Current Perspective to Physical Science Research Vol. 8

In this work, a flavour theory of a neutrino mass model based on \(A_4\) symmetry is considered to explain the phenomenology of neutrino mixing. Neutrino flavor conversion was first detected in solar and atmospheric neutrinos. The discovery of neutrino oscillations proved the violation of flavor in the lepton sector and the need for extensions of the Standard Model. Since then, lepton masses, mixings, and flavor violation have been actively researched through global fits to oscillation data. The spontaneous symmetry breaking of \(A_4\) symmetry in this model leads to tribimaximal mixing in the neutrino sector at a leading order. We consider the effect of \(Z_2 \times Z_2\) invariant perturbations in neutrino sector and find the allowed region of correction terms in the perturbation matrix that is consistent with \(3\sigma\) ranges of the experimental values of the mixing angles. We study the entanglement of this formalism on the other phenomenological observables, such as \(\delta_{cp}\) phase, the neutrino oscillation probability \(P(v_\mu\rightarrow\)\(v_e)\) , the effective Majorana mass \(\vert m_{ee}\vert\) and \(m_{ve}^{eff}\) . A \(Z_2 \times Z_2\) invariant perturbations in this model is introduced in the neutrino sector which leads to testable predictions of \(\theta_{13}\) and CP violation. By changing the magnitudes of perturbations in neutrino sector, one can generate viable values of \(\delta_{cp}\) and neutrino oscillation parameters. Next we investigate the feasibility of charged lepton flavour violation in type-I seesaw models with leptonic flavour symmetries at high energy that leads to tribimaximal neutrino mixing. We consider an effective theory with an \(A_2 \times Z_2 \times Z_2\) symmetry, which after spontaneous symmetry breaking at high scale which is much higher than the electroweak scale leads to charged lepton flavour violation processes once the heavy Majorana neutrino mass degeneracy is lifted either by renormalisation group effects or by a soft breaking of the \(A_4\) symmetry. In this context the implications for charged lepton flavour violation processes like \(\mu\rightarrow\mathsf{e}\gamma, \tau\rightarrow\mathsf{e}\gamma, \tau\rightarrow\mu\gamma\) are discussed. A more comprehensive version of the generalised CP methodology and its potential to produce other hypothetically and realistic ansatz forms for the lepton mixing matrix will be presented in our future work.

The Einstein field equations allow simple and interesting solutions for topological passage through hypothetical tunnels connecting two asymptotically flat portions of the same universe or two asymptotically flat universes. The solution would act as a shortcut passage between two distant regions of space-time. They can be used for constructing a time machine, for which a stable traversable WH is required. In the present article we propose a new hybrid shape function for wormhole (WH)s in the modified \(f (R,T)\) gravity. The proposed shape function satisfied the conditions of WH geometry. The geometrical behavior of WH solutions is discussed in both anisotropic and isotropic cases respectively. Also, the stability of this model is obtained by determining the equilibrium condition. The radial null energy condition and weak energy condition are validated in the proposed shape function indicating the absence of exotic matter in modified \(f (R,T)\) gravity. The existence of a physically acceptable WH is possible by using the newly proposed shape function in the framework of modified gravity theories. Future work needs to focus on how far this shape function supports the observational consequence of the WH geometry.

This paper presents the optimization of the multi-quantum well-based Light Emitting Diode (LED) structure. Technology has been developed for LEDs of red, violet, green, blue etc but for Solid-State lighting, it is also important to concentrate on white lights due to their high-energy efficiency and reliable lifetime.  We investigate the electrical and optical properties of the device on several factors like well width, barrier width, and the number of quantum wells and then optimize the structure. The structure has been considered to have epitaxial layers of Gallium Nitride and Indium Gallium Nitride material to be grown using Metal Organic Chemical Vapour Deposition on a C-plane Sapphire substrate of thickness 300 nm. The device is optimized for a well width and barrier width of 3nm and 6nm respectively, consisting of five quantum wells. Simulations were carried out using the Silvaco ATLAS TCAD simulation program (Silvaco International, USA). The optimized Multiple Quantum Well LED structures were indigenously grown by the MOCVD system on a c-plane (0001) sapphire substrate. Blue LEDs at the chip level were fabricated. I-V characteristics were measured for the fabricated chips. Fabricated blue LED has a peak emission wavelength of 453 nm which is in the blue region.

