042476   MANDAL K, MONDAL A K, CHAKRABORTY A, PETERS E E, CRIDER B P, ANDREOIU C, BENDER P C, CROSS D S, DEMAND G A, GARNSWORTHY A B, GARRETT P E, HACKMAN G, HADINIA B, KETELHUT S, KUMAR A, LEACH K G, MCELLISTREM M T, PORE J, PRADOS-ESTÉVEZ F M, RAND E T, SIN (Chemistry Dep, Kentucky Univ, Kentucky 40506-0055, USA, Email: anagha.chakraborty@visva-bharati.ac.in) : Probing the low-lying level structure of ⁹⁴Zr through β¯ decay. Indian J Pure appl phys 2020, 58(4), 223-7.

Low-lying states of ⁹⁴Zr are populated following b^- decay of ⁹⁴Y, and the emitted g rays from ⁹⁴Zr are detected using the 8p spectrometer composed of 20 Compton-suppressed HPGe detectors. High- statistics coincidence data have been used for the placement of very weak decay branches in the level scheme. Combining the results of level lifetimes from a previous experiment and the precisely measured branching ratio values of the weak decay branches from the present experiment, it is possible to extract the B(E2) values for all the possible decay branches from a given level. These values are helpful for proper identification of the collective and non-collective states of ⁹⁴Zr. The experimental findings have been compared with predictions from shell-model calculations with a limited valence space; however, these calculations are inadequate in reproducing all of the measured spectroscopic quantities.

2 illus, 1 table, 6 ref

042475   SUNITHAA A M, RUDRASWAMYA B , SURYANARAYANA S V , NAGARAJA K , KARKERA M, PASHA I , H B (Physics Dep, Bangalore Univ, Bengaluru - 560 056, Email: kamsalinagaraj@gmail.com) : Measurement of ⁹²Mo(n,α)⁸⁹Zr and ⁹⁷Mo(n,p)⁹⁷Nb reactions at the neutron energy 13.52 MeV with covariance analysis. Indian J Pure appl phys 2020, 58(4), 218-22.

The cross sections have been estimated for the Nuclear reactions ⁹²Mo(n,α)⁸⁹Zr and ⁹⁷Mo(n,p)⁹⁷Nb produced in Purnima neutron generator at neutron energy of 13.52±0.0045 MeV using activation analysis and off-line γ -ray spectrometric techniques. ²⁷Al(n,α)²⁴Na has been used as a monitor reaction. The covariance analysis for these cross sections has been carried out by taking into consideration of partial uncertainties of different attributes and correlations between the attributes. The cross section values of the present study have been compared with EXFOR, ENDF data of various libraries and theoretical data of TALYS-1.8 code.

2 illus, 4 tables, 31 ref

042474   NAGARAJA A M , MANJUNATHA H C, SOWMYA N, RAJ S A C (Physics Dep, Government Coll for Women, Kolar - 563 101, Email: manjunathhc@rediffmail.com) : Cluster radioactivity in superheavy nuclei ^299-302120. Indian J Pure appl phys 2020, 58(4), 207-12.

The cluster radioactivity is an unusual decay process observed in superheavy nuclei. When a cluster nuclei are emitted, the residual or daughter nuclei is having doubly magic nuclei or it may be neighbourhood of the same. We have studied cluster radioactivity [⁴He, ⁶Li, ⁹Be, ^20,22Ne, ²³N, ^24-26Mg, ^28-30Si, ³¹P, ^32-34S, ³⁵Cl, ^36,38,40Ar, ^40-46Ca ] in the superheavy nuclei ^299-302120 using the nuclear and proximity model. The calculated cluster decay half-lives are compared with that of the other theoretical models such as Univ¹, NRDX², UDL³ and Horoi⁴. From the comparison of different models we have observed that the cluster nuclei with ⁴He, ⁹Be, ²²Ne, ²⁶Mg, ³⁰Si, ³⁴S, ⁴⁰Ca and ⁴⁶Ca are having smaller logarithmic half-lives than the exotic cluster decay modes.

5 illus, 2 tables, 46 ref

042473   KUMAR K, THAKUR N (Physics Dep, M L S M Coll, Sundernagar - 175 018, Email: kameshwarkumar01@gmail.com) : Conduction mechanism and defect density of states in amorphous Te₁₅ (Se_100-xBi_x)₈₅ glassy alloys. Indian J Pure appl phys 2020, 58(3), 189-92.

The present paper reports the dc conductivity measurement up to 100 V for pallets of Te₁₅ (Se_100-xBi_x)₈₅ (x=0, 1, 2, 3, 4 at  %) glassy alloys in temperature range (303-343 K). The dc conductivity is calculated from the I-V characteristics curves of the pellets of bulk samples prepared by melt quenching technique. The samples obey Ohm’s law in the lower (0-25 V) voltage range whereas the behaviour in the higher (25-100 V) voltage range is non-ohmic. The experimental results for all the samples fit well with the theory of space charge limited conduction SCLC for uniform distribution of localized states in the mobility gap. The density of defect states is calculated for the glassy alloys and is found to increase with Bi content. The increase in defect density of states can be explained on basis of electro negativity difference of Bi as compared to host elements. The increase in dc conductivity is probably due to Se-Bi bond concentration in the Se-Te-Bi glasses.

6 illus, 2 tables, 30 ref

042472   SHARMA R, BISHT A (Mathematics and Scientific Computing Dep, National Institute of Technology, Hamirpur - 177 005, Email: raj.juit@gmail.com) : Effect of buoyancy and suction on Sisko nanofluid over a vertical stretching sheet in a porous medium with mass flux condition. Indian J Pure appl phys 2020, 58(3), 178-88.

The present article investigates the flow and heat transfer of Sisko nanofluid over a permeable vertical stretching surface in a porous medium. The effect of buoyancy, suction, and viscous dissipation has been taken into account. Buongiorno’s model of nanofluid consisting of thermophoresis and Brownian diffusion has been considered. Moreover, zero nanoparticle mass flux condition is employed at the boundary which leads to a more realistic physical problem. Using a suitable transformation governing partial differential equations of fluid flow are transformed into a set of nonlinear ordinary differential equations (ODEs). The numerical solution of nonlinear ODEs are obtained using the finite difference technique in MATLAB. The influence of physical parameters viz. buoyancy parameter (λ*), porosity parameter (β*), thermophoresis parameter (Nt*), suction parameter (f), Sisko material parameter (A*), Brinkman number (Br*), Brownian diffusion parameter (Nb*) and Lewis number (Le*) on velocity, temperature and nanoparticle volume fraction are shown graphically. Moreover, to understand the physical phenomenon in the boundary layer region, the numerical values of skin friction and Nusselt number are calculated and presented through table values. It has been found that the Brownian diffusion has a negligible impact on Nusselt number relative to the results obtained in previous studies, where nanoparticle volume fraction on the boundary was actively controlled. The obtained results disclose that the buoyancy parameter increases the velocity of fluid while it reduces the temperature. Suction parameter reduces both velocity and temperature, whereas the porosity parameter reduces velocity and enhances the temperature and nanoparticle volume fraction.

17 illus, 5 tables, 44 ref

042471   BHAVYAA P , MELAVANKIB R, KUSANURC R, THIPPERUDRAPPA J (Physics Dep, M S Ramaiah Institute of Technology, Bengaluru - 560 054, Email: melavanki73@gmail.com) : Preferential solvation and bimolecular quenching reactions of boronic acid dye at very low quencher concentrations studied by fluorescence spectrum in toluene and butanol binary mixtures. Indian J Pure appl phys 2020, 58(3), 168-77.

Inferable from the significance of solvent mixtures in practical chemistry, toluene (TL) and butanol (BL) mixtures are used to studyfluorescence behavior of boronic acid dye 2-methoxy-5-fluoro-phenyl boronic acid (2MEFPBA). At the inception, preferential solvation is examined in TL-BL, to understand specific and nonspecific interactions. Suppan’s dielectric enrichment model is further used to understand the nonideality and dielectric enrichment in TL-BL mixtures for preferential solvation. Bimolecular quenching reaction studies of 2MEFPBA with aniline as quencher are made in mixtures of TL–BLto know the effect of viscosity and dielectric constant variation at room temperature. The quenching process is studied in all solvent mixtures by steady state and transient state method. Quenching is characterized by S-V plots having upward curvature. Analysis of modified S-V equations which accounts both static and dynamic quenching allows calculating bimolecular quenching rate constant. The bimolecular quenching reactions are found to be significantly larger. Further finite sink approximation model is invoked so as to check whether reactions are diffusion limited. The extents of these rate parameters demonstrate that positive deviations in the Stern-Volmer (S-V) plot are because of the presence of apparent static and dynamic quenching process.

