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This paper investigates the energy performance and sizing criteria of 5th generation district heating and cooling (5GDHC) networks as a function of the heat distribution temperature in the building systems connected to the district network. An energy simulation model of a 5GDHC network was developed in Modelica for a case study located in Denmark. Calculations were carried out for four different building heating systems. Simulation results show that reducing the heat distribution temperatures from 70 ◦C to 23 ◦C leads to around 40% annual electric energy savings (from 10.4 kWh/m2 to 6.2 kWh/m2) for the operation of the heat pumps. Heat distribution temperatures of 23 ◦C cause higher water mass flow rates through the network, leading to annual electric energy consumption for the circulation pumps that are almost doubled (from 0.16 kWh/m2 to 0.3 kWh/m2) compared to the reference case at 70 ◦C. Furthermore, the paper discusses how the results obtained from the Danish case study can be generalized and applied to other cases using a simplified mathematical approach. It is found that about 1.5% of electric energy savings can be achieved for each temperature degree reduction in the heat distribution system.

Irisin is a myokine that is secreted from skeletal muscle during exercise and increases lipid metabolism, converting white adipose tissue to brown adipose tissue. Recent studies have shown conflicting results in relation to chronic and acute exercise and irisin. The aim of this study was to evaluate the effects of chronic and acute exercise training on circulating (plasma/serum) irisin level in healthy subjects. We conducted a search of Cochrane Library, PubMed, ISI, Scopus, Embase, and Pedro up to September 2021. A random effects network meta-analysis was performed to calculate the pooled estimate of standardized mean difference (SMD) for acute and chronic exercise effects on irisin level, using Hedge’s g statistic. Of the 16 studies included, six were acute exercise studies (175 participants). The aerobic (Hedge’s g = 0.23 ; 95% CI: -0.58, 1.03) and the anaerobic exercises (Hedge’s g = 0.12 ; 95% CI: -0.45, 0.70) were associated with the increased level of irisin, compared to the control. In the ten chronic exercise studies (433 participants), the resistance training was superior to anaerobic and aerobic training ( P score = 0.632). However, comparing acute and chronic exercise studies, acute training showed the most excellent potential as the best treatment to improve the irisin level ( P score = 0.721). This network meta-analysis showed that acute aerobic exercise has a more effect on irisin levels than acute anaerobic exercise. Also, chronic resistance training has the greatest additive effect on irisin levels compared to chronic aerobic and anaerobic training.

Precision ventilation is used in open-plan offices to establish micro-climate zones according to the metabolic requirements of its occupants. The aim of this study is to determine design criteria and highlight the opportunities and limitations for precision ventilation in large-scale offices. The simulations and experiments were conducted under steady state conditions with fixed airflow from all active chilled beams (ACBs) and constant room temperatures. A temperature difference of 3.5K was maintained between supply and room air in all cases with and without occupants. Results showed that precision ventilation can simultaneously establish low-level (

Aggregators are emerging players in the future power markets which aggregate the flexibility of small consumers. This paper proposes a hierarchical model-based scheme to activate the energy flexibility of multi-zone buildings through a direct aggregation mechanism. The novelty lies in considering the power market mechanism in which consumers try to remain committed to their bids without violating their desired comfort levels. In the proposed approach, a high-level control layer determines an hourly energy budget for the whole building according to price signals and reports it to an aggregator. A lower-level dispatch layer then distributes the pre-planned hourly energy budget among different zones. At this level, the emphasis is on keeping the energy consumption as close to the pre-planned budget as possible while satisfying the comfort requirements. In addition, this layer computes the available real-time up and down regulating power and reports them to the aggregator. For comparison, we develop both a centralized and a decentralized model predictive control (MPC) scheme for the high-level control layer. Furthermore, a decentralized MPC with variable prediction horizon is designed for the lower-level dispatch layer. The proposed method is applied to a detailed multi zone building model developed in a high-fidelity simulation environment. The results show that the proposed scheme can keep its commitment to the aggregator to a large extent (by more than 93%) while maintaining the desired comfort levels. In addition, it is seen that the centralized model reduces energy costs and exhibits between 0.5% and 2.5% better commitment to the pre-planned budget in comparison with the decentralized one at the cost of sacrificing comfort to some extent. Moreover, some preliminary results regarding available up and down regulating power for residential buildings are reported for the first time.

