037303   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

036053   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

035992   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

035991   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

035852   VILA N A, CARDOSA L, TOUBES D R (Vigo Univ, Spain, Email: lucyalves.lucilia@gmail.com) : Occupational risk prevention in the management of companies in the electricity sector. The case of Galicia (Spain). J Sci Ind Res 2020, 79(01), 30-4.

The present work aims at analysing the awareness and prevention in the management system of companies in the electricity sector, in order to detect the main shortcomings, seeking to improve in terms of occupational risk prevention. After collecting and analyzing a sample of 180 surveys, numerous shortcomings have been detected in the sector of electrical and telecommunications installations in Galicia (Spain), including the lack of established goals and objectives in preventive matters or the absence of the use of preventive modalities.

3 tables, 12 ref

035821   ELKHALIG M M H (Physics Dep, Qassim Univ, Saudi Arabia, Email: 141261@qu.com.sa) : First principles investigation of electronic and magnetic - propertiess 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

035820   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

035818   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 1nA 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

035817   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

035814   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

035812   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

035811   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

035810   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

035809   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

035808   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

035807   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

035794   KUMAR S S, SUDARSHAN M, CHAKRABORTY A (Physics Dep, Kanchi Mamunivar Centre for Post Graduate Studies (Autonomous), Puducherry- 605 008, Email: santhosh.physics@gmail.com) : Trace elements analysis of Biophytum sensitivum (L.) DC. by EDXRF spectroscopy and its therapeutic role in diabetes mellitus. Indian J Biochem Biophys 2020, 57, 8-14.

Minerals and trace elements, as structural components of tissues, play vital role in cellular and basal metabolism. The Little Tree Plant, Biophytum sensitivum (L.) DC., locally called Lajalu, is a well-known medicinal herb, traditionally considered as one of the 10 flowers used since ancient time for healthy life. In Ayurveda, it is used to treat various ailments viz., asthma, insomnia, convulsions, cramps, stomach ache, chest complaints, inflammation, tumours and skin disorders. In this study, we analyzed the elemental contents of its leaves and roots using EDXRF spectroscopy, and tried to find possible correlation with its nutritional and curative effects. The elements Ca, K, Si, Cl, P, and S were found in the highest concentration in leaf, in the descending order, but in the root, K took the leading position. The results have been discussed with reference to the established role of these elements in physiology and pathology of human life with special focus on its role in bone building, controlling the sugar level and wound healing capacity of patients with diabetes mellitus.

2 illus, 1 tables, 46 ref

035793   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

035789   NEGRETA C P, ACOSTA M A F, MULIA J, ROSAS L A M, GONZALEZ D O (Autonomous Univ, Mexico, Email: dog@uaemex.mx) : Structural variations induced by temperature changes in rotavirus VP6 protein immersed in an electric field and their effects on epitopes of the region 300-396. J Nucl Phys Mat Sci Rad A 2020, 7(2), 189–94.

Rotavirus diarrhea is an infectious intestinal disease that causes about 215 thousand deaths annually in infants under five years old. This virus is formed by three layers of concentric proteins that envelop its genome, from which VP6 structural protein is the most conserved among rotavirus serotypes and an excellent vaccine candidate. Recent studies have shown that structural proteins are susceptible to losing their biological function when their conformation is modified by moderate temperature increments, and in the case of VP6, its antigen efficiency decreases. We performed an in silicoanalysis to identify the structural variations in the epitopes 301-315, 357-366, and 376-384 of the rotavirus VP6 protein-in a hydrated medium- when the temperature is increased from 310 K to 322 K. In the latter state, we applied an electric field equivalent to a low energy laser pulse and calculated the fluctuations per amino acid residue. We identified that the region 301-315 has greater flexibility and density of negative electrical charge; nevertheless, at 322 K it experiences a sudden change of secondary structure that could decrease its efficiency as an antigenic determinant. The applied electric field induces electrical neutrality in the region 357-366, whereas in 376-384 inverts the charge, implying that temperature changes in the range 310 K-322 K are a factor that promotes thermoelectric effects in the VP6 protein epitopes in the region 300-396.

4 illus,1 tables, 27 ref

035788   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

035786   PEREZ T A V, LOPEZ J M H, BARBOSA E M, ALONSO B D C (Faculty of Physical Sciences Mathematics Benemérita Univ, Mexico, Email: antonio_2827@hotmail.com) : Study of CT images processing with the implementation of MLEM algorithm using CUDA on NVIDIA’S GPU framework. J Nucl Phys Mat Sci Rad A 2020, 7(2), 165–71.

