003931   SIVARANJANI R, THAYUMANAVAN A, SRIRAM S (Physics Dep, SASTRA Deemed Univ, Thanjavur - 613 401, Email: sukansriram@gmail.com) : Photocatalytic activity of Zn-doped Fe₂O₃ nanoparticles: A combined experimental and theoretical study. Bull Mater Sci 2019, 42(4), 185.

Iron oxide (Fe₂O₃) nanoparticles were synthesized by a simple co-precipitation method. The effect of Zn concentration on Fe₂O₃ nanoparticles was investigated by structural and electronic properties. X-ray diffractograms indicate the formation of a hematite Fe₂O₃ structure. The calculated particle sizes for undoped-Fe₂O₃ and Zn-doped Fe₂O₃ are 31 and 15 nm, respectively. The photocatalytic test was performed against methylene blue to find the efficiency of the photocatalytic activity of the prepared nanoparticles. From the results, it is found that compared to undoped-Fe₂O₃, the efficiency of Zn-doped Fe₂O₃ increases considerably. To understand the mechanism behind the photocatalytic activity, a DFT-based calculation was performed to measure the band edge positions of the undoped and Zn-doped Fe₂O₃ nanostructures and the results are matched well with experimentally observed values.

6 illus, 2 tables, 27 ref

003942   YOUB O, AZIZ Z, BOUABDELLAH B, CHENINE D, LANTRI T (Abdelhamid Ibn Badis Univ, Mostaganem, Algeria, Email: oumelkheiryoub@yahoo.com) : First principles investigation of the structural, electronic, thermal and transport properties of new ternary auride X₃AuO (X = K and Rb) semiconductors. Bull Mater Sci 2019, 42(4), 183.

We report the structural, electronic, thermal and transport properties of two new ternary aurides containing gold atom X₃AuO (X = K and Rb) using the full-potential linearized augmented plane wave method, based on the density functional theory. To describe the exchange-correlation potential, we have employed the generalized gradient approximation–Perdew– Burke–Ernzerhof (GGA–PBE) scheme of the GGA. The computed ground state properties are in good accordance with the experiments. Moreover, Tran–Blaha-modified Becke–Johnson (TB–mBJ) potential improves the electronic properties and gives accurate band gaps. Both anti-perovskites X₃AuO are semiconductors with an indirect band gap. Furthermore, the inclusion of spin–orbit coupling effects on the band structure along with TB–mBJ approximation splits the valence band of our compounds and reduces their band gap energy. The thermodynamic properties including heat capacity (C_V), thermal expansion (α) and Debye temperature (D) are also estimated. The transport properties as function of temperature are calculated using the BoltzTrap code; therefore, these two materials are very appropriate for thermoelectric devices at high temperatures.

4 illus, 1 table, 56 ref

003938   TIWARI S, TAMRAKAR R K, UPADHYAY K, ROBINSON C S (Applied Physics Dep, Bhilai Institute of Technology, Chhattisgarh - 491001, Email: raunak.ruby@gmail.com) : Synthesis, structural and luminescence properties of Dy³⁺ activated GdAlO₃ phosphors by a solid state reaction method under a N₂ atmosphere. Bull Mater Sci 2019, 42(4), 181.

Dysprosium (Dy³⁺) ion-doped GdAlO₃ nanophosphors were fabricated by using a high temperature solid state reaction method. X-ray diffraction measurements were used to investigate the phase and crystal size of these phosphors. The morphology of the powder was observed by scanning electron microscopy. The band structure of the phosphor was determined by recording the UV absorption spectra and Tauc plot. The optical behaviour of the phosphors was determined by measuring their photoluminescence (PL) spectra. The PL spectra show characteristic blue (489 nm) and green (567 nm) emissions corresponding to the energy level transitions of Dy³⁺.

9 illus, 1 table, 23 ref

003918   PRASADINI K W, PERERA K S, VIDANAPATHIRANA K P (Wayamba Univ of Sri Lanka, Kuliyapitiya, Sri Lanka, Email: kumudu31966@gmail.com) : Performance of a rechargeable cell using an ionic liquid gel polymer electrolyte and natural graphite electrode. Bull Mater Sci 2019, 42(4), 180.

With the concepts of green environment and the priority given on economical aspects, a great deal of research activities has been diverted towards clean and low-cost device fabrication. Central focus was on eliminating the use of toxic and expensive materials like Li and different solvents. Application of ionic liquid-based gel polymer electrolytes (GPEs) and non-Li electrodes can address many shortcomings associated with liquid, solid and GPEs. In the present study, characteristics of a rechargeable cell with 1-ethyl-3-methylimidazolium trifluoromethanesulphonate-based GPE having Zn and Sri Lankan natural graphite electrodes have been investigated. For characterization, electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge discharge test have been performed at room temperature. The open circuit voltage of the cell was about 1V. Specific charge and discharge capacities of the cell were 4.66 and 2.99 mA h g⁻¹, respectively. Moreover, efficiency of the specific charge was 80.2 % over 500 cycles, while efficiency of specific discharge was 92 % over 1000 cycles. These results proved the suitability of the electrolyte and electrodes investigated in the present study to be used well in rechargeable cells.

6 illus, 10 ref

003916   PARANGUSAN H, PONNAMMA D, AL-MAADEED M A A (Qatar Univ, Doha, Qatar, Email: lekshmi_deepa@yahoo.com) : Effect of cerium doping on the optical and photocatalytic properties of ZnO nanoflowers. Bull Mater Sci 2019, 42(4), 179.

Photocatalytic performances of the synthesized cerium doped (Ce-doped) ZnO nanoflowers are reported in this work. A microwave-assisted sol–gel method is adopted for the synthesis of the nanomaterial and its structural and morphological features are characterized. While doping, the Ce³⁺ ions occupy the sites of Zn²⁺ ions in the hexagonal ZnO lattice, which is investigated by means of X-ray diffraction studies and energy dispersive X-ray analysis. At higher Ce³⁺ concentrations, ultraviolet (UV) light absorption is quite high as evidenced by the UV–Vis absorption spectra. The photoluminescence study demonstrates higher oxygen vacancy and zinc interstitials for the Ce-doped ZnO compared to the undoped ZnO. Ce-doping improves the electrical properties of the sample as well. Finally, it is established that the Ce-doped ZnO nanoflower is highly efficient in UV degrading the methylene blue organic dye.

12 illus, 3 tables, 61 ref

003894   JAYALEKSHMY N L, THOMAS J K, SOLOMON S (Physics Dep, Mar Ivanios Coll, Thiruvananthapuram - 695 015, Email: samdmrl@yahoo.com) : Preparation, characterization and properties of LnSmWO₆ (Ln = Nd and Dy) nanofunctional ceramics. Bull Mater Sci 2019, 42(4), 178.