10 illus, 3 tables, 40 ref

042470   RAJ R K (Electronics and Communication Engineering Dep, Engineering Coll, Ajmer - 305 025, Email: rajeshraj@ecajmer.ac.in) : SIW cavity-backed patch antenna for X-band applications. Indian J Pure appl phys 2020, 58(3), 164-7.

In this paper, substrate integrated waveguide (SIW) based cavity-backed patch antenna is presented. The performance of the proposed antenna in terms of gain and cross-polarization levels is improved by inserting a pair of shorting pins in nearby non-radiating edges of the rectangular patch. The maximum gain realized for the proposed design is 8.6 dBi at the resonant frequency of 10 GHz with 95 % efficiency, which is much higher than that of the conventional patch antenna. The proposed design exhibits an impedance bandwidth of 870 MHz, ranging from 9.59 GHz to 10.46 GHz. Moreover, the proposed design owns unidirectional and stable radiation characteristics in the boresight direction. The simulated results are validated with fabrication and measurement which show a close agreement with each other.

4 illus, 2 tables, 15 ref

042469   KHAN M U, FANAI A L, RAI S (Physics Dep, Mizoram Univ, Aizawl - 796 004, Email: srai.rai677@gmail.com) : Spectroscopic properties of Sm³⁺ and CdS co-doped in sol-gel silica glass. Indian J Pure appl phys 2020, 58(3), 157-63.

Sm³⁺- doped silica glass co-doped with CdS nanoparticles have been prepared by sol-gel method. FTIR spectra of the samples at different annealing temperatures show the gradual removal of hydroxyl group. XRD pattern shows crystalline nature of the silica host along with CdS peak. The optical absorption and fluorescence properties have been investigated using Judd-Ofelt theory. The Judd-Ofelt intensity parameters have been obtained from the absorption spectrum following the trend Ω₂ > Ω₄ > Ω₆ and the large value of Ω₂ indicates covalency of the rare earth bonding. Under excitation with 370 nm, photoluminescence peaks have been observed in the green, yellow, orange and red region as a result of radiative relaxation from the ⁴G_5/2 state.

7 illus, 4 tables, 38 ref

042468   KANTHIMATHIA M, AMUTHAB R, VAITHIYANATHANC D, SHARMA S S (Electronics and Communication Engineering Dep, Sri Sairam Engineering Coll, Chennai - 600 044, Email: kanthimathi.ece@sairam.edu.in) : Energy efficient decision fusion for differential space-time block codes in wireless sensor networks. Indian J Pure appl phys 2020, 58(2), 147-56.

The non-coherent techniques that do not require the channel state information have gained significant interest especially when multiple transmitter and receiver nodes are involved in communication. In this paper, we analyze the energy efficiency of differential and coherent cooperative Multiple-input Multiple-output (MIMO) method using space-time block codes (STBC). We exploit the benefits of the extension of the observation interval of differential STBC to three blocks in Wireless sensor networks (WSNs). We propose an energy efficient decision fusion (EEDF) algorithm in WSNs which utilizes the benefits of Multiple symbol differential detection (MSDD) decision fusion by optimally selecting the ring amplitude of the differential amplitude phase shift keying (DAPSK) constellation. The simulation results show that processing differential multiple symbols provides significant energy saving compared to the conventional two-symbol processing. Furthermore, significant performance gain is achieved for the proposed algorithm compared to 16 DPSK MSDD decision fusions.

13 illus, 5 tables, 24 ref

042467   THORAT H N, MURUGKAR A (Physics Dep, Dr Babasaheb Ambedkar Marathwada Univ, Aurangabad - 431 004, Email: phys.hnthorat@gmail.com) : Thermo-acoustical properties of carbamide and N, N-dimethylformamide binary mixture at different temperatures. Indian J Pure Appl Phys 2020, 58(3), 141- 6.

Density, viscosity and ultrasonic velocity of binary mixture of carbamide with N, N-dimethylformamide have been measured at temperatures of 10 °C, 20 °C, 30 °C and 40 °C and at atmospheric pressure. From these experimental measurements the thermo-acoustical parameters such as acoustic impedance (Z), adiabatic compressibility (β), relaxation time (τ), intermolecular free length (L_f) and Gibb’s free energy of activation (DG) have been calculated. The variations in these parameters have been correlated to derive the intermolecular interactions taking place between the species of present binary mixture.

8 illus, 3 tables, 40 ref

042466   VASHIST P , PATIAL B S, ANJALI , TRIPATHID S K, THAKUR N (Physics Dep, Government Coll Sunni, Shimla - 171 301, Email: bspatial@gmail.com) : Iso-conversional study of crystallization activation energy of amorphouscrystallization transformation for Se₇₉Te₂₀Pb₁ glass using non-isothermal differential scanning calorimetry technique. Indian J pure appl phys 2020, 58(3), 135-40.

The ternary Se₇₉Te₂₀Pb₁ chalcogenide glass is prepared using melt quenching technique. Differential scanning calorimetry technique (DSC) is used to investigate the kinetics of crystallization of amorphous-crystallization (a-c) phase transformation under non-isothermal conditions at three different heating rates; 5, 10 and 15 ° C min^-1. The variation of crystallized activation energy (E_c) with crystallized fraction (ϰ) and hence, with temperature (T) is investigated using five iso-conversional methods namely KAS, OFW, Friedman, Tang and Chen and Starink. It is found that E_c is not constant but vary with ϰ as well as T. Thus, the iso-conversional analysis of investigated glass indicates that the assumption of constant E_c is not appropriate.

8 illus, 1 tables, 39 ref

042458   KUMARI CH S , RAO N S , BEGHAM SK A, BABU S S , RAO G D,RAO K V (KL Deemed to be Univ, Guntur District - 522 502, Andhra Pradesh) : Formulation techniques of lipid based nanoparticles: SLN/NLCS, its evaluation and applications. Int J Res Pharm Chem 2020, 10(1), 111- 24.

This review represents the usage of SLN and NLCs regarding their advantages, formulation methodology, characterization and applications. If suitably investigated, SLNs/NLCS may open new prospects in therapy of complex diseases. Solid lipid nanoparticles (SLN) were formulated at the emergence of the 1990s as a replaced carrier system to emulsions, liposomes and polymeric nanoparticles. SLN are aqueous colloidal dispersions, the matrix of which consists of solid biodegradable lipids. Nano structured lipid carriers (NLCs) are drug-delivery systems consists of both solid and liquid lipids as a core matrix. It was shown that NLCs has some advantages for drug therapy over conventional carriers, including higher solubility, the ability to enhance storage stability, improved permeability and bioavailability, reduced adverse effect, prolonged half-life, and tissue-targeted delivery. SLN and NLCs are manufactured by techniques like high pressure homogenization, solvent diffusion method ultrasonication, solvent emulsification etc. Both SLN/NLCs have applications in for parenteral, nasal, respiratory, ocular, rectal, and topical, in chemotherapy, etc.

8 tables, 28 ref

040483   SANGEETHA A, SHARMILA T (Chemical Engineering Dep, Periyar Maniammai Institute of Science & Technology, Thanjavur - 613 403, Tamilnadu, Email: asangeetha@pmu.edu) : Hydrodynamic behaviour of a laboratory scale hybrid upflow anaerobic sludge blanket reactor. Indian J Chem Technol 2020, 27(2), 161-5.

