000903   Amar A, Kumar N (Physics Dep, Bhupendra Narayan Mandal Univ, Bihar, Email: anupam9215@gmail.com) : Effects of different junction parameters on junction conductances of crossed metallic carbon nanotubes. Bull Pure Appl Sci-Sect C 2021, 40D(1), 56-62.

We have studied the effect of different junction parameters on the junction conductances made of two crossed metallic carbon nanotubes. We have found that because of the intrinsic asymmetries of the junction, forward and backward tunneling between one tube and the other are unequal. Passing a current in one tube leaded to the development of non zero voltage across the other one, a zero field Hall like conductance for the junction was found. We have found that this zero field Hall conductance relates to the contact conductance of the junction. The result also shows that the electronic properties of the junction sensitively depend on the degree of matching between the tube lattices. This matching is controlled by the crossing angel, which resulted in an intertube conductance that varied by an order of magnitude for different angles. We have derived a tunneling matrix element that coupled the low energy electronic states on the two tubes. The magnitude of the coupling was determined by the intertube separation of the crossing angle. We have found that the intrinsic symmetries of the junction created a discrepancy between the forward and backward hopping between the tubes. Using Landauer-Buttiker formalism, we have calculated the different conductances of the four terminal junctions. We have found that the contact conductance scaled inversely with the zero field Hall conductance of the junction. We have also found that the two crucial parameters in determining the conductance are the tube chiralities and the crossing angle. The obtained results were found in good agreement with previously obtained results.

4 illus, 29 ref

000902   Kumar J S, Kumar A (Physics Dep, Bhupendra Narayan Mandal Univ, Bihar, Email: jayphysics108@gmail.com) : Surface wave propagation on carbon nanotube bundle and characteristics by high attenuation. Bull Pure Appl Sci-Sect C 2021, 40D(1), 49-55.

We have studied the surface wave propagation on carbon nanotube bundle and its characteristics by high attenuation. The slow wave propagation along conducting carbon nanotubes and the high conductivity compared with metallic conductors like copper made these structures for high frequency applications. The property reduced the size of antenna and passive circuits. It was found that the complex surface wave propagation has a significant attenuation coefficient at lower frequency band. This attenuation coefficient induces highly damping effect which reduces the active part of the dipole length. Thus, dipole lie always below resonance and input impedance be always capacitive. The conductivity and electromagnetic wave interaction of the conducting carbon nanotubes have also important features in comparison with traditional conductors like copper wires of the same size. The quantum capacitances of the order of the electrostatic capacitance of the transmission line. This property has two main effects on electromagnetic wave propagation along the carbon nanotube transmission line, slow wave propagation and high characteristic impedance. The wave propagation on the arms of the dipole is highly attenuated such that the active part of the dipole is such smaller than the physical length of the dipole itself. Thus, the dipole always be a short dipole and could not be resonant in any case. The result shows that the advantage of size reduction combined with surface wave propagation is used only in high frequency bands above 100 GHz. The attenuation coefficient has a moderate effect in the frequency band from 10 to 100 GHz. The resonance mechanism occurred when the incident wave at the feeding point adds constructively with reflected wave from dipole ends. The obtained results were found in good agreement with previously obtained results.

4 illus, 27 ref

000901   Mishra A, Kumar A (Physics Dep, Bhupendra Narayan Mandal Univ, Bihar, Email: aradhnamishrabgp@gmail.com) : Electronic properties of graphene nanoribbons with zigzag armchair edges. Bull Pure Appl Sci-Sect C 2021, 40D(1), 44-9.

We have studied the electronic properties of graphene nanoribbons with zigzag armchair edges. We have calculated the local density of states, the single particle special function, the optical conductivity and the conductance for different geometries. We have also studied the disordered effects. The influence of disorder on the transport behavior of tight binding approach has been accepted. The conductance of edge contacted graphene nanoribbon sensitivity was found dependent on the lead graphene nanoribbon matching conditions. In this respect armchair graphene nanoribbon enabled a somewhat better current injection. Dangling bonds on the graphene nanoribbon side of the interface substantially reduced the conductance. The typical conductance of disordered graphene nanoribbons sandwiched between graphene leads in a junction set up exhibited a negative differential conductivity whenever new transport channels become available by increasing the Fermi level. This accentuates the efficiency of Anderson localization function manifested a precursor of the transition from a current carrying to an Anderson disorder induced insulating behavior which takes place when the size of the disordered active graphene region becomes infinite. The
obtained results were found in good agreement with previously obtained results.

2 illus, 23 ref

000900   KUMAR U (Physics Dep, Ganesh Dutt Coll, Bihar, Email: upendra.physics@yahoo.in) : Enhancement of high order multipole fields in optical nanoantennas. Bull Pure Appl Sci-Sect C 2021, 40D(1), 39-43.

We have studied a mathematical framework of higher-order multipole fields in the vicinity of optical nanoantennas. We have exemplified at suitably chosen Nanoantennas i.e. a Nano antenna which strongly enhances the quadruple field. The modification of excitation rates in quantum mechanical systems due to this quadrupolar enhancement was studied. The hybrid system consisting of an optical Nano antenna and a quantum mechanical three level system was studied in detail. A properly designed Nano-antenna can excite dipole for bidden transitions in three level systems due to the enhanced higher order multipole fields. The dynamics of the system is strongly altered by the presence of the nanoantenna and cannot be done by the quadrupolar enhancement alone. This can be achieved by enhancing higher order multipole fields near the antenna. A quadrupole transition as the dominant excitation channel in a three level system was considered. It was found that the enhancement of this transition significantly intensify subsequent emission processes with respect to altered emission characteristics. The effects depend on geometrical parameters; the properties of the optical nanoantenna can be tailored and hence allowed for direct implementations in spectroscopies schemes. The obtained results were found in good agreement with previously obtained results.

2 illus, 19 ref

000899   Roy K, Ghosh N K (Physics Dep, Kalyani Univ, West Bengal, Email: nkg@klyuniv.ac.in) : High-Tc superconductivity within t - t'- J - J' model. Bull Pure Appl Sci-Sect C 2021, 40D(1), 34-8.

The behaviour of high-Tc cuprates in its ground state has been examined within the t-t'-J-J' model using an exact method. The role of next-nearest-neighbor (NNN) hopping (t') and exchange (J') interactions on the charge gap, spin gap and effective exchange interaction has been investigated. Charge gap shows a gapped behavior. Spin gap curves establish a gapless behavior at small t′/t and J′/t. Also, it appears that effective exchange interaction is very much relevant in the present system.

3 illus, 20 ref

000898   Davis S (Research Foundation of Southern California, California, Email: sbdavis@resfdnsca.org) : Relativistic quantum scalar fields. Bull Pure Appl Sci-Sect C 2021, 40D(1), 25-33.

A new equation for the relativistic scalar field is derived from the correspondence with the classical commutator and covariance. It has the same form as the Klein Gordon equation with different coefficients.

3 ref

000897   Inyang E P, Ntibi J E, William E S (Physics Dep, Calabar Univ, Calabar, Nigeria, Email: etidophysics@gmail.com) : Analytical solutions of the schrödinger equation with kratzer-screened coulomb potential for a quarkonium system. Bull Pure Appl Sci-Sect C 2021, 40D(1), 14-24.

