Fiber-based masks and respirators: using decontamination methods and antimicrobial treatment to improve its reusability during pandemic

Shortage of personal protective equipment (PPE) is often projected in response to public health emergencies such as infection outbreaks and pandemics. Respiratory protective devices (RPDs), namely medical face masks and respirators, are considered the last defense for the front-line healthcare workers. Cleaning, decontamination and reuse of the disposable RPDs have been accepted by local health authorities during the pandemic period. To contribute to the mitigation of RPD shortage and ensure the safe adoption of decontamination protocols, this review discusses the regulated testing standards and the most commonly studied decontamination methods in the literature. The reuse of RPDs must fulfill three criteria: remove the microbial thread, maintain original function and structural integrity (including fitting tests) and leave no harmful residuals. Decontamination methods such as ultraviolet germicidal irradiation, moist heat and vaporized hydrogen peroxide appeared to be the most promising methods in balancing the above-mentioned criteria. However, the effectiveness of decontamination methods varies depending on the RPDs’ models, materials and design. Therefore, the adoption of protocols needs to be evidence-based with full validation in the local institutes. Additionally, new technology such as antimicrobial treated PPE that can reduce the risks of fomite during donning and doffing process with an extended lifespan should be encouraged. Overall, good training and guidance for appropriate reuse of RPDs are fundamental to ensure their efficiency in protecting front-line healthcare workers.This work was funded by the R&D project of EXMA company in co-promotion with the University of Minho NORTE-01-02B7-FEDER-048968 supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), by the UV-Fast project funded by the Portuguese Science and Technology Foundation (FCT—Fundação para a Ciência e Tecnologia) through UID/CTM/00264/2021 and the Research4COVID-19 special fund (Project 011_595803006), and PLASMAMED project (ref. PTDC/CTM-TEX/28295/2017) co-financed by COMPETE2020, under Portugal 2020 through the ERDF and FCT, and by the Qingdao Postdoctoral Application Project

Antibacterial hydrogel dressings and their applications in wound treatment

Antimicrobial hydrogels, both in semi-stiff sheets and amorphous form, have been extensively studied for wound management mainly owing to their high-water content, lower wound adherence, promoted autolysis debridement, epithelial migration, and granulation growth. Benefiting from the recent advances in materials science, biotechnology, and a growing understanding of wound microbiology, an extensive variety of antimicrobial hydrogels have been developed. These novel antimicrobial hydrogels can prevent and control microbial infection. In addition, they possess wound healing functions for improved wound management. This chapter will provide a comprehensive summary of the current studied antimicrobial hydrogels in literature and available hydrogel dressings in the market, including their design, fabrication method, and wound management efficacy in vitro or in vivo. The detailed and critical discussion of the advantages and disadvantages of each type of hydrogel dressing will provide insights into the future design of antimicrobial hydrogels for better management of wounds in clinical application

Chapter 34 - Biocompatibility of nanocellulose: Emerging biomedical applications

Nanocellulose already proved to be a highly relevant material for biomedical applications, ensued by its outstanding mechanical properties and, more importantly, its biocompatibility. Nevertheless, despite their previous intensive research, a notable number of emerging applications are still being developed. Interestingly, this drive is not solely based on the nanocellulose features, but also heavily dependent on sustainability. The three core nanocelluloses encompass cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BNC). All these different types of nanocellulose display highly interesting biomedical properties per se, after modification and when used in composite formulations. Novel applications that use nanocellulose includewell-known areas, namely, wound dressings, implants, indwelling medical devices, scaffolds, and novel printed scaffolds. Their cytotoxicity and biocompatibility using recent methodologies are thoroughly analyzed to reinforce their near future applicability. By analyzing the pristine core nanocellulose, none display cytotoxicity. However, CNF has the highest potential to fail long-term biocompatibility since it tends to trigger inflammation. On the other hand, neverdried BNC displays a remarkable biocompatibility. Despite this, all nanocelluloses clearly represent a flag bearer of future superior biomaterials, being elite materials in the urgent replacement of our petrochemical dependence