A laboratory study has been conducted to assess the performance of Hybrid Upflow Anaerobic Sludge Blanket (HUASB) Reactor in treating paper mill effluent. The hydraulic retention time (HRT) is maintained at 12 h. The organic loading rates (OLR) are calculated on the basis of COD inlet in the reactor for different flow rates and the maximum OLR is found to be 12 kg COD/m³.d. The maximum reduction of TCOD and SCOD is found to be 92 and 88 % respectively. The maximum biogas production is 4.85m³/m³.d. The hybrid up flow anaerobic sludge blanket reactor is found to be develop granules in two different inoculum sludges in early granulation and start-up has been studied. The study reveals that earlier start-up and granulation of biomass can be achieved using mixed sludge (cow dung and effective microorganisms (EM)). Scanning electron microscope (SEM) study of the granules shows predominance of Methanosarcina and Methanothrix type of species on the surface of granules. The process efficiency and biogas production is found to be increased with an increase in the organic loading rate. Methanobacterium and Methanosaeta bacteria were dominant at the end of start-up whereas Methanosarcina, cocci and rods are predominant at the end of performance studies. The size of the granules is 1 to 3 mm and exhibite good settleability. Residence time distribution (RTD) study show mixed regime flow behaviour at the end of performance study. Dispersion numbers greater than 0.2 show the reactor attained ideal mixed flow regime.

9 illus, 1 table, 20 ref

040440   VELRAJ G, KARTHIKEYAN S, CHITRA A (Physics Dep, Dr. Ambedkar Government Arts Coll, Chennai-600 039, Tamil Nadu, Email: physicskarthik@gmail.com) : Mineralization changes substituted type B carbonate of PO₄³⁻ ion in the bone minerals of an archaeological sample studied using fourier self deconvolution technique. Indian J Biochem Biophys 2020, 57(3), 277-82.

The aim of this study was to describe the compositional changes in the archaeological specimen using FTIR. Fourier deconvolution was applied in the carbonate (500-650 cm⁻¹), phosphate (900-1200 cm⁻¹), and in the amide region (1700-1600 cm⁻¹). The deconvolution of the spectra in the phosphate region 1200-900 cm⁻¹ reveals six components 960 cm⁻¹, 1010 cm⁻¹, 1020 cm⁻¹, 1030 cm⁻¹, 1110 cm⁻¹ and 1120 cm⁻¹. The bone mineral such as CO₃²⁻, PO₄³⁻ particle, collagen, and organic materials were studied in detail from the infrared spectra. The computed parameters such as collagen development, mineralization index, C/P proportion, crystalline index, and maturing of bone help us in characterizing the bone samples. The Low estimation of C/P proportion resulted in changes in Type B carbonate (PO₄³⁻) substitution. The absence of phosphate band ~1100 cm⁻¹ and formation of β sheet structure were observed in the samples studied. Increased level of mineralization resulted in the increased in the crystalline nature of the bone samples. The study indicates the utilization of FTIR using self deconvolution technique which helps in understanding the compositional changes in the archaeological sample.

2 illus, 6 tables, 23 ref

040439   CHEN Y, CHANG W, ZHU X, WANG R, TIAN F (Zhoukou Normal Univ, Zhoukou-466 001, China, Email: chen-yh75@163.com) : Fluorescence quenching and measurement of captopril in pharmaceuticals. Indian J Biochem Biophys 2020, 57(3), 270-6.

The mechanism of fluorescence quenching of the product S in the presence of captopril was studied. The maximum emission wavelength of the product S was at 405 nm with the excitation wavelength at 316 nm. It was found that the fluorescence quenching of product S was of a static one and the binding constant (K) was 9.29 × 106 J mol^-1. A linear relationship was found between the relative fluorescence intensity of the product S-captopril system and the concentration of captopril. Under optimum conditions, the linear range of the calibration curve for captopril was 2~160 μg L^-1 with a correlation coefficient of 0.9926 and a detection limit of 0.1 μg L^-1. The relative standard deviation (RSD) was 3.60 %. The analytical results of the pharmaceuticals obtained by this novel method agreed quite well with those obtained by the KIO3 titrimetry.

6 illus, 4 tables, 29 ref

044438   KAKKAR S, ARORA P K, GOYAL G (Radiation Oncology Dep, Max Super Speciality Hospital, Mohali? 160 055, Punjab, Email: sajal_kakkar@ rediffmail.com) : Punjabi version of the European Organization for research and treatment of cancer quality of life questionnaire‑OES18 and quality of life questionnaire‑OG25 modules for quality of life assessment. J Can Res Ther 2020, 16(1), 102-4.

Health‑related quality of life (HRQOL) assessment plays an important role in the decision‑making process in oncology. The aim of the study was to translate European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire (QLQ) OES18 and OG25 in Punjabi language for HRQOL assessment of patients diagnosed with esophagus and esophagogastric malignancies. The EORTC translation guidelines were duly followed to translate QLQ‑OES18 and OG25 into Punjabi language. Each set of questionnaire was independently translated by two forward translators, followed by backward translation of the reconciled version by two independent translators. The final version was submitted to the EORTC Translation Team and served to the patients for the pilot testing. The questionnaire was administered to ten patients each of esophagus and esophagogastric malignancies who were evaluated and treated at our hospital. Every patient underwent an interview to check if any of the questions was difficult, uncomfortable, or upsetting to answer. Their concerns were recorded as per the template provided by the EORTC team and due changes done if required. The EORTC QLQ‑OES18 and OG25 questionnaire has been translated to Punjabi language and subsequently approved for usage.

7 ref

040348   DESAI M V, SHAH S N (Electronics Engineering Dep, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat - 395 007, Email: mvd.svnit@gmail.com) : An observational review on influence of intense geomagnetic storm on positional accuracy of NavIC/IRNSS system. IETE Tech Rev 2020, 37(3), 281–95.

The positional accuracy of Navigation with the Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) in the low latitudes of the Indian region during the intense geomagnetic storm of 8 September 2017 being reported first time. The existence of an intense geomagnetic storm is verified with several geomagnetic indices and interplanetary field parameters. The Total Electron Content (TEC) maps from the International GNSS Service (IGS) data and the thermosphere O/N2 ratio maps from the Global Ultra Violet Imager (GUVI) are also used in the study. The one week of data (3–9 September 2017) are collected based on equatorial region (Trivandrum) and Equatorial Ionization Anomaly (EIA) region (e.g. Surat, Bombay, Hyderabad and Gandhinagar), from India, using the Accord NavIC/IRNSS dual-frequency (L5 and S-band) receivers. For the intense storm day, a comparative study is being carried out for TEC, ionospheric delay and positional accuracy for L5 band. The observations perceive the positive impact in the equatorial region while the negative impact for EIA region, with reference to quiet days of the observed week. The average $~$ 70 % and further $~$ 25 % NavIC/IRNSS system positional accuracy is improved by applying ionospheric correction and augmenting NavIC/IRNSS with GPS system respectively. This study is very much important in satellite-based navigation application for Precise Point Positioning (PPP).

11 illus, 4 tables, 25 ref

040346   SINGH A D, SOOD B Y R, DEEPAK C (National Institute of Technology, Hamirpur - 177 005, Email: digambar.singh1986@gmail.com) : Recent techno-economic potential and development of solar energy sector in India. IETE Tech Rev 2020, 37(3), 246–57.

Solar energy is an abundantly available free eco-friendly renewable energy source (RES). Solar energy holds great potential for providing a solution to the long-standing energy issues continuously faced by developing countries like India. The gap between power generation and demand is widening at an alarming rate in developing countries, especially in India. This gap can be filled by expansion of solar energy generation which has adequate potential to provide electricity. The current trends towards technical and economical potential of solar energy in India considering availability, current scenario, promotion scheme, recent investment, and strategies adopted for solar power generation has been presented in this paper. A detailed description of policies put forward by the Indian government in various states to encourage solar generation has been presented. In addition, the major achievements and future potential of RESs have also been described.

13 illus, 6 tables, 51 ref

040331   DAS A C, DWARI S, BISWAL S P ( Electronics Engineering Dep, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad, Jharkhand - 826 004, Email: sonika.priyadarsini8@gmail.com) : Cavity model-based analysis of field propagation in a six-port riblet-type directional coupler. IETE Tech Rev 2020, 37(1), 24–35.