In this work, we obtain the Schrödinger equation solutions for the Kratzer potential plus screened Coulomb potential model using the series expansion method. The energy eigenvalues is obtained in non-relativistic regime and the corresponding unnormalized eigen function. Three special cases were obtained. We applied the present results to calculate heavy-meson masses of charmonium ܿܿ̅ and bottomonium ܾܾത, and we got the numerical values for1S, 2S, 1P,2P, 3S, 4S ,1D,2D and 1F states. The results are in good agreement with experimental data and the work of other researchers.

3 illus, 56 ref

000896   Davis S (Research Foundation of Southern California, California, Email: sbdavis@resfdnsca.org) : Twistors and the amplitudes in the integrable sector of superstring theory. Bull Pure Appl Sci-Sect C 2021, 40D(1), 1-13.

Twistors can represent the spin in superstring theory and provide a theoretical explanation of the two-dimensional spherical model of elementary particles together with the surface distributions of the charges. The integrability of certain matter sectors of the strong interactions also may be traced to the action of the conformal group on collinear trajectories that occur in a twistor formulation. The amplitudes for these scattering processes in four dimensions have a representation with quantum states in a nonsupersymmetric theory defined by the low-energy limit of a solution to the N = 2 string equations with a Wick rotation of the metric with (2, 2) signature. The twistor form of an N = 2 scattering amplitude is given.

54 ref

001023   VIVEKANANDAN N, SRISHAILAM C (Central Water and Power Research Station, Maharashtra) : Selection of best fit probability distribution for extreme value analysis of rainfall. Water Energy Int 2021, 63r(10), 13-9.

Extreme Value Analysis (EVA) of rainfall is considered as one of the important aspects to arrive at a design parameter for planning, design and management of civil and hydraulic structures. This can be carried out by fitting probability distributions to the observed annual maximum rainfall series wherein the parameters of the distributions are determined by method of moments and Maximum Likelihood Method (MLM). In this paper, a study on evaluation of Extreme Value Type-1 (EV1), 2-parameter Log Normal (LN2) and Log Pearson Type-3 (LP3) distributions adopted in EVA of rainfall for Anakapalli, Atchutapuram, Kasimkota and Parvada sites is presented. Goodness-of-Fit (viz., Chi-square and Kolmogorov-Smirnov) and diagnostic (viz., root mean squared error) tests are used to evaluate the performance of probability distributions adopted in EVA of rainfall. Based on GoF and diagnostic tests results, the study identifies the LP3 (MLM) is better suited probability distribution for EVA of rainfall at Anakapalli while LN2 (MLM) for Kasimkota and EV1 (MLM) for Atchutapuram and Parvada.

5 illus, 8 tables, 20 ref

001022   SINGHAL S, KUMAR A, YAQOOT M, CHATURVEDI B K (UJVN Limited, Dehradun) : Challenges in meeting aspirations of project affected families while developing hydro power projects. Water Energy Int 2021, 63r(10), 6-12.

World Bank considers Hydro power as a source of opportunity for poverty alleviation and sustainable development beyond its conventional role of electricity generation. Role of hydropower in poverty reduction in developing countries is also emphasized by World Bank’s water sector strategy. This paper presents insights of the problem related to management of stakeholders residing in the vicinity of under development Hydro Power Projects i.e. Project Affected Families (PAFs) including those whose land has not been acquired. Paper begins by exploring the expectations of PAFs from a project by introducing the concept of aspirations. That is followed by analyzing the ill effects of improper redressal of these aspirations. Afterwards, challenges faced by the project authorities while implementing the mechanisms for meeting the aspirations of PAFs have been discussed. Paper is concluded with the discussion regarding existing efforts taken at National as well as international level. Aspirations in the context of present research will relate to the expectations of the Project Affected Families (PAF’s) from the development of Hydro Power Projects in the region.

1 illus, 3 tables, 27 ref

001021   PANDAY B K, JOSHI D (Jal Jeevan Mission, Dehradun) : Modelling for desilting chamber of naitwar mori hydro power project. Water Energy Int 2021, 63r(11), 24-8.

The paper describes in detail the physical model studies conducted for desilting arrangement of Naitwar-Mori Hydropower Project in Uttarakhand, under different operating conditions on a geometrically similar physical model built on a scale of 1:15 at Hydraulics Research Station, Bahadrabad. It has been planned to utilize the water of River Tons for power generation upto 60 MW on a run-of-the river type scheme harnessing a head of about 96.76m. Twin desilting chambers of length 130 m, width 25m and depth 13.50m have been provided in the project to remove particles of size bigger than 200micron. The model studies were conducted for a desilting arrangement consisting of power channel with its x-section having side slope of 1:1.5 and a well designed transition connecting the desilting chamber. Though, the overall silt trapping efficiency in this case was found in the range of 92 to 94 % for a silt load ranging from 2000 to 4000 PPM, majority of the silt load got deposited in the power channel itself due to low velocity in the channel resulting into very low silt flushing efficiency (SFE) i.e. around 2.5 %, which is not desirable. In order to overcome this problem, it was proposed to modify the power channel in different stages by reducing the x-sectional area of u/s transition and making the side slope of channel steeper. It was found that modifying side slope of the channel is more instrumental in improving SFE. However it needs some more modifications in the transition portion so as to improve the silt flushing efficiency (SFE) to the desired extent.

7 illus, 5 tables, 5 ref

001014   ASHOUR E H, AHEMD S E, ELSAYED S M, BASIOUNY M E, ABDELHALEEM F S (National Water Research Center, Cairo, Egypt) : Integrating geographic information system, remote sensing, and modeling to enhance reliability of irrigation network. Water Energy Int 2021, 64r(1), 6-13.

This paper focuses on applications of remote sensing (RS), geographic information system (GIS), and modeling that support water management in irrigation schemes with application examples from Egypt and Sudan. This study examines pertinent articles that describe RS applications combined with GIS and modeling to delineate parameters relevant to irrigation, such as vegetation cover, crop acreage, crop type, crop water requirements, and irrigation water supply. Derived irrigation performance indicators (IPIs) could provide efficient tools for water shortage management in irrigation schemes. RS is important for assessing the crop acreage and crop type within an irrigated area. This information can help solve basic problems associated with regional scale water use and requirements. Integrating RS, GIS, and models of the irrigation requirements and supplies for irrigation schemes is an effective method for exploring, storing, managing, and displaying spatial data and can be employed for the decision making and management functions that are necessary for the planning and management of any irrigation scheme. RS, GIS, and model integration not only help a user in the analysis and visualization of spatial and non-spatial data in the form of maps but also in the development of custom tools. This paper presents a tool outline that involves the integration of RS, GIS, and models that can be used by irrigation managers to overcome water shortages and improve the performance of irrigation systems.

3 illus, 3 tables, 20 ref

001013   AGRAVATT A, SONI B P (Gujarat Energy Transmission Corporation Limited, Gujarat) : Maintenance, monitoring & strengthening of substation grounding – Experience of GETCO. Water Energy Int 2021, 64r(2), 46-53.

