes air mixing, while the LEDs inactivate the pathogens at a high flow rate and sufficient kill rate. The conceptual design is portable and can fit into ventilation ducts. Computational fluid dynamics and UVC ray methods were used for analysis. The design produces a kill rate above 97% for COVID and tuberculosis and above 92% for influenza A at a flow rate of 100 L/s and power consumption of less than 300 W. An analysis of the dust-filter performance yields the irradiation and flow fields.
ABSTRACT
Airborne transmission via aerosol particles without close human contact is a possible source of infection with airborne viruses such as SARS-CoV-2 or influenza. Reducing this indirect infection risk, which is mostly present indoors, requires wearing adequate respiratory masks, the inactivation of the viruses with radiation or electric charges, filtering of the room air, or supplying ambient air by means of ventilation systems or open windows. For rooms without heating, ventilation, and air conditioning (HVAC) systems, mobile air cleaners are a possibility for filtering out aerosol particles and therefore lowering the probability of indirect infections. The main questions are as follows: (1) How effectively do mobile air cleaners filter the air in a room? (2) What are the parameters that influence this efficiency? (3) Are there room situations that completely prevent the air cleaner from filtering the air? (4) Does the air cleaner flow make the stay in the room uncomfortable? To answer these questions, particle imaging methods were employed. Particle image velocimetry (PIV) was used to determine the flow field in the proximity of the air cleaner inlet and outlet to assess regions of unpleasant air movements. The filtering efficiency was quantified by means of particle image counting as a measure for the particle concentration at multiple locations in the room simultaneously. Moreover, different room occupancies and room geometries were investigated. Our results confirm that mobile air cleaners are suitable devices for reducing the viral load indoors. Elongated room geometries, e.g., hallways, lead to a reduced filtering efficiency, which needs to be compensated by increasing the volume flow rate of the device or by deploying multiple smaller devices. As compared to an empty room, a room occupied with desks, desk separation walls, and people does not change the filtering efficiency significantly, i.e., the change was less than 10%. Finally, the flow induced by the investigated mobile air cleaner does not reach uncomfortable levels, as by defined room comfort standards under these conditions, while at the same time reaching air exchange rates above 6, a value which is recommended for potentially infectious environments.
ABSTRACT
The risk of COVID-19 infection from virulent aerosols is particularly high indoors. This is especially true for classrooms, which often do not have pre-installed ventilation and are occupied by a large number of students at the same time. It has been found that precautionary measures, such as the use of air purifiers (AP), physical distancing, and the wearing of masks, can reduce the risk of infection. To quantify the actual effect of precautions, it is not possible in experimental studies to expose subjects to virulent aerosols. Therefore, in this study, we develop a computational fluid dynamics (CFD) model to evaluate the impact of applying the aforementioned precautions in classrooms on reducing aerosol concentration and potential exposure in the presence of index or infected patients. A CFD-coupled Wells–Riley model is used to quantify the infection probability (IP) in the presence of index patients. Different cases are simulated by varying the occupancy of the room (half/full), the volumetric flow rate of the AP, two different locations of the AP, and the effect of wearing masks. The results suggest that using an AP reduces the spread of virulent aerosols and thereby reduces the risk of infection. However, the risk of the person sitting adjacent to the index patient is only marginally reduced and can be avoided with the half capacity of the class (physical distancing method) or by wearing face masks of high efficiencies.
ABSTRACT
Natural ventilation can play an important role towards preventing the spread of airborne infections in indoor environments. However, quantifying natural ventilation flow rates is a challenging task due to significant variability in the boundary conditions that drive the flow. In the current study, we propose and validate an efficient strategy for using computational fluid dynamics to assess natural ventilation flow rates under variable conditions, considering the test case of a single-room home in a dense urban slum. The method characterizes the dimensionless ventilation rate as a function of the dimensionless ventilation Richardson number and the wind direction. First, the high-fidelity large-eddy simulation (LES) predictions are validated against full-scale ventilation rate measurements. Next, simulations with identical Richardson numbers, but varying dimensional wind speeds and temperatures, are compared to verify the proposed similarity relationship. Last, the functional form of the similarity relationship is determined based on 32 LES. Validation of the surrogate model against full-scale measurements demonstrates that the proposed strategy can efficiently inform accurate building-specific similarity relationships for natural ventilation flow rates in complex urban environments.