A cavity model-based analysis of electric field propagation inside a six-port Riblet-type directional coupler has been presented in this paper. Though cavity modeling technique is not very new and was previously applied to different rectangular waveguide-based passive networks to find their network parameters, for the first time it has been used here to analyze the field propagation inside a six-port Riblet-type directional coupler. From the analysis, the frequency response of the network has been estimated. Since the main objective of this work is to analyze the field propagation inside a passive network, not to present another network, a six-port Riblet-type directional coupler that is already proposed in literature has been considered. The numerical analysis has been verified by comparing the scattering parameters data obtained from the cavity model analysis with CST Microwave Studio simulation data and measured data available in the literature.

17 illus, 14 ref

040329   YADAV V K (Vikram Sarabhai Space Centre, Thiruvananthapuram, Kerala - 695 022, Email: vkyadavcsp@gmail.com) : Alfvèn wave detection at first lagrangian point with magnetic field measurements∗. IETE Tech Rev 2020, 37(1), 3–11.

Plasma wave is one of the special features of any space plasma system. One such wave, namely Alfvèn wave, is a magnetic disturbance which during its propagation picks ions from the background plasma in such a way that the ions stick to the magnetic field lines moving along the propagation direction. Alfvèn waves are generated in the presence of a strong background magnetic field and are observed emanating from the Sun and are predicted to exist in the interplanetary medium, interstellar medium and supergiant stars. A number of exotic phenomena, including generation of a variety of plasma waves, take place in the vicinity of the sun. However, the in-situ measurements are not possible due to the hostile conditions existing near the Sun. The solar plasma waves emanating from the Sun spread out in all directions and moves towards Earth also. The first Lagrangian (L1) point is an ideal location to study the solar plasma processes remotely. Magnetic field measurements from two missions WIND and ACE operating at the L1 point are analysed to decipher the signatures of plasma waves existing there. The effect of Alfvèn wave on the local magnetic environment is clearly observed from the magnetic field measurements along with the solar wind parameters at the L1 point which are presented in this paper.

13 illus, 1 table, 23 ref

040319   THAMIZHARASI A, JAYASUDHA J S (Computer Science and Engineering Dep, Mohandas Coll of Engineering and Technology, Trivandrum, Kerala, Email: radhatamil2000@gmail.com) : An illumination pre-processing method using the enhanced energy of discrete wavelet transform for face recognition. IETE J Res 2020, 66(2), 160–71.

Automatic face recognition is useful in a wide range of applications. The accuracy of a face recognition system is adversely affected due to illumination variations. This study presents an illumination pre-processing method, “Enhanced Energy Discrete Wavelet Transform”, to increase recognition accuracy of front view faces under varying illuminations. This method is implemented as follows. A two-dimensional Discrete Wavelet Transform (2D DWT) decomposes the original image into four frequency sub-bands, namely low-low, low-high, high-low and high-high. The energy of each subband is computed. A weighting scheme is employed to increase the energy. The weighting scheme computes weight of sub-band based on its energy and threshold. The new sub-bands are obtained by multiplying sub-band, weight and weighting factor. Then, the new four sub-bands are added to create enhanced energy DWT image. The face recognition is carried out using Gabor magnitude features. The experiments are conducted in facial images of Yale, Pose Illumination Expression (PIE) and Extended Yale B. The results proves that low-low sub-band has maximum weight. The performance analysis is carried out using different threshold and weighting factor values. The weighting factor increases energy of low-low sub-band. The analysis of energy enhancement shows increase in energy of 20.96 % and 31.88 % in CMU PIE and Extended Yale B, respectively. The increase of energy improves the brightness of image. The recognition accuracy in CMU PIE and Extended Yale B is 99.02 % and 99.82 %, respectively. The comparative analysis with the state-of-the-art methods proves that the proposed method is an effective illumination pre-processing method.

6 illus, 7 tables, 26 ref

040314   ROY P, BERA J N, SARKAR G, CHOWDHURI S (Applied Physics Dep, Calcutta Univ, Kolkata, West Bengal - 700 073, Email: roypritha09@gmail.com) : Performance evaluation and filter design aspects of single-phase inverter under different loading conditions. IETE J Res 2020, 66(1), 103–14.

This paper describes the power quality issues at the output of an inverter. The role of a filter and its design aspects at the output of a single-phase inverter in order to minimize the different harmonic content associated with various modulation schemes is illustrated. The relationship of the cut-off frequency of a second-order filter along with the switching frequency as well as on the type of modulation is established. The procedure to choose the values of L and C components of LC filter to reduce the overall THD following the IEEE std.1547 is also illustrated. The performance of the total system for different linear and non-linear loading conditions along with variations in input voltage and output loading is evaluated. The entire system and its performance is verified using MATLAB-based simulink models and satisfactory results are obtained.

17 illus, 11 tables, 20 ref

040313   TUMMALA A S L V, ALLURI H K R, RAMANARAO P V (Electrical & Electronics Engineering Dep, GMR Institute of Technology, Rajam, Andhra Pradesh - 532 127, Email: ayyarao.tummala@gmail.com) : Optimal control of DFIG wind energy system in multi-machine power system using advanced differential evolution. IETE J Res 2020, 66(1), 91-102.

The Vector controlled doubly fed induction generator (DFIG) wind energy system in a multi-machine power system is very sensitive to faults on transmission lines and thus affects the stability of the system. The performance of vector controlled DFIG highly depends on PI controller parameters. The objective of this paper is to optimize the performance of vector controlled DFIG in multi-machine power systems under faulty conditions by tuning the parameters using advanced differential evolution algorithm. An objective function is formulated, which drives the system with good voltage profile, reduced power oscillations under faulty conditions. The parameters of PI controller are tuned using Composite Differential Evolution algorithm. Simulations are performed on a two area benchmark problem in Matlab/Simulink. The simulation results of the optimized DFIG wind energy system are compared with the actual existed system. The simulation results show that the overall performance and stability of the optimized system are enhanced.

24 illus, 1 table, 39 ref

046324   SINHA N P (Magdh Univ, Bodh Gaya- 824 234, Email: nagmaniprasadsinha@gmail.com) : Estimation of laser linewidth. J Pure Appl & Ind Phys 2020, 10(11), 16-21.

The laser linewidth for 514.5 nm, 501.7 nm, 496.5 nm, 488 nm, 476.5 nm has been estimated by applying the classical formula. The linewidth corresponding to various length of resonance cavity as well as for the various output power has been estimated for each value of he wavelength. We have used the formula ∆$\omega$_C= c$\mathrm{\delta }$c/2L and ∆$\omega$_L = h$\omega$0.(∆$\omega$_c)² / 2P  where ∆$\omega$_c is cavity resonance width ∆$\omega$_L is line width for the laser output and $\mathrm{\delta }$c=1-ܴR₁R₂ where ܴ R₁ and ܴR₂ are the power reflection coefficient of the cavity minors at the laser frequency.

7 illus, 5 ref

046323   NARAYAN R, KARTHIKEYAN L, AISHA SIDHICK S M, PRASAD M V N, SHEKAR G L (ISRO, Karnataka- 560 008, Email: narkal@gmail.com) : Aerospace MEMS pressure transducer packaging techniques to withstand surge pressure and radiation. J Pure Appl & Ind Phys 2020, 10(6), 7-15.

In the field of aerospace engineering pressure measurement is playing a vital role in terms of health monitoring of the system and control application. MEMS technology based pressure sensors are extremely appealing for optimizing the size and mass of aerospace system sensors with improvement in their functional performance. In view of the harsh and remote environment of aerospace application, reliability and repeatability are the crucial issues that are holding back MEMS from playing a larger role in space applications. The presently used sensors for pressure measurement have limitations concerning sensitivity, accuracy and long-term stability. The aerospace application involving MEMS based pressure sensors is of particular interest in this study and analysis. However, it has several challenges namely viz., efficient packaging, interface, immunity to radiation and tolerances on assembly and final testing and evaluation. These sensors have to work under harsh and volatile environments, which demands utmost reliability, and long-term performance stability. In launch vehicle and ground testing of propulsion systems application, the performance of this pressure sensors is very critical to analyse with respect to performance of the vehicle and its subsystems. Hence, the design and packaging of MEMS transducers have to be done in such a way that it has to withstand all the fight against the environmental conditions. In this article, the impact of surge pressure and radiation effects on MEMS pressure transducer along with the design improvement techniques are presented.