Determination of airflow rates is an inevitable part of the energy-efficient control of ventilation systems. To achieve efficient control, the flowmeters used must be suitably accurate and create minimum disturbance to the airflow. In this study, we evaluate the quantitative performance characteristics of an innovative micro-electromechanical systems (MEMS) flowmeter, a so-called Elastic Filament Velocimetry (EFV), in ventilation ducts. Two versions of the EFV-sensor, i.e., an 11-nanoribbon and a 22-nanoribbon variety, were evaluated in laboratory studies. The results indicate that the 11-nanoribbon sensor is more suitable for air velocity measurements in ducts than the 22-nanoribbon sensor. The 11-nanoribbon sensor can measure air velocities from 0.3 m/s. The maximum variation of the sensor-output is 3% for velocities over 0.5 m/s. Calibration models have been developed for the 11-nanoribbon sensor. The error due to model calibration is lower than ±5% for velocities over 0.6 m/s. Moreover, laboratory studies were performed to investigate the airflow disturbance in a duct system due to the EFV sensor. The results were compared with the corresponding disturbance caused by two different types of self-averaging probes. At a bulk velocity of 3 m/s, the self-averaging probes introduced a greater pressure drop by at least 50% compared to the EFV-sensor.

Latent heat thermal energy storage (LHTES) with Phase Change Materials (PCM) represents an interesting option for Thermal Energy Storage (TES) applications in a wide temperature range. A tubular encapsulation model of an LHTES with PCM was developed, and the calculated data were analyzed. In addition, a parametric analysis for the preferable system geometry is presented. Organic paraffin RT18 with a melting point of 18 ◦C was utilized as PCM for different geometries of LHTES, and the addition of internal and external fins and their influence on LHTES thermal conductivity was investigated. One-step heat exchange from outdoor air to PCM and from PCM to water characterizes the LHTES system in solidification and melting processes, respectively. A 2D axisymmetric model was developed using Comsol Multiphysics 6.0. The LHTES unit performance with PCM organic paraffin RT18 encapsulated in electrospun fiber matrices was analyzed. The study results show that longer internal fins shorten the melting and solidification time. The phase change process was accelerated by 31.12% in the charging compared to the case with no fins of the same external tube diameter. Direct contact of PCM electrospun fiber matrix with 23 ◦C water showed instant melting, and the phase change process was accelerated by 99.97% in the discharging cycle. Latent heat thermal energy storage (LHTES) with Phase Change Materials (PCM) represents an interesting option for Thermal Energy Storage (TES) applications in a wide temperature range. A tubular encapsulation model of an LHTES with PCM was developed, and the calculated data were analyzed. In addition, a parametric analysis for the preferable system geometry is presented. Organic paraffin RT18 with a melting point of 18 °C was utilized as PCM for different geometries of LHTES, and the addition of internal and external fins and their influence on LHTES thermal conductivity was investigated. One-step heat exchange from outdoor air to PCM and from PCM to water characterizes the LHTES system in solidification and melting processes, respectively. A 2D axisymmetric model was developed using Comsol Multiphysics 6.0. The LHTES unit performance with PCM organic paraffin RT18 encapsulated in electrospun fiber matrices was analyzed. The study results show that longer internal fins shorten the melting and solidification time. Direct contact of PCM electrospun fiber matrix with 23 °C water showed instant melting, and the phase change process was accelerated by 99.97% in the discharging cycle.

Cognitive impairment is common in people living with neuromyelitis optica spectrum disease (NMOSD) and multiple sclerosis (MS). However, there is little published data on intelligence quotient (IQ) in NMOSD patients. Therefore, we performed the present study to compare IQ scores across NMOSD, MS, and control groups.In this cross-sectional study, 49 NMOSD (30 with positive aquaporin4 antibody), 41 MS, and 20 control individuals were recruited. The IQ score for each person was measured using Wechsler Adult Intelligence Scale-Revised (WAIS-R). Participants were reported on eleven scores of subsets, verbal IQ (VIQ), performance IQ (PIQ), and full score IQ (FSIQ).The scores of FSIQ, VIQ, PIQ, vocabulary, similarities, and digit-symbol in NMOSD and MS individuals were lower than the control group. Relative to control, NMOSD patients reported a lower score of information. We found no difference between NMOSD and MS groups, except in vocabulary and similarities. No significant difference between seropositive and seronegative NMOSD groups was observed except for the information and block design. In NMOSD group, a greater EDSS score was associated with decreased scores of FSIQ, VIQ, and PIQ. Being employed and being married were associated with greater scores of VIQ and PIQ, respectively. In both NMOSD and MS groups, advanced education was associated with increased scores of FSIQ and VIQ.Our study showed decreased IQ scores in NMOSD and MS. Further studies are required to examine intellectual quotient in people with NMOSD and MS.