ABSTRACT
An approach to online laboratory exercises for analytical chemistry students with demonstrated practical exercises through the use of remote-controlled gas chromatography (GC) instrumentation is discussed. The approach allows for a practical-based learning activity to be carried out by students who are unable to attend in-person laboratory exercises and was conducted during the COVID-19 pandemic. Learning activities focused on the operation of GC instrumentation were completed prior to a research-based analysis activity being conducted by students. At the end of this experiment, the students are expected to understand, independently operate, and learn how to achieve better separation through the manipulation of GC settings, such as split/splitless injections, carrier gas flow rate, and oven temperature, and apply principles of GC to a practical application. Additional flexibility from this approach could also be beneficial during postpandemic and/or in the circumstance where students cannot physically attend the class.
ABSTRACT
Introduction: During the recent covid-19 vaccination campaign, the number of ICSRs reported by patients and professionals has dramatically increased, reaching up to almost 1 M declarations only in Europe (EMA numbers). To deal with such growing amount of data, Synapse Medicine®, in collaboration with The French National Agency for Medicines and Health Products Safety (ANSM), have developed an artificial intelligence (AI) tool, the Medication Shield, which, based on a natural language processing algorithm, is able to detect ADRs from patients' reports and to code them into an appropriate MedDRA preferred term (PT). Before the covid-19 pandemic, this system was successful in detecting ADRs from the patient reports declared through the French web national reporting system (1, 2). However, how it behaves in conditions of higher reporting flow rate is unknown at present. Objective: To evaluate the performance of the Medication Shield in detecting vaccine-related ADRs from patients' ICSRs declared across the covid-19 vaccination campaign. Methods: A machine learning (ML) pipeline composed by a light Gradient Boosting Machine ensemble model was employed to detect and code covid-19 vaccine-related ADRs from patients' ICSRs declared through the web reporting system during the vaccination campaign (Jan 2021-Apr 2022). The encoding of regional pharmacovigilance centers was employed as the reference ground truth to train the algorithm in a supervised manner. Moreover, a panel of three pharmacologists, with significant experience in ADRs encoding, was set-up to perform a case-by-case analysis of 200 hundreds reports for which the algorithm provided improper encoding. Results: Overall, 65.191 ICSRs were extracted and used to train our ML algorithm. Of this, 54.987 were employed to validate the system. Importantly, almost 86% of the ICSRs were related to covid vaccines. Because the percentage of newly reported ADRs increased over time and was higher for vaccine than not-vaccine related reports, we split the training and validation sets in batches with similar ADRs distribution. Performance evaluation is currently under process. Initial feedbacks from the analysis performed by the experts are showing an uneven distribution of false positive and false negative across samples. Results from the other experts are needed to confirm this finding. Conclusion: The core findings of this study will be gathered in the forthcoming weeks and be ready for the ISoP meeting in September. This work will provide new insights about the effectiveness of deploying AI as a support to treat real world data in a context of sanitary crisis.
ABSTRACT
Knowing particle penetration efficiencies and concentration distributions in an inlet channel of a sampling device is beneficial for the robust assessment, attribution and quantification of nanoparticles produced by various activities. The aim of this research is to evaluate the effect of the presence or absence of a conical column inside a hollow tapered cylinder on the nanoparticle penetration efficiency and its outlet concentration profile for different flow rates. The particle penetration characteristics of various sizes from 3 nm to 20 nm were numerically investigated by using the flow field and convection diffusion equations within the hollow tapered cylinder. Firstly, the proposed model of the nanoparticle penetration efficiency for the hollow tapered cylinder with the conical column is validated with the experimental data in the literature. Then, the results indicate that the concentration at the outlet of the hollow tapered cylinder with the conical column exhibits annular profiles for 3 nm and 5 nm nanoparticles at a flow rate of 2.0 L/min, which is found to avoid centralizing the particles in the exit area. In addition, the penetration efficiency of nanoparticles can be improved by increasing flow rates or removing the conical column inside the hollow tapered cylinder. Finally, the ring-shaped concentration profile of the 10 nm nanoparticles at the outlet of the hollow conical cylinder with the conical column becomes more obvious as the flow rate decreases. This study interprets and quantitatively decides the nanoparticle penetration efficiency and its exit concentration profile for the hollow tapered cylinder with or without the conical column. Therefore, the results can provide some useful design references for the transport of nanoparticles in the hollow tapered cylinder.