In a recent global scenario, rapid load growth, technological advancement and raised living standards has emphasized power utilities to provide reliable, uninterrupted and quality power supply to the end consumers. Efficient and Effective Grounding system plays important role in keeping uninterrupted and reliable power with increasing fault levels of substations. Earthing is also of prime importance as it directly deals with human safety. Gujarat Energy Transmission Corporation Ltd. (GETCO) operates around 2000 EHV substations across the state, has taken many initiatives towards improvement of grounding system across its network in a way to fulfil the commitment to deliver quality power supply. This paper will delineate mainly three distinguished Grounding enhancement practices for effective strengthening, maintenance and monitoring of the earthing system of GETCO network. (a) Adoption of Maintenance Free Treated Earthing: To mitigate the maintenance challenges of conventional Cast Iron Pipe type earthing and to improve its life, GETCO has started installing Maintenance Free Earth pits at all EHV substations since 2014. The paper describes in detail the technical specification and drawing adopted for maintenance free earthing and modality of execution as per site condition. The acceptance criteria for ground Enhancement material through tests like leaching, sulphur detection, corrosion and resistivity tests, is also discussed in detail. (b) The Earthing Adequacy study(EAS): This study was carried out in GETCO for 14 nos. of critical substations of more than 50 years old where earthing has considerably got weakened. The purpose for performing this EAS is to access the entire switchyard grounding for its healthiness. Moreover, to ensure efficient and unambiguous earthing installations at all upcoming EHV substations, GETCO has made the Earthing Adequacy study mandatory since the year 2015. In this paper, the parameters attribute and methodology to conduct EAS in accordance with standards and to levy necessary stitching of weak earthing areas based on derived parameter is explained. (c) Strengthening of earthing of specially designed Load shedding transformers (LST), which is a special drive being done for more than 4600 nos. of 11kV agriculture feeders across the Gujarat state. This paper reports the special grounding scheme derived for earthing the LST phase wire that draws continuous current even during normal operating condition. The assessment for pre and post earthing installation and the result testified for earthing parameters is discussed. By implementing effective earthing measures through adoption of various Grounding Enhancement practices, GETCO have witnessed several benefits like improved availability of transmission network, reduced nos. of interruptions and safe operating scenario which have marked significant impact on system operation.

7 illus, 7 tables, 8 ref

001012   DWIVEDI V, JHA A K (NHPC Ltd, Faridabad, Haryana) : Proposal for renovation & modernization of baira siul power station. Water Energy Int 2021, 64r(2), 39-45.

Renovation, modernization and uprating (RM&U) is required for power plant which have outlived their normative operating life. R&M of Hydro Power plants is a cost effective way to bridge the wide gap between demand and supply of power at less cost and lower gestation period of about 3 to 4 years as against construction period of 6 to 7 years for new power plant. RM&U programmes may be taken up timely to prevent deterioration in operation of generating units which may lead to their premature retiring. By R&M programme, the generating plant can be made to operate for another extended period of 20 to 25 years with improved reliability and availability. This paper describes various aspects regarding planning for R&M and life extension of Bairasiul power station for various Civil, Hydro mechanical and Electromechanical components.

4 ref

001011   SINHA A, RANJAN A (Bses Rajdhani Power Limited, New Delhi) : Rooftop solar PV projects – saviour of discoms or vicious cycle of death. Water Energy Int 2021, 64r(2), 33-8.

Govt. of India has set an ambitious target of 40 GWp of Rooftop solar to be installed in our country by 2022. Against the target, the actual commissioning has been about 15% of this target till date. While the reasons for the same may vary across states, this paper examines whether promotion of rooftop solar PV across the consumers through the Power Distribution Utility led / facilitated models & initiatives can drive India’s rooftop solar story. Rooftop Solar PV is a Distributed Energy Resource (DER) which has advantage of being an embedded network element as well as a source of power generation. The solar power generation generally follows the morning / day peak of Indian utilities, India being a tropical country. The paper highlights the initiatives undertaken by BSES Rajdhani to implement the Rooftop Solar City initiative in a structured format, to reap benefits (estimated through a framework developed named Value of Grid Connected Rooftop Solar (VGRS)) and enable the transformation of the present day Discom to a Distribution System Operator. There is a need to focus on solarisation of residential roofs through innovative business models, which shall help in introducing equitable retail tariff across consumer segments, optimizing the need for cross-subsidized tariff and govt. subsidy to electricity consumers. The initiative, if implemented in holistic manner, has potential of positively impacting the availability of competitive green electricity availability for commercial and industrial consumers, while reducing the challenges of Open Access for the Discom. Besides, the residential consumers can become self dependent to a large extent, thereby having a sustainable source of low cost power. In Delhi, Hon’ble Delhi Electricity Regulatory Commission (DERC) has already introduced the models of Group Net Metering (GNM) and Virtual Net Metering (VNM), which is a good start for introduction of P2P trading of surplus solar power amongst consumers subsequently, leading to beginning of Retail Market reforms. Besides, Rooftop Solar has a positive impact on reducing the wire losses of Discoms, as well as providing relief to the LV distribution network from congestion especially during peak summer days. The paper concludes that Rooftop Solar PV, if deployed strategically, can be very beneficial for Discoms, especially it can play an enabling role in its transition to DSO. There is a need for innovation in Business model focussing on residential consumers and evaluation of rooftop solar PV projects from a holistic perspective is desired by the Discoms

12 illus, 5 ref

001008   SEN S, KHANNA M, RATHORE K, DAS P S, KUMAR A, PANDEY P, PRAKASH V M S, SHEKHAR S (Central Transmission Utility of India Limited, New Delhi) : Fault current limiter using series reactors in Indian power system. Water Energy Int 2021, 64r(3), 52-8.

The Indian Transmission Grid is divided into five regions viz. Eastern Region (ER), North-eastern Region (NER), Northern Region (NR), Western Region (WR) and Southern Region (SR) with each region comprising of several states. All the above five regions are presently synchronised to form a single pan India Power Grid resulting in increased stiffness of the Indian Grid and improved system reliability. Further, the Indian Grid is interconnected with the neighbouring countries viz. Bangladesh, Nepal, Bhutan with plan for further interconnection with Sri Lanka. Further, each region has utilities, which are responsible for Generation, Transmission and Distribution of power in the state. To meet the growing power demand, particularly in Northern region and Western region, generation capacity addition associated with commensurate expansion and strengthening of the transmission and distribution network are being carried out due to which the short circuit (fault) levels at a number of stations are approaching or exceeding the designed equipment ratings. This may cause severe mechanical & thermal stresses on the equipments leading to insulation problems, equipment failure/damage and unwanted operation of the associated protection systems. One way to restrict fault levels within the design limits would be to upgrade the substation by replacement of switchgear, earth mat and other associated material/equipments. However, the option is costly and may not be feasible as it involves long periods of continuous shutdown. This paper explains the planning process and the studies carried out to limit fault current through implementation of the series reactor in context of the Indian national grid. Various aspects like economic benefits of the series reactor compared to up gradation of the switchyard equipments corresponding to higher Short Circuit levels, selection of reactor ratings and its placement in substation, performance of series reactor under steady state and under transient conditions have also been discussed. Mitigation measures adopted to control the Transient recovery voltage (TRV) associated with switching of dry type air core reactors have also been mentioned. The paper also describes the field experience gained during installation & commissioning of these Series reactors in 400kV Bus and on 400kV Lines in 400kV Ballabhgarh and Mandola existing substations in NCR area.

