Airflow Systems Research Articles

Thermal-biomechanical manikin applied in turbulent airflow and vibration systems in transient conditions

This paper applied a thermal-biomechanical manikin in turbulent airflow and vibration systems in transient conditions. This numerical model evaluated the thermal and biomechanical components to which the human body is subjected. The first one considers the first-order equations systems based on the thermal numerical model, while the second one considers the second-order equations systems based on the vibration numerical model. This second-order equations system is converted into a first-order equation system. The resolution of the thermal and biomechanical numerical models is made through the Runge-Kutta-Fehlberg method with error control. The thermal numerical model is used in the study of the steady-state and transient conditions when the skin is subjected to mean and turbulent airflow. The biomechanical numerical model is used in the study of the human body vibrations applied to the feet, that a standing person is subjected, using periodical and random vibration signals of the floor. The thermal analysis shows that with an air fluctuation velocity, the skin temperature reduces slightly. The amplitude of the vibration in the lower body section is higher than in the upper body section. The introduction of the randomised vibration, in the periodical vibration, the human body vibration increases the fluctuation level.

Odor Dilution Assessment for Explosive Detection

Canine olfaction is a highly developed sense and is utilized for the benefit of detection applications, ranging from medical diagnostics to homeland security and defense prevention strategies. Instrumental validation of odor delivery methods is key to standardize canine olfaction research to establish baseline data for explosive detection applications. Solid-phase microextraction gas chromatography (SPME/GC-MS) was used to validate the odor delivery of an olfactometer. Three explosive classes were used in this study: composition C-4 (C-4), trinitrotoluene (TNT), and ammonium nitrate (AN). Dynamic airflow sampling yielded the successful detection of previously reported target volatile organic compounds (VOCs): 2,3-dimethyl-2,3-dinitrobutane (DMNB) in C-4 and 2-ethylhexan-1-ol (2E1H) in ammonium nitrate and TNT across odor dilutions of 80%, 50%, 25%, 12%, and 3%. C-4 highlighted the most reliable detection from the olfactometer device, depicting a response decrease as a function of dilution factor of its key odor volatile DMNB across the entire range tested. TNT only portrayed 2-ethylhexan-1-ol as a detected odor volatile with a detection response as a function of dilution from 80% down to 12%. Comparatively, ammonium nitrate also depicted 2-ethylhexan-1-ol as an odor volatile in the dynamic airflow sampling but with detection only within the upper scale of the dilution range (80% and 50%). The results suggest the importance of monitoring odor delivery across different dilution ranges to provide quality control for explosive odor detection using dynamic airflow systems.

Kinetic Models of Wood Biomass Drying in Hot Airflow Systems

Kinetic Models of Wood Biomass Drying in Hot Airflow Systems

Indoor and outdoor NO2 and SO2 levels in 13 randomly selected preschools from 7 districts in Mpumalanga Province, South Africa

AbstractBackgroundAir pollution is a serious worldwide issue, where both outdoor and indoor air quality have a substantial impact on the health of children. Children are more vulnerable to the effects of air pollution due to their developing respiratory systems and higher respiration rates than adults. These children dedicate a substantial amount of time to the preschool setting. The study sought to evaluate the concentration of NO2 and SO2 in both outdoor and indoor environments of preschool facilities.MethodsConcurrently, the levels of NO2 and SO2 were measured indoors and outdoors at 13 randomly selected preschools in 7 districts in Mpumalanga Province, South Africa. Radiello passive air samplers were employed to collect gaseous samples.ResultsThe mean levels of NO2 indoors and outdoors were within the recommended criteria outlined by the World Health Organization (WHO), specifically target levels 1–3. Additionally, these values were also below the air quality guides outlined by South Africa, both for yearly and 1‐h mean measurements. Nevertheless, both levels remained above the suitable threshold of 10 µg m−3 outlined by the WHO air quality guidelines.ConclusionsIt is important to implement proactive measures such as enhancing airflow systems, employing air filters and reducing potential sources of air pollution in preschools, to aid in reducing exposure to indoor and outdoor NO2 and SO2.