ABSTRACT
COVID-19 has exacerbated the need for viewing medical oxygen as a precious drug and thus work towards its conservation which ensures optimal supply to the patient. This paper describes the practical implementation of a 'plug-and-play' automatic oxygen flow-rate controller for clinical use suitable for low-flow oxygen therapy. A microcontroller based electronic controller drives the extent of opening/closing of a proportional valve in line with the clinical oxygen supply line. The controller output is based on the pulse oximeter readings and the mode of operation chosen by the caregiver. It controls the oxygen flow-rate with an accuracy of 0.1 liters per minute (LPM) around the desired flow-rate. In the automatic mode, The flow-regulator is programmed through the control algorithm to enhance oxygen conservation. To ensure patient comfort, sudden changes in flow-rate are avoided and the rate of change of flow-rate is capped at 1 LPM per minute. © 2022 IEEE.
ABSTRACT
Medical waste contains biohazard, such as dry medical waste from the Centre of Public Health Services (PUSKESMAS) should be burning out, especially in the pandemic of covid 19. One of the possible solution is burning the waste by using incinerator. Basic concept of incinerator is controlled high temperature combustion, thus it should be perfect condition to burnt out the hazardous waste. Heat energy that exposed while incinerator operated should having high potency to be used for other purposes such as water heater and carbonization process. This research aims to develop an incinerator which can be used not only as high temperature burner (as incinerator’s main function), but also for water heater system and carbonization process, in the same time. The incinerator designed as mini portable incinerator since it will be used in a center of public health services (PUSKESMAS). Both of hot water and charcoal produced while incinerator operation can be used for sanitation purposes in the PUSKESMAS itself. Combustion process temperatures, smoke quality, safety factor, and energy utilities are the parameters which were determined as incinerator performance. Some design improvement has been done to the original design by Pradipta and Agustina [1] in order to improve the incinerator performance. The latest design performance is showing that combustion temperature successfully increased up to 980 °C for combustion rate of 9 kg waste/hour. Utilization of heat energy produced by combustion process inside the chamber has been successfully produce 2-2,5 kg of good quality coconut shell charcoal and hot water of 83 °C at 6 lt/minute flow rate.
ABSTRACT
Microfluidics devices have widely been employed to prepare monodispersed microbubbles/droplets, which have promising applications in biomedical engineering, biosensor detection, drug delivery, etc. However, the current reported microfluidic devices need to control at least two-phase fluids to make microbubbles/droplets. Additionally, it seems to be difficult to make monodispersed microbubbles from the ambient air using currently reported microfluidic structures. Here, we present a facile approach to making monodispersed microbubbles directly from the ambient air by driving single-phase fluid. The reported single-phase-fluid microfluidic (SPFM) device has a typical co-flow structure, while the adjacent space between the injection tube and the collection tube is open to the air. The flow condition inside the SPFM device was systematically studied. By adjusting the flow rate of the single-phase fluid, bubbles were generated, the sizes of which could be tuned precisely. This facile bubble generator may have significant potential as a detection sensor in detecting viruses in spread droplets or haze particles in ambient air.
ABSTRACT
The objective of this research was to investigate the behavior and conditions for CO2 adsorption using a mixture of CO2/N2 over a fixed-bed column of zeolite 5A. The study was performed with a variation in gas composition of CO2/N2 as a 20/80, 50/50, and 80/20 volume %, the adsorption temperatures as 298, 333, and 373 K and the total feed flow rates as 1, 2, and 4 L/h under 100 kPa pressure. The Bohart–Adams, Yoon–Nelson, and Thomas models were used to predict the breakthrough behavior of CO2 adsorption in a fixed column. Furthermore, the adsorption mechanism has been investigated using the kinetics adsorption of pseudo-first-order, pseudo-second-order, Boyd model, and intraparticle model. Increasing the CO2 composition of a gas mixture resulted in a high CO2 adsorption capacity because of the high partial pressure of CO2. The capacity of CO2 adsorption was decreased with increasing temperature because of physical adsorption with an exothermic reaction. The CO2 adsorption capacity was also decreased with increasing feed flow rates with inadequate time for CO2 adsorbates diffusion into the pores of the adsorbent before exiting the packed bed. The CO2 adsorption by zeolite 5A confirmed that the physical adsorption with intraparticle diffusion was the rate-controlling step of the whole process.
