Covalent organic frameworks and metal-organic frameworks against pathogenic viruses and antibiotic-resistant bacteria: Diagnostic and therapeutic applications

Antimicrobial resistance and antiviral infections statistics show that the number of global cases has been exponentially increasing;thus there is an unmet need for developing alternatives rather than to continue conventional strategies such as antibiotic administration, since they failed to show promise especially during the past few decades. Among different porous materials, metal-organic frameworks (MOFs) are a class of porous coordination polymers broadly explored in nano- and biomedicine due to their desirable properties, including excellent surface area, structural variability, the richness of their crystal structures/architectures, allowing for engineering synergies between metal nodes, functional linkers, encapsulated substrates or nanoparticles, heterogeneous catalysis, ion exchange, controlled and targeted drug delivery, energetics, etc. MOF-based sensing platforms have shown suitable potentials for specific viral detection. Covalent organic frameworks (COFs) are porous crystalline organic materials with two- or three-dimensional structures, which can be employed for reducing the interaction between the spike protein of SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) in addition to other inhibitory effects. These frameworks can be applied for encapsulating antibiotics or antiviral agents against pathogens;they have been also studied for photodynamic inactivation of pathogenic bacteria. Herein, the most recent advancements pertaining to the applications of these frameworks for specific detection and inhibition of pathogenic viruses and antibiotic-resistant bacteria are cogitated, focusing on important challenges and perspectives. This review also provides expert recommendations on the future development and utility of these frameworks to manage antimicrobial resistance and infectious diseases more efficiently. © 2023 Elsevier Ltd

Influence of surface finishing of hardwood cross-section on sound absorption performance

This study aimed to evaluate the sound absorption performance depending on surface finishing of the hardwood cross-section. The sound absorption performance of wood cross-sections was evaluated after band saw cutting, sandpaper polishing, and staining. The sound absorption performance was best following the band saw cutting and no other treatment. On the other hand, stain blocked the pores and decreased the sound absorption performance. This study suggests that finishing methods that preserve the integrity of vessels need to be considered when using wood as a sound-absorbing material.

A green strategy to recycle the waste PP melt-blown materials: From 2D to 3D construction.

The demand for polypropylene (PP) melt-blown materials has dramatically increased due to the COVID-19 pandemic. It has caused serious environmental problems because of the lack of effective treatment for the waste PP melt-blown materials. In this study, we propose a green and sustainable recycling method to create PP sponges from waste PP melt-blown material for oil spill cleaning by freeze-drying and thermal treatment techniques. The recycling method is simple and without secondary pollution to the environment. The developed recycling method successfully transforms 2D laminar dispersed PP microfibers into elastic sponges with a 3D porous structure, providing the material with good mechanical properties and promotes its potential application in the field of oil spill cleaning. The morphology structure, thermal properties, mechanical properties, and oil absorption properties are tested and characterized. The PP sponges with a three-dimensional porous network structure show an exceedingly low density of >0.014 g/cm3, a high porosity of <98.77 %, and a high water contact angle range of 130.4-139.9°. Moreover, the PP sponges own a good absorption capacity of <47.61 g/g for different oil and solvents. In particular, the compressive modulus of the PP sponges is 33.59-201.21 kPa, which is higher than that of most other fiber-based porous materials, indicating that the PP sponges have better durability under the same force. The excellent comprehensive performance of the PP sponges demonstrates the method developed in this study has large application potential in the field of the recycle of waste PP melt-blown materials.