Precision ventilation is developed to achieve thermal comfort for occupants in an office by creating micro-climate zones. The present study aims to achieve individual thermal comfort for occupants with different metabolic rates by using higher airspeeds for enhancing heat transfer. The variable jet interaction between two ACBs with JetCone adjustments cause higher velocity jets to reach different regions of the occupied zone. The colliding jets from the center of a thermal isolated room were moved towards different zones in an office configuration with a constant room temperature of 23 °C. This study was conducted for five different cases in a room divided into four zones according to occupants’ metabolic rates. The experimental and CFD results show that occupants facing symmetrical airflow distribution and with a constant 1.2 metabolic rate (Case 1) had a similar predicted mean vote (PMV) index. The zones with higher-metabolic-rate occupants, i.e., 1.4 met and 1.6 met in cases 2 and 3 were exposed to air velocities up to 0.4 and 0.5 m/s, respectively. In case 4, the air velocity in the single zone with 1.6 met occupants was raised to 0.6 m/s by targeted airflow distribution achieved by adjusting JetCones. These occupants with higher metabolic rates were kept thermally neutral, in the −0.5 to +0.5 PMV range, by pushing the high velocity colliding jets from the center towards them. In case 5, the results showed that precision ventilation can maintain the individual thermal comfort of up to three different zones (in the same office space) by exposing the occupants with metabolic rates of 1.2, 1.4, and 1.6 met to airspeeds of 0.15, 0.45, and 0.55 m/s, respectively.

The applications of Active Chilled Beam (ACB) technology have increased over the two decades and received a lot of attention in research publications due to its ability to provide a suitable indoor climate for building occupants with minimum energy use. In the literature, no comprehensive review on ACB systems has been reported. This study provides a review of the ACB technology by investigating its functions, component and control strategies, design and testing techniques, and its applications for office buildings. Literature shows that ACB systems fulfil sensible cooling demands for office setups and can provide a space-friendly solution by making effective use of ceiling space in buildings. The cooling demands can be met with high induction rates, proper coil circuitry design, and optimum chilled water supply temperature. The high induction rates with more even air-jet patterns inside the terminal unit of ACBs can be achieved by using nozzles of different sizes, cross-sections, and lengths. Studies show that a reduction in energy use up to 30% can be achieved by ACBs as compared to conventional HVAC systems.

One of the major changes regarding HVAC systems in new or renovated residential buildings is the incorporation of heating in the ventilation system, providing an air heating system. In buildings equipped with air heating systems, indoor climate is commonly controlled based on a reference zone, which leads to unsatisfactory thermal condition in the other zones. In addition, this strategy is not energy-efficient for buildings due to overheating that can occur in some zones. This study presents control logic for a novel-designed demand-controlled ventilation and air heating system and develops a variable air volume (VAV) control strategy to ensure an energy-efficient operation of the system, while providing a satisfactory indoor climate conditions. The air heating system can change airflow rate and air temperature in each room quickly and accurately enabling the control of indoor climate on a room level within a dwelling. The performance of the air heating system, in terms of its effect on thermal comfort and indoor air quality in each room as well as the stability of the system has been evaluated through a full-scale laboratory experiment. The experimental result indicated the ability of the system to satisfy different temperature set-points ranging from 20 °C to 25 °C in different zones with ±0.3°C deviation from the set-points, while the system was remained stable when temperature set-points were changed in several zones during the experiment. Individual indoor air quality requirements were also satisfied with providing the required supply airflow rate to each zone, while the supply fan was running based on the critical zone reset control strategy to achieve an energy-efficient operation.