In medicine, the acquisition process in Computed Tomography Images (CT) is obtained by a reconstruction algorithm. The classical method for image reconstruction is the Filtered Back Projection (FBP). This method is fast and simple but does not use any statistical information about the measurements. The appearance of artifacts and its low spatial resolution in reconstructed images must be considered. Furthermore, the FBP requires of optimal conditions of the projections and complete sets of data. In this paper a methodology to accelerate acquisition process for CT based on the Maximum Likelihood Estimation Method (MLEM) algorithm is presented. This statistical iterative reconstruction algorithm uses a GPU Programming Paradigms and was compared with sequential algorithms in which the reconstruction time was reduced by up to 3 orders of magnitude while preserving image quality. Furthermore, they showed a good performance when compared with reconstruction methods provided by commercial software. The system, which would consist exclusively of a commercial laptop and GPU could be used as a fast, portable, simple and cheap image reconstruction platform in the future.

5 illus, 1 tables, 37 ref

035785   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

035784   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

035783   RIOS K D L, GARCIA C M, ACOSTA L, MARTINEZ R G, CARRILLO M A M, ORTIZ M E (National Autonomous Univ, Mexico, Email: acosta@fisica.unam.mx) : Preliminary measurements of Be-10/Be-7 ratio in rainwater for atmospheric transport analysis. J Nucl Phys Mat Sci Rad A 2020, 7(2), 145–51.

The meteoric cosmogenic beryllium has been used as an essential geophysical tracer in the analysis of atmospheric flows and erosion soils since 1960. The first measurements Be-7 and Be-10 concentrations in rainwater from Mexico, have been carried out by using gamma decay spectroscopy and AMS techniques, respectively for each isotope. With this it was possible to report a preliminar value for the Be-10/Be-7 isotopic ratio in such environmental samples. The present work described preliminary results related to rainwater collected at mountain and metropolitan areas. Results are compared with predictions and previous measurements for both radioisotopes, observing a very sensible behavior particularly for the case of Be-7 activities.

5 illus, 2 tables, 29 ref

035782   DUQUE M G T, RAYA C C, MENDOZA A N, BERNAL S R (National Autonomous Univ, Mexico, Email: guadalupetduque@gmail.com) : Behavior of poly-a onto kaolin. J Nucl Phys Mat Sci Rad A 2020, 7(2), 139–43.

A combination of geochemical variables is necessary to explain the origin of life on Earth. Thus, in this work the sorption of Poly-A on a clay mineral (kaolinite) was studied to get an insight about the sorption capacity at different times and pH values, as well as to confirm the capabilities of the clay to protect the sorbate from an external source of ionizing radiation. Poly-A presented a high percentage of sorption in the clay, especially in acidic environments, and this percentage sharply decrease in alkaline media. On the other hand, Poly-A’s recovery was higher in the system with clay, confirming its protection role.

4 illus, 17 ref

035781   COLIN M C, HOMS E R, LOPEZ J A (Bruker AXS GmbH, Germany, Email: mcdaniel@unt.edu) : A data mining perspective of XRF elemental analysis from pueblo people’s pottery. J Nucl Phys Mat Sci Rad A 2020, 7(2), 129–38.

Hierarchichal clustering was used to identify elemental signatures in artifacts attributed to the Pueblo peoples. The artifacts in this study are pottery samples found at different sites in the state of New Mexico, USA. Three methods were applied: complete, average, and Ward. Their corresponding cophenetic correlation coefficients were used to contrast the three methods. Elemental characterization was only based on X-ray fluorescence excitation from a portable spectrometer with silver anode.The elemental correlations here disclosed by data mining techniques are expected to guide further archaelogical studies and assist experts in the assessment of provenance and historical ethnographic studies.

8 illus, 2 tables, 27 ref

035780   PRIETO E, HALLADO L X, GUERROR A, ALVAREZ I, CISNEROS C (Avenida Univ, Mexico, Email: carmen@fis.unam.mx) : Effect of laser radiation on biomolecules. J Nucl Phys Mat Sci Rad A 2020, 7(2), 123–8.

Time of flight laser photoionization has been used to study the response of some molecules of biological interest under laser radiation. One of the questions of great interest today is the effect of radiation on DNA and RNA molecules. Damage to these molecules can be caused directly by radiation or indirectlyby secondary electrons created by radiation. As response of the radiation field fragmentation process can occur producing different ions with kinetic energies of a few electron volts. In this paper wepresent the results of the interaction of 355nm laser with the nitrogen bases adenine(A) and uracil(U) using time-of-flight spectrometry and the comparison of experimental results on the effects of laser radiation in (A) and (U) belonging to two different ring groups, purines and pyrimidines respectively, which are linked to form the AU pair of the RNA.

