Surface modification of PMMA polymer and its composites with PC61BM fullerene derivative using an atmospheric pressure microwave argon plasma sheet

Inactivation of microorganisms on fabrics using plasma-activated nebulized mist driven by different plasma gases

The disinfection of fabrics is crucial in preventing the spread of infectious diseases caused by pathogenic microorganisms to maintain public health. A previous study proved that plasma-activated nebulized mist (PANM) could effectively inactivate microorganisms both in aerosol and attached to the surface. In this study, the PANM driven by different plasma gases were employed to inactivate microorganisms on diverse fabrics. The PANM could efficiently inactivate a variety of microorganisms, including bacteria, fungi, and viruses, contaminating different fabrics, and even across covering layers of different fabrics. The mites residing on the cotton fabrics both uncovered and covered with various types of fabrics were also effectively inactivated by the PANM. After 30 times repeated treatments of the PANM, notable changes were observed in the color of several fabrics while the structural integrity and mechanical strength of the fabrics were unaffected and maintained similarly to the untreated fabrics with slight changes in elemental composition. Additionally, only trace amounts of nitrate remained in the fabrics after the PANM treatment. Therefore, the PANM treatment supplied an efficient, broad-spectrum, and environmentally friendly strategy for industrial and household disinfection of fabrics.

On the Dynamic Contact Angle of Capillary-Driven Microflows in Open Channels

The true value of the contact angle between a liquid and a solid is a thorny problem in capillary microfluidics. The Lucas-Washburn-Rideal (LWR) law assumes a constant contact angle during fluid penetration. However, recent experimental studies have shown lower liquid velocities than those predicted by the LWR equation, which are attributed to a velocity-dependent dynamic contact angle that is larger than its static value. Inspection of fluid penetration in closed channels has confirmed that a dynamic angle is needed in the LWR equation. In this work, the dynamic contact angle in an open-channel configuration is investigated using experimental data obtained with a range of liquids, aqueous and organic, and a PMMA substrate. We demonstrate that a dynamic contact angle must be used to explain the early stages of fluid penetration, i.e., at the start of the viscous regime, when flow velocities are sufficiently high. Moreover, the open-channel configuration, with its free surface, enhances the effect of the dynamic contact angle, making its inclusion even more important. We found that for the liquids in our study, the molecular-kinetic theory is the most accurate in predicting the effect of the dynamic contact angle on liquid penetration in open channels.

Button shear testing for adhesion measurements of 2D materials

Two-dimensional (2D) materials are considered for numerous applications in microelectronics, although several challenges remain when integrating them into functional devices. Weak adhesion is one of them, caused by their chemical inertness. Quantifying the adhesion of 2D materials on three-dimensional surfaces is, therefore, an essential step toward reliable 2D device integration. To this end, button shear testing is proposed and demonstrated as a method for evaluating the adhesion of 2D materials with the examples of graphene, hexagonal boron nitride (hBN), molybdenum disulfide, and tungsten diselenide on silicon dioxide and silicon nitride substrates. We propose a fabrication process flow for polymer buttons on the 2D materials and establish suitable button dimensions and testing shear speeds. We show with our quantitative data that low substrate roughness and oxygen plasma treatments on the substrates before 2D material transfer result in higher shear strengths. Thermal annealing increases the adhesion of hBN on silicon dioxide and correlates with the thermal interface resistance between these materials. This establishes button shear testing as a reliable and repeatable method for quantifying the adhesion of 2D materials.

PMMA bone cement with L-arginine/nano fish bone nanocomplex for apatite formation

Bone cement is one of the materials used in orthopaedics that serves various functions, such as binding bone implants, replacing damaged bones and filling spaces within bones. Various materials have been used to synthesize bone cement, and one promising material for further research is fish bone waste-based bone cement. This study investigates the potential of fish bone waste-based bone cement by incorporating nano fish bone (NFB) and L-arginine (L-Arg) protein into polymethyl methacrylate (PMMA) to examine apatite growth. NFB derived from the Salmo salar fish positively influences osteoblast cell proliferation and differentiation, while L-Arg enhances biocompatibility and antibiotic properties. The NFB/L-Arg combination holds promise in accelerating new bone formation and cell growth, both of which are crucial for fracture healing and bone remodelling. Tensile strength tests reveal the superior performance of BC-PMMA-1-NFB/L-Arg (36.11 MPa) compared with commercial PMMA (32 MPa). Immersion tests with simulated body fluid (SBF) solution for 7 days reveal accelerated apatite layer formation, emphasizing the potential benefits of NFB/L-Arg in bone cement applications.

