Current Applied Materials - Volume 1, Issue 1, 2022

Radar is a delicate detection device and since its evolution different techniques for reducing electromagnetic reflections have been discovered. This paper provides a concise review on fundamentals of absorption which reduce radar cross section from stealth target with which radar cross section affects the survivability and mission capability. The reduction of radar cross section depends on dielectric and magnetic properties of the material. The first section reviews the Radar Absorbing Material (RAM) in order to provide a background on fundamentals, various stealth techniques for absorption and its properties at microwave frequencies. The second section reviews the Multi-Walled Carbon Nanotubes and their different composites by encapsulation of other metals, polymers or epoxies into it and its microwave absorption properties were studies at microwave frequencies. Multi-Walled Carbon Nanotubes based composites for microwave absorption are reviewed on the basis of various factors; material composition, reflection loss performance, thickness, complex permittivity, complex permeability, dielectric tangent loss, magnetic tangent loss, bandwidth, and frequency band.

Titanium-based two-dimensional (2D) and layered compounds with open and stable crystal structures have attracted increasing attention for energy storage and conversion purposes, e.g., rechargeable alkali-ion batteries and hybrid capacitors, due to their superior rate capability derived from the intercalation-type or pseudocapacitive kinetics. Various strategies, including structure design, conductivity enhancement, surface modification, and electrode engineering, have been implemented to effectively overcome the intrinsic drawbacks while simultaneously maintaining their advantages as promising and competitive electrode materials for advanced energy storage and conversion. Here, we provide a comprehensive overview of the recent progress on Ti-based compound materials for high-rate and low-cost electrochemical energy storage applications (mainly on rechargeable batteries and supercapacitors). The energy storage mechanisms, structure-performance relations, and performance-optimizing strategies in these typical energy storage devices are discussed. Moreover, major challenges and perspectives for future research and industrial application are also illustrated.

Background: Compositionally modified Pb(Zr0.95Ti0.05)O3 (PZT 95/5) ferroelectric materials have been extensively investigated in past decades for many important applications. However, few study on pure PZT95/5 ceramics have been reported.

Objective: Herein, pure PZT95/5 ceramics were successfully prepared, and their microstructure and phase transition behaviors under external fields were studied.

Methods: The pure PZT95/5 ceramics were prepared by the conventional solid state reaction using a mixed oxide route. The microstructure and its properties under different external fields were measured.

Results: The X-ray diffraction patterns indicated that the virgin pure PZT95/5 ceramics exhibit an orthorhombic antiferroelectric phase, which has also been evidenced by the superlattice reflections in the SAED pattern. While a rhombohedral ferroelectric symmetry crystal structure was observed in the poled samples suggesting that an electric field induced antiferroelectric to ferroelectric phase transition takes place. Pure PZT95/5 ceramics exhibit a quenched ferroelectric hysteresis loop with a remnant polarization of ~8μC/cm² under 3.5kV/mm. Temperature dependence dielectric response indicated that the orthorhombic antiferroelectric to cubic paraelectric phase transition occurs at 225^oC, corresponding to its Curie temperature. A shard depolarization behavior and dielectric anomalies were observed under ~240 MPa hydrostatic pressure.

Conclusion: The depolarization mechanism of pure PZT95/5 ceramics under hydrostatic pressure is attributed to the hydrostatic pressure-induced FE-AFE phase transition. These results will offer fundamental insights into PZT95/5 ceramics for pulsed power supply applications.

Background: Perylene Diimide (PDI) is among the most investigated non-fullerene electron acceptor for Organic Solar Cells (OSCs). Constructing PDI derivatives into three-dimensional propeller-like molecular structures is not only one of the viable routes to suppress the over aggregation tendency of the PDI chromophores but also rise possibilities to tune and optimize the optoelectronic property of the molecules.