4 illus, 2 tables, 16 ref

035779   RIVERA A L, BELTRAN S R, MENDOZA A N (Institute of Nuclear Sciences, Mexico, Email: ana.rivera@nucleares.unam.mx) : Radiation induced reactions of succinic acid in aqueous solution: An agent-based model. J Nucl Phys Mat Sci Rad A 2020, 7(2), 117–21.

An approach to studying the formation of critical bio-organic compounds in the early Earth is tosimulate in the laboratory possible processes that may occur in primitive scenarios. In this context,it can be studied the evolution of succinic acid in an aqueous media exposed to gamma radiation, asstarting material produced more complex prebiotic molecules. To describe the products generated bythe interaction of the different elements under radiation, there is a mathematical model that considerschemical reactions as nonlinear ordinary differential equations based on the mass balance of all thespecies, that has been implemented here by an agent-based model. In this simulation, each chemicalspecies involved is considered as an agent that can interact with other species with known reactionrates, and the radiation is taken as a factor that promotes product formation. The results from the agentbasedmodel are compared with the molar concentrations of succinic acid, and its products obtained inthe lab. Simulation shows the exponential decomposition of succinic acid due to gamma radiation atroom temperature in agreement with the laboratory model.

1 illus, 17 ref

035778   RIVERA A L, BELTRAN S R, MENDOZA A N (Institute of Nuclear Sciences, Mexico, Email: ana.rivera@nucleares.unam.mx) : Radiation induced reactions of succinic acid in aqueous solution: An agent-based model. J Nucl Phys Mat Sci Rad A 2020, 7(2), 117–21.

An approach to studying the formation of critical bio-organic compounds in the early Earth is tosimulate in the laboratory possible processes that may occur in primitive scenarios. In this context,it can be studied the evolution of succinic acid in an aqueous media exposed to gamma radiation, asstarting material produced more complex prebiotic molecules. To describe the products generated bythe interaction of the different elements under radiation, there is a mathematical model that considerschemical reactions as nonlinear ordinary differential equations based on the mass balance of all thespecies, that has been implemented here by an agent-based model. In this simulation, each chemicalspecies involved is considered as an agent that can interact with other species with known reactionrates, and the radiation is taken as a factor that promotes product formation. The results from the agentbasedmodel are compared with the molar concentrations of succinic acid, and its products obtained inthe lab. Simulation shows the exponential decomposition of succinic acid due to gamma radiation atroom temperature in agreement with the laboratory model.

1 illus, 17 ref

035777   RIVERA A L, BELTRAN S R, MENDOZA A N (National Autonomous Univ, Mexico, Email: ana.rivera@nucleares.unam.mx) : Radiation induced reactions of succinic acid in aqueous solution: An agent-based model. J Nucl Phys Mat Sci Rad A 2020, 7(2), 117–21.

An approach to studying the formation of critical bio-organic compounds in the early Earth is to simulate in the laboratory possible processes that may occur in primitive scenarios. In this context, it can be studied the evolution of succinic acid in an aqueous media exposed to gamma radiation, asstarting material produced more complex prebiotic molecules. To describe the products generated by the interaction of the different elements under radiation, there is a mathematical model that considers chemical reactions as nonlinear ordinary differential equations based on the mass balance of all the species, that has been implemented here by an agent-based model. In this simulation, each chemical species involved is considered as an agent that can interact with other species with known reaction rates, and the radiation is taken as a factor that promotes product formation. The results from the agentbased model are compared with the molar concentrations of succinic acid, and its products obtained in the lab. Simulation shows the exponential decomposition of succinic acid due to gamma radiation atroom temperature in agreement with the laboratory model.

1 illus, 17 ref

035776   CINAUSERO M, CASTELLI A M S, BOHUS L S, PALFALVI J, ESPINOSA G (National Autonomous Univ, México, Email: espinosa@fisica.unam.mx) : PADC-NTM applied in 7Li+Pb at 31 MeV reaction products study. J Nucl Phys Mat Sci Rad A 2020, 7(2), 109–15.