Isovalent substitution of lanthanide ions in Ln₂WO₆ (Ln = lanthanides) nanoceramics can probe into multifunctional applications due to their unique structural and electronic properties. In this work Sm³⁺ ions in the Sm₂WO₆ nanoceramics were partially replaced with Nd³⁺ and Dy³⁺ ions and their structural, optical and ionic transport properties were studied. The size and structure of the nanocrystalline LnSmWO₆ (Ln = Nd and Dy) compounds prepared through a combustion method were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM). UV–Visible spectroscopy and photoluminescence spectroscopy were used for the investigation of optical and electronic properties of the nanoceramics. Bulk ceramics prepared from the nanoparticles achieved high-density during the sintering process and the surface morphology of the dense NdSmWO6 was imaged using scanning electron microscopy. The electrical properties of the dense ceramics were analysed using impedance spectroscopy. XRD analysis carried out on the prepared materials showed a single-phase monoclinic structure for the nanoceramics. A combined analysis of FTIR and Raman studies showed the presence of Ln–O and O–W–O vibrations, which confirm the monoclinic structure. Particulate properties investigated through the TEM imaging showed that the prepared materials are polycrystalline aggregates. Optical studies carried out on the nanoparticles showed absorption in the UV region and emission in the visible region. Impedance spectroscopic studies conducted on bulk ceramics imply that these are good oxide ion conductors at high-temperature.

12 illus, 1 table, 50 ref

003939   TRIPATHI D, DEY T K (Physics and Material Science and Engineering Dep, Jaypee Institute of Information Technology, Noida - 201 309, Email: dineshazm83@gmail.com) : Effect of particle size distribution on thermo-mechanical properties of NiO filled LDPE composites. Bull Mater Sci 2019, 42(4), 174.

The effect of nickel oxide (micro) addition on thermo-physical and mechanical properties of low density polyethylene (LDPE) has been studied. The samples have been prepared by the melt mixing process. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) of the samples have been performed for micro-structural characterization and surface morphology, respectively. The XRD result confirms that the crystallinity of LDPE is affected by NiO addition, whereas the agglomeration of nickel oxide can be seen in the SEM photographs of LDPE samples having higher NiO loading. The thermal stability of the samples has been checked from DSC and TGA analyses under nitrogen atmosphere. The thermal stability of LDPE improves with the addition of a small amount of NiO particles. However, the peak melting temperature of LDPE/NiO composites decreases due to the dispersion of nickel oxide in the LDPE matrix. Again, the thermal conductivity of LDPE/NiO composites measured by a KD₂ prothermal analyser increases approximately two times for 40 wt.% of NiO loaded LDPE composites. This increase in the thermal conductivity of LDPE may be explained on the basis of a model based on particle size distribution. The coefficient of linear thermal expansion (CTE) of the samples has been measured by a thermo-mechanical analyser as a function of temperature. The experimental value of CTE is well explained by taking the inter-phase volume and interaction between the filler particles and matrix into account. The mechanical properties of LDPE/NiO composites show an improvement with NiO addition and are explained in the light of various models and correlations.

8 illus, 1 table, 44 ref

003921   RAMASAMY N, ARUMUGAM V, RAJKUMAR S (Central Institute of Plastics Engineering and Technology (CIPET), Chennai 600 032, Email: rajkumar.s@mail.utoronto.ca) : Surface modification of Kevlar fibre fabric and its influence on the properties of Kevlar/epoxy composites. Bull Mater Sci 2019, 42(4), 173.

The present study addresses the enhancement of interfacial interaction between Kevlar and epoxy through surface modification of Kevlar fabric using various chemical treatments. The chemically modified aramid surface was examined by Fourier transformed infrared spectroscopy, energy dispersive spectroscopy, scanning electron microscopy (SEM), dynamic mechanical analysis and wettability characteristics. The Kevlar/epoxy composites were prepared using the hand lay-up process. Furthermore, the influence of surface modification was validated through the mechanical characteristics of Kevlar/epoxy composites. The study reveals that the chemical treatment of the Kevlar surface increases the polar functional groups and improves the interfacial adhesion between fibre and epoxy. The surface energy, work of adhesion and performance of Kevlar composites were studied for treated and untreated fibres. The tensile and flexural moduli were increased up to 38 % in treated Kevlar fibre compared with untreated fibre. It was observed from SEM analysis that adhesive failure bonds rely on chemical bonds at the interface of fibre matrix composites and cohesive failure at the fibre matrix was decreased.

7 illus, 2 tables, 42 ref

003927   SHAIKH M N, ZAFAR Q, PAPADAKIS A (Physics Dep, Management and Technology Univ, Lahore 54000, Pakistan, Email: qayyumzafar@gmail.com) : A study of electromagnetic light propagation in a perovskite-based solar cell via a computational modelling approach. Bull Mater Sci 2019, 42(4), 169.

Recently, there has been huge surge of scientific interest in organic–inorganic hybrid perovskite solar cells by virtue of their high efficiency and low cost fabrication procedures. Herein, we examine the light propagation inside a planar perovskite solar cell structure (ITO/TiO₂/ZnO/CH₃NH₃PbI₃/Spiro-OMeTAD/Al) by solving the Helmholtz equation in the finite element-frequency domain. The simulations were conducted using the COMSOL multiphysics finite element solver to carry out the two-dimensional optical modelling of simulated solar cells in the visible region. It has been observed that shorter wavelengths of light are significantly absorbed by the top region of the photoactive perovskite layer. Specifically, at a wavelength of 400 nm, the effective optical power penetration decays to zero at only 40 % of the overall length of the photoactive layer. This observation has been attributed to the high absorption coefficient of the CH₃NH₃PbI₃ perovskite material at shorter wavelengths. However, at longer wavelengths, the incident light propagates deeper into the photoactive layer, reaching 100 % penetration. Based on the numerical computation, a maximum generation rate of ∼3.43×10²³ m³s⁻¹ has been observed in the photoactive layer at a wavelength of 550 nm.

6 illus, 50 ref

003884   BHATTACHARYYA S R, GAYEN R N (Physics Dep, Presidency Univ, Kolkata - 700 073, Email: rabin.physics@presiuniv.ac.in) : Fabrication and characterization of transparent nanocrystalline ZnO thin film transistors by a sol–gel technique. Bull Mater Sci 2019, 42(4), 167.

A nanocrystalline zinc oxide (ZnO) thin film-based metal–insulator–semiconductor thin film transistor (MIS TFT) was fabricated by a facile sol–gel technique onto silicon di-oxide/indium tin oxide-coated glass substrates. The microstructural study of the ZnO thin films indicated uniform crystalline growth with typical (002) X-ray diffraction peaks for h-ZnO with a wurtzite structure. The optical transmittance of the ZnO thin films was >80 % in the visible region of the electromagnetic spectrum. The field effect transistor (FET) aluminium top contacts were fabricated using suitable shadow masking. The transfer characteristics of a typical ZnO MIS FET revealed nonlinearity in a linear plot. From the slope and crossover, we obtained a first estimate of field effect mobility (μ) and threshold voltage (V_T) of 0.13 cm² V⁻¹ s⁻¹ and 1.03 eV, respectively. The ZnO TFT operated in enhanced mode with n-channel characteristics and the drain current on–off ratio was 10⁵. The deposition parameter needs to be optimized to obtain TFTs with a higher modulation ratio and larger field-effect mobility.

5 illus, 24 ref

003935   TAHMASEBI N, SEZARI S, ABBASI H, BARZEGAR S (Physics Dep, Jundi-Shapur Univ of Technology, Dezful 64615334, Iran, Email: tahmasebi@jsu.ac.ir) : Investigation of photodegradation of rhodamine B over a BiOX (X = Cl, Br and I) photocatalyst under white LED irradiation. Bull Mater Sci 2019, 42(4), 166.