5 illus, 4 tables, 2 ref

003320   BUPPAN P, SOMMATAS A, KO-AMORNSUP W, SUNGKHARATA N, TRIWATCHARLEEKORN L (Health Promotion Dep, Srinakharinwirot Univ, Nakhon Nayok, Thailand) : Detection of the colistin-resistant MCR-1 gene in escherichia coli isolates in retail pork from fresh markets in Bangkok, Thailand. Asian Jr of Microbiol Biotech Env Sc 2021, Vol 23 (2), 126 - 30.

This study aimed to investigate the presence of colistin resistance (the mcr-1 gene) in E. coli isolates in retail pork. A total of 900 retail pork samples were collected from 36 fresh markets in Bangkok from January to October 2018. We collected E. coli that were isolated from MacConkey agar and Eosin Methylene Blue agar and screened the presence of the mcr-1 gene by using PCR. Results showed the MICs to colistin of the 900 studied isolates, colistin resistance (MIC ≥ 2 mg/l) was identified in 9.44 % (85/900) confirmed E. coli isolates. The size of the mcr-1 amplicon was 309 bp. The mcr-1 gene was detected in 37.65 % (32/85) samples. The highest frequency was observed in the mcr-1 genes from Thawi Watthana (75.00 %). The data demonstrated that the mcr-1 gene was highly prevalent in retail pork purchased from the fresh markets in Bangkok, suggesting that active surveillance of the mcr-1 gene is imperative in curtailing its spread.

1 illus, 2 tables, 10 ref

003309   GANESH K E (Physics Dep, B.M.S Coll of Engineering, Bengaluru - 560 019) : Satellite data based study on long term variation of black carbon over Bengaluru, Karnataka, India. Asian Jr of Microbiol Biotech Env Sc 2021, Vol 23 (1), 61 - 5.

Black Carbon (BC) content in the atmosphere is an important parameter which tells us about the contribution of fossil fuel burning in altering cloud structure and monsoon. Total Aerosol Optical Thickness (AOT) data and AOT due to BC at 550nm have been collected along with necessary parameters from NASA’s Giovanni website for the period 2010 to 2018 for the continental south Indian location Bengaluru of Karnataka state, India. It has been found that during November-2011 the percentage contribution of AOT– BC towards total AOT at 550 nm is found to be least (0.69 %). On the other hand, during February-2017 the percentage contribution of AOT–BC records highest value (11.54 %). On annual average scale, the year 2011 records lowest contribution of AOT–BC (5.218 %), whereas the year 2016 records the highest contribution of AOT–BC (6.73 5%) towards total AOT at 550nm. Also it has been observed that there is a small reduction in Incoming short wave solar radiation (ISR) from 2010 (99.63 W/m2 ) to 2018 (86.73 W/m² ) indicating the accumulation of particulates in the atmosphere. However there appears no significant change in the outgoing long wave radiation (OLR) from the year 2010 (226.39 W/m2 ) to 2018 (230.08 W/m² ). The reason for change in BC concentration over year with possible justification is discussed in this paper.

7 illus, 1 table, 9 ref

003212   NAGANANDHINI S P, SANGEETHA T, ARIVAZHAGAN G (Physics Dep, Thiagarajar Coll, Madurai - 625 009, Email: arivuganesh@gmail.com) : Intermolecular interactions in acetonitrile + acetone binary mixtures: FTIR spectroscopic studies. Asian J Chem 2021, 33 (6), 1452 - 6.

FTIR spectra of neat acetone (ACT), neat acetonitrile (AN) and their binary solutions at various molar ratios 1:2, 1:3, 2:1 and 3:1 (AN:ACT) have been recorded in 4000-400 cm^-1 region at room temperature. The acetone is a self-associated molecule and existed as a mixture of monomers, dimers and trimers. The acetonitrile is also a mixture of monomer and weakly bonded dimers. The acetone is associated through the H-bond interaction (ACT)C-H···O=C(ACT) and the acetone and acetonitrile molecules are interacted through the non-classical H-bonds (ACT) C-H···N≡C (AN) and (AN) C-H···O=C (ACT).

3 illus, 1 table, 39 ref

003202   DINESHKUMAR P, NAGANANDHINI S P, SANGEETHA T, ARIVAZHAGAN G (Physics Dep, Thiagarajar Coll, Madurai - 625 009, Email: arivuganesh@gmail.com) : H-Bond interactions in triethylene glycol-acetonitrile binary solutions: FTIR spectral studies. Asian J Chem 2021, 33 (6), 1385 - 8.

FTIR spectral signature of neat acetonitrile (AN), triethylene glycol (TEG) and their binary solutions at various mole fractions of acetonitrile/ triethylene glycol have been obtained. The spectral features endorse that multimers of various orders coexist in liquid phase of triethylene glycol. When triethylene glycol was dissolved in acetonitrile, the combination of multimers present in neat triethylene glycol seems to be not disturbed much but C≡N···H(CH₂/H-O) and (AN methyl)H···O(TEG C-O-C) heteromolecular H-bonds have been formed between the triethylene glycol multimers and acetonitrile in all the solutions. The strength of these interactions were found to be acetonitrile/triethylene glycol concentration dependent.

4 illus, 1 table, 21 ref

003160   THANGARASU S, SIVA V, ATHIMOOLAM S, BAHADUR S A (Physics Dep, Kalasalingam Academy of Research and Education, Krishnankoil - 626 126, Email: sthangarasu@gmail.com) : Synthesis, spectroscopic studies, antimicrobial activity and computational calculations on 3-nitroanilinium dihydrogen phosphate. Asian J Chem 2021, 33 (5), 1099 - 1106.

3-Nitroanilinium dihydrogen phosphate (3NADP) has been synthesized and crystallized successfully using the method of solvent evaporation solution growth. The molecular structure has been optimized and geometrical parameters of 3NADP also have been analyzed using B3LYP function with density functional theory (DFT) and Hartree-Fock (HF) methods with a 6-311++G(d,p) basis set. The comparison between computed vibrational spectra and experimental result shows an appreciable agreement. The thermal stability of 3NADP crystal was analyzed using TG/DTA and the melting point was identified at 209 ºC. The properties like electronegativity, chemical hardness, electrophilicity index and chemical potential of the crystal were determined through HOMO-LUMO study. Lower band gap value obtained in frontier molecular orbital analysis and favours the possible biological activity of 3NADP. The grown crystals was also screened for the antimicrobial activity against some specific potentially threatening microbes.

7 illus, 6 tables, 25 ref

003158   VENKATESAN A, ARULMANI S, CHINNASAMY E, SENTHIL S, SARAVANAN M E R (Physics Dep, Government Arts Coll, Salem - 636 007, Email: merajasaravanan@gmail.com) : Growth, experimental studies and DFT calculations on gallic acid 5-nitrouracilate single crystals for non-linear optical applications. Asian J Chem 2021, 33 (5), 1085 - 9.