Passive nuclear track methodology (NTM) is applied to study charged particles products of the reaction ⁷Li+Pb at ~ 31 MeV. It is a contribution to the 8pLP Project (LNL-INFN-Italy) in where we show analternative approach to register charged particle from reaction fragments by PADC detection. The main advantage is that the passive system integrates data over the whole experiment and has its importance for low rate reaction processes. Reaction products as well as scattered beam particles are determined from track shape analysis. Some limitations are inherent to NTM since a priori knowledge is required to correlate track size distribution given by each type of particle emerging from the target. Results show that the passive technique gives useful information when applied in reaction data interpretation for a relatively large range of particle types.

6 illus, 1 tables, 10 ref

035774   CRUZ L P C, MENDOZA A N, BARBERO A H (Radiation Chemistry and Radio chemistry Dep, National Autonomous Univ, Mexico, Email: negron@nucleares.unam.mx) : Stability of glycine in saline solutions exposed to ionizing radiation. J Nucl Phys Mat Sci Rad A 2020, 7(2), 83–7.

The stability of biologically important molecules, such as amino acids, being subjected to high radiation fields is relevant for chemical evolution studies. Bodies of water were very important in the primitive Earth. In these bodies, the presence of dissolved salts, together with organic molecules, could influence the behavior of the systems in prebiotic environments.The objective of this work is to examine the influence of sodium chloride on the stability of the amino acid glycine when subjected to high radiation doses. The analysis of the irradiated samples was followed by HPLC coupled with a UV-VIS detector. The results show that glycine in aqueous solutions (without oxygen) decomposed around 90 % at a dose of 91 kGy. In the presence of salts, up to 80 % ofthe amino acid was recovered at the same dose. Laboratory simulations demonstrate a protective role for sodium chloride (specifically the chloride ion) to glycine against an external source of ionizing radiation.

3 illus, 9 ref

035773   LOPEZ A L M, HURTADO M F G, CASTENEDA J C, MENDOZA A N, BERNAL S R, HEREDIA A (National Autonomous Univ, Mexico, Email: negron@nucleares.unam.mx) : Spectrophotometric study of polymeric dyesgels after a gamma irradiation process for its possible use as a radiation dosimeter. J Nucl Phys Mat Sci Rad A 2020, 7(2), 77–81.

This work aims to evaluate a dosimetric system composed of green malachite supported in agarose. Previous work showed that solutions of green malachite irradiated at 1 to 40 kGy present a linear behavior. This system is a gel composed of green malachite (2.5×10^–3 M), sodium benzoate (1 %), and agarose (1 %) that was exposed tovarious doses of gamma irradiation. The irradiated systems were measured with a UV-V is spectrophotometer at 619 nm. Experimental parameters (such as dose rate,doses, and temperature) were controlled and optimized for reproducible and reliable results. More studies are needed to propose a dosimeter in the system in the range of 1.8 to 4.0 kGy.

3 illus, 1 tables, 7 ref

035772   MIRANDA J (National Autonomous Mexico Univ, Mexico, Email: miranda@fisica.unam.mx) : How do uncertainties in atomic parameters influence theoretical predictions of x-ray production cross sections by proton impact?. J Nucl Phys Mat Sci Rad A 2020, 7(2), 71–6.

The emission of characteristic X-rays induced by proton impact is a phenomenon known since the first half of the 20th century. Its more widely known application is the analytical technique Particle Induced X-ray Emission (PIXE). Several models have been developed to calculate, first, ionizationcross sections and then the subsequent X-ray production cross sections. However, to carry out the comparisons of these predictions with experimental data it is necessary to use atomic parameters databases (fluorescence yields, Coster-Kronig transition probabilities, emission rates) that also have experimental uncertainties. In this work it is demonstrated how these values do not allow to decide which model describes more accurately the cross sections, due to a final “theoretical uncertainty”obtained through the propagation of the original uncertainties.

3 illus, 33 ref

035771   HOLLIDAY R L, YOUNG J M, SINGH S, MCDANIEL F D, ROUT B (Physics Dep, North Texas Univ, USA, Email: mcdaniel@unt.edu) : Feasibility of formation of Ge1-x-ySixSny layers with high Sn concentration via Ion implantation. J Nucl Phys Mat Sci Rad A 2020, 7(2), 65–70.

By increasing the Sn concentration in Ge_1-ySn_y and Ge_1-x-ySi_xSn_y systems, these materials can be tuned from indirect to direct bandgap along with increasing electronic and photonic properties. Efforts havebeen made to synthesize Sn-Ge and Ge-Si-Sn structures and layers to produce lower energy direct bandgap materials. Due to low solid solubility of Sn in Ge and Si-Ge layers, high concentrations of Sn are not achieved by traditional synthesis processes such as chemical vapor deposition or molecular beam epitaxy. Implantation of Sn into Si-Ge systems, followed by rapid thermal annealing or pulse laser annealing, is shown to be an attractive technique for increasing Sn concentration, which can increase efficiencies in photovoltaic applications. In this paper, dynamic ion-solid simulation results are presented. Simulations were performed to determine optimal beam energy, implantation order, and fluence for a multi-step, ion-implantation based synthesis process.