In this study, a low temperature precipitation method was applied to prepare BiOX (X = Cl, Br and I) nanostructures using HCl, HBr and HI as halogen sources. The as-prepared samples were characterized by various techniques such as X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy and nitrogen adsorption–desorption analysis. The photoactivity of BiOX samples to degrade rhodamine B (RhB) molecules in aqueous solution was investigated under white LED irradiation. The results indicated that BiOCl exhibits a higher photodegradation performance in comparison with BiOBr and BiOI. Ninety six percent of the RhB molecules was degraded over BiOCl after 25 min light irradiation, whereas under the same conditions, the degradation efficiencies of BiOBr and BiOI samples are 62 and 24%, respectively. The enhanced photodegradation activity of BiOCl is ascribed to the higher specific surface area which increases the physical adsorption of RhB molecules on the photocatalyst surface. Moreover, the photodegradation mechanism and the main radical species in the degradation reactions over BiOCl were investigated.

9 illus, 43 ref

003915   PANT N, VERMA A L, PANDEY S D (Applied Physics Dep, Amity Univ, Noida 201313, Email: alverma@amity.edu) : Effect of vanadyl doping on relative intensities of factor group split Raman bands in potassium oxalate monohydrate. Bull Mater Sci 2019, 42(4), 164.

We report Raman spectral studies of pure potassium oxalate monohydrate, K₂C₂O₄ ·H₂O (POM) and its doped varieties with 1 and 5 % vanadyl concentrations at room temperature. Apart from many other interesting changes in the Raman spectra on doping with VO²⁺, one of the most intriguing observations is the change in relative intensities of factor group split components of several Raman bands including some bands in the lattice mode region. We have explained the relative intensity changes of factor group split components in terms of locking of adjacent C₂O₄−H₂O−C₂O₄−H₂O chains due to vanadyl doping in the POM lattice. The reduction in the intensities of water bands on vanadyl doping also supports this view.

5 illus, 2 tables, 14 ref

003940   WANG H, HAN D, XU J, YANG L (Guilin Univ of Electronic Technology, Guilin 541004, People’s Republic of China, Email: wh65@tom.com) : Influence of Ni doping on the structural, ferroelectric, magnetic and optical properties of Bi_0.85Nd_0.15Fe_1-xNi_xO₃ thin films. Bull Mater Sci 2019, 42(4), 163.

Bi_0.85Nd_0.15Fe_1−xNi_xO₃ (x = 0.025–0.125) thin films were synthesized by applying a sol–gel method on fluorine-doped tin oxide substrates. The influence of Ni doping concentration on the structure, leakage current, ferroelectric, magnetic and optical properties of Bi_0.85Nd_0.15Fe_1−xNi_xO₃ thin films was investigated. Bi_0.85Nd_0.15Fe_1−xNi_xO₃ thin films are polycrystalline films that present a single perovskite structure without any impurity phase when the Ni doping concentration is below 0.1 and present a Bi₂Fe₄O₉ phase when the Ni doping concentration is above 0.1. The grain size of the films and their holes gradually decrease with an increase in the Ni doping amount. The saturation magnetization of Bi_0.85Nd_0.15Fe_1−xNi_xO₃ thin films increases with Ni content. However, appropriate Ni doping concentration can decrease the leakage current and enhance the ferroelectric polarization and optical transmittance of the films. Meanwhile, the absorption edge has a slight red shift. Bi_0.85Nd_0.15Fe_1−xNi_xO₃ thin films possess better combination properties at a leakage current density of 4.27 × 10⁻⁹ A cm⁻², ferroelectric polarization of 28.58μC cm⁻², saturation magnetization of 2.08 emu cm⁻³ and transmittance of over 85 % when the Ni doping concentration, x is 0.05.

6 illus, 1 table, 24 ref

003893   JAIN V, CHANDRA A R, LAKSHMI N, REDDY V R, JANI S (Applied Physics Dep, Amity Univ, Gwalior - 474 005, Email: sneh.jani@gmail.com) : Magnetic behaviour of ⁵⁷Fe/Co/Al multilayers deposited on a glass substrate. Bull Mater Sci 2019, 42(4), 161.

Multilayers of ⁵⁷Fe/Co/Al 20 and 40 trilayers (TLs) prepared on a glass substrate using ion beam sputtering deposition techniques have been studied. Magnetization curves obtained at different angles show the anisotropic nature of both the samples. Both samples show strong in-plane uniaxial anisotropy. Negative δm values suggest that dipolar type interactions between grains contribute to the in-plane uniaxial anisotropy. Angular dependence of coercivity indicates that the magnetization reversal mechanism is different for both samples. The variation in coercivity with azimuthal angle is well reproduced in the 20 TL sample using the modified Kondorsky model and by the Stoner–Wohlfarth model in the 40 TL sample.

6 illus, 2 tables, 20 ref

003924   SAGAR R, RAIBAGKAR R L (Post Graduate Studies and Research in Applied Electronics Dep, Gulbarga Univ, Gulbarga - 585 106, Karnataka, Email: rlraibagkar@rediffmail.com) : Microstructure and transport properties of multiwall carbon nanotube-reinforced barium zirconium titanate ceramics. Bull Mater Sci 2019, 42(4), 159.

The influence of multiwall carbon nanotubes (MWCNTs) reinforced on microstructures and their transport properties on pure and cerium-substituted barium zirconium titanate (BZT) ceramics are reported in this study. The MWCNTs were prepared by a low-temperature sonochemical/hydrothermal method using dichloromethane as a carbon source. These MWCNTs were mixed with the as-prepared ceramic powders before heat treatment to obtain a reinforced product. The scanning electron micrographs reveal the successful incorporation of carbon nanotubes in BZT ceramics. The temperature dependent direct current (dc)-resistivity was less for MWCNT-reinforced ceramics in contrast to that of pure ceramics. The decrease in the dc resistivity was due to the superior electrical behaviour of MWCNTs, which act as a connector between ceramic grains. The Seebeck coefficient of cerium-substituted-BZT improved after reinforcing the MWCNTs.

4 illus, 28 ref

003895   KARIMI T, HAGHIGHATZADEH A (Physics Dep, Islamic Azad Univ, Ahvaz, Iran, Email: haghighatzadeh@gmail.com) : Enhanced photocatalytic activity of SnO₂ NPs by chromium (Cr) concentration. Bull Mater Sci 2019, 42(4), 158.

This study reports the synthesis of un- and chromium (Cr)-doped tin dioxide (SnO₂) nanoparticles (NPs) through chemical precipitation and their application for photodegradation of methylene blue dye. The obtained NPs were characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, elemental mapping and ultraviolet–visible (UV–Vis) spectroscopy. The TEM and XRD results demonstrated that the SnO₂ NPs are spherical and contain polycrystalline tetragonal crystals. UV–Vis spectra showed that increasing the concentration of the Cr dopant enhances the light absorption potential of the SnO₂ NPs. Finally, the findings of the photocatalytic experiments performed for 120 min in ultraviolet irradiation under ambient conditions revealed an improvement in the degradation efficiency of the SnO₂ NPs by Cr doping.

9 illus, 2 tables, 61 ref

003905   LIU L, JI Y, LIU L (Shandong Jianzhu Univ, Shandong, People’s Republic of China, Email: 2922977166@qq.com) : First principles calculation of electronic, phonon and thermal properties of hydrogenated germanene. Bull Mater Sci 2019, 42(4), 157.