Ventilation performance evaluation of an operating room with temperature-controlled airflow system in contaminant control: A numerical study

This article investigates the efficacy of temperature-controlled airflow systems in modern operating rooms for contaminant control, a critical factor in preventing surgical site infections. We have conducted experimental measurements in an operating room equipped with temperature-controlled ventilation to map the airflow field and contaminant dispersion (airborne particles with diameters ranging from 0.5 to 1 μm). The results were used to validate the computational fluid dynamics code, which was then employed to simulate and examine different conditions, including contaminant release locations and air supply rates. Realizable k-epsilon and passive scalar models were utilized to simulate airflow and airborne particle phases. We assessed the airflow distribution and contaminant dispersion, utilizing indices such as ventilation and air change efficiency scales. The analysis provided quantitative insights into the distribution and removal of contaminants, as well as the speed at which the room air was replaced. Contamination was found to be effectively reduced when contaminants were released near exhaust outlets or under central unidirectional inlets. The presence of the operating table caused a big distortion of the central downward airflow, forming a horizontal air barrier at the periphery. Under this unique interior configuration, an appropriate air supply ratio between central and periphery zones was required to achieve optimal overall ventilation performance.

Experimental analysis of airborne contaminant distribution in an operating room with different ventilation schemes

Experimental and numerical investigations were performed in a research operating room to compare laminar air flow and turbulent mixing ventilation systems in reducing the concentrations of airborne germs and surgical smoke in operating room air. In addition, measurements at scattered positions were conducted to find positions that are suited best for airborne monitoring in real-time during surgeries. In the experiments, particle counters were used to sample tracer aerosols originating from the wound area and the facial area of the thermal manikins representing surgical staff. The results showed that it is important to perform monitoring close to the areas with high hygiene requirements. Increasing the air change rate with turbulent mixing ventilation significantly reduced the number of airborne particles, however, not in the surgical microenvironment. Our findings show varying results considering the particle concentration using laminar air flow compared to turbulent mixing ventilation. With laminar air flow, higher contaminant levels are obtained in the areas with a high demand for contamination reduction. In contrast, laminar air flow was more effective in reducing the concentration of surgical smoke in the facial areas of the surgical staff. Regarding airborne germs, monitoring should be performed at the instrument tables and close to the wound area to evaluate the risk for surgical side infections. These results can support the development of guidelines and best practices for operating room ventilation design and maintenance to improve patient safety and reduce the risk of healthcare-associated infections.

Patterns of microparticles in blank samples: A study to inform best practices for microplastic analysis

Quality assurance and quality control (QA/QC) techniques are critical to analytical chemistry, and thus the analysis of microplastics. Procedural blanks are a key component of QA/QC for quantifying and characterizing background contamination. Although procedural blanks are becoming increasingly common in microplastics research, how researchers acquire a blank and report and/or use blank contamination data varies. Here, we use the results of laboratory procedural blanks from a method evaluation study to inform QA/QC procedures for microplastics quantification and characterization. Suspected microplastic contamination in the procedural blanks, collected by 12 participating laboratories, had between 7 and 511 particles, with a mean of 80 particles per sample (±SD 134). The most common color and morphology reported were black fibers, and the most common size fraction reported was 20–212 μm. The lack of even smaller particles is likely due to limits of detection versus lack of contamination, as very few labs reported particles <20 μm. Participating labs used a range of QA/QC techniques, including air filtration, filtered water, and working in contained/‘enclosed’ environments. Our analyses showed that these procedures did not significantly affect blank contamination. To inform blank subtraction, several subtraction methods were tested. No clear pattern based on total recovery was observed. Despite our results, we recommend commonly accepted procedures such as thorough training and cleaning procedures, air filtration, filtered water (e.g., MilliQ, deionized or reverse osmosis), non-synthetic clothing policies and ‘enclosed’ air flow systems (e.g., clean cabinet). We also recommend blank subtracting by a combination of particle characteristics (color, morphology and size fraction), as it likely provides final microplastic particle characteristics that are most representative of the sample. Further work should be done to assess other QA/QC parameters, such as the use of other types of blanks (e.g., field blanks, matrix blanks) and limits of detection and quantification.

