Size- and time-dependent particle removal efficiency (PRE) of different protective respiratory masks were determined using a standard aerosol powder with the size of particles in the range of an uncoated SARS-CoV-2 virus and small respiratory droplets. Number concentration of particles was measured by a scanning mobility particle sizer. Respiratory protective half-masks, surgical masks, and cotton washable masks were tested. The results show high filtration efficiency of FFP2, FFP3, and certified surgical masks for all sizes of tested particles, while protection efficiency of washable masks depends on their constituent fabrics. Measurements showed decreasing PRE of all masks over time due to transmission of nanoparticles through the mask-face interface. On the other hand, the PRE of the fabric is governed by deposition of the aerosols, consequently increasing the PRE.

Molybdenum disulfide (MoS₂) has emerged as a promising material for next-generation electronics and optoelectronic devices. MoS₂ nanotubes (NTs) and their collapsed ribbon-like shapes (collapsed NTs) synthesized via chemical vapour transport (CVT) under chemical equilibrium typically exhibit low structural defect densities. However, defects and surface damage can arise during device fabrication or operation, leading to a significant degradation in performance, stability, and operational lifetime. These imperfections also induce hysteresis, which adversely affects the device switching behaviour. While the influence of charge trapping at the MoS₂/substrate interfaces, on the MoS₂ surface, and at intrinsic defects, such as sulfur vacancies and dangling bonds, on device performance has been extensively studied, MoS₂ NTs, with their unique curved morphology, introduce additional charge-trapping mechanisms not observed in planar MoS₂ structures. In this work, a combination of scanning tunnelling microscopy (STM), Kelvin probe force microscopy (KPFM), and conductive atomic force microscopy (c-AFM) was employed to examine how structural irregularities, including terminated layers, surface-grown flakes or NTs, and highly strained areas, affect charge injection, redistribution, and the resulting effects on electrical characteristics in collapsed NTs. The results reveal that structural defects act as charge traps, scattering centres, and transport barriers, giving rise to a reduced carrier mobility, localized charge accumulation, and spatially inhomogeneous charge distribution. These findings underscore the crucial role of structural and electrical characterization with nanoscale resolution in the design of defect-tolerant, high-performance devices based on transition metal dichalcogenides (TMDs).

Pollutants and infectious diseases can spread through air with airborne droplets and aerosols. A respiratory mask can decrease the amount of pollutants we inhale and it can protect us from airborne diseases. With the onset of the COVID-19 pandemic, masks became an everyday item used by a lot of people around the world. As most of them are for a single use, the amount of non-recyclable waste increased dramatically. The plastic from which the masks are made pollutes the environment with various chemicals and microplastic. Here, we investigated the time- and size-dependent filtration efficiency (FE) of aerosols in the range of 25.9 to 685.4 nm of five different natural materials whose FE was enhanced using electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) fibres. A scanning electron microscope (SEM) was used to determine the morphology and structure of the natural materials as well as the thickness of the PVDF fibres, while the phase of the electrospun fibres was determined by Raman spectroscopy. A thin layer of the electrospun PVDF fibres with the same grammage was sandwiched between two sheets of natural materials, and their FE increased up to 80%. By varying the grammature of the electrospun polymer, we tuned the FE of cotton from 82.6 to 99.9%. Thus, through the optimization of the grammage of the electrospun polymer, the amount of plastic used in the process can be minimized, while achieving sufficiently high FE.

The properties of thin polymer films are influenced by the size of the fillers, their morphology, the surface properties and their distribution/interaction in the polymer matrix. In this work, thin polymer composite films with MoO₃ or SiO₂ nano and micro fillers in PVDF-HFP/PVP polymer matrix were successfully fabricated using the solvent casting method. The effects of different types, sizes and morphologies of the inorganic fillers on the crystallization of the PVDF-HFP polymer were investigated, as well as the effects on the thermal and mechanical properties of the composites. Scanning electron microscopy, ATR-FTIR spectroscopy, differential scanning calorimetry, nanoindentation and uniaxial mechanical tests were used for characterization. The results showed that MoO₃ nanowires thermally stabilized the polymer matrix, induced crystallization of the PVDF-HFP polymer in all three polymorphs (α-, β-, γ-phase) and formed a geometrical network in the polymer matrix, resulting in the highest elastic moduli, hardness and Young’s modulus.

Minor sulphur incorporation stabilizes intermediate MoI _{2− x} S _x nanowires, guiding the formation of Mo ₆ S ₂ I ₈ nanowires with controlled morphology and tunable electronic properties.