Germanene is a basic building block of two-dimensional materials of germanium and it exhibits many unique electronic properties. It is necessary for germanene to tuning its electronic band structure for future applications. The electronic and vibrational properties of germanene, germanane, single-sided semi-hydrogenated germanene and single-sided full-hydrogenated germanene (FHgermanene) were analysed by density function theory. It was found that hydrogenation effectively leads to germanene transition from metallic to semiconductors. Meanwhile, phonon dispersion showed that germanane and FHgermanene are stable. For the same Ge/H ratio in the structure, the thermal properties of germanane and FHgermanene are consistent. The hydrogenation process provides a novel method to tune the properties of germanene with unprecedented potentials for future nanoelectronics.

4 illus, 1 table, 29 ref

003880   AL-HUSSEINI A M, LAHLOUH B (Physics Dep, Jordan Univ, Amman 11942, Jordan, Email: a.taha@ju.edu.jo) : Influence of pyramid size on reflectivity of silicon surfaces textured using an alkaline etchant. Bull Mater Sci 2019, 42(4), 152.

Surface texturing of p-type monocrystalline silicon (100) is well known as one of the best methods to reduce reflection losses and to increase light trapping and light absorption probability. Pyramid surface textures play a major role in reducing the reflectance of monocrystalline silicon surfaces. In this paper, the size of pyramids formed on the surface of p-type silicon substrates and by changing the etching characteristics during the texturing process of silicon were studied and evaluated. The pyramids that formed on the crystalline silicon surface formed light traps that led to increased light absorption efficiency. The pyramid size effects on the percent reflectivity were evaluated at normal incidence and an inverse relationship between the percent reflectivity and the pyramid size was found. The size of the pyramids was controlled by controlling the texturing process by changing the concentrations of potassium hydroxide (KOH) and isopropyl alcohol (IPA) and by controlling the etching process time. In this work, the optimized etching conditions were determined as a solution prepared with 20 wt % KOH and 3 wt % IPA for wet etching at a reaction temperature of 80^◦C and an etching time of 40 min. The lowest value for percent reflectivity of the patterned surfaces was 9.7 % and it was achieved for pyramid bases close to 4 μm as measured at a wavelength of 650 nm.

18 illus, 1 table, 29 ref

003919   PRINCY S S, SREEJA B S, MANIKANDAN E, RADHA S, BATHE R N, JAIN R, PRABHU S S (Electronics and Communication Engineering Dep, SSN Coll of Engineering, Tamil Nadu - 603110, Chennai, Email: sasiprincys@ssn.edu.in) : An ultrafast laser micromachined broadband terahertz frequency selective surface. Bull Mater Sci 2019, 42(4), 151.

The purpose of this paper is to focus on the frequency selective surface (FSS) filter structure which exhibits a broadband frequency response operating in the terahertz (THz) frequency regime. The achievement of the broadband frequency response has been accomplished by means of only invoking the FSS structure excluding the presence of a ground plane and also excluding the multilayered FSS technique. The FSS filter is simulated using CST Microwave Studio. This simulation has been carried out using Teflon as the substrate which is a dielectric over which the conductive material gold with a thickness of 2 μm is coated in which the FSS filter structure is designed with periodic hexagonal aperture unit cells. The structure of the proposed frequency selective surface filter helps in achieving a broadband frequency response with a bandwidth of 300 GHz centred at 0.36 THz. The designed FSS structure is a bandpass filter and it exhibits the most imperative properties of angle resolvability and polarization insensitivity. The fabrication of the same has been carried out using the laser micromachining process.

12 illus, 2 tables, 13 ref

003892   ISLAM M S, ANINDYA K N, BHUIYAN A G, HASHIMOTO A (Electrical and Electronic Engineering Dep, Khulna Univ of Engineering and Technology, Khulna 9203, Bangladesh, Email: sheraj_ruet@yahoo.com) : Deconvolution of Raman spectra of disordered monolayer graphene: An approach to probe the phonon modes. Bull Mater Sci 2019, 42(4), 147.

This paper explores the phonon modes from the Raman spectrum of disordered monolayer epitaxial graphene using the deconvolution technique. The phonon density of states (PDOS) of pristine monolayer graphene has been enumerated and convoluted by a Gaussian function to check the accuracy of the deconvolution process. We show that the original PDOS is recovered by deconvolution of the convoluted spectrum with the same spread function. We propose that the PDOS of pristine monolayer graphene is similar to that of the relative intensity of the deconvoluted Raman spectrum of disordered epitaxial graphene. These results could be used for identifying the intensity of individual phonon modes to justify the structure, and probing the mechanism of changing the phonon modes with various types of defects formed in graphene.

5 illus, 29 ref

003923   RANI S, LAL B, SAXENA S, SHUKLA S (Physics Dep, Lovely Professional Univ, Phagwara - 144 411, Email: suman.rani@lpu.co.in) : Optical properties of TAG co-doped with Ce and Eu. Bull Mater Sci 2019, 42(4), 144.

Nanopowder samples of terbium aluminum garnet (TAG) doped with Ce and Eu were prepared by a sol–gel technique followed by sintering in air at various temperatures (maximum of 1100^◦C). The investigated concentrations of both the dopants were 0.1, 0.5 and 1.0 mol %. Nine powder samples prepared by the permutation of the doping concentrations were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD) and optical spectroscopic techniques. SEM and TEM investigations confirmed the nano-structure of the prepared powders while EDX not only confirmed the doping of Ce and Eu in TAG but also eliminated the possibility of any interfering impurities. Powder XRD showed that the basic structure of TAG did not change on doping which was further confirmed by Fourier-transform infrared studies. However, optical absorption and Raman scattering investigations showed the distortion of the TAG lattice on doping. Emission (photoluminescence) in the spectral region of 400–700 nm was observed when excited by 280 nm radiation. The intensity of this emission showed interesting dopant concentration dependence. The emission from TAG co-doped with 0.5 mol % of both Ce and Eu is of particular interest as its calculated colour chromaticity coordinates ‘x and y’ were found as x = 0.35 and y = 0.35 which are very close to that of sun light at noon indicating its potential as a material for the white light source.

14 illus, 2 tables, 20 ref

003878   ABDULLAH H Y (Salahaddin Univ, Erbil, Iraq, Email: hewayaseen@gmail.com) : A comparative study of potential energy curves with RKRV curves for the ground states of I2, F2 and CO molecules. Bull Mater Sci 2019, 42(4), 142.

The latest molecular constant potential energy curves used for the electronic ground states of I2, F2 and CO molecules are constructed by the Rydberg–Klein–Rees–Vanderslice (RKRV) method. The Morse, Rydberg, Hulbert– Hirschfelder and extended Rydberg potential functions compare each other and have good agreement with RKRV curves for these molecules. The percentage deviations from RKRV curves are drawn at the same abscissa scale. These curves show that the extended Rydberg potential energy curve deviation is < 0.5−2 % error to dissociation limit.

3 illus, 2 tables, 25 ref

003898   KHATRI A, RANA P S (Physics Dep, D.C.R. Univ of Science and Technology, Murthal - 131 039, Email: drpawansrana.phy@dcrustm.org) : Visible light photocatalysis of methylene blue using cobalt substituted cubic NiO nanoparticles. Bull Mater Sci 2019, 42(4), 141.