7 illus, 1 tables, 11 ref

025124   NANDAKUMAR H, SUBRAMANIA A K, SRIVASTAVA S (Physics Dep, Sri Sathya Sai Institute of Higher Learning, Anantapur - 515 134, Email: hari@radiosai.org) : Sub-4-micron full-field optical coherence tomography on a budget. Sadhana 2018, 43(6), 97.

We evaluate the construction and performance of an ultra-low-cost full-field optical coherence tomography (FF-OCT) instrument, also known as an optical coherence microscope. Although the cost of construction of the instrument from off-the-shelf parts is at least ten times lower than those of commercial products, sub-4-micron axial and lateral resolutions are obtained, albeit at the cost of higher acquisition times. Standard test samples are imaged and the performance of the instrument is evaluated. The device is found to be useful in measuring length, dispersion and group refractive index as well. Suggestions for bettering performance are discussed.

7 illus, 28 ref

025123   SENTHILKUMAR G, PANCHAPAKESAN N R (Indian Institute of Technology, Chennai - 600 036, Email: gsk.mach23@gmail.com) : Effect of flapping kinematics on aerodynamic force of a flapping two-dimensional at plate. Sadhana 2018, 43(5), 72.

Potential applications of flapping-wing micro-aerial vehicles (MAVs) have prompted enthusiasm among the engineers and researchers to understand the flow physics associated with flapping flight. An incompressible Navier–Stokes solver that is capable of handling flapping flight kind of moving boundary problem is developed. Arbitrary Lagrangian–Eulerian (ALE) method is used to handle the moving boundaries of the problem. The solver is validated with the results of problems like inline oscillation of a circular cylinder in still fluid and a flat plate rapidly accelerating at constant angle of attack. Numerical simulations of flapping flat plate mimicking the kinematics of those like insect wings are simulated, and the unsteady fluid dynamic phenomena that enhance the aerodynamic force are studied. The solution methodology provides the velocity field and pressure field details, which are used to derive the force coefficients and the vorticity field. Time history of force coefficients and vortical structures gives insight into the unsteady mechanism associated with the unsteady aerodynamic force production. The scope of the work is to develop a computational fluid dynamic (CFD) solver with the ALE method that is capable of handling moving boundary problems, and to understand the flow physics associated with the flapping-wing aerofoil kinematics and flow parameters on aerodynamic forces. Results show that delayed stall, wing–wake interaction and rotational effect are the important unsteady mechanisms that enhance the aerodynamic forces. Major contribution to the lift force is due to the presence of leading edge vortex in delayed stall mechanism.

13 illus, 4 tables, 15 ref

025122   ZHANG P (Yangtze Normal Univ, China, Email: zhangp007@foxmail.com) : Monte Carlo simulation of secondary electron images for gold nanorods on the silicon substrate. Pramana - J Phys 2018, 90(6), 0081.

Recently, gold nanorods (Au NRs) have attracted much attention because at a particular photoelectricity the gold nanorods present a characteristic which is different from other types of Au nanomaterials with various shapes. Accurate measurement of aspect ratios does provide very high value of optical property for Au NRs. Monte Carlo (MC) simulation is thought of as the most accurate tool to perform size measurement through extracting structure parameters from the simulated scanning electron microscopy (SEM) image which best matches the experimental one. In this article, a series of MC-simulated secondary electron (SE) images have been taken for Au NRs on a silicon substrate. However, it has already been observed that the two ends of Au NRs in the experimental SEM image is brighter than that of the middle part. It seriously affects the accuracy of size measurement for Au NRs. The purpose of this work is to understand the mechanism underlying this phenomenon through a series of systematical analysis. It was found that the cetyltrimethylammonium bromide (CTAB) which covers the Au NRs indeed can alter the contrast of Au NRs compared to that without CTAB covering. However, SEs emitting from CTAB are not the reason for the abnormal brightness at the two ends of NRs. This work reveals that the charging effect might be the leading cause for this phenomenon.

9 illus, 22 ref

025121   GOYAL M, GUPTA B R K (Physics Dep, GLA Univ, Mathura - 281 406, Email: monika.goyal@gla.ac.in) : Shape, size and temperature dependency of thermal expansion, lattice parameter and bulk modulus in nanomaterials. Pramana - J Phys 2018, 90(6), 0080.