Production of syngas by methods alternative to steam reforming of methane now becomes more popular due to both environmental and commercial reasons. Transformation of oxygenates obtained from biomass and dry reforming of natural gas appears to be the most effective. This review considers problems related to the design of efficient structured catalysts for natural gas and biofuels transformation into syngas. Their active components are comprised of fluorite, perovskite, and spinel oxides or their nanocomposites (both bulk and supported on high surface area Mg-doped alumina or MgAl₂O₄) promoted by platinum group metals, nickel and their alloys. The mechanism of the main reactions was studied by using such methods as SSITKA, kinetic transients and pulse techniques. A complex of modern structural, spectroscopic and kinetic methods was applied to elucidate atomic-scale factors controlling their performance and stability to coking, such as dispersion of metals/alloys, strong metal-support interaction and oxygen mobility/reactivity as dependent upon their composition and synthesis procedures. Monolithic catalysts comprised of optimized active components loaded on structured substrates with a high thermal conductivity demonstrated high activity and stability to coking in processes of natural gas and biofuels reforming into syngas. A pilot-scale axial reactor equipped with the internal heat exchanger and such catalysts allowed to efficiently convert into syngas the mixture of natural gas, air and liquid biofuels in the autothermal reforming mode at low (~50 – 100°C) inlet temperatures and GHSV up to 40 000 h^-1. This study reviews the fundamental bases for the production technology of highly efficient and stable coking structured catalysts with nanocomposite active components for natural gas and biofuel transformation into syngas. Design of reactors for these catalysts with efficient control of the heat and mass transfer in these processes provides bases for their industrial production, thus solving the problems of green energy development.

We use Newtonian mechanics to calculate the deflection angels of starlight passing around the Sun and the planets in the solar system, as well as the deflection angels of stars visible from Earth. The calculation is based on the premise that ether (Dark matter), which is a medium for light waves (electromagnetic waves), has a mass that is affected by gravity. We calculate the angle of deflection of starlight passing at perigee around the Moon and planets in our solar system. We calculate the angle of deflection of sunlight visible from Earth at sunset(sunrise) and starlight just before it disappears in the night sky. We show that the actual observed value of starlight passing around the Sun matches the calculated deflection angle using Newtonian mechanics. This means that ether (Dark matter), which has mass, exists in any space in the universe.

Gamma-ray bursts (GRBs) stand out as the most potent occurrences in the cosmos and hold promise as consistent benchmarks for cosmological inquiries. Analysis of data collected by NASA's Swift satellite unveils a trend in the distribution of GRB frequency, peaking within a redshift range of 1 to 3. Within this paper, we categorize GRBs by their duration and deliberate on the source of their parent entities. Our investigation illuminates the mechanisms behind the formation of supermassive black holes and massive stars during the early stages of the universe, demonstrating how these processes, alongside other pertinent phenomena, contribute to the heightened occurrence of GRBs that peak at elevated redshift levels.

The main objective of this study is to develop a solar-powered mosquito trap equipped with air quality monitoring. Controlling mosquito infestations is a persistent issue that needs ongoing observation and accomplishment. This is because mosquitoes can transmit a number of fatal diseases, and each year they cause the deaths of one million people. The traditional preventative techniques, which involve employing insecticides and bug zappers, are not as successful and have a variety of negative effects on the ecosystem, including the extinction of beneficial insects, changes in mosquito biology, and altered climates. In this study, a solar-powered mosquito trap is created to trap mosquitoes by sucking them in using a fan while being attracted to a built-in LED to lure them into the trap. An air quality monitor is equipped to observe the change of temperature and carbon dioxide (CO2) of the surroundings and as a method to centralize the installation of the trap. The monitor display and air quality data retrieval are processed by an Arduino microcontroller. In the prototype observation, it was shown that the temperature increased proportional to CO2 concentration. The power efficiency of this device increased by 30% when using a solar panel. At optimal sunlight exposure and adequate battery capacity, the device would run for more than 24 hours and would get charged instantly on the next day when sunlight is present. With the air quality monitoring, it will be easier to centralize the installation of the mosquito trap and create a guideline on the suitability of installing the mosquito trap in a particular area.

This paper presents a numerical study of a buried hemispherical double-tube soil heat exchanger utilizing geothermal energy. Since the local air wall exchange coefficient throughout the heat exchanger is unknown, a mathematical study based on the unsteady Green's function theory was developed. The complexity of the geometry prompted us to conduct a numerical study that allowed us to obtain results reflecting the importance of heat exchange. There are many applications, especially storing energy underground to optimize greenhouses according to seasonal cycles. Numerical calculations were performed using CFD code to determine the temperature distribution and verify the reliability, accuracy and physical authenticity of this work.