Effect of turbulent and laminar flow mechanisms on airflow patterns and CO2 distribution in an operating room: a numerical analysis

Considering the risk of infection in surgeries, maintaining an acceptable indoor air quality in the operating rooms (ORs) to ensure the health and safety of patients and surgical team is very essential. Since airflow is one of the primary mechanisms for transmitting of infections and pollution, it is crucial to examine the air distribution systems in the ORs. In the present study the effect of turbulent and laminar airflow (TAF/ LAF) systems on the air and CO2 distribution in an OR was examined. The effects of inlet and outlet configurations were evaluated for seven different models. The results indicated that the LAF systems is superior over TAF systems. Based on the findings, the LAF with the air curtain configuration brings about the minimum CO2 concentration level in the OR. The results showed that LAF with the air curtain model is able to decrease the CO2 concentration by about 64.66% and 88.96% on central plane, which passes along the body patient on 1.14 m and 1.7 m above the floor, respectively compared to the existing model.

From Alpha to Omicron: A Radiation Oncology Network's Biocontainment-Based COVID-19 Experience

PurposeTo develop the safest possible environment for treating urgent patients with COVID-19 requiring radiation, we describe the unique construction of negative air pressure computed tomography simulator and linear accelerator treatment vaults in addition to screening, delay, and treatment protocols and their evolution over the course of the COVID-19 pandemic. Methods and MaterialsConstruction of large high-efficiency particulate air filter air-flow systems into existing ductwork in computed tomography simulator rooms and photon and proton treatment vaults was completed to create negative-pressure rooms. An asymptomatic COVID-19 screening protocol was implemented for all patients before initiation of treatment. Patients could undergo simulation and/or treatment in the biocontainment environments according to a predefined priority scale and protocol. Patients treated under the COVID-19 protocol from June 2020 to January 2022 were retrospectively reviewed. ResultsNegative air-flow environments were created across a regional network, including a multi-gantry proton therapy unit. In total, 6525 patients were treated from June 2020 through January 2022 across 5 separate centers. The majority of patients with COVID-19 had radiation treatment deferred when deemed safe. A total of 42 patients with COVID-19, who were at highest risk of an adverse outcome should there be a radiation delay, were treated under the COVID-19 biocontainment protocol in contrast to those who were placed on treatment break. For 61.9% of patients, these safety measures mitigated an extended break during treatment. The majority of patients (64.3%) were treated with curative intent. The median number of biocontainment sessions required by each patient was 6 (range, 1-15) before COVID-19 clearance and resumption of treatment in a normal air-flow environment. ConclusionsConstructing negative-pressure environments and developing a COVID-19 biocontainment treatment protocol allowed for the safe treatment of urgent radiation oncology patients with COVID-19 within our department and strengthens future biopreparedness. These biocontainment units set a high standard of safety in radiation oncology during the current or for any future infectious outbreak.

Urban climatic maps for environmental planning in Manizales, Colombia

Air pollution is a serious environmental problem in Latin American cities. Although the problem is widely studied, collaborative solutions from city planners and urban climatologists have been slow to evolve. In this article, we demonstrate the severity of the problem in the mountain city of Manizales, Colombia, and offer “urban climatic mapping” as an appropriate tool to ease communication between scientists and planners. We take a comprehensive approach involving topographic, demographic, and atmospheric datasets, which are assembled and analysed in a GIS environment. Our maps show that the mountain-valley wind patterns in Manizales are critically important for ventilating the city and improving air quality. We therefore give planning recommendations to protect and enhance the natural airsheds and airflow systems of Manizales through modification of the built form. Recommendations are also given to reduce pollutant loading in the narrow streets of the historical centre, and to expand the network of environmental monitoring stations across the city. The expansion is designed in accordance with international guidelines for siting meteorological instruments in urban areas, and is intended to serve new uses for the network data, to include community planning, environmental mapping, and urban climate education.