Objective: In this work, we reported the design, synthesis, and characterization of three electron-accepting materials, namely BOZ-PDI, BTZ-PDI, and BIZ-PDI, each with three PDI arms linked to benzotrioxazole, benzotrithiazole, and benzotriimidazole based center cores, respectively.

Methods: The introduction of electron-withdrawing center cores with heteroatoms does not significantly complicate the synthesis of the acceptor molecules, but drastically influences the energy levels of the propeller-like PDI derivatives.

Results: The highest power conversion efficiency was obtained with benzoxazole-based BOZ-PDI reaching 7.70% for its higher photon absorption and charge-transport ability.

Conclusion: This work explores the utilization of electron-withdrawing cores with heteroatoms in the propeller-like PDI derivatives, which provides a handy tool to construct high-performance non-fullerene acceptor materials.

Background: Cadmium Sulfide (CdS) based semiconductors are of great interest for different high-end applications because they pose a direct bandgap (2.42 eV). CdS are used as the main constituent material in many applications, namely solar cells, electroluminescent, and quantum dot light-emitting diodes. Transition metal-doped CdS revealed considerable influence in the bandgap, photoluminescence properties and peak energy upon increasing the metal content.

Objective: In this work, we study the single-phase cubic structure of CdS. Photoluminescence spectra revealed a strong blue emission peak located at about 445 nm.

Methods: We investigate the Co-doping CdS semiconductor nanoparticles prepared via the chemical co-precipitation method using thiophenol as template, 300°C/2h in vacuum optimum temperature and period of annealing to yield nanosized particles. Morphology and structural studies of the particles were using XRD, and TEM, respectively.

Results: XRD and TEM studies for the calcined samples revealed a cubic structure. The crystalline size was in the range of 10-17 nm. Thermogravimetric analysis (TGA) was employed to stabilize the temperature of annealing for the samples. The blue shift in the spectra and the band gap value of Co-doped CdS nanoparticles were estimated using UV-vis absorption spectra. Photoluminescence spectra revealed a strong blue emission peak around 445 nm indicating the presence of surface states within the bandgap region, which is a characteristic feature of nanoparticles.

Conclusion: XRD analysis indicated zinc blend structure and the intensity decreased with increasing Co content. TEM images show that the particles are spherical in shape with average sizes around 13 nm. Luminescence of the synthesized nanoparticles exhibited blue emission between 400 – 500 nm with the peak located at about 445 nm. The emission intensity increased with the increase in Co concentration.

In many previous studies, liquorice plant (Glycyrrhiza glabra) extracts have been found to contain more than 300 natural compounds, most of which are triterpenoids and flavonoids, and show promising results in clinical studies for treating many microbial and viral infections. Triterpenoids, like glycyrrhizic acid, have shown anti-SARS-CoV activity in vitro. Experimentally, certain glycyrrhizic acid derivatives have shown increased activity by many folds against SARS-associated viruses. These compounds can potentially inhibit the replication cycle of SARS-associated viruses by interfering with the viral gene expression or by inhibiting the spike protein expression, which in turn inhibits the adhesion and entry of the virus. Although the therapeutic has shown great antiviral activity in vitro, but in vivo, its efficiency deteriorates till it reaches the liver for metabolism. In the current review, we analyze the unique replication strategy of SARS-CoV-2 and glycyrrhizic acid as a potential drug against SARS-CoV-2. We also discuss possible nanoformulations of glycyrrhizic acid for efficient drug delivery in humans and as a potent therapeutic strategy for COVID-19.

Background: The strategy to form functional structures based on powder technology relies on the concept of nanoparticles characteristics. Rare-earth sesquioxides (RE2O3; RE as Y, Tm, Eu) exhibit remarkable properties, and their fields of application include energy, astronomy, environmental, medical, information technology, industry, and materials science. The purpose of this paper is to evaluate the characteristics of RE2O3 nanoparticles as a bottom-up strategy to form functional materials for radiation dosimetry.

