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.

Two dimensional (2D) MXenes as an emerging class of materials for antimicrobial applications: properties and mechanisms

MXenes have gained significant importance in many applications in the fields of energy, environment and healthcare. The versatile features of MXenes enable them as a wonder material for their wide category of applications. Tunable surface chemistry and nano-dimensional layered features of MXenes are accounted for their improved multifunctional properties among the other two-dimensional materials. Of various applications, MXenes show the relevant properties toward antimicrobial disinfection of bacteria, fungi and viruses including the SARS responsible for COVID-19. Therefore, the development, characterizations and mechanism of MXenes-based materials are important to bring these advanced materials for their real-time antimicrobial applications. In this context, this review presents a glimpse of MXenes in terms of their synthesis processes, characterizations, antimicrobial properties, and elucidate their mechanism of actions toward antibacterial, antifungal and antiviral activities. Finally, it concludes with a future perspective of MXenes towards their biomedical applications.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review.

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

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.

Virus deformation or destruction: size-dependence of antiviral and virucidal activities of gold nanoparticles

Over the last 10 years, the antiviral and antimicrobial activities of non-functionalised inorganic nanoparticles against different pathogens were experimentally shown. This effect has attracted the attention of scientists due to the COVID-19 pandemic;however, its mechanism is still unclear. For understanding the mechanism of nanoparticle’s action, it is important to know how this action depends on the parameters of nanoparticles and the properties of a pathogen. In the work, we have studied the action of gold nanoparticles on the viruses outside and inside the cell and compared this action with two sizes of nanoparticles and two types of viruses. The study has been conducted for adenovirus and H1N1 influenza virus, and gold nanoparticles of 5 nm and 20 nm diameter. Virucidal and antiviral actions were observed experimentally for both sizes of nanoparticles against both viruses. It has also been shown with the electron microscopy that the viruses may be destructed in 2 h after adsorption of 5 nm gold nanoparticles on their surface;and that the viruses may change their shape in 2 h after adsorption of 20 nm nanoparticles on their surface. The model of physical adsorption of nanoparticles on the virus surface due to near-field interaction was used to explain observed results.

Recent Advances in Metal Chalcogenide Quantum Dots: From Material Design to Biomedical Applications

With the rapid progress in nanomaterials and biochemistry, there has been an explosion of interest in biomolecule-modified quantum dots (QDs) for biomedical applications. Metal chalcogenide quantum dots (MCQDs), as the most widely studied QDs, have attracted tremendous attention in the biomedical field on account of their unique and excellent optical properties and the ease of biomolecular modifications. Herein, important advances in MCQDs over recent years are reviewed, from materials design to biomedical applications. Especially, this review focuses on the challenges encountered in the applications of MCQDs in biomedical fields and how these problems can be solved by rational design of synthesis methods and modifications, which have opened a universal route to develop the functionalized MCQDs. Moreover, recent processes in bioimaging, biosensing, and cancer therapy based on MCQDs are examined, including the rapid detection and diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review provides broad insights into MCQDs in the biomedical field and will inspire material researchers to develop MCQDs in the future.

Current Status and Challenges of Analytical Methods for Evaluation of Size and Surface Modification of Nanoparticle-Based Drug Formulations.

The present review discusses the current status and difficulties of the analytical methods used to evaluate size and surface modifications of nanoparticle-based pharmaceutical products (NPs) such as liposomal drugs and new SARS-CoV-2 vaccines. We identified the challenges in the development of methods for (1) measurement of a wide range of solid-state NPs, (2) evaluation of the sizes of polydisperse NPs, and (3) measurement of non-spherical NPs. Although a few methods have been established to analyze surface modifications of NPs, the feasibility of their application to NPs is unknown. The present review also examined the trends in standardization required to validate the size and surface measurements of NPs. It was determined that there is a lack of available reference materials and it is difficult to select appropriate ones for modified NP surface characterization. Research and development are in progress on innovative surface-modified NP-based cancer and gene therapies targeting cells, tissues, and organs. Next-generation nanomedicine should compile studies on the practice and standardization of the measurement methods for NPs to design surface modifications and ensure the quality of NPs.

Preparing and Characterizing Novel Biodegradable Starch/PVA-Based Films with Nano-Sized Zinc-Oxide Particles for Wound-Dressing Applications