Are Operating Rooms With Laminar Airflow a Risk for Inadvertent Perioperative Hypothermia During Ureterorenoscopic Lithotripsy Under Spinal Anesthesia? A Prospective Randomized Clinical Trial.

Inadvertent perioperative hypothermia (IPH), defined as a core temperature &lt;36°C, is common during a surgical procedure and is associated with high morbidity and mortality. Laminar (LAS) and conventional airflow systems (CAS) are used frequently for clean microenvironmental surgical areas in operating rooms. In LAS, the cold airflow is directed toward the patient, unlike CAS. Does this airflow in LAS cause heat loss from the patient by convection more than CAS? We aimed to compare the IPH frequencies of these airflow systems on patients who underwent ureterorenoscopic lithotripsy (ureterorenoscopic surgery) under spinal anesthesia. The study was a prospective, parallel-group, randomized trial. A total of 246 volunteers were included in the study and divided into group LAS (n = 123) and group CAS (n = 123). Randomization of patients was performed using the closed-envelope method (as 1:1).The tympanic membrane temperature of patients was measured before spinal anesthesia ( T0 ) and then every 15 minutes ( T n ) during the procedure. The IPH ratio and the change of the tympanic temperatures (Δ T ) were recorded (clinical trial number: IRCT20180324039145N5). In total, there were no statistical differences between the IPH ratios of group LAS and group CAS (61.2% [71 of 116] versus 49.6% [57 of 115], respectively; P = 0.075). The IPH ratio was 55.4% (128 of 231). The tympanic temperatures of patients decreased about 0.64°C (0.45°C) at the 30th minute. In both groups, Δ 30 was similar (0.62; 95% confidence interval, 0.52-0.72 [ P = 0.65]; 95% confidence interval, 0.55-0.74 [ P = 0.236], respectively). The risk for IPH of both LAS and CAS in the operating room is similar during ureterorenoscopic surgery.

Ventilation and energy efficiency in Air Systems for future buildings: a four dimensions approach

Recent pandemic events are combined with a growing awareness of environmental issues, a general focus on sustainability and responsibility for future generations. All these issues converge towards a general need to improve the performance of buildings and at the same time reduce energy costs. This paper presents four different areas of improvement applicable to air systems on which it is felt that the time has come to focus conceptual and technological efforts. The four dimensions of the proposed improvement are as follows: The reduction of air leakage, the optimization of air diffusion control in VaV applications, the implementation of selective systems for the removal of specific contaminants, the system-wide contextualization of heat recovery from exhaust air. The four directions indicated are considered to offer the greatest potential for optimization in the context of air systems, and this is all the more true if these paths are taken simultaneously. They are aimed at minimizing energy effort (i.e., treated air flow rates) while maximizing performance in terms of maintaining indoor air quality. This can be done by repositioning the boundaries that until now have not allowed the full potential offered by a wise application of variable airflow systems. The approach presented is mainly a performance-based approach re-evaluated in the light of improvements in manufacturing and component characterization technologies, the possibility of considering air systems as a potentially synergistic part of more complex systems, and new sensitivities developed following the advent of pandemic events. The potential improvements in percentage terms from such an action promise to be greater than any single component implementation, but they require a change of attitude on the part of designers and a readiness on the part of manufacturers to work towards the development of standardized procedures applicable on a large scale.