Degradation of Polymethylmethacrylate (PMMA) Bioreactors Used for Algal Cultivation

This paper depicts characteristics of degradation of walls of bioreactors made of polymethylmethacrylate (PMMA) which was used to culture algae. The degradation processes take place stimulated by lighting of external surface and interaction with cultured species on internal surface. Results presented are representative for degradation of a bioreactor tube after the 4-year cultivation of Chlorella sp. Microscopic observations, roughness and transmission tests showed that changes have occurred on the inner surface. The result of use is a decrease in transmission and an increase in roughness. Microscopic observations showed that particles remained after culture, especially in cracks.

Influence of Plasma Treatment on Surface Characteristics of Aluminum Alloy Sheets and Bonding Performance of Glass Fiber-Reinforced Thermoplastic/Al Composites

This study focuses on modifying the surface of an AA 5052-H32 aluminum alloy using plasma treatment. Discharge power, exposure time, and working gas were adjusted as process parameters to improve the adhesion between the aluminum alloy and glass fiber-reinforced thermoplastic (GFRTP) polycarbonate composite. The surface composition and morphology of the aluminum alloy sheet were analyzed by X-ray photoelectron spectroscopy and scanning electron microscopy, and surface roughness and wettability were evaluated using a surface roughness-measuring instrument and contact angle goniometry, respectively. The bonding performance of GFRTP/aluminum alloy was also assessed. The surface of the aluminum alloy was subjected to chemical treatment prior to plasma treatment. The results revealed that nitrogen plasma treatment led to a substantial increase (25%) in bonding strength due to the synergistic effect of rough surface mechanical bonding and chemical bonding through functional groups between the aluminum alloy and GFRTP. However, the improvement in surface wettability by plasma treatment is time dependent and may gradually diminish over time due to the re-adsorption of hydrocarbon contamination from the surrounding air.

[Synthetic bone replacement substances]

Bone substitute materials have been successfully used for bone defects in orthopedics and trauma surgery for a long time; however, there are cases, especially in bone defects with a critical size, in which the treatment is complicated. Nowadays, multiple bone substitute materials are available. Autologous cancellous bone grafts remain the gold standard among the bone replacement materials; however, donor site morbidity and the limited availability of autologous cancellous bone represent restrictions for autologous bone grafting. Allogeneic cancellous bone grafts have also been successfully for years in the treatment of bone defects; however, infection rates of more than 10% have been described for the use of allogeneic cancellous bone. By introducing synthetic bone substitutes further alternatives are currently available to the user for the individual treatment of bone defects. The aim of this study is to demonstrate the advantages and disadvantages of various synthetic bone substitute materials.

Treatment of Polymeric Films Used for Printed Electronic Circuits Using Ambient Air DBD Non-Thermal Plasma

This study aims to present the properties of the polymeric films after being subjected to DBD plasma treatment in atmospheric conditions. Three different commercial films of polyester (Xerox Inkjet transparencies and Autostat CUS5 Clear film) and polycarbonate (Lexan™ 8010 MC) have been considered for the tests. The surface wettability has been evaluated based on static water contact angle (WCA) for different treatment times varying between 0.2 s and 30 s, the results revealing a maximum WCA decrease compared to a pristine of up to 50% for Xerox films, 75% for Autostat and 70% for Lexan. The persistence of the hydrophilic effect induced by the plasma treatment has also been verified for up to 72 h of storage after treatment, the results indicating a degradation of the treatment effects starting with the first hours after the treatment. The WCA stabilizes to a value inferior to the one corresponding to pristine in the first 24 h after plasma treatment. The adhesion forces, as well as preliminary surface morphology evaluations have been determined for the considered films using atomic force microscopy (AFM). The adhesion forces are increased together with the prolongation of the plasma treatment application time, varying from initial values of 165 nN, 58 nN and 204 nN to around 390 nN, 160 nN and 375 nN for Xerox, Autostat and Lexan films, respectively, after 5 s of DBD treatment. For the considered materials, the results revealed that the plasma treatment determines morphological changes of the surfaces indicating an increase in surface roughness.