5 illus, 12 ref

044326   DURGA G P, RAJESH A N, KUMAR T V L (Physics Dep, SRM Institute of Science and Technology, Kattankulathur, Tamil nadu, Email: lkumarap@hotmail.com) : Projections of CMIP5 evaporation data sets under future climate change scenarios and comparison with estimates from the observations over peninsular India. J Agrometeorol 2020, 22(2), 186-90.

Present study commences from the time series analysis of evaporation data sets obtained from the Coupled Modeled Inter comparison Project of Phase 5 (CMIP5) for the study period 1979 to 2100 under the RCP 4.5 and 8.5 emission scenarios over Interior Peninsular region during the Northeast monsoon (October to December) period. Further, a comparative analysis has been carried out with the evapotranspiration (ET) estimated from the Hargreaves and Samani (1982) using the temperature data of India Meteorological Department for the period 1979 to 2005. Our results show that evaporation trends are increasing with more prominence in RCP 8.5 scenario. This increase in evaporation has been attributed to increase in air temperature which is an undisputed fact under future climate change scenario. Different climate models of CMIP5 show mixed response by displaying the positive and negative correlations with the Hargreaves ET over the study region. The results of the study will be useful in understanding the bias between the modeled data sets and the estimates of ET from the observations.

4 illus, 1 table, 15 ref

044307   KUMUTHINI R, SELVARAJAN P, SELVARAJ S (Physics Dep, Sadakathullah Appa Coll, Tirunelveli, Email: erduraimuth@gmail.com) : Growth impedence and SHG studies of aluminium flouride doped sodium fluoro antimonate crystals. J Adv Sci Res 2020, 11(1), 232-5.

Single crystals of sodium fluoro antimonate and aluminium fluoride doped sodium fluoro antimonate were grown by solution method with slow evaporation technique. Complex impedance has real part of impedance (Z') and imaginary part of impedance (Z'') and these values have been measured using an impedance analyzer at different frequencies and temperatures. Variations of real and imaginary part of impedance (Z') and (Z'') with frequency for ASFA13 crystal at different temperatures are plotted. Nyquist plots have been drawn between Z' and Z'' and these plots are presented. From plots the grain boundary resistance for the sample are obtained to be 50 x10³ â„¦ at 30 ^°C, 10x10³ â„¦ at 50 ^°C, 5x10⁷ â„¦ at 70 ^°C and 1.3x10⁸ â„¦ at 90 ^°C. The relative second harmonic generation (SHG) efficiency was measured by Kurtz powder technique using an Nd: YAG laser operating at 1064 nm. The relative SHG efficiency value of ASFA13 sample found to be 0.65 times that of KDP.

5 illus, 15 ref

044298   SELVAKUMAR S, RAJASEKARAN T R, SABARINATHAN V, RAJASEKHAR R V J (Renewable Energy Science Dep, Manonmaniam Sundaranar Univ, Abishekapatti, Tirunelveli, Email: kumartv188@gmail.com) : Experimental study on the performance of solar collector with nano sized materials. J Adv Sci Res 2020, 11(1), 187-90.

Carbon and metal oxide based coatings are widely used for photo thermal conversion. The collectors collect the sun’s energy, transform this radiation into heat, and then transfer this heat into a fluid, water or air, which has many applications in household and industries. In the present investigation, carbon and metal oxide based coatings were prepared and the coatings were affected on metal absorbers. The coatings on the metal absorbers were characterized and it was found that the sizes of constituents in the coatings were in nanoranges.  The coated absorbers were integrated in solar collectors and the thermal efficiency of the solar heating collectors was experimentally found. It was found that the thermal enhancements in working fluid varied from 18.4 to 25.5 ⁰C, 19.0 to 26.9 ⁰C and 22.3 and 29.9 ⁰C in solar collectors with three different nano-structured absorbers. It was also found that the thermal performances of these solar heating collectors were as per standard specifications. The research revealed that the thermal performances of the solar heating collector with nano-structured absorbers were 1.2 %, 1.4 % and 1.5 % higher than that of the conventional solar heating collector. On the basis of the research outcomes of the present investigation, it could be concluded that the nano-sized carbon and metal oxide coated absorbers would be utilized in solar collectors so as to harvest their enhanced thermal performances.

1 illus, 4 tables, 11 ref

044285   BAZEERA A Z, SELVARAJ S, MOHAMED A S (Physics Dep, M.D.T.Hindu Coll, Tirunelveli, Email: meeran.jull@gmail.com) : First order hyperpolarizability, homo-lumo and vibrational analysis of l-isoleucine, l-isoleucine maleate (lim) and l-isoleucine oxalate (lio) by DFT methods. J Adv Sci Res 2020, 11(1), 88-93.

In this work, the molecular structure, harmonic vibrational frequencies of L- isoleucine (LI), L-isoleucine Maleate (LIM) and L-isoleucine Oxalate (LIO) have been investigated. The optimized molecular geometries, first order hyperpolarizabilities and vibrational frequencies have been calculated using B3LYP/6-31G. The HOMO and LUMO energy calculation reveals that the charge transfer exist within the molecules. The Fourier Transform Infrared (FT-IR) of LIM and LIO are recorded in the regions 4000-400 cm^-1.  The observed and calculated wave numbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectra.  

2 illus, 6 tables, 16 ref

044284   RINU S K, QUEEN M A J, UDHAYA P A (Physics Dep, Holy Cross Coll, Nagercoil, Email: crisrinu2@gmail.com) : Synthesis, structural characterization and antibacterial applications of calcium nanoparticles. J Adv Sci Res 2020, 11(1), 83-7.

Inorganic nanoparticles for biomedical applications have undergone extensive investigations in recent years. Among different inorganic drug carriers, calcium carbonate (CaCO₃) nanoparticles show unique advantages due to their ideal biocompatibility and the potential as delivery system for loading different categories of drugs. Calcium derivatives have great potential to be applied in bone and teeth related disorders due to their ideal biocompability with the natural bone and teeth structures and the biodegradability as well. Calcium carbonate and calcium hydrogen phosphate nanoparticles are synthesized by wet chemical precipitation method. X-ray diffraction studies are made to determine the structural properties. The optical behavior of both calcium nanoparticles are studied by UV characterization. The band gaps of both the samples are also found.  The antibacterial activity was tested on Gram negative and Gram positive bacterial strains.

6 illus, 1 table, 12 ref

040152   INDUMATHI K, PRAVEENA G (Physics Dep, PSGR Krishnammal Coll for Women, Coimbatore - 641 004, Tamil Nadu, Email: gopalpraveena@gmail.com) : Absorption spectra of the backbone tailored GA and CT nucleic acid strands. Adv Appl Res 2020, 12(1), 12-6.

The excitation properties of peptidic chain tailored single strand nucleic acids such as GA (purine strand) and CT (pyrimidine strand) was studied using Time Dependent Density Functional Theory (TDDFT). The existence of ground state geometries of the GA and CT were confirmed by the optimization at B3LYP/6-31G* level of theory from DFT method. The singlet excitation calculations were also made for considered systems at the same level of theory used for optimization. In order to understand the effect of tailoring the peptidic chain as a backbone instead of phosphate group in natural nucleic acid constructs, the various excited electronic properties such as HOMO-LUMO energy gap (E_gap ), vertical excitation energy (VE), oscillator strength (OS) and UV-vis gap and DOS spectrum were calculated. The results revealed that the absorption properties of both strands significantly enhanced when compared to the natural nucleic acid strands, which suggested that the replacement of the DNA backbone had great potential towards improved excitation properties for electronic and optical related applications.

4 illus, 1 table, 11 ref

039950   INDUMATHI K, PRAVEENA G (Physics Dep, PSGR Krishnammal Coll for Women, Coimbatore - 641 004, Email: gopalpraveena@gmail.com) : Absorption spectra of the backbone tailored GA and CT nucleic acid strands. Adv Appl Res 2020, 12(1), 12-6.