Dysphagia is one of the most common symptoms in multiple sclerosis (MS) patients. It can reduce the quality of life and increase the risk of mortality by developing complications such as aspiration pneumonia. The present study was conducted to estimate the prevalence of dysphagia in MS patients and investigate the associations between dysphagia and disease characteristics. The Persian version of the DYMUS questionnaire was used to assess dysphagia in 865 patients with MS, including 738 (85.3%) relapsing–remitting MS (RRMS), 106 (12.3%) secondary progressive MS (SPMS), and 21 (2.4%) primary progressive MS (PPMS). Also, demographic and clinical data, including age, sex, smoking status, Expanded Disability Status Scale (EDSS) score, disease duration, disease-modifying therapies exposure, initial symptoms of MS, were recorded. The mean (SD) age was 37.95(9.25) years, and 83.1% of the participants were female. The prevalence of dysphagia was estimated to be 25.4% among all patients. According to the DYMUS questionnaire results, the prevalence of dysphagia in RRMS, SPMS, and PPMS patients was 22.2%, 44.3%, and 42.9%, respectively. After multivariate analysis the current EDSS score (OR = 1.197, CI: 1.062, 1.350, p = 0.003), cerebellar impairment (OR = 1.335, CI: 1.450, 4.716, p = 0.004) and motor dysfunction (OR = 1.651, CI: 1.004, 2.715, p = 0.048) emerged as the risk factors for dysphagia. Since dysphagia, as previously mentioned, is a common symptom in multiple sclerosis, particularly in SPMS and PPMS courses, active screening for this condition is recommended in all patients, particularly those with identified risk factors.

The accumulation of thermal energy in construction elements during daytime, and its release during a colder night period is an efficient and green way to maintain a comfortable temperature range in buildings and vehicles. One approach to achieving this goal is to store thermal energy as latent heat of the phase transition using the so-called phase-change materials (PCMs). Vegetable oils came recently into focus as cheap, widely available, and environmentally friendly PCMs. In this study, we report the thermal properties of PCMs based on tamanu and coconut oils in three configurations: pure, emulsion, and encapsulated forms. We demonstrate the encapsulation of pure coconut- and tamanu-oil emulsions, and their mixtures and mixtures with commercial PCM paraffins in fiber matrices produced by a coaxial electrospinning technique. Polycaprolactone (PCL) was used as a shell, the PCM emulsion was formed by the studied oils, and sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) were used as emulsifiers. The addition of commercially available paraffin RT18 into a 70/30 mixture of coconut and tamanu oil, successfully encapsulated in the core of a PCL shell, demonstrated latent heats of melting and solidification of 63.8 and 57.6 kJ/kg, respectively.

High concentration particulate matter (PM) has been a serious environmental problem in China and other developing countries. Electrostatic-based purification technology is a method to remove airborne particles, and can reduce the energy consumption of ventilation fans in buildings because of its low pressure drop. In this study, we developed a new pin-to-plate corona discharger with particle-free external air protection to prevent particles polluting the surface of discharge pins. By using an optical microscope, we observed a certain number of particles deposited on the non-protected (exposed pins) and few particles deposited on the protected pins after they operating for 3 weeks. We experimentally studied the long-term performances of the exposed and protected pins in single-pass PM removal efficiency and ozone production. The results showed that the protected pins produce less ozone and have higher breakdown voltage than the exposed pins. Experimental results indicated that the improved pin-to-plate corona discharger has better long-term performance and is safer than the exposed one. The results of the research can give an understanding of how to improve electrostatic-based purification technologies toward stable discharging for high removal efficiency of particles. High concentration particulate matter (PM) has been a serious environmental problem in China and other developing countries. Electrostatic-based purification technology is a method to remove airborne particles, and can reduce the energy consumption of ventilation fans in buildings because of its low pressure drop. In this study, we developed a new pin-to-plate corona discharger with particle-free external air protection to prevent particles polluting the surface of discharge pins. By using an optical microscope, we observed a certain number of particles deposited on the non-protected (exposed pins) and few particles deposited on the protected pins after they operating for 3 weeks. We experimentally studied the long-term performances of the exposed and protected pins in single-pass PM removal efficiency and ozone production. The results showed that the protected pins produce less ozone and have higher breakdown voltage than the exposed pins. Experimental results indicated that the improved pin-to-plate corona discharger has better long-term performance and is safer than the exposed one. The results of the research can give an understanding of how to improve electrostatic-based purification technologies toward stable discharging for high removal efficiency of particles.

The amount of heat load in open-plan offices has a significant impact on room air distribution, which in return can also influence occupants’ productivity. The aim of this study is to investigate the impact of different thermal heat loads on air velocities, colliding effects, and room air circulation patterns. The full-scale laboratory experiments were conducted in a 4.2 m * 4 m * 2.8 m (L × W × H) thermal isolated room. The heat sources of 300 W and 600 W were placed in the occupied region to observe changes in air velocity at 1.1m fixed heights. The average air velocities were increased up to 30% by doubling up the heat loads. The smoke tests and CFD results through vertical and horizontal profiles showed that colliding effect is minimized with an increase of heat loads, but large air circulation patterns (vortexes) are formed in locations of the colliding of jets, near the heat sources and the floor.