A theoretical model is described here for studying the effect of temperature on nanomaterials. The thermodynamic equation of state (EoS) proposed by Goyal and Gupta in High Temp.-High Press. 45, 163 (2016); Oriental J. Chem. 32(4), 2193 (2016), is extended in the present study using Qi and Wang model [Mater. Chem. Phys. 88, 280 (2004)]. The thermal expansion coefficient is expressed in terms of shape and size and used to obtain the isobaric EoS of nanomaterials for the change in volume V/V0V/V0. The variation in V/V0V/V0 with temperature is estimated for spherical nanoparticles, nanowires and nanofilms. It is found that the volume thermal expansivity decreases as size of the nanomaterial increases, whereas V/V0V/V0 increases with temperature across nanomaterials of different sizes. The lattice parameter variation with temperature is studied in Zn nanowires, Se and Ag nanoparticles. It is found that lattice constant increases with increase in temperature. Also, bulk modulus is found to increase with temperature in nanomaterials. The results obtained from the present model are compared with the available experimental data. A good consistency between the compared results confirms the suitability of the present model for studying thermal properties of the nanomaterials.

4 illus, 1 table, 29 ref

025120   JOSHI G, G RAVI, MUKHERJEE S (Nirma Univ, Ahmedabad- 382 481, Email: jgareema@gmail.com) : A new linear plasma device for the study of plasma waves in the electron magnetohydrodynamics regime. Pramana - J Phys 2018, 90(6), 0079.

A new, user-friendly, linear plasma device has been developed in our laboratory where a quiescent (Δn/n≈1%Δn/n≈1%), low temperature (1–10 eV), pulsed (3–10 ms) plasma can be produced over a large uniform region of 30–40 cm diameter and 40 cm length. Salient features of the device include the flexibility of tuning the plasma density in the range of 10101010 to 1012cm−31012cm−3 and capability of scanning the plasma and field parameters in two dimensions with a precision of < 1 mm. The plasma is produced by a multifilamentary cathode and external magnetic field by Helmholtz coils, both designed and constructed in-house. The plasma parameters can be measured by Langmuir probes and electromagnetic field parameters by miniature magnetic probes and Rogowski coils. The plasma produced is uniform and essentially unbounded for performing experiments on waves and turbulence. The whole device can be operated single-handedly by undergraduate or graduate students. The device can be opened, serviced, new antennas/probes installed and ready for operation in a matter of hours. Some results on the excitation of electromagnetic structures in the context of electron magnetohydrodynamics (EMHD) are also presented to demonstrate the suitability of the device for carrying out such experiments. 

14 illus, 1 table, 19 ref

025119   REDDY A N K, HASHEMI M, KHONINA S N (Samara National Research Univ, Russia, Email: naarereddy@ssau.ru; naarereddy@gmail.com) : Apodization of two-dimensional pupils with aberrations. Pramana - J Phys 2018, 90(6), 0077.

The technique proposed to enhance the resolution of the point spread function (PSF) of an optical system underneath defocussing and spherical aberrations. The method of approach is based on the amplitude and phasemaskinginaringapertureformodifyingthelightintensitydistributionintheGaussianfocalplane(YD =0) and in the defocussed planes (YD = π and YD = 2π). The width of the annulus modifies the distribution of the light intensity in the side lobes of the resultant PSF. In the presence of an asymmetry in the phase of the annulus, the Hanning amplitude apodizer [cos(πβρ)] employed in the pupil function can modify the spatial distribution of light in the maximum defocussed plane (YD =2π), results in PSF with improved resolution.

6 illus, 3 tables, 27 ref

025118   TIRANDAZ H, MOLLAEE A K (Hakim Sabzevari Univ, Iran, Email: tirandaz@hsu.ac.ir) : On synchronisation of a class of complex chaotic systems with complex unknown parameters via integral sliding mode control. Pramana - J Phys 2018, 90(6), 0076.

Chaotic systems demonstrate complex behaviour in their state variables and their parameters, which generate some challenges and consequences. This paper presents a new synchronisation scheme based on integral sliding mode control (ISMC) method on a class of complex chaotic systems with complex unknown parameters. Synchronisation between corresponding states of a class of complex chaotic systems and also convergence of the errors of the system parameters to zero point are studied. The designed feedback control vector and complex unknown parameter vector are analytically achieved based on the Lyapunov stability theory. Moreover, the effectiveness of the proposed methodology is verified by synchronisation of the Chen complex system and the Lorenz complex systems as the leader and the follower chaotic systems, respectively. In conclusion, some numerical simulations related to the synchronisation methodology is given to illustrate the effectiveness of the theoretical discussions.

