Raimonds Meija

Core-shell electrospun fibers represent a promising platform for formulating poorly water-soluble drugs as amorphous solid dispersions with enhanced dissolution and physical stability. This study developed and characterized coaxial electrospun fibers containing the antidiabetic drug empagliflozin (EMPA) with drug loadings up to 22% w/w, using a Soluplus-EMPA core and Kollicoat Smartseal shell architecture. Comprehensive solid-state characterization confirmed complete amorphization across all compositions and intimate molecular-level mixing stabilized by drug-polymer hydrogen bonding. Raman microscopy mapping verified the intended core-shell structure with spatial separation of drug-rich core from polymer shell. Systematic comparison against film-cast amorphous solid dispersions and physical mixtures of identical composition (18% w/w) confirmed superior dissolution and drug release performance of the electrospun fibers. Under accelerated stability conditions (3 months at 40°C/75% RH) the electrospun fibers showed the same stability as the film-cast formulation, in contrast to the physical mixture crystallizing within one week. Notably, dynamic vapor sorption analysis revealed that electrospun fibers absorbed less moisture than film-cast ASD despite their higher surface area and porous structure, attributed to the protective barrier function of the Kollicoat shell. These findings establish core-shell electrospun fibers as an advantageous platform combining rapid dissolution with moisture-resistant stability for empagliflozin formulation.

For high-performance lithium-ion batteries (LIBs), Bi ₂ Se ₃ /MXene/SWCNT heterostructures emerge as a possible anode choice.

Novel copper oxide–multiwalled carbon nanotube hybrid nanostructured composites showed a high Seebeck coefficient (∼700 μV K⁻¹) and power factor (∼4 μW m⁻¹ K⁻²), exceeding the values reported for the state-of-the-art counterparts.

This work is devoted to the development of epoxy-encapsulated zinc oxide-multiwalled carbon nanotubes (ZnO–MWCNT) hybrid nanostructured composites and the investigation of their thermoelectric performance in relation to the content of MWCNTs in the composite. For the preparation of nanocomposites, self-assembling Zn nanostructured networks were coated with a layer of dispersed MWCNTs and subjected to thermal oxidation. The resulting ZnO–MWCNT hybrid nanostructured networks were encapsulated in commercially available epoxy adhesive. It was found that encapsulation of ZnO–MWCNT hybrid networks in epoxy adhesive resulted in a simultaneous decrease in their electrical resistance by a factor of 20–60 and an increase in the Seebeck coefficient by a factor of 3–15, depending on the MWCNT content. As a result, the thermoelectric power factor of the epoxy-encapsulated ZnO–MWCNTs hybrid networks exceeded that of non-encapsulated networks by more than 3–4 orders of magnitude. This effect was attributed to the ZnO–epoxy interface’s unique properties and to the MWCNTs’ contribution. The processes underlying such a significant improvement of the properties of ZnO–MWCNT hybrid nanostructured networks after encapsulation in epoxy adhesive are discussed. In addition, a two-leg thermoelectric generator composed of epoxy-encapsulated ZnO–MWCNT hybrid nanocomposite as n-type leg and polydimethylsiloxane-encapsulated CuO–MWCNT hybrid nanocomposite as p-type leg characterized at room temperatures showed better performance at temperature difference 30 °C compared with the similar devices, thus proving the potential of the developed nanocomposites for applications in domestic waste heat conversion devices.

The changes in global energy trends and the high demand for secondary power sources, have led to a renewed interest in aqueous lithium-ion batteries. The selection of a suitable anode for aqueous media is a difficult task because many anode materials have poor cycling performance due to side reactions with water or dissolved oxygen. An effective method for improving the characteristics of anodes in aqueous electrolyte solutions is adding carbon nanotubes (CNTs) to the electrode materials. For a better comprehension of the mechanism of energy accumulation and the reasons for the loss of capacity during the cycling of chemical current sources, it is necessary to understand the behaviour of the constituent components of the anodes. Although CNTs are well studied theoretically and experimentally, there is no information about their behaviour in aqueous solutions during the intercalation/deintercalation of lithium ions. This work reveals the mechanism of operation of untreated and annealed single-walled carbon nanotubes (SWCNT) anodes during the intercalation/deintercalation of Li⁺ from an aqueous 5 M LiNO₃ electrolyte. The presence of -COOH groups on the surface of untreated SWCNTs is the reason for the low discharge capacity of the SWCNT anode in 5 M LiNO₃ (3 mAh g⁻¹ after 100 cycles). Their performance was improved by annealing in a hydrogen atmosphere, which selectively removed the -COOH groups and increased the discharge capacity of SWCNT by a factor of 10 (33 mAh g⁻¹ after 100 cycles).

In recent years, aqueous rechargeable lithium-ion batteries (ARLIBs) have attracted attention as an alternative technology for electrical storage. One of the perspective battery anode materials for application in ARLIBs is Bi₂Se₃, which has already shown good perspectives in the application of conventional lithium-ion batteries (LIBs) that use organic electrolytes. In this study, the electrochemical properties of Bi₂Se₃ thin films with two different layers on the electrode surface—the solid electrolyte interphase (SEI) and the Bi₂O₃ layer—were investigated. The results of this work show that the formation of the SEI layer on the surface of Bi₂Se₃ thin films ensures high diffusivity of Li⁺, high electrochemical stability, and high capacity up to 100 cycles, demonstrating the perspectives of Bi₂Se₃ as anode material for ARLIBs.

Arrays of aligned carbon nanotubes (CNTs) are anisotropic nanomaterials possessing a high length-to-diameter aspect ratio, channels passing through the array, and mechanical strength along with flexibility. The arrays are produced in one step using aerosol-assisted catalytic chemical vapor deposition (CCVD), where a mixture of carbon and metal sources is fed into the hot zone of the reactor. Metal nanoparticles catalyze the growth of CNTs and, during synthesis, are partially captured into the internal cavity of CNTs. In this work, we considered various stages of multi-walled CNT (MWCNT) growth on silicon substrates from a ferrocene–toluene mixture and estimated the amount of iron in the array. The study showed that although the mixture of precursors supplies evenly to the reactor, the iron content in the upper part of the array is lower and increases toward the substrate. The size of carbon-encapsulated iron-based nanoparticles is 20–30 nm, and, according to X-ray diffraction data, most of them are iron carbide Fe₃C. The reasons for the gradient distribution of iron nanoparticles in MWCNT arrays were considered, and the possibilities of controlling their distribution were evaluated.

Due to their layered structure and high theoretical capacity, bismuth chalcogenides have been proposed as anodes in organic electrolyte Li- and Na-ion batteries. On the other hand, their electrochemical properties in aqueous systems have not been reported. Here, the electrochemical performance of Bi₂Se₃ thin films in 1 M NaNO₃ aqueous electrolyte is presented. This aqueous Bi₂Se₃ system was found to have up to two orders of magnitude increased diffusion coefficients, compared to other anode materials in Na electrolyte-based systems, as well as limited anode electrode degradation over 5 CVs and significant changes in the anode after 30 CVs.