This article provides a state-of-the-art review on emerging applications of smart tools such as data analytics and smart technologies such as Internet-of-things (IoT) in case of design, management and control of energy storage systems. In particular, we have established a classification of the types and targets of various predictive analytics for estimation of load, energy prices, renewable energy inputs, state of the charge, fault diagnosis, etc. In addition, the applications of information technologies, in particular, use of cloud, IoT systems, building management systems (BMS) and building information modeling (BIM) and their contributions tomanagement of energy storage systems will be reviewed in details. The paper concludes by highlighting the emerging issues in smart energy storage systems and providing directions for future research. This article provides a state-of-the-art review on emerging applications of smart tools such as data analytics and smart technologies such as internet-of-things in case of design, management and control of energy storage systems. In particular, we have established a classification of the types and targets of various predictive analytics for estimation of load, energy prices, renewable energy inputs, state of the charge, fault diagnosis, etc. In addition, the applications of information technologies, and in particular, use of cloud, internet-of-things, building management systems and building information modeling and their contributions to management of energy storage systems will be reviewed in details. The paper concludes by highlighting the emerging issues in smart energy storage systems and providing directions for future research.

Urban Building Energy Simulation (UBES) is an efficient tool to investigate and subsequently reduce energy demand of urban areas. Nevertheless, UBES has always been a challenging task due the trade-off between accuracy, computational speed and parametrization. In order to reduce these computation and parameterization requirements, model reduction and simplification methods aim at representing building behaviour with an acceptable accuracy, but using less equations and input parameters. This paper presents the development and validation results of a simplified urban simulation model based on the ISO 13790 Standard and written in the Modelica language. The model describes the thermo-physical behaviour of buildings by means of an equivalent electric network consisting of five resistances and one capacitance. The validation of the model was carried out using four cases of the ANSI/ASHRAE Standard 140. In general, the model shows good accuracy and the validation provided values within the acceptable ranges.

Air filtration is of vital importance for creating healthy breathing indoor air. Particle filters can cause relatively high air resistance and large energy consumption in building ventilation systems. Electrostatically assisted metal foam (EAMF) filters have been developed to provide relatively high efficiency with low air resistance. This study reported a method of fast fabricating cross-linked PVDF nanofibers inside nickel foams by air-drawn electrospinning. The improved EAMF-PVDF filter is flameproof, which provides high security in practices. The new filter increases the absolute efficiency for PM0.3-0.5 (particulate matter between 0.3 and 0.5 μm in aerodynamic diameter) of the bare EAMF filter by 15% and keeps an average efficiency of 83.1% for 28-day filtering outdoor air at the filtering velocity of 1 m/s. Besides, the daily efficiency fluctuation of EAMF filter shrank from 27.3% to 3.4% after adding nanofibers. The fabricated nanofibers can be cleaned off by burning when reaching the life span, and then a repeated fast fabrication can regenerate the high efficiency. This work provides a new route to combining electrostatic stable polymer nanofibers with flameproof metal foam for fabricating air filters with high efficiency, low air resistance and fire resistance.

Buildings in cities are one of the major contributors of carbon emissions worldwide. Thus improving building energy efficiency is one of the key strategies towards sustainable urbanization. Urban building energy modeling (UBEM) is a valuable methodology to tackle these challenges, as it provides users with the energy demand of the building stock, scenarios evaluation, peak loads and other useful analyses. This paper presents an open-source tool to automatically convert 3D building models into ready-to-run Modelica models for urban energy simulations. The software enables users to create 3D building geometries, perform data enrichment and execute model generation of ready-to-run reduced order Modelica models. The software is written in Python and it has been developed as an add-on for the 3D creation application Blender. The first part of the paper describes the general approach and the architecture of the tool. In the second part, a demonstration of the tool’s capabilities is illustrated.

Ventilation systems are the primary way of eliminating airborne pathogenic particles in an operating room (OR). However, such systems can be complex due to factors such as different surgical instruments, diverse room sizes, various staff counts, types of clothing used, different surgical types and duration, medications, and patient conditions. OR ventilation should provide a thermally comfortable environment for the surgical staff team members while preventing the patient from suffering from any extreme hypothermia. Many technical, logistical, and ethical implications need to be considered in the early stage of designing a ventilation system for an OR. Years of research and a significant number of publications have highlighted the controversy and disagreement among infection specialists, design engineers, and ventilation experts in this context. This review article aims to provide a good understanding of OR ventilation systems in the context of air quality and infection control from existing research and provide multidimensional insights for appropriate design and operation of the OR. To this end, we have conducted a systematic review of the literature, covering 253 articles in this context. Systematic review and meta-analyses were used to map the evidence and identify research gaps in the existing clinical, practical, and engineering knowledge. The present study is categorized into six research focuses: ventilation system, thermal comfort, staff work practice and obstacles, door operation and passage, air cleaning technology, emission rate, and clothing systems. In the conclusion, we summarize the key limitations of the existing studies and insights for future research direction.