4 illus, 33 ref

025117   BHATT K, RANI C, VAID M, KAPOOR A, KUMAR P, KUMAR S, SHRIWASTAWA S, SHARMA S, SINGH R, TRIPATHI C C (Kurukshetra Univ, Kurukshetra - 136 119, Email: kapilbhattuiet@gmail.com) : A comparative study of graphene and graphite-based field effect transistor on flexible substrate. Pramana - J Phys 2018, 90(6), 0075.

In the present era, there has been a great demand of cost-effective, biodegradable, flexible and wearable electronics which may open the gate to many applications like flexible displays, RFID tags, health monitoring devices, etc. Due to the versatile nature of plastic substrates, they have been extensively used in packaging, printing, etc. However, the fabrication of electronic devices requires specially prepared substrates with high quality surfaces, chemical compositions and solutions to the related fabrication issues along with its non-biodegradable nature. Therefore, in this report, a cost-effective, biodegradable cellulose paper as an alternative dielectric substrate material for the fabrication of flexible field effect transistor (FET) is presented. The graphite and liquid phase exfoliated graphene have been used as the material for the realisation of source, drain and channel on cellulose paper substrate for its comparative analysis. The mobility of fabricated FETs was calculated to be 83cm²/Vs83cm²/Vs (holes) and 33cm²/Vs33cm²/Vs (electrons) for graphite FET and 100cm²/Vs100cm²/Vs (holes) and 52cm²/Vs52cm²/Vs (electrons) for graphene FET, respectively. The output characteristic of the device demonstrates the linear behaviour and a comprehensive increase in conductance as a function of gate voltages. The fabricated FETs may be used for strain sensing, health care monitoring devices, human motion detection, etc.

6 illus, 1 table, 31 ref

025116   REVATHY J S, ANOOJA J, KRISHNAVENI R B, GANGADATHAN M P, VARIER K M (Physics Dep, Univ Coll, Thiruvananthapuram- 695034) : Effective atomic numbers in some food materials and medicines for γ-ray attenuation using 137Cs γ-ray. Pramana - J Phys 2018, 90(6), 0072.

A light-weight multichannel analyser (MCA)-based γ-ray spectrometer, developed earlier at the Inter University Accelerator Centre, New Delhi, has been used as part of the PG curriculum, to determine the effective atomic numbers for γ attenuation of 137Cs γ-ray in different types of samples. The samples used are mixtures of graphite, aluminum and selenium powders in different proportions, commercial and home-made edible powders, fruit and vegetable juices as well as certain allopathic and ayurvedic medications. A narrow beam good geometry set-up has been used in the experiments. The measured attenuation coefficients have been used to extract effective atomic numbers in the samples. The results are consistent with XCOM values wherever available. The present results suggest that the γ attenuation technique can be used as an effective non-destructive method for finding adulteration of food materials.

3 illus, 7 tables, 9 ref

025115   LI Y, LIU J G (Beijing Univ of Posts and Telecommunications, China, Email: 395625298@qq.com) : Multiple periodic-soliton solutions of the (3+1)-dimensional generalised shallow water equation. Pramana - J Phys 2018, 90(6), 0071.

Based on the extended variable-coefficient homogeneous balance method and two new ansätz functions, we construct auto-Bäcklund transformation and multiple periodic-soliton solutions of (3+1)(3+1)-dimensional generalised shallow water equations. Completely new periodic-soliton solutions including periodic cross-kink wave, periodic two-solitary wave and breather type of two-solitary wave are obtained. In addition, cross-kink three-soliton and cross-kink four-soliton solutions are derived. Furthermore, propagation characteristics and interactions of the obtained solutions are discussed and illustrated in figures.

12 illus, 37 ref

025113   KOMATHIRAJ K, SHARMA R (Physics Dep, P.D. Women’s Coll, Jalpaiguri - 735 101, Email: rsharma@associates.iucaa.in) : A family of solutions to the Einstein-Maxwell system of equations describing relativistic charged fluid spheres. Pramana - J Phys 2018, 90(5), 0068.

In this paper, we present a formalism to generate a family of interior solutions to the Einstein–Maxwell system of equations for a spherically symmetric relativistic charged fluid sphere matched to the exterior Reissner– Nordström space–time. By reducing the Einstein–Maxwell system to a recurrence relation with variable rational coefficients, we show that it is possible to obtain closed-form solutions for a specific range of model parameters. A large class of solutions obtained previously are shown to be contained in our general class of solutions. We also analyse the physical viability of our new class of solutions.

