The theoretical background and technical capabilities of the free liquid surface (nozzle-less) electrospinnig process is described. The process is the basis of both laboratory and industrial production machines known as NanospiderTM and developed by Elmarco s.r.o. Technical capabilities of the machines (productivity, nanofiber layer metrics, and quality) are described in detail. Comparison with competing/complementary technologies is given, e.g. nozzle electrospinning, nano-meltblown, and islets-in-the sea. Application fields for nanofiber materials produced by various methods are discussed. Consistency of the technology performance and production capabilities are demonstrated using an example of polyamide nanofiber air filter media.

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The term aerogel is used for unique solid-state structures composed of three-dimensional (3D) interconnected networks filled with a huge amount of air. These air-filled pores enhance the physicochemical properties and the structural characteristics in macroscale as well as integrate typical characteristics of aerogels, e.g., low density, high porosity and some specific properties of their constituents. These characteristics equip aerogels for highly sensitive and highly selective sensing and energy materials, e.g., biosensors, gas sensors, pressure and strain sensors, supercapacitors, catalysts and ion batteries, etc. In recent years, considerable research efforts are devoted towards the applications of aerogels and promising results have been achieved and reported. In this thematic issue, ground-breaking and recent advances in the field of biomedical, energy and sensing are presented and discussed in detail. In addition, some other perspectives and recent challenges for the synthesis of high performance and low-cost aerogels and their applications are also summarized.

There is a growing public interest in utilizing biomass and biomaterials to obtain products with high sustainability and less harm to the environment. This study reports on using electrospinning technique to produce nanofiber membranes based on homogeneous polymeric blends of gum Arabic, polyvinyl alcohol, and silver nanoparticles. The produced interconnected membranes were cross-linked via heat and plasma treatments, and the membranes were characterized for their chemical and physical characteristics. Fourier transform infrared spectroscopy shows a cross-linking of gum Arabic and polyvinyl alcohol through esterification during the heat treatment, and through graft polymerization with methyl groups after methane plasma treatment. The mechanical performance of the membranes showed an increase in the modulus of elasticity in the longitudinal direction (parallel to electrospun nanofibers) from 85 ± 4 MPa to 148 ± 5 MPa compared with the transverse direction. Also, well-dispersed nanoparticles in the spinning solution tend to increase the elasticity from 41 ± 3 MPa to 148 ± 5 MPa, while the agglomeration of these nanoparticles decreases the mechanical properties of the nanofibers. Results of the biodegradation tests confirmed the significant biodegradable nature of the produced nanofibers, where 99.09% of the material was degraded within 28 days. Moreover, samples showed significant bactericidal activity against Micrococcus luteus with significantly less-observed bacteria in the measured plate, while the inhibition zone for Escherichia coli was 1 cm. The produced biodegradable electrospun membranes have multiple potential applications in many fields; especially for medical, antibacterial, and food packaging. This work reports the results for moisture and oxygen transfer of the membranes as a proposed application in food wrapping.