Background: As an important inflammatory marker, study of C-reactive protein (CRP) changes over time may lead to better identification of risk factors of cardiovascular disease. We evaluated the relationship between CRP changes and lifestyle, metabolic syndrome (MS) and body mass index (BMI) in middle-aged women and explored potential bias from attrition. Materials and Methods: We studied 1234 participants in the Isfahan cohort study – a longitudinal population-based study of adults older than 35 years living in urban and rural areas of three counties in central Iran. Data were collected every 6 years since 2001 (3 points). Random effects model was used to evaluate the effects of behavioural risk factors and MS on CRP, with pattern mixture model to account for cohort attrition. Results: Mean CRP levels decreased over time (Est = −0.066, P < 0.001). MS (Est = −0.195, P < 0.001), BMI (Est = 0.022, P < 0.001), physical activity (Est = −0.009, P = 0.002) and history of smoking (Est = −0.399, P = 0.002) were independently associated with increases in CRP. Pattern mixture model showed that CRP decreased in participants with monotone measurement (Est = −0.032, P < 0.001), as well as intermittent measurement (Est = −0.022, P < 0.001), with no association in participants who responded at all points (Est = −0.015, P = 0.083). Conclusion: In this study, the rate of changes in CRP level in middle-aged women over time was higher in participants who were irregularly measured than those who measured continuously. MS, BMI and physical activity may be related to the CRP changes over time in middle-aged women.

BackgroundWe conducted this systematic review to identify factors associated with coronavirus disease (COVID-19) susceptibility and outcomes among people with multiple sclerosis (MS).MethodsAvailable studies from PubMed, Scopus, EMBASE, Web of Science, and gray literature including reference list and conference abstracts were searched from December 1, 2019, through April 12, 2021. We included cross-sectional, case-control, and cohort studies that reported risk factors of contracting COVID-19 or its outcome in patients with MS on univariate or multivariate regression analyses.ResultsOut of the initial 2719 records and 1553 conference abstracts, a total of 20 studies were included. Factors associated with COVID-19 susceptibility were reported in 11 studies and risk factors for infection outcomes were discussed in 10. History of contact with an infected is strongly suggested as a risk factor for COVID-19 susceptibility. Other factors that could be associated with contracting infection are younger age, relapsing course, and anti-CD20 agents. The evidence suggests that increasing age, greater MS severity, treatment with anti-CD20 agents, previous use of corticosteroids, and specific comorbidities (obesity and coronary artery disease) could be independently associated with worse infection outcomes. Male sex is likely to be a risk factor for more severe disease. The black or African American race was reported as a possible risk factor.ConclusionDue to a paucity of research and methodological issues, no risk factors for COVID-19 susceptibility and outcomes neither be confirmed nor excluded. Further large studies are needed to address factors associated with COVID-19 susceptibility and severity.

Nanofibre filters may offer new properties not available in commercial fibre filters. These include a higher surface area and the ability to include novel materials within the fibres. In addition the small size allows potential gains in performance due to the slip-flow phenomenon in which normal gas viscosity does not apply to objects smaller than the mean free path of the gas. We tested the properties of novel electrospun fibre filters generated from polyvinyl alcohol solutions, optionally embedded with nano-grains of photocatalytic TiO2 and activated charcoal. The tested materials exhibited pressure drops in the range of 195 Pa to 2693 Pa for a face velocity of 5.3 cm/s and a removal efficiency greater than 97% for 12–480 nm particles. Basis weights for the filters ranged from 16.6 to 67.6 g/m2 and specific surface areas ranged from 1.4 to 17.4 m2/g. Reactivity towards volatile organic compounds (VOCs) was achieved by irradiating the photocatalytic filters with ultraviolet light. It is necessary to solve the problems connected to the absorbance of VOCs and further reduce the resistance to airflow in order for these filters to achieve widespread use. The incorporation of reactive air filtration into building ventilation systems will contribute to improved indoor air quality.