The excitation properties of peptidic chain tailored single strand nucleic acids such as GA (purine strand) and CT (pyrimidine strand) was studied using Time Dependent Density Functional Theory (TDDFT). The existence of ground state geometries of the GA and CT were confirmed by the optimization at B3LYP/6-31G* level of theory from DFT method. The singlet excitation calculations were also made for considered systems at the same level of theory used for optimization. In order to understand the effect of tailoring the peptidic chain as a backbone instead of phosphate group in natural nucleic acid constructs, the various excited electronic properties such as HOMO-LUMO energy gap (E ), vertical excitation energy (VE), oscillator strength (OS) and UV-vis gap and DOS spectrum were calculated. The results revealed that the absorption properties of both strands significantly enhanced when compared to the natural nucleic acid strands, which suggested that the replacement of the DNA backbone had great potential towards improved excitation properties for electronic and optical related applications.

4 illus, 1 table, 11 ref

039382   ASMI H, YEB F B, BOUZEKRAOUI Y, BONUTTI F (Physics Dep, Mohammed V Univ, Rabat Morocco, Email: youssef0fsr@gmail.com) : Optimization of scatter correction method in samarium-153 single-photon emission computed tomography using triple-energy window: A monte carlo simulation study. Indian J Nucl Med 2020, 35(3), 210-5.

In single‑photon emission computed tomography imaging, the presence of scatter degrades image quality. The goal of this study is to optimize the main‑ and sub‑energy windows for triple‑energy window (TEW) method using Monte Carlo SImulating Medical Imaging Nuclear Detectors (SIMIND) code for samarium‑153 (Sm‑153) imaging. The comparison is based on the Monte Carlo simulation data with the results estimated using TEW method. Siemens Symbia gamma‑camera equipped with low‑energy high‑resolution collimator was simulated for Sm‑153 point source located in seven positions in water cylindrical phantom. Three different main‑energy window widths (10 %, 15 %, and 20 %) and three different sub‑energy window widths (2, 4, and 6 keV) were evaluated. We compared the true scatter fraction determined by SIMIND and scatter fraction estimated using TEW scatter correction method at each position. In order to evaluate the image quality, we used the full width at half maximum (FWHM) computed on the PSF and image contrast using Jaszczak phantom. The scatter fraction using TEW method is similar to the true scatter fraction for 20 % of the main‑energy window and 6 keVsub‑energy windows. For these windows, the results show that the resolution and contrast were improved. TEW method could be a useful scatter correction method to remove the scatter event in the image for Sm‑153 imaging.

7 illus, 5 tables, 27 ref

039344   ASMI H, BENTAYEB F, BOUZEKRAOUI Y, BONUTTI F, DOUAMA S (Physics Dep, Mohammed V Univ, Morocco, Email: youssef0fsr@gmail.com) : Energy window and collimator optimization in lutetium-177 single-photon emission computed tomography imaging using monte carlo simulation. Indian J Nucl Med 2020, 35(1), 36-9.

In lutetium‑177 (Lu‑177) single‑photon emission computed tomography (SPECT) imaging, the accuracy of activity quantification is degraded by penetrated and scattered photons. We assessed the scattered photon fractions in order to determine the optimal situation and development of correction method. This study proposes to compare the image quality that can be achieved by three collimators. Siemens Medical System Symbia fitted with high‑energy (HE), medium‑energy (ME), and low‑energy high‑resolution collimators was simulated using the SIMIND Monte Carlo code simulation code. Counts were collected in three different main‑energy window widths (20 %, 15 %, and 10 %) for Lu‑177 point source. Primary and scattered point spread functions and also geometric, penetration, scattering were drawn and analyzed. In Lu‑177 imaging, a 20 % of main‑energy window and ME collimator were found to be optimal. HE collimator can be used when the resolution is not required. 

6 illus, 3 tables, 13 ref

039343   AL-SHAKHRAH I A-R (Physics Dep, Jordhan Univ, Amman, Jordan, Email: issashak@yahoo.com) : Determination and comparison of radiation absorbed dose to the blood, by applying different techniques, for patients, suffering from differentiated thyroid cancer. Indian J Nucl Med 2020, 35(1), 28-35.

Radiation absorbed dose to the red bone marrow, in the therapy of differentiated thyroid carcinoma (DTC) with 131I (radioiodine), cannot be measured directly. The absorbed dose to the blood seems to be a good first- order approximation of the radiation absorbed dose to the hematopoietic system and a better means to quantify exposure from therapy than the total amount of activity administered. The aim of this research was to determine the radiation absorbed dose to the blood, for patients suffering from differentiated thyroid cancer. Twenty seven patients, 22 women and 5 men, suffering from DTC were enrolled in this study. We applied four formulas and we compared between the estimated values of absorbed dose that were obtained by three formulas and those that obtained by fourth (standard one). All the values of absorbed dose that obtained by one of the techniques were regularly highly estimated, even though they have an excellent correlation (99 %) with the standard value. Highly overestimated or highly underestimated results that can be obtained by certain method or technique are not desirable, because they tend to exaggerate, by increasing or decreasing, the radiation protection procedures.o convert the values of absorbed dose from S.I unit (mGy/MBq) to traditional unit (rad/mCi), we can simply multiply the values that expressed in S.I units by a factor of 3.7, and we don’t need to apply complicated formulas, which were applied by other researches.

6 illus, 1 table, 35 ref

039163   ELKHALIG M M H (Physics Dep, Qassim Univ, Saudi Arabia, Email: 141261@qu.com.sa) : First principles investigation of electronic and magnetic - properties of double Perovskites A₂NRuO₆ (A₂=Ba₂, BaLa; N=V, Cr and Fe). Indian J Pure Appl Phys 2020, 58(02), 120-6.

The electronic and magnetic properties of double perovskites A₂NRuO₆ (A₂ = Ba₂, BaLa; N = V, Cr, Fe) have been investigated using the first-principles density-functional theory (DFT) within the generalized gradient approximation (GGA) and GGA+U schemes. All compounds of (A₂ = Ba²⁺) and doped (A₂ = Ba²⁺La³⁺) crystallize in a cubic structure with (Fm-3m) space group. The GGA results of (A₂ = Ba²⁺) predict half-metallic (HM), semiconductor and metallic character when (N = V, Cr, Fe), respectively which are completely stabilize at the HM nature within (A₂ = Ba²⁺La³⁺) compounds. By including the exchange-correlation energy in GGA+U scheme, all compounds show a HM property, except for Ba₂FeRuO₆ which appears as an insulating material. In addition, GGGA and GGA+U calculations of spin magnetic moments suggest a ferrimagnetic (FI) character for A₂NRuO₆ (N = V and Cr), switch to a ferromagnetic (FM) nature when N = Fe. It is found that the two ions of N³⁺– Ru⁵⁺ (A₂ = Ba₂) and N³⁺– Ru⁴⁺ (A₂ = BaLa) are governed by the antiferromagnetic interactions N³⁺ (3d)–O^2– (2p)–Ru⁵⁺∕ Ru⁴⁺ (4d) in high∕ low spin magnetic moments states.

6 illus, 5 tables, 22 ref

039162   CHANDRA A, CHANDRA A, DHUNDHEL R S (Shri Shankaracharya Institute of Professional Management and Technolog, Raipur- 492 015, Email: archanachem.chandra@gmail.com) : Electrolytes for sodium ion batteries: A short review. Indian J Pure Appl Phys 2020, 58(02), 113-9.

Synthesis routes and ion conduction phenomenon in sodium ion conducting solid electrolytes have been reported in the present chapter. The different experimental and theoretical tools have been explained for preparation and ion conduction mechanism of solid electrolytes. The working principle of some polymer electrolyte based conductors has been explained.

10 illus, 16 ref

039159   ENTESHAN B, USHAKIRAN, JOHN T (Physico-Mechanical Metrology Section, New Delhi- 110 012, Email: bushra3024@gmail.com) : Automation for calibrating a precision current source by Ohm's law method. Indian J Pure Appl Phys 2020, 58(02), 99-105.

We present the design of a program developed in LabVIEW for automating the calibration of a precision current source by the Ohm’s law method. The program in addition to automating the instrument setup and measurement performs uncertainty computations in accordance with guide to the expression of uncertainty in measurement (GUM) and produces the calibration report and saves a record of the calibration process with all relevant information. The program has been tested for calibrating Keithley 6430 remote source meter in the current range of 1 nA to 100 mA. While there are several benefits from the automation, but the most significant one is the achievement of low uncertainties in calibrating the current source.

