COMPARATIVE PARAMETRIC ANALYSIS OF GAS FLOW IN THREE DIFFERENT DESIGNS OF IN-LINE SCRUBBER BOTTOM INLET

In this study, gas flow fields were simulated using ANSYS 2020R2, Fluid Flow Fluent computational fluids dynamic (CFD) software based on the continuity, velocity, temperature, energy and k - e turbulence. The overall objective of the study is to compare the velocity maps inside the wet scrubber system for three different In-Line scrubber bottom inlet designs. Also, the behavior of the temperature of the mixture inside the scrubber is studied according to the number of nozzles provided by each system from those proposed for study. The numerical simulation using CFD is an effective method to study the flow characteristics of a counter-flow wet scrubber system and the most efficient wet scrubber model is the one with several. The results show that the residuals have a very good job of converging at minimum flow contours and vectors at the inlet across the scrubbing chamber and outlet shows a distributed flow. The speed of water droplets sprayed by the nozzles during mixing with waste gas in the scrubber chamber is double at model with 52 nozzles compared to the first model, equipped with only 13 nozzles. The velocity of clean gases discharged to the ship’s hull shows increases of over 100% of the values, with the increase of the number of nozzles. Spray nozzles improve mixing between the scrubbing liquid and waste gas, by injecting liquid through nozzles to create a fine droplet spray pattern. In this study it can be seen how the number of nozzles influences the quality of the mixture between the scrubbing liquid and waste gas.

Distinguishing between Isobaric Ions Using Microdroplet Hydrogen–Deuterium Exchange Mass Spectrometry

Isobaric ions having the same mass-to-charge ratio cannot be separately identified by mass spectrometry (MS) alone, but this limitation can be overcome by using hydrogen–deuterium exchange (HDX) in microdroplets. Because isobaric ions may contain a varied number of exchangeable sites and different types of functional groups, each one produces a unique MS spectral pattern after droplet spray HDX without the need for MS/MS experiments or introduction of ion mobility measurements. As an example of the power of this approach, isobaric ions in urinary metabolic profiles are identified and used to distinguish between healthy individuals and those having bladder cancer.

Distinguishing Between Isobaric Ions Using Microdroplet Hydrogen-Deuterium Exchange Mass Spectrometry

Isobaric ions having the same mass-to-charge ratio cannot be separately identified by mass spectrometry (MS) alone, but this limitation can be overcome using hydrogen-deuterium exchange (HDX) in microdroplets. Because isobaric ions may contain a varied number of exchangeable sites and different types of functional groups, each one produces a unique MS spectral pattern after droplet spray HDX without the need for MS/MS experiments or introduction of ion mobility measurements. As an example of the power of this approach, isobaric ions in urinary metabolic profiles are identified and used to distinguish between healthy individuals and those having bladder cancer.

Entamoeba gingivalis and Trichomonas tenax in Periodontal Disease

This review is aimed at elucidating the role of Entamoeba gingivalis and Trichomonas tenax in the aetiology of periodontal disease. Periodontal disease results from localised inflammation of the periodontium due to plaque accumulation and if left untreated can lead to loss of teeth. Although dental plaque is composed mainly of bacteria, Entamoeba gingivalis and Trichomonas tenax, both of which are protozoan parasites have been found in plaque and implicated in periodontal disease. E. gingivalis is an amoeba associated with poor oral hygiene while T. tenax is a pyriform flagellate that lives in the tartar around the teeth, cavities of carious teeth, necrotic mucosal cells in the gingival margins of gums and pus pockets in tonsillar follicles. These parasites are transmitted by close contact, saliva, droplet spray and kissing or use of contaminated dishes, cups, spoons and forks as well as drinking water. Age, gender, socio-economic status, dental condition and gingival pathology have been reported to influence the presence of the parasite. Genetic variability and stress are also some of the factors that determine the transition of the periodontium at some gingival sites from healthy to inflame. Researchers have observed that the prevalence and severity of periodontitis is higher in developing countries than developed countries. But with good oral hygiene, regular scaling and polishing and use of antiparasitic drugs, periodontal disease caused by these parasites can be prevented and periodontal health restored.