ABSTRACT
The COVID-19 disease causes severe symptoms like fever, cough, and respiratory disorder like streptococcus pneumonia. Essential oil in cajuput is oil is believed to have effect to reduce respiratory disorder due to COVID-19. While the cajuput oil is not proven to prevent or to heal COVID-19 patients, the treatments using cajuput oil are proven helpful to ease the symptoms. Indonesia as a tropical country has large-scale cultivation of cajuput plants, for example in 2017, Sumedang and Majalengka areas produced up to 4 tons raw material or 10 kg in a day. In producing cajuput oil, there are some steps required for oil extraction and distillation including modified steam distillation method used in this study. This method of essential oil extraction process may use a large amount of heat to produce steam. Geothermal residual heat in the form of brine can be an alternative used to extract eucalyptus oil on small scale. This study shows the material balance analysis for the cajuput oil production with 10 kg cajuput leaves per day from Sumedang and Majalengka areas using Wayang Windu geothermal power plant brine at 180.7°C with 0.05 kg/s mass flow rate. Wayang Windu geothermal power plant itself was chosen because the distance is not too far from cajuput source, which is around 99.7 km. In this study the cajuput oil extraction produces around 57.918 × 10−3 kg of cajuput oil for daily production time 100 min/day.
ABSTRACT
Energy consumption is steadily increasing with the ever-growing population, leading to a rise in global warming. Building energy consumption is one of the major sources of global warming, which can be controlled with renewable energy installations. This paper deals with an advanced evacuated hybrid solar photovoltaic–thermal collector (PVT) for simultaneous production of electricity and domestic hot water (DHW) with lower carbon emissions. Most PVT projects focus on increasing electricity production by cooling the photovoltaic (PV). However, in this research, increasing thermal efficiency is investigated through vacuum glass tube encapsulation. The required area for conventional unglazed PVT systems varies between 1.6–2 times of solar thermal collectors for similar thermal output. In the case of encapsulation, the required area can decrease by minimizing convective losses from the system. Surprisingly, the electrical efficiency was not decreased by encapsulating the PVT system. The performance of evacuated PVT is compared to glazed and unglazed PVTs, and the result shows a 40% increase in thermal performance with the proposed system. All three systems are simulated in ANSYS 18.1 (Canonsburg, PA, USA) at different mass flow rates and solar irradiance.
ABSTRACT
Considering a simple regenerative Brayton cycle, the impact of using different fuel blends containing a variable volumetric percentage of hydrogen in methane was analysed. Due to the potential of hydrogen combustion in gas turbines to reduce the overall CO2 emissions and the dependency on natural gas, further research is needed to understand the impact on the overall thermodynamic cycle. For that purpose, a qualitative thermodynamic analysis was carried out to assess the exergetic and energetic efficiencies of the cycle as well as the irreversibilities associated to a subsystem. A single step reaction was considered in the hypothesis of complete combustion of a generic H2/CH4 mixture, where the volumetric H2 percentage was represented by fH2, which was varied from 0 to 1, defining the amount of hydrogen in the fuel mixture. Energy and entropy balances were solved through the Engineering Equation Solver (EES) code. Results showed that global exergetic and energetic efficiencies increased by 5% and 2%, respectively, varying fH2 from 0 to 1. Higher hydrogen percentages resulted in lower exergy destruction in the chamber despite the higher air-excess levels. It was also observed that higher values of fH2 led to lower fuel mass flow rates in the chamber, showing that hydrogen can still be competitive even though its cost per unit mass is twice that of natural gas.
ABSTRACT
Inhalation therapy has an ancient history and has been recognized as the most effective and safe way of delivering pharmaceutical compounds directly to the airways for the treatment of respiratory diseases. Nowadays, a great variety of devices exist;nebulizers, soft mist inhalers (SMIs), pressurized Metered Dose Inhalers (pMDIs) and single- or multi-dose Dry Powder Inhalers (DPIs). The choice for the optimal device is patient-specific and depends on the advantages and disadvantages of each device category, and the patients' age and capacity to use them correctly. Factors that determine therapeutic success, apart from the previously mentioned, are: the physician-patient relationship, the patient's opinion, willingness, and preferences for certain medical devices, and proper training on device use. Various sources of evidence indicate that frequent change of devices is associated with treatment failure and should be avoided in order to achieve good therapeutic outcomes. The most frequently used types of inhalation devices for management of chronic and acute obstructive respiratory diseases are the pMDIs. Despite having some environmental footprint and requiring a good technique by the users to achieve reliable therapeutic effects, these devices are essential tools for primary care physicians and pulmonologists. In the COVID-19 era, and despite diametrically opposed opinions on the appropriateness of using nebulizers, most experts recommend against their use in order to reduce the potential risk of spreading the SARS-CoV-2 virus. If required, most experts recommend the use of pMDI via a spacer, except for life threatening exacerbations. The ongoing research, to improve the underlying technologies of these devices, introduce environmentally friendlier propellants and combine these devices with modern applications of telemedicine and artificial intelligence, creates new pathways for the continuous utilization of these inhalation devices in everyday clinical practice.