Metal-Air Batteries—A Review

Metal–air batteries are a promising technology that could be used in several applications, from portable devices to large-scale energy storage applications. This work is a comprehensive review of the recent progress made in metal-air batteries MABs. It covers the theoretical considerations and mechanisms of MABs, electrochemical performance, and the progress made in the development of different structures of MABs. The operational concepts and recent developments in MABs are thoroughly discussed, with a particular focus on innovative materials design and cell structures. The classical research on traditional MABs was chosen and contrasted with metal–air flow systems, demonstrating the merits associated with the latter in terms of achieving higher energy density and efficiency, along with stability. Furthermore, the recent applications of MABs were discussed. Finally, a broad overview of challenges/opportunities and potential directions for commercializing this technology is carefully discussed. The primary focus of this investigation is to present a concise summary and to establish future directions in the development of MABs from traditional static to advanced flow technologies. A systematic analysis of this subject from a material and chemistry standpoint is presented as well.

Application of Smart Oven Technology as an Effort to Increase Smoked Egg Production and Quality in Sania MSME

Mitra Home salted egg industry SANIA MSME is an MSME that engages in duck cultivation and the production of Smoked Salted Eggs. SANIA MSME was founded by a duck breeder group in 2008 in Kawedusan Ponggok Village, Blitar. Smoked salted eggs are known for their burnt/smoky aroma and greasy egg yolks. Smoked egg production is done manually using the use of smoking drums. These manual devices are only capable of baking 150 grains per day. Meanwhile, damage due to smoking with an oven drum can reach up to 15-20%. This can reduce profits by up to 20% per cycle of the smoking process. Damage occurs when users forget or are too late to lower the drum oven's temperature before it reaches temperatures of 1000C or more. The uneven heat can also result in a reduction to taste and greasiness of the egg yolks. Manual ovens take 7-10 hours at 80-900C to cook. From discussions with partners, it was discovered that they needed egg smoking ovens that feature thermoregulators and can produce even flows of smoke automatically. There is a need for technological innovation in the egg fumigation equipment category in the form of smart egg smoking ovens complete with thermoregulators and automatic smoke airflow systems. Smart ovens have the potential to increase productivity by 75% with a faster smoking process of 3-4 hours. The service method was carried out by way of producing a design for smart ovens, socialization and assistance in the use of the device, assistance in the production of smoked eggs, and program evaluation. The results of the mentoring activity suggested that the production of smoked eggs can increase by 70% with the level of cooking damage sitting at less than 10% and an improvement in the product's taste.

Air Flow Disinfection from COVID-19 Based on Doped Atanase Coating Using Atmospheric Plasma