Surface Coating of Needle-Punched Nonwovens with Meltblown Nonwovens to Improve Acoustic Properties

Unlike the term sound insulation, which means reducing the penetration of noise into other areas, sound absorption means reducing the reflection and energy of the sound on the surface. It has become a highly noticed issue in recent years because the noise in our daily life is increasing day by day, and it causes some health and comfort disorders. In many areas, textiles have been used for acoustics control and noise absorption purposes. The purpose of this work is to determine the most effective media for sound absorption performance and its relation to thermal conductivity from needle-punched nonwoven, meltblown nonwoven and hybrid forms in different arrangements of these fabrics. To provide comparable samples, both needle-punched nonwoven and meltblown nonwoven samples were produced from 100% Polypropylene fibres. According to sound absorption tests, the hybrid-structured sample having a composition similar to the needle-punched nonwoven sample placed at the bottom of our study, while the meltblown nonwoven sample placed as a face layer outperformed the rest of the samples in terms of sound absorption and thermal conductivity. ‘Meltblown only’ samples had remarkably higher sound absorption efficiency than most of the samples, while the ‘needle-punched nonwoven only’ sample had the lowest sound absorption efficiency in all frequencies.

Hydrophobic RuO2/Graphene/N-doped porous carbon hybrid catalyst for Li-air batteries operating in ambient air

Li–air batteries have received significant attention for their ultrahigh theoretical energy density. However, the byproducts induced by attacking air hinder the conversion of Li–O2 batteries to Li–air batteries. Humidity is one of the main obstacles, not only causing side reactions with the discharge products but also leading to rapid corrosion of the lithium anode. Here, we fabricated a novel composite hydrophobic catalyst by loading RuO2 and graphene on N-doped porous carbon. The catalyst was endowed with hydrophobicity and showed superior catalytic performance and low affinity to water in the air. A Li–air battery equipped with this novel composite catalyst exhibited eminent cycling performance in pure oxygen (over 470 h), humid oxygen [∼40% relative humidity (RH), over 310 h], and ambient air (∼42% RH, over 330 h) at a current density of 500 mA g−1, and the discharge specific capacity increased from 13122.1 to 19358.6 mAh g−1. © 2022

Hygienic Design of HVAC Systems for Hospitals

Hygienic design of the Air Handling Unit (AHU), the custom-designed industrial HVAC system used in hospitals, laboratories, and similar sterile areas to supply clean, filtered, and conditioned air, has become more prevalent during the covid-19 pandemic. Improper maintenance of the air handling system can carry germs or viruses at any stage. This study concentrates explicitly on Air Handling Units used in hospitals, which should maintain higher quality standards than conventional air handling systems to reduce all kinds of dirt, debris, mold, and bacteria from the system. Throughout the paper, the critical parameters and control points of the air handling units for hospitals are analyzed from a hygienic viewpoint, and the existing hygienic design standards are explained through an implemented case study.

Considerations Using Additive Manufacture of Emulsion Inks to Produce Respiratory Protective Filters Against Viral Respiratory Tract Infections Such as the COVID-19 Virus

This review paper explores the potential of combining emulsion-based inks with additive manufacturing (AM) to produce filters for respiratory protective equipment (RPE) in the fight against viral and bacterial infections of the respiratory tract. The value of these filters has been highlighted by the current severe acute respiratory syndrome coronavirus-2 crisis where the importance of protective equipment for health care workers cannot be overstated. Three-dimensional (3D) printing of emulsions is an emerging technology built on a well-established field of emulsion templating to produce porous materials such as polymerized high internal phase emulsions (polyHIPEs). PolyHIPE-based porous polymers have tailorable porosity from the submicron to 100 s of μm. Advances in 3D printing technology enables the control of the bulk shape while a micron porosity is controlled independently by the emulsion-based ink. Herein, we present an overview of the current polyHIPE-based filter applications. Then, we discuss the current use of emulsion templating combined with stereolithography and extrusion-based AM technologies. The benefits and limitation of various AM techniques are discussed, as well as considerations for a scalable manufacture of a polyHIPE-based RPE.

The Diffusion Behavior of CO2 Adsorption from a CO2/N2 Gas Mixture on Zeolite 5A in a Fixed-Bed Column

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.