The growth and characterization of gallic acid 5-nitrouracilate (GA5NU) single crystals were grown using slow evaporation solution growth technique at room temperature. Single crystal XRD analysis revealed that the grown crystal belongs to monoclinic crystal system. HOMO-LUMO and molecular electrostatic potential (MEP) has been visualized and analyzed. The presence of various functional groups present in the host material was examined using FTIR spectra. Mechanical stability of the grown crystal is validated using Vickers microhardness study and the grown crystal belongs to soft material category. Various hardness parameters like fracture toughness, brittleness index, elastic stiffness constant, tensile strength and other hardness parameters were also calculated. Thermal stability of the grown crystal was also determined. The second harmonic generation (SHG) efficacy of grown crystal was 2.97 times higher than potassium dihydrogen phosphate (KDP), which makes the grown crystal as suitable candidate material for non-linear optical applications.

7 illus, 5 tables, 22 ref

003136   STANLYKENINXAVIER L, ELANGOVAN P, SARAVANAKUMAAR M S S (Physics Dep, Saraswathi Narayanan Coll, Madurai - 625 022, Email: drelangovanphysics@gmail.com, 2ssaravanakumar@gmail.com) : Fabrication of Non-precious vanadium tungsten nanocomposite for enhanced electrocatalytic oxygen reduction reaction. Asian J Chem 2021, 33 (4), 919 - 24.

For the commercialization of alkaline fuel cells and metal air batteries, the advances in non-precious, cheap, stable electrocatalysts for the oxygen reduction reaction (ORR) and highly active remain a major problem. To overcome this problem, a facile approach was established to fabricate non-precious metal electrocatalysts, such as nanoparticles, pristine V₂O₅ and their WO₃ hybrids. This is the first study reporting the utilization of monoclinic-WO₃-nanocrystal-coupled V₂O₅ that serves as ORR catalysts. Compared with 50 wt.% WO₃ with 50 wt.% V₂O₅ (VW-2) spheres and pristine V₂O₅, the hybrid catalyst of 25 wt.% WO₃ and 75 wt.% V₂O₅ (VW-1) spheres exhibits outstanding catalytic activity towards ORR. In addition, the hybrid of 25 wt.% WO₃ and 75 wt.% V₂O₅ (VW-1) exhibits a higher long-term durability and catalytic activity than high-quality commercial Pt/C catalysts, which renders the composites of WO₃/V₂O₅ composites hybrid a highcapacity candidate for non-precious, high-performance, metal-based electrocatalysts having high efficiency and low cost for electrochemical energy conversion. The enhanced activity of WO₃/V₂O₅ composites is mainly obtained from the improved structural openness in the V₂O₅ tunnel structure when coupled with WO₃.

7 illus, 30 ref

003127   GIRIJA R, MARY S S, BALAKRISHNAN G (Physics Dep, St. Peter's Institute of Higher Education and Research, Chennai - 600 054, Email: celstel1968@gmail.com) : Synthesis and characterization of pure and nitrogen doped titanium oxide nanocrystallites for visible light photocatalytic applications. Asian J Chem 2021, 33 (4), 853 - 8.

The pure and nitrogen doped titanium oxide (TiO₂) nanocrystallites were synthesized using sol-gel technique. The synthesized nanoparticles were characterized to examine the microstructural, optical and photocatalytic properties. The XRD studies of pure and doped TiO₂ showed the formation of polycrystalline tetragonal structure with anatase phase. The crystallite sizes were calculated and found to be 17 and 15 nm for the pure and N-doped TiO₂, respectively. FTIR studies indicated that the N-doped TiO₂ bands are stronger compared with pure TiO₂, indicating the more hydroxyl groups. FESEM studies showed the uniform formation of TiO₂ nanocrystallites and spherical in shape with agglomeration. The photoluminescence spectra of the samples show emission peaks, indicating the band to band shift having the energy gap of 2.9 eV. The photocatalytic performance of the nanocatalyst was studied using methylene blue dye under visible light irradiation for 90 min. The photocatalytic efficiency of 66.9% and 85.8% is obtained for the pure and N-doped TiO₂, respectively.

7 illus, 27 ref

003121   SELVARENGAN P (Physics Dep, Kalasalingam Academy of Research and Education, Krishnankoil - 626 126, Email: p.selvarengan@klu.ac.in) : Density functional theory reactivity studies on X₃N@C₈₀ (X = Sc, Gd, Lu) Fullerenes. Asian J Chem 2021, 33 (4), 814 - 8.

Density functional theory studies have been performed to reveal the reactivity of the sites in Sc₃N@C₈₀, Gd₃N@C₈₀ and Lu₃N@C₈₀ endohedral fullerenes. The condensed Fukui functions have been calculated using Mulliken atomic charges. The calculations show that the carbon atom sites are in direct contact with the endohedral cluster favourable nucleophilic attack. Similarly, the carbon atoms which are away from the direct bonding with the cluster are favourable for the electrophilic attack. This is also confirmed from the charge transfer analysis. It is noted that the spin multiplicity decides the reactivity sites and stability of the Gd₃N@C₈₀ system. The HOMOLUMO gap value indicates that Gd₃N@C₈₀ with S = 7 is stable than the S = 21 system. Finally, present studies indicate that the charge transfer between the C₈₀ cage and X₃N plays a major role to determine the reactivity of the sites in the C₈₀ cage.

2 illus, 2 tables, 34 ref

003087   SUDHAKAR Y, BASKARAN G S, PRASAD P S, RAO D R, FLOWER G L (Physics Dep, Andhra Loyola Coll, Vijayawada - 520 008, Email: sbalc@rediffmail.com) : Effect of some modifier ions in CuO doped sodium borosilicate antibacterial bioglass. Asian J Chem 2021, 33 (3), 591 - 9.

A set of sodium borosilicate glasses mixed with different modifier oxides, viz., Li₂O, MgO, CaO and ZnO, doped with antimicrobial oxide viz. CuO were synthesized. The structural (FT-IR spectroscopy, SEM and XRD) and bioactivity studies of the glasses were carried out before and after 30 days of immersion in simulated body fluid (SBF) under static conditions. Optical absorption spectra of all the glasses exhibited a broad absorption band identified due to ² B_1g→² B_2g octahedral transition of Cu²⁺ ions. Glass microstructure is analyzed using SEM images and XRD patterns to authenticate glass bioactivity (viz. to confirm whether there is formation of hydroxyapatite (HAp) layer on the surface). For further confirmation of the formation of HAp on the surface of the post immerse samples, the FTIR spectra were recorded. The spectra revealed some vibrational peaks of calcium phosphate. Solubility (weight loss due to immersion in SBF) percentage is found to be different for different modifiers mixed glasses containing antibacterial CuO. SEM results confirm apparent nodular calcium phosphate microcrystalites. It is observed that the addition of antimicrobial oxide has a positive effect on the bioactivity of glass and make these glasses as fourth-generation biomaterials, which are being extensively used to heal the wounds in the human body by facilitating the growth of soft tissues.

10 illus, 5 tables, 49 ref

000809   TEMGIRE S, BORAH A, KUMTHEKAR S, IDATE A (Lovely Professional Univ, Jalandhar, Punjab) : Recent trends in ready to eat/cook food products: A review. J Pharma Innov 2021, 10(5), 211-7.