Currently UV disinfection equipment is used to some extend to combat COVID-19 pandemic in high human traffic areas. Infections spread very quickly from person to person inside of closed air flow systems as in airplanes. Often using this equipment is prohibited due to harmful UV radiation and ozone emission.Therefore, safer solution is needed. Adding hydroxyl radicals to air flow is equally efficient to UV/ozone in virus disinfection, but safer as neither UV used, nor ozone generation.UV disinfection equipment market projects to reach USD 9.2 billion by 2026 from an estimated USD 4.8 billion in 2021, at a CAGR of 14.0% from 2021 to 2026. This marketplace can be captured by the hydroxyl generators.Hydroxyl radicals attack essential cell components and are therefore lethal to pathogenic viruses and bacteria – both in the air and on surfaces. Pathogenic viruses suffer from oxidation of their surface structures. Hydroxyl radicals disrupt the lipid envelope and/or capsid around the virus, causing lysing.However, the rate of generation of these radicals should exceed 1015 OH molecules cm−3s−1 to reach a globally averaged OH concentration ([OH]g) above 106 molecules cm−3 to inactivate SARS with the same efficiency as the UV light. The anatase TiO2 particles are used to generate these hydroxyl groups through photocatalytic reaction. The photon flux around of 2 × 10 15 photons cm − 2 s−1 is required to achieve this rate of the hydroxyl generation. Pure atanase has wide band gap – thus need UV for photocatalysis, and low quantum yield due to electron-hole recombination. We solve these problems by modifying band gap and by using small nanoparticles.We use Nitrogen doping of TiO2 to narrow the band gap. Thus, photocatalysis under visible light is enabled, no UV required. We use 20 nm nanoparticle coating instead of thick blanket TiO2 films thus mitigating hole recombination and increasing quantum yield.Efficiency is additionally increased by enlarging the surface area - laminate nanoparticles onto the 3D light transmitting hollow article, like matrix made from the fused together capillaries with the inner diameter around 0.5 mm and length around 5-10 mm. It increases the rate of generation of the hydroxyl groups due to accessibility of the photons to the TiO2 nanolayer illuminated from outside and inside. Also, the photocatalytic process can be promoted by electric field applied to the matrix . The field separates charge carriers thus reducing the recombination between electrons and holes and, thus better quantum yield, improved photocatalytic performance.With our atmospheric plasma beam technology and equipment we fabricate the hydroxyl reactor. We form a 3D matrix laminated by the TiO2 nanolayer. Our laminating instrument is a focused plasma beam generated by the atmospheric pressure inductively coupled plasma (ICP) discharge in nitrogen. Precursor is a commercial anatase TiO2 nanoparticles injected into this discharge. Nitrogen atoms incorporate into the interstitial positions of the TiO2 lattice of the nanoparticles. The supersonic plasma beam is generated by the nozzle attached to the plasma reactor and the TiO2 nanoparticles with increased nitrogen content are deposited on the inner walls of the capillaries of the matrix.This laminated matrix is encircled by the top and bottom metal meshes connected to the high voltage capacitor. This is a key part of the hydroxyl generator incorporated into the racetrack-like bore of the commercial Dyson air purifier. The matrix is positioned between two flanges closing the bore of the Dyson purifier from both sides. One of them supports the LED emitting photons piercing the matrix and the opposite one supports the mirror directing the reflected light back to the matrix and doubling the illumination. Humid air flow is generated by the Dyson air filter and injected into the gap between the LED and the top of the matrix. Water thus delivered to the TiO2 nanolayer for photocatalytic hydroxyl radicals’ generation.It is reasonable to suppose that nanocoating, doping and electric field novelties will lead to a synergistic effect and increase photocatalytic activity to inactivate SARS and its highly contagious Delta variant. Inserting our hydroxyl generator into commercial Dyson air purifier increases cost-efficiency and time-to-market.

A comparison of energy harvesting from cement and asphalt on road pavement using thermoelectric module

Energy harvesting from road pavements was studied using thermoelectric generator (TEG) modules, where solar heat energy on the road pavement was transferred directly to electrical energy. Cement and asphalt pavements were examined and compared. The asphalt pavement had better solar energy adsorption due to its black surface. The hot surface of the TEG modules was attached to the underside of the pavement, while the cool surface was enclosed by a cooling system. Natural airflow and water-cooling systems were investigated and compared. The electromotive force (e.m.f.) voltages were directly related to the temperature difference between the hot and cool surfaces of the TEG modules. The e.m.f. voltage from the asphalt showed superior performance compared to that from cement with both natural airflow and water cooling. Moreover, the water-cooling system provided a larger temperature difference, allowing a greater e.m.f. voltage to be generated from the TEG module. The maximum e.m.f. from asphalt was about 168.5 mV, which was about 25.4% (ca. 134.4 mV) higher than that from cement with the water-cooling system.

The application value of operating room ventilation with laminar airflow for surgical site infection: A protocol for a systematic review and meta-analysis.