Modeling and simulation of the potential indoor airborne transmission of SARS-CoV-2 virus through respiratory droplets

Respiratory viruses are transported from an infected person to other neighboring people through respiratory droplets. These small droplets are easily advected by air currents in a room and can potentially infect others. In this work, the spread of droplets released during coughing, talking, and normal breathing is numerically analyzed in a typical conference room setting. The room space is occupied by ten people, with eight people sitting around a conference table and two people standing. Four different scenarios are considered, with the air-conditioning turned on/off and people wearing/not-wearing masks, to understand the spread of respiratory droplets inside the room. The flow in the room is simulated using a multiphase mixture model with properties computed for the inhaled and exhaled air using fundamental gas relations. The transport of respiratory droplets is analyzed using the discrete phase model with a range of droplet sizes fitted to data from previous experimental studies. The mask is modeled as porous media with the properties of a woven fabric computed using a newly developed model for multilayered homemade masks. The human inhalation and exhalation are modeled using analytical functions to mimic the biological flow patterns during breathing, coughing, and talking. Important observations about the air flow and dispersion of respiratory droplets in the conference room are presented based on the numerical analysis. Animations of all the results are included to provide insight into flow physics of the various dynamic conditions occurring in the room during an ongoing meeting. Although this study is conducted for a typical conference room, the newly developed models and techniques can be applied to other confined environments. © 2022 Author(s).

Emerging Biomedical and Industrial Applications of Nanoporous Materials

Nanoporous materials is a fast-growing subset of nanomaterials with unique intrinsic properties. The advances in fabrication and characterization techniques have enabled scientists to tailor the properties and design a wide range of application specific nanoporous materials. This chapter highlights the key technological advancements that nanoporous materials have achieved in the frontiers of biomedical engineering across analyses, diagnostics and therapeutics. It draws attention to progressive studies like the membrane based organ-on-a-chip (OOC) models of the blood brain barrier and human alveolar that contributed to the advancements in the drug development studies of neurological diseases and COVID-19 to neurochemical biosensing and artificial portable kidneys (Fan et al., ACS Nano 13:8374–8381, 2019;Wang et al., Biotechnol. Bioeng. 114:184–194, 2017;Zhang et al., Adv. Sci. 8:1–14, 2021;Zhou et al., Anal. Chem. 91:3645–3651, 2019). A brief account of the versatile industrial applications of nanoporous materials in chromatography, nanoreactors, energy storage and cutting-edge concepts like nanosized photonic data storage is also illustrated with representative cases. © 2022, Springer Nature Switzerland AG.

Numerical analysis of the efficiency of face masks for preventing droplet airborne infections

In this study, the flow field around face masks was visualized and evaluated using computational fluid dynamics. The protective efficiency of face masks suppressing droplet infection owing to differences in the shape, medium, and doubling usage is predicted. Under the ongoing COVID-19 pandemic condition, many studies have been conducted to highlight that airborne transmission is the possible transmission route. However, the virus infection prevention effect of face masks has not been sufficiently discussed and, thus, remains as a controversial issue. Therefore, we aimed to provide a beneficial index for the society. The topology-free immersed boundary method, which is advantageous for complex shapes, was used to model the flow in the constriction area, including the contact surface between the face and mask. The jet formed from the oral cavity flow out through the surface of the mask and leaks from the gap between the face and mask. A Darcy-type model of porous media was used to model the flow resistance of masks. A random variable stochastic model was used to measure particle transmittance. We evaluated the differences in the amount of leakage and deposition of the droplets during exhalation and inhalation, depending on the differences in the conditions between the surgical and cloth masks owing to coughing and breathing. The obtained results could be useful for epidemiological measures by numerically showing the particle suppression effect of the face mask. This includes both exhalation and inhalation. © 2022 Author(s).