Now a day’s ready to eat and ready to cook food product have acquired large food market because it is closest replacement to our regular food. Food habits and cooking methods are massively changes in last few years because of urbanization, changes in culture and social modification. We discuss three categories of Ready to eat/cook food products such as based on fruits and vegetables, based on cereals and pulses, based on meat, poultry and fish. Various processing technologies are used for development of this type of food including extrusion, baking, sterilization, puffing, coating, cold plasma, HPP, etc. Packaging and microbial safety of such food products are important to increase shelf life. In this review, we are headlights the recent trends and technologies for development of RTE/RTC food. These types of food are healthy, convenient and accessible but excess intake can be harmful to our health.

51 ref

000807   DHOLARIYA P K, BORKAR S, BORAH A (Lovely Professional Univ, Jalandhar, Punjab) : Prospect of nanotechnology in food and edible packaging: A review. J Pharma Innov 2021, 10(5), 197-203.

Nanotechnology represents an efficient and important tool for increasing the shelf life of food. Reducing the size of Nanometric scale gives material distinct and improves the properties when compared to a larger system. Edible coatings are usually prepared with the help of natural polymers that are non-toxic, economical and readily available. The new tendencies are to use edible coating as carries of functional ingredient by incorporating antimicrobial, ant browning, and nutraceutical agent to improve the quality of fruits and vegetables. In recent research, it has been found that nanotechnology can bring revolutionary changes in various department of food, post harvesting management, food storage and packaging, bio sensor, medicine, nutrient and nutraceutical delivery, ingredients and additives, and also bioprocessing of food.

2 tables, 47 ref

000801   THAKUR J, BORAH A (Lovely Professional Univ, Phagwara, Punjab) : Microcapsules of bioactive compounds from fruits and vegetables waste and their utilization: A review. J Pharma Innov 2021, 10(5), 151-7.

Fruits and vegetables have crucial role in human nutrition. Due to presence of various bioactive compounds, they are consumed processed, minimally processed as well as raw. In fruit and vegetable processing industries, the generation of their wastes are becoming a serious nutritional and environmental issue. These wastes still contain many bioactive compounds and their recovery from industry wastes has received significant attention. These bioactive compounds are sensitive to heat, light and oxygen; therefore, entrapment of these bioactive compounds is necessary to provide them protection from degradation against the environmental conditions. Additionally, microencapsulation process has been used for improving bioavailability, stability, delivery and controlled release of bioactive compounds. The aim of this review is to compile the results of extraction of different bioactive compounds by different methodologies and then their incorporation into probiotics in order to develop a functional food product with improved health and nutritional characteristics.

1 table, 72 ref

000749   SIVAKUMAR M, BALASUBRAMANIAN R (Physics Dep, Arignar Anna Government Arts Coll, Namakkal- 637 002, Email: drrbala@yahoo.com) : Spinodal and thermodynamic limit of superheat of gold. Sci Vis 2021, 21(1), 12-6.

A four-parameter generalized Berthelot equation of state has been employed to determine the spinodal and the thermodynamic limit of superheat of liquid gold. It is established that gold obeys the two-parameter law of corresponding states. It is also established that the new parameters introduced in the attractive term of the equation of state are thermodynamic similarity parameters. It is shown that liquid gold can be superheated to a temperature 6719 K. That is, liquid gold, under rapid heating, can be superheated to temperature 3476 K above the boiling temperature without undergoing liquid-vapour phase transition. Above this temperature, liquid gold will undergo explosive boiling owing to homogeneous nucleation.

2 illus, 3 tables, 22 ref

000469   KANNAN S, KALIAPERUMAL R, PAZHANIVELAN S, KUMARAPERUMAL R, SIVAKUMAR K (Remote Sensing and GIS Dep, TNAU, Coimbatore, Tamil Nadu) : Paddy area estimation in Nagapattinam district using sentinel-1A SAR data. J Pharma Innov 2021, 10(2), 112-6.

A Research study was conducted to estimate the paddy area in the Nagapattinam district of Tamil Nadu using Sentinel 1A SAR data through multi-temporal feature extraction. Multi-temporal Sentinel 1A data of GRD data at VH polarizations were obtained for the study area at 12 days intervals. Collected data were processed using MAP scape-RICE software. Sentinel 1A is an active SAR microwave data, which captures the crop characteristics irrespective of the weather condition and illumination. Ground truth observations collected during cropping period were used to derive the paddy signature from the processed satellite images. The dB values extracted as signature then subjected to the multi-temporal feature extraction method for delineating the paddy growing areas. Around 99, 00, 700 ha was mapped as the paddy growing area in Nagapattinam district. Accuracy assessment was done with 40 percent of the ground truth data. The overall classification accuracy was 94 percent with a kappa score of 0.88.

4 illus, 8 ref

000715   SIMHA P P, RAMANAN R V (Vikram Sarabhai Space Centre, Thiruvananthapuram, Kerala, Email: padmanabhapsimha@gmail.com) : Optimal low-thrust GTO–GSO transfers using differential evolution. Sadhana 2021, 46, 1.

Transfers from geosynchronous transfer orbits (GTO) to geosynchronous orbits (GSO) using electric propulsion have been optimized in the current study. Both time-optimal and fuel-optimal trajectories are generated. Three-dimensional equations of motion are considered for the system dynamics. The indirect approach based on optimal control theory is followed and the resulting two-point boundary value problem is solved using differential evolution, a search-based global optimization technique. Optimal trajectories for various mission scenarios are obtained using differential evolution and compared to transfers presented in literature.

12 illus, 8 tables, 8 ref

000707   ZHOU R, GAO W (Astronautics Science and Mechanics Dep, Harbin Institute of Technology, Harbin, China, Email: gaoweicheng@sina.com) : Effects of stiffener geometric parameters on the buckling and postbuckling response of composite I-stiffened panels. Sadhana 2021, 46, 9.

The buckling instability and post-buckling carrying capacity are major concerns in the engineering design of composite stiffened panels and are influenced by a series of design parameters. This work investigated the rule and mechanism of the stiffener flange widths effects on the buckling instability and post-buckling response of composite I-stiffened panels under axial compression. With the compression experiments, the buckling instability and post-buckling response of the composite I-stiffened panels were obtained and further used in the validation of the finite-element (FE) model. A parametric study was then implemented in analyzing the effects of stiffener flange widths on the structural buckling instability and post-buckling response. The results indicate that skin-stiffener debonding and intra-laminar damage are the main failure modes. The structural buckling instability, carrying capacity and failure behavior are sensitive to the parameters of stiffener flange widths. The bottom flange width w_b linearly affects the critical buckling load, but has no effects on the buckling mode. The top flange width w_t simultaneously affects the critical buckling load and buckling mode, and an obvious buckling mode change occurs around a critical w_t value. Both the bottom and top flange widths affect the structural damage process, failure mode and carrying capacity obviously

22 illus, 3 tables, 30 ref

000688   TIWARI N, MOHARANA M K (Vellore Institute of Technology, Vellore, Tamil Nadu, Email: nishant.tiwari@vit.ac.in) : Effect of conjugate heat transfer in single-phase laminar flow through partially heated microtubes. Sadhana 2021, 46, 28.