The present study review the ground state confinement energy term in the Brus equation for the bandgap energy of a spherically shaped semiconductor quantum dot within the framework of effective mass approximation. Bandgap variation in a nanometer sized semiconductor is due to Confinement energy. A good estimate of the confinement energy is important for optoelectronic based applications of quantum dot.  The Schrodinger wave equation for a spherical nanoparticle in an infinite spherical potential well was solved in spherical polar coordinate system. Physical reasons in contrast to mathematical expediency were considered and solution obtained. The result reveals that the shift in the confinement energy is less than that predicted by the Brus equation as was adopted in most literatures. A “bird eye" view of the brus equation reveals that it is nothing but a Schrodinger equation modified to account for the effect of an electron-hole pair (exciton) confined to a nanometric spherical shaped semiconductor referred to as quantum dot. It is blind to the varied crystal structures that exist for semiconductors.

This chapter emphasizes the Schottky behaviour of the Cadmium Telluride (CdTe) quantum dots (QDs) fabricated by a simple drop casting method. The CdTe QDs have been synthesized by the Single Injection Hydrothermal (SIH) method and the QDs are collected for 30 minutes of synthesis duration. The Powder X-ray Ray Diffraction (PXRD) data reveals the hexagonal crystal structure of particle size is 6.83 nm 30 mins CdTe QDs. The TEM images clearly divulge the crystalline nature and systematic array of the QDs. The elemental composition of the CdTe QDs is confirmed by the EDAX spectra. The van der Pauw Hall measurement clearly indicates the higher mobility of the QDs and also the p-type conductivity. The Schottky diode behaviour of the as synthesized CdTe QDs is understood from the I-V characteristics of the fabricated diode.

Aims: To synthesize the cadmium telluride quantum dots by using single injection hydrothermal method. The fundamental characterization techniques like PXRD, TEM image and EDAX spectrum are performed on the quantum dot study the structural, morphological and elemental composition.  The electrical parameters and type of conductivity are studied by using the van der Pauw Hall measurement. The quantum diode is fabricated using a very simple drop casting technique and its Schottky behaviour is studied.

Study Design:  Synthesis, Characterization, Fabrication and characterization of the CdTe QDs diode.

Place and Duration of Study: Synthesis: Department of Physics, Fabrication: Department of Physics. Characterizations: CeNSE, Indian Institute of Science, Bangalore

Methodology: The two sets of CdTe QDs have been synthesized. The QDs are further applied for different characterizations. The fabricated diode was subjected to study its I-V characteristics.

Results: The CdTe QDs synthesized by single injection hydrothermal method are considered for the fabrication of a diode. Before the drop cast fabrication of CdTe QDs diode, fundamental characterizations like PXRD, TEM image, EDAX spectrum The QDs diode is fabricated by drop casting method of CdTe QDs on to ITO glass substrate. Linear I-V characteristics of the QDs diode signifies the good interconnection established between the Quantum dots and reduced GB defects. From the I-V characteristics it is found that, a diode fabricated using CdTe QDs of 30 minutes synthesis exhibit good Schottky. The higher ideality factor indicates the non-thermionic emission responsible for the diode performance. This makes it here prominent to mention that a very simple synthesis and fabrication technique can be employed to study the diode. This also illustrates that the only simple and very less expensive laboratory set ups can be employed to fabricate a diode based on CdTe QDs.

Conclusion:  A very simple and yet an effective method of synthesis of CdTe QDs has been emphasized. The hexagonal crystalline structure of the CdTe QDs elaborated here possess neat arrangement of the QDs which is observed from the TEM image. The electrical parameters measured show the p-type conductivity. The fabricated diode exhibits Schottky behaviour when studied for its I-V characteristics.

The semiconductor \((Bi_{1-x}Sb_x)_2Te_3\) solid solutions obtained by cation substitution Bi\(\to\)Sb are well-known as promising materials used in thermoelectric (TE) cooling devices. The polycrystalline samples of these solid solutions in the range of compositions x = 0 - 0.07 were synthesized, and the dependences of microhardness, electrical conductivity, the Hall coefficient, the Seebeck coefficient, and mobility of charge carriers on x were obtained at room temperature. It was established that in the concentration dependences of all studied properties, the anomalies are observed at the small content of introduced components which indicated the presence of a phase transition. It was assumed that this phase transition has a percolation nature and indicates that at a certain concentration of the impurity component (Sb), a continuous chain of interacting impurity atoms that penetrates the crystal (an infinite cluster) is formed, and then the interaction becomes collective. The experimental results are analyzed in terms of percolation theory considering alloy scattering and spatial correlations of impurity centers. The obtained data are another confirmation of our earlier stated assumption about the universal character of critical phenomena of percolation type accompanying the transition from impurity discontinuum to impurity continuum. The existence of these critical phenomena should be taken into account when developing and interpreting the properties of materials.