Fiber-Based Masks and Respirators: Using Decontamination Methods and Antimicrobial Treatment to Improve Its Reusability during Pandemic

Shortage of personal protective equipment (PPE) is often projected in response to public health emergencies such as infection outbreaks and pandemics. Respiratory protective devices (RPDs), namely medical face masks and respirators, are considered the last defense for the front-line healthcare workers. Cleaning, decontamination and reuse of the disposable RPDs have been accepted by local health authorities during the pandemic period. To contribute to the mitigation of RPD shortage and ensure the safe adoption of decontamination protocols, this review discusses the regulated testing standards and the most commonly studied decontamination methods in the literature. The reuse of RPDs must fulfill three criteria: remove the microbial thread, maintain original function and structural integrity (including fitting tests) and leave no harmful residuals. Decontamination methods such as ultraviolet germicidal irradiation, moist heat and vaporized hydrogen peroxide appeared to be the most promising methods in balancing the above-mentioned criteria. However, the effectiveness of decontamination methods varies depending on the RPDs’ models, materials and design. Therefore, the adoption of protocols needs to be evidence-based with full validation in the local institutes. Additionally, new technology such as antimicrobial treated PPE that can reduce the risks of fomite during donning and doffing process with an extended lifespan should be encouraged. Overall, good training and guidance for appropriate reuse of RPDs are fundamental to ensure their efficiency in protecting front-line healthcare workers

Fiber-Based Masks and Respirators: Using Decontamination Methods and Antimicrobial Treatment to Improve Its Reusability during Pandemic

Shortage of personal protective equipment (PPE) is often projected in response to public health emergencies such as infection outbreaks and pandemics. Respiratory protective devices (RPDs), namely medical face masks and respirators, are considered the last defense for the front-line healthcare workers. Cleaning, decontamination and reuse of the disposable RPDs have been accepted by local health authorities during the pandemic period. To contribute to the mitigation of RPD shortage and ensure the safe adoption of decontamination protocols, this review discusses the regulated testing standards and the most commonly studied decontamination methods in the literature. The reuse of RPDs must fulfill three criteria: remove the microbial thread, maintain original function and structural integrity (including fitting tests) and leave no harmful residuals. Decontamination methods such as ultraviolet germicidal irradiation, moist heat and vaporized hydrogen peroxide appeared to be the most promising methods in balancing the above-mentioned criteria. However, the effectiveness of decontamination methods varies depending on the RPDs’ models, materials and design. Therefore, the adoption of protocols needs to be evidence-based with full validation in the local institutes. Additionally, new technology such as antimicrobial treated PPE that can reduce the risks of fomite during donning and doffing process with an extended lifespan should be encouraged. Overall, good training and guidance for appropriate reuse of RPDs are fundamental to ensure their efficiency in protecting front-line healthcare workers

Preparation and absorbing properties of Fe/Fe3C/Fe3O4@C magnetic microspheres

Thinness, lightness, width, strength are people's pursuit of efficient electromagnetic wave (EMW) absorption materials. Fe/Fe3C/Fe3O4@C magnetic microspheres were prepared by high temperature calcination of food-grade ferric citrate and source through hydrothermal reaction. By changing the molar ratio of ferric citrate and sucrose, the influence of the content of ferric citrate on the EMW absorption performance of the composite was investigated, and the electromagnetic parameters were effectively controlled to optimize impedance matching. The experimental results show that when the molar ratio of iron citrate and sucrose is 5:3, it has better EMW absorption performance: when the thickness is 2.5 mm, the minimum reflection loss (RL) is -50.17 dB, and the effective absorption band width less than -10 dB is 3.52 GHz. The excellent EMW performance is mainly due to the synergistic effect of the rich interface, porous structure and magnetic properties of Fe/Fe3C/Fe3O4