To analyze conjugate effect under partially heated condition, two-dimensional numerical study is performed for single-phase laminar flow through microtubes. Constant heat flux is applied on outer surface along the heating length of the microtube. For partial heating, the microtube is divided into three parts of 6 mm (L₁), 48 mm (L₂) and 6 mm (L₃). Three cases are considered for partial heating: (a) insulated across L₁ and L₃ and heating across L₂, (b) insulated across L₁ and heating across L₂ and L₃ and (c) insulated across L₃ and heating across L₁ and L_2. For direct comparison, heating across full length of the microtube is also considered. Parametric variations include microtube wall thickness to inner radius ratio (dsf), and solid to fluid conductivity, ratio (ksf) and flow Re. Presence of axial wall conduction is assessed in terms of dimensionless wall temperature and heat flux at the solid–fluid interface, dimensionless bulk fluid temperature, and local and average Nusselt number. The results indicate that there exists an optimal value of average Nusselt number for certain value of ksf at which dominance of axial wall conduction is smaller. Additionally, to highlight the effect of axial wall conduction, local heat flux distribution at the solid–fluid interface is also explored.

7 illus, 2 tables, 32 ref

000687   TAMRAKAR M, KOMMURI U K (VIT Campus, Tamil Nadu- 600 127, Email: tamrakar.maruti@gmail.com) : EBG–AMC–HIS characteristics analysis of QBTR unitcell. Sadhana 2021, 46, 29.

In this paper the quad bend triangular resonator (QBTR) structure is used as a metamaterial unitcell for metasurface characteristics analysis. This paper presents the metasurface properties like electromagnetic band gap (dispersion diagram), reflection phase S₁₁ (deg) and surface impedance Z₁₁ (Ὠ) of a unitcell. The unitcell analysis shows similarities in operating frequency band for these metasurface characteristics. The QBTR metasurface performance is validated using a wideband dipole antenna. The antenna gain of 5 dBi is achieved with QBTR metasurface for frequency range 3.2–6.7 GHz. The QBTR metasurface is orthogonal symmetric and can be used for dual-polarized wideband frequency applications like WLAN (5.15–5.85 GHz) and NR 5G sub-6-GHz (3.3–5.0 GHz).

7 illus, 10 ref

000671   BANERJEE P, CHAKRABARTI A, BALLABH T K (Physics Dep, Jadavpur Univ, Bhopal, Madhya Pradesh, Email: payelbanerjee54@gmail.com) : Accelerated single linkage algorithm using the farthest neighbour principle. Sadhana 2021, 46, 45.

Single Linkage algorithm is a hierarchical clustering method which is most unsuitable for large dataset because of its high convergence time. The paper proposes an efficient accelerated technique for the algorithm for clustering univariate data with a merging threshold. It is a two-stage algorithm with the first one as an incremental pre-clustering step that uses the farthest neighbour principle to partially cluster the database by scanning it only once. The algorithm uses the Segment Addition Postulate as a major tool for accelerating the pre-clustering stage. The incremental approach makes it suitable for partial clustering of streaming data while collecting it. The Second stage merges these pre-clusters to produce the final set of Single Linkage clusters by comparing the biggest and the smallest data of each pre-cluster and thereby converging faster in comparison to those methods where all the members of the clusters are used for a clustering action. The algorithm is also suitable for fast-changing dynamic databases as it can cluster a newly added data without using all the data of the database. Experiments are conducted with various datasets and the result confirms that the proposed algorithm outperforms its well-known variants.

12 illus, 3 tables, 27 ref

000663   KUMAR A S, SOWRIRAAJAN A V E, DIXIT C S B, MUKUNDA H S (Jain Univ, Kanakapura Road, Bangalore, Email: shivakumarannaiappa@gmail.com) : Experiments on unsteady pool fires – effects of fuel depth, pan size and wall material. Sadhana 2021, 46, 53.

This paper presents specifically designed experiments to understand the effect of range of parameters on pool burn behavior with liquid fuels. Experiments have been conducted on pool fires with 0.1–2 m diameter pans and depths of 40, 50, 60 and 90 mm with n-heptane fuel depths up to 30 mm floated on water and without water in an indoor fire laboratory. Pans of 0.2 m dia are made of glass, stainless steel, mild steel and aluminum and larger diameter pans only of mild steel. The experiments conducted include some with fuel initial temperature effects at 300, 319 and 343 K. Data on temporal evolution of mass burn, pan wall temperatures, temperatures inside the liquid at some depths and gas phase temperatures at select heights from the pool surface have been obtained from the experiments. Results show that at larger fuel depths of ( 30 mm), a burn mass flux of 60–75 g/m²s is reached even in 0.2 m dia pans. This flux is expected only in large pans of about 2 m size. Regarding pan material effect, glass pans show mildly increasing low flux values (10–15 g/m²s) and mild steel and aluminum pans show an initial low flux value ( 10 g/m²s) and then a sharp change to large flux values depending on the depth.  At larger depths, the flux values go up to 65 g/m²s. In case of stainless steel, the mass flux variation occurs smoothly all through towards increasing values. As regards the water depth below the fuel, the decrease in the average burn rate is about 1 % per mm water depth up to 20 mm for all pans with diameter below 0.5 m. Larger size pans with burn rate controlled largely by radiation show much reduced effect of the water depth. In order to correlate the data with diverse parameters a dimensionless number, Mpc, has been invoked using scaling laws, and a correlation that provides a good estimate of the mass burn flux including all the effects considered earlier has been deduced. The data set thus generated provides the basis for a more detailed model to predict the mass loss history and other parameters.

15 illus, 5 tables, 18 ref

000661   BURMASHEVA N V, PRIVALOVA V V, PROSVIRYAKOV E Y (Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russian Federation, Email: nat_burm@mail.ru) : Layered Marangoni convection with the Navier slip condition. Sadhana 2021, 46, 55.

A new exact solution to the problem of Marangoni layered convection is obtained. This solution describes a layered steady-state flow of a viscous incompressible fluid at varying gradients of temperature and pressure. The velocity components depend only on the transverse coordinate; the temperature and pressure fields are three-dimensional. The Marangoni effect is observed on the upper free surface of the fluid layer. On the lower solid surface of the fluid layer, three different cases of defining boundary conditions are considered: the no-slip condition, the perfect slip condition and the Navier slip condition. The obtained exact solution is determined by the interaction of three flows: a flow caused by pressure drop (the Poiseuille flow), a flow caused by heating/cooling and the effect of the gravity force (the thermogravitational flow), and a flow caused by heating/cooling and the fluid surface tension effect (the thermocapillary flow). The obtained exact solutions in the case of each of the three types of boundary conditions specified on the lower surface are analyzed in detail. It has been proved that, when certain ratios of the boundary value problem parameters are fulfilled, the velocity components may acquire stagnation points, this being indicative of the presence of counterflow areas in the fluid layer under consideration. In particular, the presence of up to two stagnation points in each of the two longitudinal velocity components may cause a stratification of the velocity field in more than two regions. The obtained exact solution of the Marangoni layered convection problem can describe flows in thin films through the variation of the geometric anisotropy factor.

8 illus, 45 ref

000431   NIAMJAN N, SIRISATHITKUL C, CHEEDKET S (Thailand Center of Excellence in Physics, Bangkok- 104 00, Thailand) : Substitution effect of magnetic materials in halbach cylinder for magnetic refrigerators. Proc Natl Acad Sci India Sect A Phys Sci 2021, 91(1), 189-94.

