In Situ Vanadium-Deficient Engineering of V2 C MXene: A Pathway to Enhanced Zinc-Ion Batteries.

This research examines vanadium-deficient V2 C MXene, a two-dimensional (2D) vanadium carbide with exceptional electrochemical properties for rechargeable zinc-ion batteries. Through a meticulous etching process, a V-deficient, porous architecture with an expansive surface area is achieved, fostering three-dimensional (3D) diffusion channels and boosting zinc ion storage. Analytical techniques like scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and X-ray diffraction confirm the formation of V2 C MXene and its defective porous structure. X-ray photoelectron spectroscopy further verifies its transformation from the MAX phase to MXene, noting an increase in V3+ and V4+ states with etching. Cyclic voltammetry reveals superior de-zincation kinetics, evidenced by consistent V3+ /V4+ oxidation peaks at varied scanning rates. Overall, this V-deficient MXene outperforms raw MXenes in capacity and rate, although its capacity diminishes over extended cycling due to structural flaws. Theoretical analyses suggest conductivity rises with vacancies, enhancing 3D ionic diffusion as vacancy size grows. This work sheds light on enhancing V-based MXene structures for optimized zinc-ion storage.

Reactive Powder Concrete Containing Basalt Fibers: Strength, Abrasion and Porosity.

The paper presents the test results of basalt fiber impact on a compressive and flexural strength, resistance to abrasion and porosity of Reactive Powder Concrete (RPC). The reasons for testing were interesting mechanical properties of basalt fibers, the significant tensile strength and flexural strength, and in particular the resistance to high temperatures, as well as a relatively small number of RPC tests performed with those fibers and different opinions regarding the impact of those fibers on concrete strength. The composition of the concrete mix was optimized to obtain the highest packing density of particles in the composite, based on the optimum particle size distribution curve acc. to Funk. Admixture of basalt fibers was used in quantity 2, 3, 6, 8 and 10 kg/m3, length 12 mm and diameter 18 µm. A low water-to-binder ratio, i.e., from 0.24, was obtained through application of a polycarboxylate-based superplasticizer. The introduction of up to 10 kg/m3 of basalt fibers to RPC mix was proved to be possible, while keeping the same w/c ratio equal to 0.24, with a slight loss of workability of the concrete mix as the content of fibers increased. It was found that the increase of the fiber content in RPC to 10 kg/m3, despite the w/c ratio was kept the same, caused reduction of the concrete compressive strength by 18.2%, 7.8% and 13.6%, after 2, 7, and 28 days respectively. Whereas, the flexural strength of RPC increased gradually (maximum by 15.9%), along with the fiber quantity increase up to 6 kg/m3, and then it reduced (maximum by 17.7%), as the fiber content in the concrete was further increased. The reduction of RPC compressive strength, along with the increase in basalt fibers content, leads to the increase of the total porosity, as well as the change in pore volume distribution. The reduction of RPC abrasion resistance was demonstrated along with the increase of basalt fibers content, which was explained by the compressive strength reduction of that concrete. A linear relation between the RPC abrasion resistance and the compressive strength involves a high determination coefficient equal to 0.97.

Evaluation of the Mechanical, Physical, and Anti-Fungal Properties of Flax Laboratory Papersheets with the Nanoparticles Treatment.

In the present study, novel mixed additives of Chitosan or Paraloid B-72 combined with nanoparticles (NPs) of Ag, ZnO, or cellulose (NCL) were examined for their effects on the mechanical, optical, and fungal inhibition properties of the papersheets produced. The highest tensile, tear, and burst indices of the papersheets were observed for flax pulp treated with additives of Paraloid B-72 + ZnO NP (1%), Chitosan + ZnO NP (3%), and Chitosan + NCL (3%) at levels of 59.93 N·m/g, 18.45 mN·m2/g, and 6.47 kPa·m2/g, respectively. Chitosan + ZnO NP (1%) added to flax pulp showed the highest fungal mycelial inhibition (FMI) (1.85%) against Aspergillus flavus. Chitosan + Ag NP (1%) exhibited the highest FMI percentage (11.48%) when added to pulp against A. terreus. Pulp treated with Paraloid B-72 + Ag NP (1%) exhibited the highest activity against Stemphylium solani with an FMI value of 3.7%. The results indicate that the technological properties of the papersheets were enhanced with the addition of novel mixtures to the pulp.