This study reports the facile co-precipitation synthesis of pure and cobalt substituted NiO nanoparticles. The cubic crystalline structure of the synthesized NiO nanoparticles was confirmed through X-ray diffraction. Structural behaviour, morphological, elemental composition and optical properties of the prepared nanoparticles are investigated by Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersive spectrum, transmission electron microscopy and UV–Vis spectroscopy. The optical band gap is determined using UV spectra and is observed to decrease with an increase in cobalt ion concentration. Furthermore, methylene blue dye solution has been used to investigate the photocatalytic ability of the synthesized nanoparticles in the presence of sunlight. It is found that percentage degradation in dye concentration increases with irradiation time and also with the increase in the concentration of doping of cobalt in NiO. The dye solution is found to degrade to 94 % within 50 min in the presence of solar radiation and the Ni_0.6Co_0.4O sample.

12 illus, 2 tables, 56 ref

003903   KUMAR S, THAKUR N (Physics Dep, Himachal Pradesh Univ, Shimla 171005, Email: shammirathor18@gmail.com) : Synthesis, structural and optical properties of K_0.5Na_0.5NbO₃ thin films prepared by spin coating route. Bull Mater Sci 2019, 42(4), 135.

In this paper, lead-free sodium potassium niobate thin films have been prepared by using a chemical solution deposition-based spin coating route. The effect of different anealing temperatures on structural and optical properties has been studied. The phase analysis of thin films was investigated by using X-ray diffraction analysis. The microstructure and surface roughnes of thin films were studied by using atomic force microscopy. Raman spectroscopy analysis revealed that increase in annealing temperature gives rise to better crystallinity and perovskite phase. Optical parameter of thin films has been studied by using reflectance spectroscopy at room temperature. Photoluminescence analysis has been conducted by using an exciting wavelength of 300 nm at room temperature.

8 illus, 1 table, 19 ref

003928   SINGH B, DAS B (Physics Dep, Lucknow Univ, Lucknow - 226 007, Uttar Pradesh, Email: bs2801514@gmail.com) : The synthesis and study of structural, optical and electrical behaviours of tin oxide/polyaniline (SnO₂/PANI) nanocomposites. Pramana – J Phys 2019, 93(2), 32.

A series of tin oxide (SnO₂)/polyaniline (PANI) nanocomposites with loading of different wt % of PANI were synthesised using a solution-based processing method for improving the structural and physical properties of tin oxide. The effect of PANI loading on the gross structure, surface morphology, optical properties and electrical properties of SnO2/PANI nanocomposites was investigated. The scanning electron micrographs (SEM) show congruent dispersal of PANI in the tin oxide matrix where the gross/average structure is unchanged as revealed by powder X-ray diffraction (PXRD). A slight change in the lattice parameter of the pristine rutile crystalline structure SnO₂ and its nanocomposites has been recorded. However, the crystallite size has been found to decrease from 60 to 40 nm with different wt % loading of PANI. The presence of characteristic Fourier transform infrared (FT-IR) peaks dovetail to C–H, C=C, NH₂, C–C and the energy-dispersive analysis of X-rays (EDAX) confirm the development of the PANI nanocomposite. Photoluminescence (PL) spectroscopic study shows the gradual decrement in the intensity of the emission peak at 611 nm due to the disappearance of surface defects associated with oxygen vacancies. The uniform dispersion of PANI at the nanoscale significantly enhanced the electrical properties, e.g. four orders of magnitude changes in electrical conductivity and carrier mobility.

5 illus, 3 tables, 33 ref

003858   MARAJ E N, IQBAL Z, BIBI J (Mathematics Dep, HITEC Univ, Taxila 47700, Pakistan, Email: ehnber@gmail.com) : Performance of resistance in the variation on a nano thin film flow influenced by thermal deposition: The Buongiorno model. Pramana – J Phys 2019, 93(2), 31.

In the current study, the flow of Casson liquid thin film, together with heat transfer towards a stretching surface extracting out from a narrow slit in the presence of a magnetic field, viscous dissipation and thermal radiation effects, is examined. The contribution of nanoparticles is investigated by employing the Buongiorno model. Mathematical modelling is carried out in the Cartesian coordinate system and similarity analysis is opted for simplification. The numerical analysis is performed in the reduced system using the shooting method. The effects of the prominent parameters are discussed using line and bar graphs. The key finding is that the temperature drop is prominent in the case of Casson nanofluid compared to the nanofluid.

25 illus, 25 ref

003926   SHAIK S, TIWARI A K, RAMAKRISHNA S A (Materials Science and Engineering Dep, Indian Institute of Technology Kanpur, Kanpur - 208 016, Email: saleemsk@iitk.ac.in) : Alcohol sensor based on gold-coated nanoporous anodic alumina membrane. Pramana – J Phys 2019, 93(2), 30.

We report a refractive index sensor consisting of a gold-coated nanoporous anodic alumina membrane on aluminium substrate that can distinguish between different kinds of alcohols such as methanol and ethanol due to their different refractive indices. The nanoporous volume allows the loading of liquids with low surface energy into its nanopores. Upon dipping one end of the membrane into the alcohol, the entire nanoporous surface experiences wetting. The wavelength shift of the Fabry–Perot resonating modes formed between the gold-coated nanoporous alumina surface and aluminium on the other side due to the changed effective refractive index form the basis of the sensor. The sensitivity of the nanosensor to the refractive index of the loaded liquid is sufficient to distinguish between different alcohols such as methanol, ethanol and isopropanol, and to detect about 5–10 % of methanol in a methanol–ethanol mixture.

4 illus, 1 table, 39 ref

003909   MOHAMMADMORADI Y, YAGHOBI M (Islamic Azad Univ, Amol, Iran, Email: m.yaghoubi@iauamol.ac.ir) : Tunnel magnetoresistance in the B_nN_n(n = 12, 24) cages. Pramana – J Phys 2019, 93(2), 25.

In this study, the effects of the type of the cage, the bias and gate voltages on spin transport properties of electrons in magnetic tunnel junction (MTJ) of B_nN_n (n = 12, 24) cages were investigated by theoretical methods. For a gate voltage (V_g) more than 0.5 V, the device became electrically conductive at V_b = 0.5 V. The electric current increased linearly for bias voltages more than |V_b| = 1 V at V_g = 0.0 V. The maximum value of the tunnel magnetic resistance (TMR) ratio was ∼75 % for B₁₂N₁₂ and 60% for B24N24 molecules. The maximum values of TMR against the bias voltage (V_b) were seen at 1.6 V (−1.6 V) for B₁₂N₁₂ and 0.0 V for B₂₄N₂₄. At V_b = 0.5 V, the TMR ratio was changed by varying the gate voltage. Finally, the spin transport properties of the B₁₂N₁₂ cage were compared with those of the B₂₄N₂₄ and C₆₀ cages.

9 illus, 37 ref

003906   LIU N, WEN X-Y (Beijing Information Science and Technology Univ, Beijing 100192, China, Email: xiaoyongwen@163.com) : Modulational instability and dynamics of rational soliton solutions for the coupled Volterra lattice equation associated with 4 × 4 Lax pair. Pramana – J Phys 2019, 93(2), 23.