Given recent worldwide environmental concerns, biodegradability, antibacterial activity, and healing properties around the wound area are vital features that should be taken into consideration while preparing biomedical materials such as wound dressings. Some of the available wound dressings present some major disadvantages. For example, low water vapor transmission rate (WVTR), inadequate exudates absorption, and the complex and high environmental cost of the disposal/recycling processes represent such drawbacks. In this paper, starch/polyvinyl alcohol (PVA) material with inserted nano-sized zinc-oxide particles (nZnO) (average size ≤ 100 nm) was made and altered using citric acid (CA). Both ensure an efficient antibacterial environment for wound-dressing materials. The film properties were assessed by UV–Vis spectrometry and were validated against the UV light transmission percentage of the starch/ polyvinyl alcohol (PVA)/ zinc-oxide nanoparticles (nZnO) composites. Analyses were conducted using X-ray Spectroscopy (EDX) and scanning electron microscopy (SEM) to investigate the structure and surface morphology of the materials. Moreover, to validate an ideal moisture content around the wound area, which is necessary for an optimum wound-healing process, the water vapor transmission rate of the film was measured. The new starch-based materials exhibited suitable physical and chemical properties, including solubility, gel fraction, fluid absorption, biodegradability, surface morphology (scanning electron microscopy imaging), and mechanical properties. Additionally, the pH level of the starch-based/nZnO film was measured to study the prospect of bacterial growth on this wound-dressing material. Furthermore, the in vitro antibacterial activity demonstrated that the dressings material effectively inhibited the growth and penetration of bacteria (Escherichia coli, Staphylococcus aureus).

Mechanisms of instantaneous inactivation of SARS-CoV-2 by silicon nitride bioceramic.

The hydrolytic processes occurring at the surface of silicon nitride (Si3N4) bioceramic have been indicated as a powerful pathway to instantaneous inactivation of SARS-CoV-2 virus. However, the virus inactivation mechanisms promoted by Si3N4 remain yet to be elucidated. In this study, we provide evidence of the instantaneous damage incurred on the SARS-CoV-2 virus upon contact with Si3N4. We also emphasize the safety characteristics of Si3N4 for mammalian cells. Contact between the virions and micrometric Si3N4 particles immediately targeted a variety of viral molecules by inducing post-translational oxidative modifications of S-containing amino acids, nitration of the tyrosine residue in the spike receptor binding domain, and oxidation of RNA purines to form formamidopyrimidine. This structural damage in turn led to a reshuffling of the protein secondary structure. These clear fingerprints of viral structure modifications were linked to inhibition of viral functionality and infectivity. This study validates the notion that Si3N4 bioceramic is a safe and effective antiviral compound; and a primary antiviral candidate to replace the toxic and allergenic compounds presently used in contact with the human body and in long-term environmental sanitation.

Polymeric paint coated common-touch surfaces that can kill bacteria, fungi and influenza virus.

In the current situation of COVID-19 pandemic, the role of surfaces in transmitting pathogens is clearer than ever. Herein, we report an organo-soluble, quaternary antimicrobial paint (QAP) based on polyethyleneimine (PEI) which was coated on a wide range of surfaces such as polyvinylchloride (PVC), nylon, rubber, aluminum. The coating completely killed drug-resistant bacteria. It showed rapid bactericidal properties with complete killing in 45 min of exposure and lowered bacterial adherence, asserting self-sterilizing nature. The coating exhibited complete killing of stationary phase cells of bacteria. The coating killed drug-resistant C. albicans strains. Importantly, QAP coating showed complete killing of influenza virus (H1N1).

Hard Nanomaterials in Time of Viral Pandemics.

The SARS-Cov-2 pandemic has spread worldwide during 2020, setting up an uncertain start of this decade. The measures to contain infection taken by many governments have been extremely severe by imposing home lockdown and industrial production shutdown, making this the biggest crisis since the second world war. Additionally, the continuous colonization of wild natural lands may touch unknown virus reservoirs, causing the spread of epidemics. Apart from SARS-Cov-2, the recent history has seen the spread of several viral pandemics such as H2N2 and H3N3 flu, HIV, and SARS, while MERS and Ebola viruses are considered still in a prepandemic phase. Hard nanomaterials (HNMs) have been recently used as antimicrobial agents, potentially being next-generation drugs to fight viral infections. HNMs can block infection at early (disinfection, entrance inhibition) and middle (inside the host cells) stages and are also able to mitigate the immune response. This review is focused on the application of HNMs as antiviral agents. In particular, mechanisms of actions, biological outputs, and limitations for each HNM will be systematically presented and analyzed from a material chemistry point-of-view. The antiviral activity will be discussed in the context of the different pandemic viruses. We acknowledge that HNM antiviral research is still at its early stage, however, we believe that this field will rapidly blossom in the next period.

Surface Chemistry Can Unlock Drivers of Surface Stability of SARS-CoV-2 in a Variety of Environmental Conditions.

The surface stability and resulting transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), specifically in indoor environments, have been identified as a potential pandemic challenge requiring investigation. This novel virus can be found on various surfaces in contaminated sites such as clinical places; however, the behavior and molecular interactions of the virus with respect to the surfaces are poorly understood. Regarding this, the virus adsorption onto solid surfaces can play a critical role in transmission and survival in various environments. In this article, we first give an overview of existing knowledge concerning viral spread, molecular structure of SARS-CoV-2, and the virus surface stability is presented. Then, we highlight potential drivers of the SARS-CoV-2 surface adsorption and stability in various environmental conditions. This theoretical analysis shows that different surface and environmental conditions including temperature, humidity, and pH are crucial considerations in building fundamental understanding of the virus transmission and thereby improving safety practices.