Prediction of Wall and Indoor Hygrothermal Properties of Rammed Earth Folk House in Northwest Sichuan

The climate crisis is one of the most important problems today. In the process of human building, the use of cement, steel, and other industrial materials in the process of building construction and recycling has brought a huge burden to the natural environment. Earth is one of the oldest building materials, its availability and insulation make it an excellent constructive solution in human history. Among several existing earth construction techniques, rammed earth is one of the most relevant. In this paper, a numerical model of the rammed earth folk house in Mianyang was established, and an experimental device was built to verify it. With the typical meteorological year data of Mianyang in northwest Sichuan, the heat and moisture transfer in rammed earth wall, as well as the indoor thermal and moisture environment were numerically simulated. The results show that the rammed earth wall weakens the temperature fluctuation of the inner surface of the wall and makes the peak temperature of the inner surface of the wall lag the outer surface. The relative humidity in the center of the rammed earth wall can be maintained at about 60%, both in winter and summer. The moisture absorption and desorption capacity of rammed earth walls without inner decorative materials is about three times that of gypsum board, and the use of a waterproof coating will render the rammed earth wall almost unable to adjust the indoor relative humidity. Additionally, the use of decorative materials will increase the fluctuation range of indoor relative humidity and the risk of mold breeding.

Current Practice and Potential Associated with Timber-Based Solutions for Buildings Retrofitting

Current buildings are responsible for the highest energy consumption, exceeding polluting sectors such as industry and transports. In Portugal, a large part of the building stock was built in the 1970s and 1980s, but buildings dated from the 1960s and 1970s are the ones with the most anomalies and worst quality of construction and, therefore, worst energy performance. The renovation of those buildings can represent an excellent opportunity to correct and improve their energy deficiency and, with that, to promote a more sustainable building stock. The ETICS system is the most used for the renovation of buildings in Portugal due to its lower cost, quick application and thermal efficiency, but it doesn’t solve other problems that may exist, such as structural safety and interior organization of the existing building. The application of prefabricated systems in the envelope has proved to be successful in improving energy efficiency, allowing new volumes and extra areas while contributing to the structural resilience of existing buildings. This paper aims to describe the current situation of the buildings renovation in Portugal and to discuss the potential of innovative envelope retrofitting solutions, using natural materials like timber, and is more concerned with the problems of existing buildings and the need for comfort and space for the occupants.

Automatic Hand Sanitizing Glove

The sudden change in the daily routine caused by the impact of Covid-19 has been given a new name called 'The New Normal'. This new normal has affected many lives in various ways. Usage of mask has become one among the other usual thing which we do as in our daily part of life. The mask helps in reducing the spread to a certain level, but it can never completely stop the spread. We must follow various measure to break the chain of virus. Only usage of mask or social distancing will not help to control the spread. The proposed automatic hand sanitizing glove will be one of the best ways to stop the spread. As most of the virus transmission takes place through hand, we are proposing an automatic hand sanitizing glove. The automatic hand sanitizing glove consists of a dc motor which could pump the sanitizer all over the outer surface of glove which is made of porous material. This glove is made of a quick dry material hence it won't remain wet for long period of time. This pumps continuously in regular intervals of time. In this way, we can sanitize our hands without applying sanitizer directly on our skin. The comprehensive study regarding the glove is discussed in the following headings. © 2021 IEEE.

Facile preparation of antibacterial MOF‐fabric systems for functional protective wearables

Metal‐organic frameworks (MOFs) have shown numerous potentials as promising materials to address real‐world problems. However, their practical utilization in commercial products was largely limited by the lack of downstream processing methodologies to transform MOF powders into functional products. In this study, a commercially viable solution for the general synthesis of MOF‐fabric composites was introduced. On account of coordination bonding between poly(acrylic acid) and MOF substrates, MOF powders securely adhered onto the surface of fabric materials via a drip cast method to give MOF‐fabric composites easily. This strategy can be applied to different MOF types, as well as a wide variety of fabric materials. The prepared materials showed excellent bacterial killing efficacy attributed to the embedded HKUST‐1 MOF. In light of the recent coronavirus disease 2019 pandemic, this methodology could enable the large‐scale fabrication of essential MOF‐based personal protective wearables (e.g., clothing and masks) for use by healthcare professionals.