5 illus, 2 tables, 17 ref

039157   RAO P S, PRAKASH O, SHARMA R P (Basic & Applied Science Dep, National Institute of Technology, Papum Pare - 791 112, Email: rpsharma@nitap.ac.in) : Heat transfer in combined convective magnetohydrodynamic motion of nanofluid holding different shapes of nanoparticles in a channel under the influence of heat source. Indian J Pure Appl Phys 2020, 58(02), 87-98.

Heat transfer in mixed convection unsteady MHD flow of an incompressible nanofluid in a channel under the influence of heat source is studied. The channel with non-uniform walls temperature is taken in a perpendicular direction with a transverse magnetic field. Based on the substantial boundary conditions, three different flow conditions are examined. The problem is formed in PDEs with substantial boundary conditions. Four different forms of nanoparticles of identical volume fraction are employed in traditional base fluid water (H₂O). Solutions for momentum and energy are attained by the perturbation method and examined graphically in different graphs. It is established that viscosity and thermal conductivity are the mainly well-known variables accountable for different results of velocity and temperature. It is also found that increasing heat source leads to an increase in nanofluid velocity and temperature and nano-size particles instance platelet and blade shapes have lesser momentum as related to brick and cylinder size of nanoparticles.

25 illus, 2 tables, 43 ref

039153   RAO P S G, SIRIPURAM R, SRIPADA S (Physics Dep, JNTUHCEJ, Telangana- 505 501, Email: sripada_suresh2020@rediffmail.com) : Structural and optical properties of TeO₂- SeO₂-Na₂O glass system. Indian J Pure Appl Phys 2020, 58, 50-62.

80 TeO₂-(20-x) SeO₂-xNa₂O (where x = 0, 5, 10, 15, 20 mol %) ternary glass system have been successfully prepared by conventional melt-quenching method. The non-crystalline nature of the tested glass samples has been confirmed by X-ray diffraction. The structural transformation in the tested glass samples has been evaluated by measuring density (ρ), molar volume (V_M), oxygen packing density (OPD) and oxygen molar volume (V₀) values. The characteristic temperature of the glass system (glass transition,Tg, crystallization, Tc ) decreases with increasing Na₂O content. Raman spectra show that addition of Na₂O to TeO₂ + SeO₂ glass may result in cleavage of Te-O-Te and Se-O-Se linkages and formation of TeO₃^- and SeO₃^- terminal groups in the glass system. FTIR spectra show that the units of TeO₄ units decrease and theunits of TeO₃ / TeO₃₊₁ increase in the tested glass samples. The cut-off wavelength (λC), optical band gap (Eopt), refractive index (n), molar refraction (RM), metallization criterion (M), molar polarizability (α_m), electronic polarizability of oxide ion (αo^2-), optical basicity (Λ), Fermi energy (E_F), dispersion energy (E_d), single oscillator energy (E₀) and Urbach energy (ΔE) have been calculated from optical absorption spectra. The reflectivity of light and extinction coefficient (k) is used to find imaginary part of dielectric constant (ε_i). The optical band gap energy and allowed transitions have been investigated using five methods; indirect, direct, indirect forbidden, direct forbidden and imaginary part of the dielectric constant. The optical band gap values of direct transition are in well agreement with the optical bandvalues of an imaginary part of dielectric constant. The obtained optical band gap values decrease with increasing sodium oxide in the glass samples. Increase in Urbach energy values in the present glass system is due to an increase in the number of defects in the glass structure. The tested glass samples possess higher values of Urbach energy, molar electronic polarizability, and optical basicity. The excitation energy E₀ decreases with the increase of Na₂O content inthe glass system.

16 illus, 7 tables, 68 ref

039145   SHASIDHAR R, CHAUDHARY N (Physics Dep, J S S Academy of Technical Education, Bengaluru- 560 060, Email: shashidharjss@gmail.com) : Thickness dependent studies of hetero-junction solar cell synthesized on quartz substrate by spray pyrolysis technique. Indian J Pure Appl Phys 2020, 58, 36-43.

Variable thickness hetero-junction solar cells synthesized on quartz substrate by spray pyrolysis technique synthesized quartz based solar cells have been found to possess cell parameters such as open circuit voltage, saturation current density, fill factor and efficiency in the range of 191 – 449 mV, 2×10^-9 – 0.11×10^-6 A cm^-2, 15 – 20 % and 0.2×10^-9 – 3.35×10^-6 % at 206 mW/cm² (at air mass 5.6), respectively. Series and shunt resistance of the solar cells have been found to vary with the thickness of semiconductor films. Thick film solar cells are found to possess reasonably good cell parameters compared to thin film solar cells due to enhancement of charge concentration, mobility, grain size, variation of optical band gap, excesses atomic percentage of Ti, Cu, Te, Sn elements in TiO₂, CuO, CdTe, SnS films and less structural defects, increment of activation energy as well as existence of mixed phase at the Schottky barrier. The optical response of hetero-junction solar cells is found to be thickness dependent. Good rectifying characteristic has been reported in the present work for both thick and thin hetero-junction solar cells. All the measurements have been performed in air without protection against oxygen gas or moisture, which shows the stability of spray pyrolyzed thin films.

6 illus, 2 tables, 44 ref

039143   VATS M, KUMAR R, SHARMA J, LUWANG M N (Amity Univ, Gurugram- 122 413, Email: mona2k42000@gmail.com) : Magnetic and luminescent multifunctional nanohybrid: Fe₃O₄@CaF2:Tb³⁺: A facile synthesis and characterization. Indian J Pure Appl Phys 2020, 58, 31-5.

In the present study, bi-functional hybrid nanomaterial has been synthesized and characterized via facile method and characterized. The synthesized nanomaterial shows both magnetic and luminescent properties which are confirmed by VSM (vibrating sample magnetometer), UV-Vis spectra and the photoluminescence emission spectra. For the magnetic phase, i.e., nanocrystalline magnetite, Fe₃O₄ is used as the core which is then functionalized using polyethylene glycol (PEG) and for the luminescent phase, polyethylenimine (PEI) functionalized CaF₂ doped with Tb³⁺ is used as the emitter. Wherein, both PEG and PEI serve the dual purpose of functionalization as well as stabilization by steric repulsion. The structure and morphology of the synthesized bifunctional hybrid nanomaterial are studied with the help of scanning electron microscopy (SEM) and X-ray powder diffraction.

7 illus, 20 ref

039142   ATTA A, HAMID H M A, FAWZY Y H A, OKR M M E (Physics Dep, Jouf Univ, Saudi Arabia, Email: alyatta2001@yahoo.com) : Ion beam and discharge characteristics of cold cathode ion source. Indian J Pure Appl Phys 2020, 58, 24-30.

In this work, some developments in the acceleration system of cold cathode ion source have been constructed to produce broad beam to be used in different industrial applications. An electrostatic probe with electrical circuit is constructed for study the extracted ion beam distribution. Broad beam 25 mm with ion current in the range of 1 mA is extracted from the constructed extraction system. The obtained optimum distance between the extraction grid and acceleration grid is 3 mm.The characteristics are measured to investigate the ion beam current I_b as a function of different parameters (discharge voltage V_d, gas pressure P, magnetic field intensity B and acceleration voltage V_acc). The magnetic field is collimated and intensifies the plasma that enhances the extracted beam current. The obtained cold cathode ion source can be used in different applications like surface etching, surface modification and deposition due to its long life and compactness.

13 illus, 33 ref

039140   BIRWAL A, MANKER N K, PATEL K (Electronic Science Dep, Delhi Univ, New Delhi - 110 021, Email: kpatel@south.du.ac.in) : Compact printed log-periodic dipole antenna (LPDA) with t-shaped arm for wide band applications. Indian J Pure Appl Phys 2020, 58, 16-23.