The coupled Volterra lattice equation associated with 4 × 4 Lax pair is under investigation, which is an integrable discrete form of a coupled KdV equation applied widely in fluids, Bose–Einstein condensation and atmospheric dynamics. First, we explore the conditions for modulational instability (MI) of the constant seed background for this equation. Secondly, we present the discrete Darboux transformation (DT) and generalised DT based on the new 4 × 4 Lax pair. Through the resulting discrete DT, the bell-shaped and anti-N-shaped soliton solutions of the coupled Volterra lattice equation are derived. Moreover, we derive the M-shaped and N-shaped rational solitons and bell-shaped and N-shaped semirational soliton solutions of the coupled Volterra lattice equation via the discrete generalised DT. Finally, we numerically study the dynamical behaviours of such soliton solutions and find that the rational and semirational soliton solutions have better numerical stability than the usual soliton solution, although three types of solutions are robust against a small noise. The results may be helpful for understanding the two-layered fluid waves near ocean shores described by the coupled Korteweg–de Vries (KdV) equation.

7 illus, 45 ref

003890   HIREMATH A, BASHA H, KETHIREDDY B, REDDY G J, NARAYANAN N S V (Mathematics Dep, Central Univ of Karnataka, Kalaburagi - 585 367, Email: gjr@cuk.ac.in) : The effect of thermal expansion coefficient on unsteady non-Newtonian supercritical Casson fluid flow past a vertical cylinder. Pramana – J Phys 2019, 93(2), 20.

A new thermodynamic computational model has been proposed for the current study, which deals with the free convective supercritical Casson fluid flow past a vertical cylinder. In this model, pressure, temperature and compressibility factor are the critical parameters to govern the thermal expansion coefficient. The present model is based on the Redlich–Kwong equation of state. Comparisons with experimental results and determined values of thermal expansion coefficient for the choice of chemical compound (isobutene) from the present study show great similarity. The chemical compound isobutane has many industrial applications. For instance, in geothermal power plant, supercritical isobutane is employed as a working fluid, it is used in the deactivated (USY alkylation) catalyst regeneration, it is used in heat pumps and many other industrial processes. Furthermore, isobutane finds extensive application as a propellant in foam products and aerosol cans, as a refrigerate gas in freezers and refrigerators, as a feedstock in industries of petrochemical importance, for standardisation of gas mixtures and emission monitoring, etc. In addition, the Casson fluid flow model can be used to study the blood flow rheology, slurry flows, etc. The numerical scheme such as Crank–Nicolson type is demonstrated to simplify the governing nonlinear coupled partial differential equations. The transient results of flow-field variables, coefficients of heat and momentum transport for a Casson fluid under supercritical condition for various values of reduced pressure and reduced temperature are computed and discussed through graphs.

14 illus, 4 tables, 44 ref

003932   SOLTANI F, BAAZIZ H, CHARIFI Z, HASSAN F E H, HAMAD B (Physics Dep, M’sila Univ, M’sila, Algeria, Email: baaziz_hakim@yahoo.fr) : Ab initio study of the fundamental properties of Zn_1−xTM_xSe (TM=Mn, Co and Fe). Pramana – J Phys 2019, 93(2), 18.

The structural, electronic, magnetic, thermal and elastic properties of Zn_1−xTM_xSe (TM = Mn, Co and Fe) ternary alloys are investigated at x = 0, 0.25, 0.50, 0.75 and 1.00 in the zincblende (B3) phase. The calculations are performed using all-electron full-potential linearised augmented plane-wave (FP-LAPW) method within the framework of the density functional theory (DFT) and the generalised gradient approximation (GGA). The electronic and magnetic properties were performed using the modified Becke–Johnson potential combined with the GGA correlation (mBJ-GGA). The electronic structures are found to exhibit a semiconducting behaviour for Zn_1−xMn_xSe and Zn_1−xCo_xSe and a half-metallic behaviour for Zn_1−xFe_xSe alloys at all concentrations, while CoSe with x = 1.00 is found to exhibit a metallic behaviour. The calculated magnetic moment per substituted transition metal (TM) Mn, Co and Fe atoms for half-metallic compounds are found to be 2.5, 1.5 and 2 μB, respectively. The p–d hybridisation between the TM d- and Se p-states reduces the local magnetic moment of Mn, Co and Fe and induces small local magnetic moments on Zn and Se sites. In addition, we discuss the mechanical behaviour of binary and ternary compounds and all compounds studied here are mechanically stable.

6 illus, 5 tables, 55 ref

003937   TELI M T (Applied Sciences Dep, Mahatma Gandhi Mission’s Jawaharlal Nehru Engineering Coll, Cidco, Aurangabad - 431 005, Email: mtteli43@gmail.com) : General electrodynamics of non-abelian vector bosons of SU(2). Pramana – J Phys 2019, 93(1), 17.

Generalised Dirac–Maxwell equations (GDM) are extended to describe non-abelian vector bosons by forming SU(2) multiplet. Noether’s conserved current is investigated by forming suitable Lagrangian for the theory. General electrodynamics (GED) equations are obtained as Euler–Lagrange equations. Higgs mechanism leads to eigenvalue problem with masses of the bosons as eigenvalues. The sources of the fields have only improper conservation. Analogous to abelian vector bosons, non-abelian vector bosons also are seen to have nuclear structure with massive nucleus. There occur two types of SU(2) sheets, each of three non-abelian vector bosons: one group contains one bradyon and two tachyon vector bosons, whereas the other group contains one tachyon and two bradyon vector bosons. Physical Z and W bosons are formed from the eigenvectors of U(1) and SU(2). The Z and W bosons do not have the same coupling strengths in SU(2).

13 ref

003889   GOSWAMI A, DUTTA A, PAUL S (Homi Bhabha National Institute, Mumbai - 400 094, Email: animesh@vecc.gov.in) : Design of a spiral inflector and transverse beam matching for K130 cyclotron at the Variable Energy Cyclotron Centre. Pramana – J Phys 2019, 93(1), 15.

This paper describes the design of a spiral inflector for inflecting heavy ion beams into the existing central region of the K = 130 Variable Energy Cyclotron at Kolkata. Simulation results of transverse beam dynamics through the spiral inflector and the effect of the fringe field on beam phase ellipses at its exit have been discussed in the absence of space charge effect. We have also made an effort to minimise the effect of inflector fringe field by properly adjusting the inflector voltage. The proper matching conditions in the central region have been obtained by optimising the system parameters of the existing axial injection line of K130 cyclotron. The tracking of particles that belong to the boundary of the optimised phase ellipses at the matching point has also been carried out in the computed electric and magnetic fields in the central region. Simulation results confirm that the optimised beam condition reduces beam losses for further acceleration in the cyclotron.

12 illus, 3 tables, 35 ref

003899   KINGNI S T, PONE J R M , KUIATE G F, PHAM V-T (Electrical Engineering Dep, Dschang Univ, Bandjoun, Cameroon, Email: mboupdapone00@gmail.com) : Coexistence of attractors in integer- and fractional-order three-dimensional autonomous systems with hyperbolic sine nonlinearity: Analysis, circuit design and combination synchronisation. Pramana – J Phys 2019, 93(1), 12.

This paper reports the results of the analytical, numerical and analogical analyses of integer- and fractional-order chaotic systems with hyperbolic sine nonlinearity (HSN). By varying a parameter, the integer order of the system displays transcritical bifurcation and new complex shapes of bistable double-scroll chaotic attractors and four-scroll chaotic attractors. The coexistence among four-scroll chaotic attractors, a pair of double-scroll chaotic attractors and a pair of point attractors is also reported for specific parameter values. Numerical results indicate that commensurate and incommensurate fractional orders of the systems display bistable double-scroll chaotic attractors, four-scroll chaotic attractors and coexisting attractors between a pair of double-scroll chaotic attractors and a pair of point attractors. Moreover, the physical existence of chaotic attractors and coexisting attractors found in the integer-order and commensurate fractional-order chaotic systems with HSN is verified using PSIM software. Numerical simulations and PSIM results have a good qualitative agreement. The results obtained in this work have not been reported previously in three-dimensional autonomous system with HSN and thus represent an enriching contribution to the understanding of the dynamics of this class of systems. Finally, combination synchronisation of such three-coupled identical commensurate fractional-order chaotic systems is analysed using the active backstepping method.