Background:The presence of biological particles in the air inside operating theatres has the potential to cause severe surgical site infections. Recently, laminar airflow systems have been regarded as a means to reducing surgical site infections using airborne microbes. Still, other publications have argued the benefits of laminar airflow systems, stating the likelihood of adverse effects. Therefore, we will conduct this systematic study to evaluate the applicational value of adopting laminar airflow systems in operating theatres to minimize surgical site infections.Methods:Reporting of this study adheres to the guidelines of Preferred Reporting Items for Systematic Review and Meta-analysis Protocols. The authors will perform a systematic search on MEDLINE, Web of Science, EMBASE, the China national knowledge infrastructure, and the Cochrane Library from their commencement until June 2021. The search will identify relevant randomized and non-randomized controlled trials that evaluates the applicational value of using laminar airflow ventilation in surgical theatres to minimize surgical site infections. There are no restrictions on language. Two authors will independently screen the identified studies, perform data extraction, and use an appropriate method to evaluate the bias risk in the included studies.Results:The work done in the present study will enhance the existing literature on the applicational value of laminar airflow ventilation in surgical theatre to reduce surgical site infections.Conclusion:The outcomes are a reference for healthcare practitioners and patients when making informed decisions regarding care during surgeries.

Model predictive control strategy using encoder-decoder recurrent neural networks for smart control of thermal environment

The development of deep learning (DL) technology provides an opportunity for accurate prediction and effective control of complex building systems. However, despite the high prediction performance of DL models, few studies integrate DL with the model predictive control (MPC) algorithm for improving building management. In this study, a DL-based MPC framework using encoder-decoder recurrent neural network is developed for real-time control of building thermal environment to exploit the advantage of both DL and MPC algorithms. In addition, to simulate the dynamic interaction between indoor airflow and HVAC systems, a co-simulation platform by integrating HVAC simulator and CFD model is developed to evaluate the proposed building control strategy. Two case studies including a confined space with mixing ventilation and an office room subjected to solar radiation are used for validation of the proposed method. The performance of the DL-based MPC algorithm for building thermal environment control is compared with the traditional proportion-integration-differentiation (PID) controller and the adaptive PID controller. Approximately 4% and 7% energy savings are achieved on average through DL-based MPC compared with adaptive and conventional PID control, respectively. The proposed DL-based MPC framework shows a promising application prospect for building automationby taking the advantage of both deep learning and MPC algorithms.

In situ observation of the deterioration process of sulfide-based solid electrolytes using airtight and air-flow TEM systems.

Sulfide-based solid electrolytes (SEs) exhibiting high ionic conductivity are indispensable battery materials for next-generation all-solid-state batteries. However, sulfide-based SEs have a major drawback in their low chemical stability in air. When exposed to H2O or O2 gas, toxic H2S is generated, and their ionic conductivity considerably declines. However, their degradation mechanism caused by air exposure has not been understood yet. To clarify the degradation process, in this study, we developed a transmission electron microscope (TEM) system to evaluate the air stability of battery materials. Using a vacuum transfer double-tilt TEM holder with a gas-flow system, the in situ observation of the degradation process was conducted for a sulfide-based Li4SnS4 glass ceramic under an air-flow environment. Consequently, electron diffraction (ED) patterns and TEM images could clearly capture morphological changes and the amorphization process caused by air exposure. Moreover, based on the analysis of ED patterns, it is observed that Li4SnS4 is likely to decompose because of the reaction with H2O in air. Therefore, this airtight and air-flow TEM system should be effective in clarifying the process of the deterioration of sulfur-based SEs during exposure to air.

The design and testing of unidirectional airflow operating theatres

This article discusses the design of unidirectional airflow systems used to ventilate operating theatres and provide low concentrations of airborne micro-organisms during surgical operations. Also described are tests that can be used to confirm that unidirectional airflow systems are well designed and perform correctly when installed and during their lifetime. Reasons are given for the failure of unidirectional airflow systems to provide low concentrations of airborne micro-organisms and reduce joint infection rates after total joint arthroplasty when compared to conventional mixed-airflow operating theatres.