Past and Current Progress in the Development of Antiviral/Antimicrobial Polymer Coating towards COVID-19 Prevention: A Review

The astonishing outbreak of SARS-CoV-2 coronavirus, known as COVID-19, has attracted numerous research interests, particularly regarding fabricating antimicrobial surface coatings. This initiative is aimed at overcoming and minimizing viral and bacterial transmission to the human. When contaminated droplets from an infected individual land onto common surfaces, SARS-CoV-2 coronavirus is able to survive on various surfaces for up to 9 days. Thus, the possibility of virus transmission increases after touching or being in contact with contaminated surfaces. Herein, we aim to provide overviews of various types of antiviral and antimicrobial coating agents, such as antimicrobial polymer-based coating, metal-based coating, functional nanomaterial, and nanocomposite-based coating. The action mode for each type of antimicrobial agent against pathogens is elaborated. In addition, surface properties of the designed antiviral and antimicrobial polymer coating with their influencing factors are discussed in this review. This paper also exhibits several techniques on surface modification to improve surface properties. Various developed research on the development of antiviral/antimicrobial polymer coating to curb the COVID-19 pandemic are also presented in this review.

A New Stripline-Based Atmospheric Pressure Microwave Plasma Sheet Source Designed for Surface Modification of Materials

A new type of microwave plasma source is presented in which plasma at atmospheric pressure is generated inside a quartz rectangular flat box placed in a stripline supplied by a 2.45 GHz coaxial line. The plasma has a sheet shape and is designed for surface modification. Electric field and power flux distributions, tuning characteristics, and power characteristics (ratios of radiated, absorbed, and entering power) are numerically studied for three configurations: open, semi-closed, and closed. The calculations show that near-zero radiation reduction is possible only for the closed configuration, while the ratio of radiated power to entering power is always greater than 30% for the other configurations. The moving plunger is not sufficient for the ratio of reflected to incident power to fall below 20% for both the closed and open configurations. This is possible for the semi-closed configuration, but then the radiated power is the highest. The experiment shows that for the same entering power, the plasma volume is largest for the closed configuration and smallest for the open configuration, which we attribute to the difference in radiated power. The plasma generated using the closed stripline configuration has a larger volume than plasma generated using the rectangular waveguide.

Synthetic Material for Bone, Periodontal, and Dental Tissue Regeneration: Where Are We Now, and Where Are We Heading Next?

Alloplasts are synthetic, inorganic, biocompatible bone substitutes that function as defect fillers to repair skeletal defects. The acceptance of these substitutes by host tissues is determined by the pore diameter and the porosity and inter-connectivity. This narrative review appraises recent developments, characterization, and biological performance of different synthetic materials for bone, periodontal, and dental tissue regeneration. They include calcium phosphate cements and their variants β-tricalcium phosphate (β-TCP) ceramics and biphasic calcium phosphates (hydroxyapatite (HA) and β-TCP ceramics), calcium sulfate, bioactive glasses and polymer-based bone substitutes which include variants of polycaprolactone. In summary, the search for synthetic bone substitutes remains elusive with calcium compounds providing the best synthetic substitute. The combination of calcium sulphate and β-TCP provides improved handling of the materials, dispensing with the need for a traditional membrane in guided bone regeneration. Evidence is supportive of improved angiogenesis at the recipient sites. One such product, (EthOss^® Regeneration, Silesden, UK) has won numerous awards internationally as a commercial success. Bioglasses and polymers, which have been used as medical devices, are still in the experimental stage for dental application. Polycaprolactone-TCP, one of the products in this category is currently undergoing further randomized clinical trials as a 3D socket preservation filler. These aforementioned products may have vast potential for substituting human/animal-based bone grafts.