Transforming Plastic Waste into Porous Carbon for Capturing Carbon Dioxide: A Review

Plastic waste generation has increased dramatically every day. Indiscriminate disposal of plastic wastes can lead to several negative impacts on the environment, such as a significant increase in greenhouse gas emissions and water pollution. Therefore, it is wise to think of other alternatives to reduce plastic wastes without affecting the environment, including converting them into valuable products using effective methods such as pyrolysis. Products from the pyrolysis process encompassing of liquid, gas, and solid residues (char) can be turned into beneficial products, as the liquid product can be used as a commercial fuel and char can function as an excellent adsorbent. The char produced from plastic wastes could be modified to enhance carbon dioxide (CO2) adsorption performance. Therefore, this review attempts to compile relevant knowledge on the potential of adsorbents derived from waste plastic to capture CO2. This review was performed in accordance with PRISMA guidelines. The plastic-waste-derived activated carbon, as an adsorbent, could provide a promising method to solve the two environmental issues (CO2 emission and solid management) simultaneously. In addition, the future perspective on char derived from waste plastics is highlighted.

Studies on the CO2 Capture by Coal Fly Ash Zeolites: Process Design and Simulation

At present, mitigating carbon emissions from energy production and industrial processes is more relevant than ever to limit climate change. The widespread implementation of carbon capture technologies requires the development of cost-effective and selective adsorbents with high CO2 capture capacity and low thermal recovery. Coal fly ash has been extensively studied as a raw material for the synthesis of low-cost zeolite-like adsorbents for CO2 capture. Laboratory tests for CO2 adsorption onto coal fly ash zeolites (CFAZ) reveal promising results, but detailed computational studies are required to clarify the applicability of these materials as CO2 adsorbents on a pilot and industrial scale. The present study provides results for the validation of a simulation model for the design of adsorption columns for CO2 capture on CFAZ based on the experimental equilibrium and dynamic adsorption on a laboratory scale. The simulations were performed using ProSim DAC dynamic adsorption software to study mass transfer and energy balance in the thermal swing adsorption mode and in the most widely operated adsorption unit configuration.

A review on coronavirus survival on impermeable and porous surfaces

We review recent studies on fomite transmission of COVID-19, caused by the novel coronavirus. In particular, we focus on survival time of coronavirus on solid and porous surfaces. Since the aqueous phase of a respiratory droplet serves as a medium for virus survival, evaporation of the droplet on a surface plays a crucial role in determining the virus survival time. While the bulk of the droplet takes a few seconds to evaporate, previous virus titer measurements revealed that the virus can survive for several hours or days on a surface. This long survival of virus has been attributed to a residual thin-liquid film which remains after drying of the bulk droplet. The evaporation of the thin-film is governed by the disjoining pressure within it and therefore, is a much slower process which causes the virus to survive longer. However, the aforesaid disjoining pressure is significantly modulated for the case of porous surfaces due to their typical geometries. This accelerates the thin-film evaporation on porous surfaces and thereby making them lesser susceptible to virus survival. Therefore, porous materials are deemed to be relatively safer for mitigating the spread of COVID-19 via fomite transmission. Using results of the reported research, we briefly discuss the possible recommendations to mitigate the spread of the disease.

A technical review of face mask wearing in preventing respiratory COVID-19 transmission.

Since the outbreak of the COVID-19 pandemic, most countries have recommended their citizens to adopt social distance, hand hygiene, and face mask wearing. However, wearing face masks has not been well adopted by many citizens. While the reasons are complex, there is a general perception that the evidence to support face mask wearing is lacking, especially for the general public in a community setting. Face mask wearing can block or filter airborne virus-carrying particles through the working of colloid and interface science. This paper assesses current knowledge behind the design and functioning of face masks by reviewing the selection of materials, mask specifications, relevant laboratory tests, and respiratory virus transmission trials, with an overview of future development of reusable masks for the general public. This review highlights the effectiveness of face mask wearing in the prevention of COVID-19 infection.