A surgical mask worn by the patient in addition to the barrier box reduces the droplet spray during endoscopy

Recent guidelines for the prevention of COVID-19 advocate that all the elective procedures should be postponed as these produce aerosols that may affect the staff engaged. Sagami R et al and Neven L et al published the use of a barrier box to prevent the spread of droplets.1, 2 We have done some modifications to this technique. Our endoscopic shield is made of three plastic square walls with a height and width of 50 cm and a length of 40 cm. The wall facing the patient has a hole of 10cm for insertion of the scope. The foot and head sides of the cube are left open. The opening in the head side helps the assistant to keep the patient in proper position, along with the mouth-piece and nasal prong. One may argue that it would lead to the spread of droplets but the previous study has shown that the droplets fall more on the wall facing the patient’s mouth, hence placing the surgical mask over the patient’s face further reduces the head-ward spread of droplets.3 This also helps to facilitate the to and fro movement of the box so that the intubation hole moves away and the intact part of the front wall faces the mouth. A surgical mask with a small hole is placed in a way that the hole is aligned with the mouthpiece hole. The shield is placed over the patient’s head. The scope is passed through the endoscopic port made in the wall of the shield facing the patient and endoscopy is performed. This technique has a few advantages. First, it gives free access to the assistant during the procedure. Second, putting the face mask further reduces the risk of the spread of droplets. Third, an appropriate window for endoscope insertion allows the operator to work at ease, especially during challenging procedures. Continuous....

Comparative Performance Testing of Respirator versus Surgical Mask Using a Water Droplet Spray Model

Background. During the SARS-CoV-2 pandemic, there was shortage of the standard respiratory protective equipment (RPE). The aim of this study was to develop a procedure to test the performance of alternative RPEs used in the care of COVID-19 patients. Methods. A laboratory-based test was developed to compare RPEs by total inward leakage (TIL). We used a crossflow nebulizer to produce a jet spray of 1–100 µm water droplets with a fluorescent marker. The RPEs were placed on a dummy head and sprayed at distances of 30 and 60 cm. The outcome was determined as the recovery of the fluorescent marker on a membrane filter placed on the mouth of the dummy head. Results. At 30 cm, a type IIR surgical mask gave a 17.7% lower TIL compared with an FFP2 respirator. At 60 cm, this difference was similar, with a 21.7% lower TIL for the surgical mask compared to the respirator. When adding a face shield, the TIL at 30 cm was further reduced by 9.5% for the respirator and 16.6% in the case of the surgical mask. Conclusions. A safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.

The Impact of Nanofluids on Droplet/Spray Cooling of a Heated Surface: A Critical Review

Cooling by impinging droplets has been the subject of several studies for decades and still is, and, in the last few years, the potential heat transfer enhancement obtained thanks to nanofluids’ use has received increased interest. Indeed, the use of high thermal conductivity fluids, such as nanofluids’, is considered today as a possible way to strongly enhance this heat transfer process. This enhancement is related to several physical mechanisms. It is linked to the nanofluids’ rheology, their degree of stabilization, and how the presence of the nanoparticles impact the droplet/substrate dynamics. Although there are several articles on droplet impact dynamics and nanofluid heat transfer enhancement, there is a lack of review studies that couple these two topics. As such, this review aims to provide an analysis of the available literature dedicated to the dynamics between a single nanofluid droplet and a hot substrate, and the consequent enhancement or reduction of heat transfer. Finally, we also conduct a review of the available publications on nanofluids spray cooling. Although using nanofluids in spray cooling may seem a promising option, the few works present in the literature are not yet conclusive, and the mechanism of enhancement needs to be clarified.