Compactness of printed log-periodic dipole antenna (LPDA) is an essential requirement in developing low-weight communication system. With this aim, in the present work, we utilized two-step approach to reduce size of this kind of antenna. First, to achieve compactness, a maximum apex angle was taken for the desired gain of 6 dBi, which reduces the boom length to minimum possible value. Secondly, after fully optimizing the width and length of each dipole, a T-shaped arm is introduced in place of straight dipole arms. For comparison, initially printed LPDA is designed with full arm structure of gain 6.5 dBi in 1.5 to 3.5 GHz band using CST Microwave Studio. In T-shaped arm LPDA, the antenna size eventually reduces by 82 % compared to full arm structure, which offers a bore sight gain level varies from 2 to 4.5 dBi in the frequency band of 1.8 to 3.5 GHz. Simulation analysis are discussed in detail along-with a size comparison of various printed LPDAs. The measured results of the fabricated LPDA with T-shaped arm are found to closely match with the simulation results.

10 illus, 4 tables, 15 ref

039138   KAUSHIK H K, KUMAR S, CHAUDHARY M G, KHAN S (SRM Univ, Modinagar- 201 204, Email: drskbhargava2011@gmail.com) : Optical properties of CdS: Pb thin layer deposited on glass substrate. Indian J Pure Appl Phys 2020, 58, 11-5.

The thermal evaporation technique has been used to deposit a polycrystalline cadmium lead sulphide thin film (Cd_1-x Pb_xS with X=0.20) in a vacuum of about 10-5 Torr at 450 °C. This Cd_1-x Pb_xS thin film has been investigated by X-ray diffraction technique. Optical constant like extinction coefficient (K), dielectric constant (€), and refractive index (n) have  been measured from transmission spectrum in wavelength range from 700 nm to 1700 nm by manifacier’s envelope method. Crystallite size estimated from the Scherrer method has been found to be 31.25 nm. Coefficient of absorption (α) as well as film thickness (t) has been estimated by means of transmission spectra. The lattice parameter (a), dislocation density (δ), inter planner spacing (d), and micro strain (ε) have been calculated. X-ray study reveals that film stoichiometry is maintained in deposited film. The optical study confirms that optical band gap of Cd_1-x Pb_xS film can be tuned from visible to near infrared region (2.42-1.20 eV) using relatively low cost technique. The red shift in optical band gap has been observed for Cd_1-x Pb_xS thin film. Pb doping increase absorbance in visible region and near infrared region compared to undoped CdS film. The large decrease in band gap has been observed which makes the film much suitable for absorbing layer in solar cells, IR detector and other photovoltaic and optoelectronic applications. In film band, gap of 1.13 eV has been achieved which shows that doping of Pb in CdS makes it suitable material for solar cell absorber and IR detectors. The film shows high transmittance (about 70 %) in near infrared region. The film is polycrystalline and highly stoichiometric.

7 illus, 23 ref

039136   PATEL S M, KALRA Y, OJHA V N, SINHA R K (Applied Physics Dep, Delhi Technological Univ, Delhi - 110 042, Email: dryogitakalra@gmail.com) : Improvement in short-circuited coaxial flange for evaluating microwave superconducting properties at low temperature. Indian J Pure Appl Phys 2020, 58, 5-10.

In the present study, we have proposed an improvement in terms of the determination of S-parameters of an open flange from its characteristic impedance and propagation constant. With the help of these S-parameters, the actual reflection coefficient of YBCO films deposited on LAO substrate is obtained from the measured reflection coefficient. The surface impedance of three YBCO films is obtained in the range of few ohms in the frequency range from 1 GHz to 40 GHz. The surface resistance of the films reduces at liquid nitrogen temperature, i.e., 77 K, whereas, the surface reactance slightly increases due to kinetic inductance. The conductivity and skin depth are also determined to validate the improvement in the method.

6 illus, 17 ref

039118   LOPEZ J A, GONZALZEZ S S R, RODRIGUEZ O H, HOLMES J, ALRCON R (Physics Dep, Texas at El Paso Univ, Texas- 79968, U.S.A, Email: jorgelopez@utep.edu) : A GEANT4 study of a gamma-ray collimation array. J Nucl Phys Mat Sci Rad A 2020, 7(2), 217–21.

Proton beam therapy uses high-energy protons to destroy cancer cells which are still uncertain about where in the body they hit. A possible way to answer this question is to detect the gamma rays produced during the irradiation and determine where in the body they are produced. This work investigates the use of collimators to determine where the proton interactions occur. GEANT4 is used to simulate the gamma production of a source interacting with a collimator. Each event simulates a number of gammas obtained as a function of the position along the detector. Repeating for different collimator configurations can thus help determine the best characteristics of a detector device.

6 illus, 1 tables, 10 ref

039111   REYES A R, CORREL G H, CASANOVA E O, MANDAUJANO H A T, HERRERA U C (Physics and Mathematics Dep, Autonomous of Ciudad Juárez univ, Mexico, Email: abdiel.ramirez@uacj.mx) : Development and validation of an X-ray imaging detector for digital radiography at low resolution. J Nucl Phys Mat Sci Rad A 2020, 7(2), 181–7.

Digital X-ray detectors are required in different sciences and applications, however many high quality devices are expensive although high-resolution images are not always required. We present an easy way to build a detector capable of forming X-ray digital images and video with a very large area (18×18 cm²). The detector is formed by three main components: scintillator, optics lenses and CCD sensor. Basically, the device converts the X-rays into visible light which is then collected by the CCD sensor. The scintillator is Gadox type, from Carestream®, 18×18 cm², regular type, lambda 547 nm. The optics lenses are generic, with manual focus and widely visual field. The CCD sensor has a size of 1/3″, 752 × 582 pixels, monochrome, 20 FPS, 12 bits ADC and pixel size of 3.8 μm. With the built detector and an X-ray source, we formed an X-ray imaging detection system to generate digital radiographs of biological or inert objects-examples are given-, as well as real-time X-ray video. Additionally, the spatial resolution limit was measured in terms of Modulation Transfer Function by the method of opaque edge from a lead sheet with a result of 1.1 Lp/mm. Finally using a filter, the focal spot of the X-ray source is measured, resulting in a diameter of 0.9 mm (FWHM).

11 illus,1 tables,15 ref

039108   QUINTOS E M, BARBOSA E M, ESPINOSA J E, ALONSO B D C, ARANDA M A, MERINO R P (Benemérita Autónoma de Puebla Univ, Mexico, Email: emoreno@fcfm.buap.mx) : Characterizing a mini gamma detector. J Nucl Phys Mat Sci Rad A 2020, 7(2), 159–63.

There are several types of gamma radiation detectors, which have different characteristics depending on its use. We designed and instrumented a gamma detector for low energies of a small and portable size to obtain spectrum from radioactive sources and from that analyze each spectrum. This instrument basically consists of a scintillator crystal coupled to a SiPM this in turn coupled to a PCB card designed with capacitors and resistors for a better signal, a voltage source of 29 volts. For signal acquisition the system must be connected to an oscilloscope this in turn is controlled by a script developed in Python. For the calibration radioactive isotopes with the same dimensions were used, caesium-137 (Cs-137), cobalto-60 (Co-60), sodium-22 (Na-22) and manganese-54 (Mn-54) as gamma ray emission.

4 illus, 3 tables, 7 ref

039107   CELIZ C A, LOPEZ A A, GUEVARA J E B, BELTRAN O F, CANALES F G (Benemérita Autónoma de Puebla Univ, Mexico, Email: olga.felix@correo.buap.mx) : Analysis of DDM into gamma radiation. J Nucl Phys Mat Sci Rad A 2020, 7(2), 153–7.

We are interested in the purpose of a dipolar fermionic particle as a viable candidate of Dark Matter (DDM). Then, we study the annihilation of dark matter into photons, considering it as a neutral particle with non-vanishing magnetic (M) and electric (D) dipolar moments. The total annihilation crosssection $\sigma$($\mathrm{\chi }$$\mathrm{\chi }$$\to$$\mathrm{\gamma }$$\mathrm{\gamma }$) is computed by starting from a general form of coupling $\mathrm{\chi \chi \gamma }$ in a framework beyond to Standard Model (BSM). We found that candidates with O(m_$\chi$ ) ~10²GeV, D 102GeV ≈10⁻¹⁶ e cm are required in order to satisfy the current cosmic relic density.

1 illus, 23 ref