The tesseract in two dimensional materials, a DFT approach

A series of novel two-dimensional materials inspired from a 4D polytope, tesseract, have been proposed by density functional theory (DFT) based computations. Both C24X12 and C16X16 (X = O, S and Se) are found to have great thermodynamic and dynamic stabilities, and C24X12 exhibited excellent thermal stability up to 1000 K. All these 2D crystals are semiconductors with 2.17 eV to 3.35 eV band gaps at the HSE06 theoretical level, except for C24S12 (4.14 eV energy gap). Moreover, the intrinsic pore sizes of C24Se12 are suitable to sieve He from the He/CH4 mixture, with over 80% separation ratio and nearly 100% selectivity. Our findings not only enlarged the boundary of the 2D family, but also offered another potential method to recover helium from natural gas at ambient conditions

A novel long-lasting antifouling membrane modified with bifunctional capsaicin-mimic moieties via in situ polymerization for efficient water purification

Capsaicin-mimic materials are promising candidates for antifouling membrane fabrication. However, the membrane fabrication is usually complicated and the long-term operation of the resulting membrane is unstable. In this work, we developed an "in situ polymerization-blending" technique to prepare capsaicin-containing polysulfone membranes. This facile one-pot synthesis applied a capsaicin derivative containing two carbon-carbon double bonds (N-(2-hydroxyl-3-methyl acrylamide-4,6-dimethyl benzyl) acrylamide, (HMDA)). The presence of carbon-carbon double bonds enabled the self-polymerization of HMDA, leading to stable anchoring of the capsaicin derivative on the membrane. The composite membrane exhibited higher pure water permeability (up to 3124.7 L m h MPa, over two times higher than that of the pure membrane) without compromising the humic acid rejection efficiency. In addition, the composite membranes also exhibited significantly improved resistance to organic fouling (humic acid) and bacteria (E. coli)/algae (Prorocentrum donghaiense) growth. The presence of unreacted carbon-carbon double bonds on HMDA also allowed gradual polymerization when exposed chronically to air or water environments, which ensured good operational stability over 2 months. The novel membrane fabrication technique in this work offers significant opportunities to exploit the unique properties of capsaicin derivatives in the fabrication of various separation membranes

Short-Term Phytoplankton Dynamics During Typhoon Season in and Near the Pearl River Estuary, South China Sea

The effect on phytoplankton dynamics of nutrient inputs from rivers within the highly eutrophic Pearl River Estuary (PRE) in China is well understood. However, the role that typhoons play in enhancing or reducing phytoplankton blooms is less well known. The primary factors controlling phytoplankton dynamics in the PRE in June-July 2009 were determined by coupling satellite remote sensing data with field observations during two successive typhoons: Nangka and Soudelor. The results revealed that the magnitude of chlorophyll a concentration (Chl) near the PRE was controlled by several key factors. (1) Vertical mixing of seawater induced by Typhoons Nangka and Soudelor led to a sudden decrease in Chl and phytoplankton abundance near the PRE, especially in picophytoplankton. (2) Following the typhoon events, increased nutrient availability associated with significant freshwater runoff promoted phytoplankton (especially Synechococcus) growth, recovery, and blooms in and near the PRE. (3) Increased freshwater input or easterly winds enhanced the extension of highly abundant phytoplankton with brackish water from the estuary into the adjacent nearshore water. (4) Phycocyanin-rich Synechococcus was endemic and a dominant picophytoplankton group in the estuarial brackish water. We propose a mechanism that describes the interactions of vertical mixing, terrestrial precipitation, freshwater discharge, nutrient inputs, and winds on short-term phytoplankton dynamics in and near the PRE during typhoon season

Flexibly and Securely Shape Your Data Disclosed to Others

This work is to enhance existing fine-grained access control to support a more expressive access policy over arithmetic operation results. We aim to enable data owners to flexibly bind a user\u27s identity with his/her authorized access target according to a given access control policy, which indicates how a piece of data obfuscated by different noises. To this end, we design a cryptographic primitive that decouples the noisy data to two components, one associated with user identity, and the other one shared and dynamically changes, with the composite of these two components evaluated and revealed at user sides. The security of our scheme is formally proven using game based approach. We implement our system on a commercial cloud platform and use extensive experiments to validate its functionality and performance