Methods: The RE2O3 nanoparticles were characterized by the following techniques: XRD, SEM, PCS, FTIR, ICP, EPR, and zeta potential.

Results: All RE2O3 samples exhibited cubic C-type structure in accordance with the sesquioxide diagram, chemical composition over 99.9%, monomodal mean particle size distribution, in which d50 value was inferior to 130 nm. Among all samples, only yttrium oxide exhibited an EPR signal, in which the most intense peak was recorded at 358mT and g 1.9701.

Conclusion: Evaluating nanoparticle characteristics is extremely important by considering a bottom-up strategy to form functional materials. The RE2O3 nanoparticles exhibit promising characteristics for application in radiation dosimetry.

Background: Recently, the CaMoO4 nanocrystal has been viewed as one of the most promising substrates for rare-earth-doped nanophosphors due to its high density, stable chemical properties, and good Deep-Ultraviolet (DUV) responding characteristics.

Aim: In this work, a green synthesis approach is proposed to obtain rare-earth-doped CaMoO4 nanodispersion with full-visible-spectra emission by using an ethanol-water mixed solvent in a Rotating Packed Bed (RPB) reactor.

Method: The obtained nanophosphors exhibited bright luminescent emission with tunable color in the range of full-visible-spectra via doping of Eu³⁺, Tb³⁺, and Dy³⁺, when they were excited by deep-ultraviolet (DUV) light. The RPB promoted the uniform distribution of rare-earth ions and the crystallinity of CaMoO4 particles, and the use of ethanol-water as solvents with no toxicity and less environmental pollution was beneficial for large-scale production.

Result: The quantum yields for nanophosphors of CaMoO4: Na⁺, Eu³⁺, CaMoO4: Na⁺, Tb³⁺, and CaMoO4: Na⁺, Dy³⁺ were measured to be 46.96%, 28.05%, and 10.27%, respectively, which were among the highest values ever reported for rare-earth-doped CaMoO4-based nanophosphors with similar morphology. The temperature-dependent luminescence of CaMoO4: Eu³⁺, Na⁺ nanophosphors was investigated in the range of 298 K - 498 K.

Conclusion: The clear correlation between luminescence intensity and temperature indicates the potential novel application areas for CaMoO4: Na⁺, Eu³⁺ nanophosphor as a non-invasive thermometer. Upon regulating different nanophosphor material ratios, the obtained product shows a flexible fluorescence towards full-visible-spectra emission.

Background: Nesting is an essential neuropsychological motor behavior that helps conserve heat for reproduction and shelter building to protect offspring from environmental change.

Aim: The aim of the present study was to investigate how putting cotton in the cage influenced the nesting behavior of female mice.

Objective: The objective of the present work is to validate and establish the role of cotton as nesting material.

Materials and Methods: The female mice (n=25), after monogamous mating, were kept individually in a separate cage for the entire gestation period to prepare for delivery. Sterile cotton was kept inside the cage after immediate delivery to observe the nesting and burrowing neuropsychological behaviour. The quality of the resulting nest was scored by a definitive 5-point nest scoring scale as 0 for no nest, 1 for the flat nest, and 2 onwards for nests covering the offspring by mice. Furthermore, the neurobehavioral maternal health was also evaluated in terms of grooming, rearing activity, mean time spent by the dam, frequency of nurturing and mean time spent on the nest for each mouse for 10min daily for 15 days.

Results: Based on scoring, out of 25 female mice, 16 were found to show a maximum score of 5, as they build a nest with which they reveal better neuropsychological nurturing behavior as compared to the remaining 4 with a score of 4 to protect their offspring from environmental change to maintain a homeostatic microenvironment.

Conclusion: Cotton was considered a suitable choice as nest-building material, which was better utilized by the swiss albino mice. It also improves nesting and burrowing performance, observed in the home cage, proving to be a valuable and easy-to-use tool for assessing motor impairment due to brain damage as well as neurobehavioral changes.