15 illus, 53 ref

003908   MAO L-F (Beijing Science and Technology Univ, Beijing 100083, People’s Republic of China, Email: mail_lingfeng@aliyun.com) : Quantum coupling and electrothermal effects on electron transport in high-electron mobility transistors. Pramana – J Phys 2019, 93(1), 11.

Based on the energy and momentum balance equations and three-dimensional Schrödinger equations, a physical model of the quantum coupling and electrothermal effects on the electron transport in GaN transistors is proposed. Quantum coupling and electrothermal effects in GaN transistors cause a reduction in the barrier height, changes in the quantised energy levels of the two-dimensional electron gas, and a decrease in the electron density and source–drain current. This model predicts that the current collapse in GaN transistors can occur under channel electrons with large transverse energy and it can be alleviated by optimising the physical device parameters. The gate length-dependent resistance predicted by the proposed model agrees well with the experimental data reported in the literature. Not only the physical mechanism but also the possibility to improve the reliability of high-electron mobility (HEMT) GaN transistors by optimising its physical parameters has been given in this model due to its analytic nature.

10 illus, 81 ref

003911   MOSAHEBFARD A, SAFAIEE R, SHEIKHI M H (Shiraz Univ, Shiraz, Iran, Email: msheikhi@shirazu.ac.ir) : Density functional theory of influence of methane adsorption on the electronic properties of a PbS cluster. Pramana – J Phys 2019, 93(1), 9.

The effect of methane adsorption on the electronic properties of a lead sulphide (PbS) cluster is investigated using density functional theory (DFT) when an oxygen molecule was previously adsorbed to the cluster. This paper studies how the pre-adsorption of oxygen influences the tendency of PbS cluster to adsorb CH₄ and variations of its electronic properties due to CH₄ adsorption. Further investigation on how these variations occur was carried out by charge transfer calculations. The discussion based on the results of this study succeeded in explaining the previously reported experimental observations.

6 illus, 1 table, 41 ref

003910   MOHAN S R, SINGH M P, JOSHI M P (Laser Materials Processing Div, Raja Ramanna Centre for Advanced Technology, Indore - 452 013, Email: raj@rrcat.gov.in; rajmho@gmail.com) : Monte Carlo simulation of charge transport in disordered organic systems using buffer lattice at the boundary. Pramana – J Phys 2019, 93(1), 8.

In this paper, we present an alternative method for simulating the charge transport in disordered organic materials by using a buffer lattice at the boundary. This method does not require careful tracking of the carrier’s hopping pattern across boundaries. The suitability of this method is established by reproducing the field dependence of mobility, carrier relaxation and carrier diffusion in disordered organic systems obtained by simulating the charge transport in a lattice without implementing any boundary conditions along the electric field direction. The significance of the buffer lattice is emphasised by simulating the field dependence of mobility without using a buffer lattice, which results in negative field dependence of mobility (NFDM) at low field regime due to the extra bias the carrier gains from the neglected hops at the boundaries along the direction of the electric field.

7 illus, 21 ref

003917   PRAKASH A, VEERESHA P, PRAKASHA D G, GOYAL M (Mathematics Dep, Karnataka Univ, Dharwad - 580 003, Email: prakashadg@gmail.com) : A new efficient technique for solving fractional coupled Navier–Stokes equations using q-homotopy analysis transform method. Pramana – J Phys 2019, 93(1), 6.

In this paper, a solution of coupled fractional Navier–Stokes equation is computed numerically using the proposed q-homotopy analysis transform method (q-HATM), and the solution is found in fast convergent series. The given test examples illustrate the leverage and effectiveness of the proposed technique. The obtained results are demonstrated graphically. The present method handles the series solution in a large admissible domain in an extreme manner. It offers us a modest way to adjust the convergence region of the solution. Results with graphs explicitly reveal the efficiency and capability of the proposed algorithm.

24 illus, 20 ref

003930   SINGH M, SARKAR A (Fuel Chemistry Div, Bhabha Atomic Research Centre, Mumbai - 400 094, Email: arnab@barc.gov.in) : Analytical evaluation of cesium emission lines using laser-induced breakdown spectroscopy. Pramana – J Phys 2019, 93(1), 2.

A laser-induced breakdown spectroscopy-based method has been successfully developed to quantify cesium (Cs) in solution using spectroscopically pure graphite planchets as a sample support. As Cs is a line-poor system, only five usable Cs atomic emission lines could be found and characterised by employing high-resolution system. The calibration curves of these emission lines were constructed under optimised experimental conditions. The analytical properties of these calibration curves were evaluated based on the usable dynamic range, R² of fitting, root mean square error cross-validation and limit of detection (LOD). The dynamic ranges of these five lines were found to be in correlation with the energy level involved in the transition. An LOD of 4 ppm was obtained using Cs(I) 852.11-nm line, which corresponds to 0.16 μg of Cs on the planchet. Based on the cross-validation approach, the best accuracy and precision (∼6 %) were obtained for 852.11 nm in <3000 ppm solutions, and the same is ∼8 % for 672.33 nm and 697.33 nm in high concentrated solution of Cs.

3 illus, 3 tables, 30 ref

003941   WANG S (Mathematics and Physics Dep, Hohai Univ, Jiangsu 213022, People’s Republic of China, Email: wsg97@163.com) : Adaptive synchronisation of complex networks with non-dissipatively coupled and uncertain inner coupling matrix. Pramana – J Phys 2019, 93(1), 1.

In this paper, the adaptive synchronisation of time-varying perturbed complex networks with nondissipatively coupled and uncertain inner coupling matrix is studied. In order to describe the actual network better, the out-coupling configuration matrix is not limited by the dissipatively coupled conditions. It is also worth pointing out that the drive system and the response system described in this paper are uncertain, and uncertainty arises in linear inner coupling matrix and unavoidable uncertain external disturbances, which is different from the past. On the basis of Lyapunov stability theory, adaptive law can be obtained and at the same time unknown bounded disturbances can be overcome.

6 illus, 26 ref

002658   NASER H, SHANSHOOL H M, HASSAN S F, DHEYAB A B (Ministry of Science and Technology, Baghdad, Iraq) : Experimental and theoretical study of the measured wavelength of laser light using Mach–Zehnder interferometer. Mapan - J Metrol Soc India 2019, 34(2), 289-94.

In this research, the experimental and theoretical studies to measure the wavelength of laser light by Mach–Zehnder interferometer were conducted. Then, the results were compared with Zemax software. The fringes have been obtained both as shining and dark. The wavelength of laser light and the diameter of fringes were calculated by the optical system. The calculation relies on the measure of the airy disk diameter, whose approximation is directly proportional to the wavelength of the laser source; and to the space between the aperture and the image plane. However, the calculation is reciprocally proportional to the diameter of the aperture. Then, the results were compared with Zemax software, where the ratio of error is very small.

