ABSTRACT
BACKGROUND: Nigella sativa L. has been widely used in the Unani, Ayurveda, Chinese, and Arabic medicine systems and has a long history of medicinal and folk uses. Several phytoconstituents of the plant are reported to have excellent therapeutic properties. In-vitro and in-vivo studies have revealed that seed oil and thymoquinone have excellent inhibitory efficacy on a wide range of both pathogenic and non-pathogenic fungi. OBJECTIVE: The present review aims to undertake a comprehensive and systematic evaluation of the antifungal effects of different phytochemical constituents of black cumin. METHOD: An exhaustive database retrieval was conducted on PubMed, Scopus, ISI Web of Science, SciFinder, Google Scholar, and CABI to collect scientific information about the antifungal activity of N. sativa L. with 1990 to 2023 as a reference range using 'Nigella sativa,' 'Nigella oil,' 'antifungal uses,' 'dermatophytic fungi,' 'candidiasis,' 'anti-aflatoxin,' 'anti-biofilm' and 'biological activity' as the keywords. RESULTS: Black cumin seeds, as well as the extract of aerial parts, were found to exhibit strong antifungal activity against a wide range of fungi. Among the active compounds, thymoquinone exhibited the most potent antifungal effect. Several recent studies proved that black cumin inhibits biofilm formation and growth. CONCLUSION: The review provides an in-depth analysis of the antifungal activity of black cumin. This work emphasizes the need to expand studies on this plant to exploit its antifungal properties for biomedical applications.
ABSTRACT
Vacancies are ubiquitous in nature, usually playing an important role in determining how a material behaves, both physically and chemically. As a consequence, researchers have introduced oxygen, sulphur and other vacancies into bi-dimensional (2D) materials, with the aim of achieving high performance electrodes for electrochemical energy storage. In this article, we focused on the recent advances in vacancy engineering of 2D materials for energy storage applications (supercapacitors and secondary batteries). Vacancy defects can effectively modify the electronic characteristics of 2D materials, enhancing the charge-transfer processes/reactions. These atomic-scale defects can also serve as extra host sites for inserted protons or small cations, allowing easier ion diffusion during their operation as electrodes in supercapacitors and secondary batteries. From the viewpoint of materials science, this article summarises recent developments in the exploitation of vacancies (which are surface defects, for these materials), including various defect creation approaches and cutting-edge techniques for detection of vacancies. The crucial role of defects for improvement in the energy storage performance of 2D electrode materials in electrochemical devices has also been highlighted.
ABSTRACT
We have studied alkaline-earth-metal-doped Y3GaO6 as a new family of oxide-ion conductor. Solid solutions of Y3GaO6 and 2% -Ca2+-, -Sr2+-, and -Ba2+-doped Y3GaO6, i.e., Y(3-0.06)M0.06GaO6-δ (M = Ca2+, Sr2+, and Ba2+), were prepared via a conventional solid-state reaction route. X-ray Rietveld refined diffractograms of all the compositions showed the formation of an orthorhombic structure having the Cmc21 space group. Scanning electron microscopy (SEM) images revealed that the substitution of alkaline-earth metal ions promotes grain growth. Aliovalent doping of Ca2+, Sr2+, and Ba2+ enhanced the conductivity by increasing the oxygen vacancy concentration. However, among all of the studied dopants, 2% Ca2+-doped Y3GaO6 was found to be more effective in increasing the ionic conductivity as ionic radii mismatch is minimum for Y3+/Ca2+. The total conductivity of 2% Ca-doped Y3GaO6 composition calculated using the complex impedance plot was found to be â¼0.14 × 10-3 S cm-1 at 700 °C, which is comparable to many other reported solid electrolytes at the same temperature, making it a potential candidate for future electrolyte material for solid oxide fuel cells (SOFCs). Total electrical conductivity measurement as a function of oxygen partial pressure suggests dominating oxide-ion conduction in a wide range of oxygen partial pressure (ca. 10-20-10-4 atm). The oxygen-ion transport is attributed to the presence of oxygen vacancies that arise from doping and conducting oxide-ion layers of one, two-, or three-dimensional channels within the crystal structure. The oxide-ion migration pathways were analyzed by the bond valence site energy (BVSE)-based approach. Photoluminescence analysis, dilatometry, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy studies were also performed to verify the experimental findings.
ABSTRACT
Improving the electronic conductivity in lithium-based compounds can considerably impact the design of rechargeable batteries. Here, we explore the influence of lithium ion vacancies on the electronic conductivity of LiFePO4, an active cathode material, by varying the crystallite sizes. We find that about 17% lithium ion vacancy concentration leads to an enhancement in electronic conductivity of about two orders of magnitude at 313 K with respect to our initial crystallite size. We attribute the enhanced electronic conductivity to the lithium ion vacancy concentration in addition to the reduced hopping length. The lithium ion vacancies are the source of polarons in LiFePO4, which increases with decreasing crystallite size due to the surface energy kinetics. The substantial increase in the polaronic sites (Fe3+) at a lower crystallite size leads to a reduction in lattice parameters including the unit cell volume. The analysis of temperature dependent dc conductivity within the framework of the Mott model of polaron conduction enables us to quantify the various physical parameters associated with polaron hopping in LiFePO4.