6 illus, 45 ref

025112   HAMMAMY M N E, ATTIA A (Physics Dep, Damanhur Univ, Egypt, Email: marwa1374@yahoo.com) : 16C-elastic scattering examined using several models at different energies. Pramana - J Phys 2018, 90(5), 0066.

In the present paper, the first results concerning the theoretical analysis of the 16C p reaction by investigating two elastic scattering angular distributions measured at high energy compared to low energy for this system are reported. Several models for the real part of the nuclear potential are tested within the optical model formalism. The imaginary potential has a Woods–Saxon shape with three free parameters. Two types of density distribution and three different cluster structures for 16C are assumed in the analysis. The results are compared with each other as well as with the experimental data to give evidence of the importance of these studied items.

8 illus, 5 tables, 32 ref

025111   ZHANG S, ZENG Y, LI Z, WANG M, XIONG L (Xiangtan Univ, China, Email: yichengz@xtu.edu.cn) : A novel grid multiwing chaotic system with only non-hyperbolic equilibria. Pramana - J Phys 2018, 90(5), 0063.

The structure of the chaotic attractor of a system is mainly determined by the nonlinear functions in system equations. By using a new saw-tooth wave function and a new stair function, a novel complex grid multiwing chaotic system which belongs to non-Shil’nikov chaotic system with non-hyperbolic equilibrium points is proposed in this paper. It is particularly interesting that the complex grid multiwing attractors are generated by increasing the number of non-hyperbolic equilibrium points, which are different from the traditional methods of realising multiwing attractors by adding the index-2 saddle-focus equilibrium points in double-wing chaotic systems. The basic dynamical properties of the new system, such as dissipativity, phase portraits, the stability of the equilibria, the time-domain waveform, power spectrum, bifurcation diagram, Lyapunov exponents, and so on, are investigated by theoretical analysis and numerical simulations. Furthermore, the corresponding electronic circuit is designed and simulated on the Multisim platform. The Multisim simulation results and the hardware experimental results are in good agreement with the numerical simulations of the same system on Matlab platform, which verify the feasibility of this new grid multiwing chaotic system.

14 illus, 34 ref

025110   MANJUNATHA H C , SOWMYA N (Physics Dep, Government Coll for Women, Kolar- 563 101, Email: manjunathhc@rediffmail.com) : Parametrisation of the experimental fusion-fission cross-sections. Pramana - J Phys 2018, 90(5), 0062.

We have presented non-linear analytical formula for fusion–fission cross-sections. This is achieved by analysing many fusion–fission experiments of the compound nuclei of atomic number range 23 Z 146 available in literature. Our parametrised formula can reproduce the fusion–fission cross-sections which agree well with the experiments. Our parametrisations depend on the charges and masses of the compound nuclei and fission fragments only. These results can be used as a guideline for estimating the fusion–fission cross-sections in those cases where measurements do not exist and also for studying new nuclei which are not yet explored.

8 illus, 3 tables, 76 ref

025109   MAHMOUD A, AHMED M, MAHMOUD S W Z (Physics Dep, Minia Univ, Egypt, Email: alaa.abutaleb@lira.bsu.edu.eg) : Optimum parameters controlling distortion and noise of semiconductor laser under analog multichannel modulation. Pramana - J Phys 2018, 90(5), 61.

This paper presents a comprehensive modelling and simulation study on the optimum parameters that control the distortion and noise of semiconductor lasers (SLs) subject to multichannel modulation for use in analog cable television (CATV) fibre links. The study is based on numerical integration of the rate equation model of the semiconductor laser. The parameters comprise the modulation index per channel (m/ch), number of loaded channels (N) and fibre length (LF ). The signal distortions include the composite second-order (CSO) and composite triple beat (CTB) distortions. The noise is assessed in terms of the relative intensity noise (RIN) and carrier-to-noise ratio (CNR). In order to achieve acceptable CNR values for SL, m/ch should be less than 7.5 and 2 % when loading 12 and 80 channels, respectively. For the CATV fibre link with LF 10 km, the increase in the number of channels from 12 to 80 corresponds to lowering the optimum value of m/ch from 7 to 1 %. The increase of LF to 50 km limits the optimum value of m/ch between 1.4 and 1 %, which corresponds to loading between 12 and 17 channels only.

8 illus, 1 table, 33 ref