23 ref

002648   KUMAR A (Mathematics Dep, K.A.P.G. Coll, Prayagraj, Uttar Pradesh) : Magneto hydrodynamic convection in a stratified flow in an inclined porous channel. Int J Multidiscip Res Dev 2019, 6(6), 95-9.

The convection in a stratified flow in an inclined porous channel bounded by two permeable layers under the influence of uniform magnetic field perpendicular to the channel is investigated. Here, we have assumed that the permeability of the fluid medium and the pressure gradient of the fluid flow are varying point to point. The flow between the permeable layers is governed by Navier—Stoke’s equations, while the flow in the porous medium is governed by Darcy’s law. The velocity field and temperature distribution are obtained and results are discussed with the help of various graphs.

3 illus, 6 ref

002676   YENER T, EFE G C, IPEK M, ZEYTIN S (Sakarya Univ, Adapazar, Turkey, Email: tcerezci@sakarya.edu.tr) : Low temperature aluminising of Inconel 718 alloy by pack cementation(ICCESEN 2017). Indian J Chem Technol 2019, 26(3), 244-7.

A novel pack-aluminizing diffusion coating has been conducted on –Inconel 718 alloy at 600 and 650°C for 2 and 4 h. The aluminising powder packs have been prepared using Al powder as a source for depositing aluminium, Al₂O₃ powder as an inert filler and ammonium chloride NH₄Cl as an activator. The microstructures of the coatings formed on the alloy surface are characterized by means of SEM/EDS and XRD analysis. Optical microscope and SEM analysis reveal that coating layers are homogenous, compact and nonporous and there is a good bonding at the interface of the coating and matrix. Layer thickness variation is measured from the surface to the matrix and changed from 10 to 40 µm which is increased with increasing process time and temperature. The hardness of the coating layer increased to 1174 HVN with the increasing process time and the temperature while the hardness of the matrix is 300 HVN.

5 illus, 1 table, 15 ref

002633   ERYILMAZ S, GUL M, INKAYA E (Physics Dep, Amasya Univ, Amasya, Turkey, Email: srpleryilmaz@gmail.com) : Investigation of global reactivity descriptors of some perillaldehyde derivatives in different solvents by DFT method. Indian J Chem Technol 2019, 26(3), 235-8.

The global reactivity descriptors of some perillaldehyde derivatives in the different solvents have been investigated by the Time-Dependent Density Functional Theory (TD-DFT/B3LYP) method with 6-311G(d,p) basis set and CPCM solvation model. The obtained results have been compared to get knowledge about the solvent effect on the reactivity properties of the compounds. It has been determined that the reactivity parameters exchange depending on the solvent polarity and molecular structure.

2 illus, 1 table, 29 ref

002645   KAUR H, SHARMA S, DURGAPAL A K (Physics Dep, Kumaun Univ, Nainital, Uttarakhand, Email: harmeenkaur.kaur229@gmail.com) : Structure and mass function of open cluster NGC 6910. J Mountain Res 2019, 14(1), 85-8.

NGC 6910 is located in a Cygnus X region, which is a ~10^◦ complex of actively star forming molecular clouds and young clusters, located at a distance of about 1.7 kpc (Reipurth & Schneider 2008). Open clusters possess many favorable characteristics for initial mass function (IMF) studies. The observed mass function of a star cluster can in principle be determined from the observed luminosity function (LF) using theoretical stellar evolutionary models. Here, we are presenting our initial results related to structure parameters, extinction, distance and mass function of open cluster NGC 6910 based on the deep and wide field mosaic images taken from 1.0 m Sampurnand telescope of ARIES, India.

3 illus, 18 ref

002622   BHATT D , CHANDOLA H C , RAWAT D S, PANDEY H C (Physics Dep, Kumaun Univ, Nainital-263001, Email: deepakbhattphysics@gmail.com) : Dual models of QCD and their implications. J Mountain Res 2019, 14(1), 63-7.

Some of the dual formulations of QCD are reviewed and analyzed for their possible implications especially in non-perturbative sector of QCD at zero temperature. Starting from the Nambu-Mandelstam idea and the ’t Hooft Abelian Projection technique, the effective formulations of QCD like the dual GinzburgLandau formulation and magnetic symmetry based dual QCD formulation have been analyzed in which dual magnetic potentials coupled with monopole field act as fundamental variables. The dual dynamics associated with these models is discussed in the quenched approximation and the analysis of symmetry breaking , flux tube configurations, confinement potential and nature of dual QCD vacuum is presented which establishes magnetic symmetry based dual QCD formulation as a more effective topological viable formulation for analysing the non-perturbative aspects of QCD.

15 ref

002642   KANDPAL C, SINGH S, MISHRA D (Physics Dep, R H Govt P G Coll, Kashipur U S Nagar-262401, Email: chitrakandpal700@gmail.com) : Study on abelian dominance of interquark potential in SU (3) lattice QCD using simulation techniques. J Mountain Res 2019, 14(1), 51-3.

It is assumed that no free quark to be found in nature. This is known as the confinement problem, is an issue which has no analytic proof till yet. But lattice QCD Monte Carlo simulations have shown that for large distances the quark antiquark potential varies linearly with interquark distance and controlled by the string tension. In the present work we have revisited the study of interquark potentials and Abelianization of QCD in Maximally Abelian gauge in context of dual superconducting picture. We have also observed the perfect Abelian dominance of the string tension for various spatial size lattices.

2 illus, 6 ref

002616   ADHIKARI M, PANT S (Physics Dep, Kumaun Univ, Nainital, Uttarakhand, Email: moonaadhikari03@gmail.com) : Ground and excited state dipole moment of 2, 5-dihydroxybenzoic acid from solvatochromic shifts. J Mountain Res 2019, 14(1), 47-50.

In present work we explore the role of solvents on the 2, 5-dihydroxybenzoic acid by using fluorescence techniques. It was found that DHBA shows spectral behaviour depending on polarity of solvents. DHBA shows generally three components at 405-415 nm, 430-450 nm, and 450-470 nm. The effects of zwitterion as well as the interplay ionic species are involved to explain the observed results.

5 illus, 6 ref

002640   JOSHI R, CHANDRA R (Physics Dep, Kumaun Univ, Nainital - 263 001, Email: reetikajoshi.ntl@gmail.com) : Kinematics and energetics of a solar jet from NOAA active region 12297. J Mountain Res 2019, 14(1), 43-6.

In this article, we have presented the study of a solar jet on March 14, 2015 recorded from the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO) satellite. The jet was observed from the solar active region NOAA AR 12297. We have discussed the dynamics and calculated the various possible energy contents of the observed jet. The estimated total energy flux liberated during the jet ejection was 2.1 x 10⁷ erg cm^-2 s ^-1 .

3 illus, 15 ref

002639   JOSHI I, GARIA J S (Physics Dep, L. S. M. Govt. P.G. Coll, Pithoragarh, Uttarakhand, Email: ilajoshi0090@gmail.com) : Dyonic field equations in arbitrary media. J Mountain Res 2019, 14(1), 39-41.

Starting with the generalized Maxwell field equation of dyon, the matrix form of generalized Maxwell field equation is formulated in a compact manner. The Maxwell field equations and Lorentz force for dyon in term of the matrix are also derived in arbitrary media (material media). It represents an additional field, which shows polarization and magnetization for the electric and magnetic charge. Finally, the Continuity equation for dyon is also derived.

8 ref