Journal of Nepal Physical Society

Editorial Vol.9(3) Special Issue

2024-01-30T10:21:17+00:00

No abstract available.

A New Gravitational Radiation from General Relativity

2024-01-30T11:24:46+00:00

Actual cosmological and galactic data is showing the possible existence of a non-visible gravitational mass. This mass has been called dark matter, and researchers are looking for an explanation of its physical nature. A new solution to Einstein’s general relativity equations is introduced here. This new solution assumes that gravity has density and can produce pressure as any other known field does. Our hypothesis does not create any mathematical contradiction with anything that is known and points to the conclusion that dark matter is a non-linear manifestation of the gravitational field.

Nickel-Doped Tungsten Disulfide for Energy Storage Applications

2024-01-30T11:39:24+00:00

Nickel-doped hexagonal pyramid-like tungsten disulfide (WS2) has been synthesized via a simple hydrothermal synthesis method and offers great promise for use in electrochemical energy storage devices such as supercapacitors. The nickel concentration of 3, 4.5, and 6 at. % was added to WS₂. Three-electrode and two-electrode configurations are used to test the electrochemical performances of the materials as prepared. The nickel doping of 4.5 at. % exhibits a high specific capacitance of 144 F g⁻¹ at a current density of 1 A g⁻¹ with an energy density of 13.3 Wh kg⁻¹ and power density of 802 W kg⁻¹ for the symmetric supercapacitor device. Increased electrochemically active surface area and decreased impedance are attributed to the improved supercapacitive performances. Finally, high specific power retention (92.1%) and Coulomb efficiency (86.0%) were demonstrated after 3,000 cycles. These results demonstrate that the synthesized nickel-doped WS₂ can be used for high-performance supercapacitor flexible electrodes.

Influence of Precursor Type on Activated Carbon Prepared by Phosphoric Acid-Chemical Activation for Supercapacitor Applications

2024-01-30T11:47:51+00:00

Phosphoric acid can be used to activate different precursors and produce activated carbon (AC), a porous material with high adsorption capacity and surface area. This research shows how AC is made using different locally available precursors, namely amla seeds and harro seeds. We compare how the carbonization temperature and the precursor type affect the surface area, pore structure, and electrochemical properties of the AC. We use different methods to analyze the AC samples, such as scanning electron microscopy, surface area, methylene blue number, iodine number, and cyclic voltammetry. We show that the best conditions for making AC depend on the type of precursor and the activation temperature.

Structural and Dielectric Studies of Ni1−xAlxFe2O4

2024-01-30T11:55:11+00:00

The nanoparticles of Ni₁−_xAl_xFe₂O₄(x = 0,0.5) were synthesized via using sol-gel route and studied the structural and dielectric effect of aluminium content on Nickel site. The X-ray diffraction (XRD) revealed the single-phase cubic spinel structure of the parent compound. The lattice constant, volume, density, bond lengths, specific surface area and crystallite size were determined from the Rietveld refinement. In the Raman analysis, there are five active modes present in the synthesized samples. FTIR spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands of metal oxygen (Fe-O) observed around 424-450 and 601-620 cm⁻¹ corresponding to the stretching vibration frequency of the metal-oxygen at the octahedral site and tetrahedral site respectively. Dielectric behaviour showed that the value of dielectric constant (ε') and tangent loss (tanδ) decreases with frequency and confirmed the general behaviour of ferrites. The AC Conductivity (σ_ac) was found lower in Ni_0.5Al_0.5Fe₂O₄ compared to NiFe₂O₄.

Al-rich AlGaN Alloys: Unique Materials for Deep UV LEDs

2024-01-30T12:05:59+00:00

Energy bandgap of Al_xGa_1−xN alloys can be tuned systematically from ∼ 3.4 to 6.1 eV by changing the alloy composition (x) from 0 to 1 and the direct bandgap nature is maintained in the entire range of alloy compositions which make the AlGaN alloys suitable materials for the development of light emitting diodes (LEDs) covering the ultraviolet (UV) spectral region from 210 to 400 nm. For LEDs in the deep UV regions (λ < 300 nm), Al-rich AlGaN alloys of Al content higher than 50% are required. Deep UV LEDs have applications in a wide range of fields including display, disinfection, medical, sensing, and communication. With recent progress in the material growth and electrical conductivity, Al-rich AlGaN alloys have emerged as unique wideband gap materials for the development of deep UV LEDs. In this review article, how the progress of Al-rich AlGaN alloys has made in terms of the material growth and electrical conductivity leading its emergence as deep UV materials have been reviewed. Challenges and prospects of the deep UV LEDs to improve the performance of the devices will also be discussed.

Neighborhood-Level Air Pollution Monitoring and Analysis in Massachusetts

2024-01-30T12:12:37+00:00

Air pollution is a significant environmental issue with far-reaching consequences for both human health and the planet. It arises from the emission of harmful pollutants, such as particulate matter, ozone, and nitrogen dioxide, into the atmosphere. These pollutants originate from various sources, including vehicles, industrial facilities, and power plants. The impacts of air pollution are wide-ranging, encompassing respiratory infections, cardiovascular disease, cancer, harm to ecosystems, and contributions to climate change. The study of air pollution is a multidisciplinary field that draws upon knowledge from physics, chemistry, biology, and engineering. Understanding the causes and effects of air pollution is crucial for developing effective strategies to mitigate its harmful effects. Physics, in particular, plays a vital role in this field by providing the tools and techniques required to measure and comprehend the behavior of pollutants. By examining air pollution, we gain insights into the factors driving this problem and can devise measures to reduce pollution levels. Moreover, this knowledge empowers individuals and societies to make informed decisions about minimizing exposure to pollutants and formulating policies and regulations that safeguard both human well-being and the environment. In our study conducted in the central Massachusetts region, we investigated the status of air pollution using a combination of Environmental Protection Agency (EPA) monitoring sites and hand-held sensors. While the EPA sites offer longterm monitoring data, hand-held devices’ flexible and affordable nature allowed us to explore air quality at the local neighborhood and street levels. By utilizing these tools, we assessed the spatial and temporal variations in air pollution within the city, aiding in the identification of localized hotspots. Such information is valuable for targeting specific areas requiring interventions and further understanding the dynamics of pollution distribution.