In this paper, we present the magnetic refrigeration by magnetocaloric effect, for which the magnetic flux distribution has been modified in the Halbach cylinder. The insertion of a soft magnetic rod in the bore led to the alternating magnetic field with two regions of high flux density for magnetization and two regions of low flux density for demagnetization of magnetocaloric materials in the annular gap. The two-dimensional numerical simulations by the finite element method using COMSOL Multiphysics and Poisson SUPERFISH demonstrated the substitution effect of neodymium–iron–boron permanent magnets by soft magnetic low-carbon steels. The optimized soft magnetic cross-sectional area of 0.04 m² in the Halbach cylinder gave the maximum flux density of 2 T in the air gap, comparable to the peak field of existing prototypes. The flux density is further increased and became the largest when the ratio of external to internal radius of the cylinder is at the maximum. The cooling performance is also affected by the size of the cylinder, and the substantial value is obtained in a practical design with reserved air gap for magnetocaloric materials.

18 ref

000430   SHUKLA D V, SRIVASTAVA A K, MISRA N (Physics Dep, Lucknow Univ, Lucknow- 226 007) : Structures and electronic properties of small alnsen (N = 1–5) clusters. Proc Natl Acad Sci India Sect A Phys Sci 2021, 91(1), 181-8.

The present study of Al_nSe_n clusters (n = 1–5) has been performed using density functional theory. The ground-state structures of these clusters along with low-lying isomers are explored. The stabilities of clusters are analysed by calculating their binding energy per atom and dissociation energy against different fragmentation channels. All Al_nSe_n clusters are found to be stable, and the structure of Al₄Se₄ cluster shows higher binding energy per atom as compared to other species. The various electronic parameters of Al_nSe_n clusters such as ionization energy, electron affinity, chemical hardness (η) and absolute electronegativity (χ) are also calculated and discussed in the present study.

30 ref

000400   HALOI A, KARMAKAR P K (Physics Dep, Tezpur Univ, Tezpur- 784 028, Email: pkk@tezu.ernet.in) : Astromodal wave dynamics in multifluidic structure-forming cloud complexes. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02031-7.

The evolutionary dynamics of bimodal pulsational mode, arising because of the long-range conjugational gravito-electrostatic interplay in viscoelastic polytropic complex multicomponent astroclouds with partial ionisation, is classically examined using a non-relativistic generalised hydrodynamic model approach. The equilibrium distribution of the diversified constitutive species forms a globally quasi-neutral hydrostatic homogeneous configuration. The primitive set of the astrocloud structuring equations specifically includes polytropic (hydrodynamic action) and nonlinear logatropic barotropic (turbulence action) effects simultaneously. A normal mode analysis over the perturbed cloud results in a unique form of sextic polynomial dispersion relation with variable poly-parametric coefficients. A numerical analysis technique is provided to show the exact nature of the modified viscoelastic (turbo-viscoelastic) pulsational mode in the two extreme hydrodynamic and kinetic regimes. It is seen that, in the former regime, the dust–charge ratio (negatively-to-positively charged grains) plays a destabilising role to the instability. In contrast, the dust–mass ratio (negatively-to-positively charged grains) develops a stabilising influence in the wave-dynamical processes. In the latter regime, the viscoelastic relaxation velocity associated with the positively charged grains acts as an amplitude stabiliser. Conversely, the viscoelastic relaxation velocity of the negatively charged grain fluid introduces destabilising influences. The unique features of the propagatory and non-propagatory mode characteristics are elaborately illustrated. The reliability of the investigated results is judiciously validated by comparing the results with the specific reports available in the literature. Lastly, the first-hand astronomical implications and applications of our study are summarily outlined.

4 illus, 1 table, 30 ref

000396   BANI W K, MAHATO M C (Physics Dep, North-Eastern Hill Univ, Shillong- 793 022, Email: mangal@nehu.ac.in) : An experimental study of recoil capillary waves and break up of vertically flowing down water jets. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02064-y.

Break up of water jets under gravity is a ubiquitous phenomenon. The role of surface tension on the instability of uniform water jets was recognised long ago by Plateau and Rayleigh. According to the Plateau– Rayleigh theory, external (or internal) perturbation waves create necks and bulges all along the uniform jet length. The perturbation waves of wavelengths larger than a certain value keep growing with time and ultimately cause the continuous jet to break up into individual drops. The effect of external perturbation waves was investigated experimentally, in most cases under gravity, and found to confirm the essentials of the theory. Recently, the idea of recoil capillary waves as a possible internal source of perturbations was emphasised. According to this idea, immediately after the break up of the jet, the tip of the remaining continuous jet (after a drop is detached) recoils. Its effect travels upstream as a recoil capillary wave which gets reflected at the mouth of the jet-issuing nozzle. The reflected capillary wave travels downstream along the jet with its Doppler-shifted wavelength as a reinforcing perturbation wave and, as a result, affecting the break up length of the jet. We set up and perform an experiment to verify the existence of these tip contraction recoil capillary waves. The results of our experiment support the existence of these recoil capillary waves. However, the effect of these capillary waves on the jet break up length is found to be small.

8 illus, 18 ref

000395   MENON V, CHATTOPADHYAY A (Confident Bellatrix, Bengaluru- 562 125, Email: ayankc@yahoo.com) : Quantum pattern matching oracle construction. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02062-0.

We propose a couple of oracle construction methods for quantum pattern matching. One of the constructs is based upon the conventional string comparison method. This, along with a unique input state preparation, when combined with the Grover’s search algorithm, results in a deterministic exact and partial pattern matching logic. The other method generates a superposition of Hamming distances between the searched pattern and all the substrings formed from the input string. The measurement statistics from a large ensemble would provide data on the closest match. We show that this method can leverage parallel computing for enhanced performance. Alternatively, it can also be combined with the minimum finding algorithm for a deterministic outcome.

8 ref

000394   GHARAATI A, ZAREIAN Z, KHALKHALI T F (Physics Dep, Payame Noor Univ, Tehran, Iran, Email: tfathollahi@aeoi.org.ir) : Investigation of the coupling efficiency between graded index photonic crystal-based flat lenses and various types of waveguides. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02061-1.

The importance of transmission, guiding and delivery of electromagnetic waves to the targeted part of a photonic circuit, leads to design couplers with high coupling efficiency. In the present work, we apply two types of photonic crystal-based flat lenses for designing the couplers. The lenses are made of annular ZrO2 rods with a triangular structure embedded in air. To design the lenses, the outer radius of the annular cylinders is kept constant while the inner radius follows two linear and parabolic functions. At the next step, the lenses are placed along a slot waveguide, conventional photonic crystal waveguide and funnel-form photonic crystal waveguide, separately, for creating coupled structures. The incident light is focussed by the graded index flat lenses and transmits through the waveguides. In the following, we study the coupling efficiency of all mentioned structures, using finite-difference time-domain and plane wave expansion methods. The results reveal that the coupled funnel-form waveguide with the linear lens gives the highest coupling efficiency, which is 7.49 dB and shows great improvement compared to the previous works.

14 illus, 29 ref

000393   HEIDARI E (Sciences Dep, Islamic Azad Univ, Bushehr, Iran, Email: ehphysics75@iaubushehr.ac.ir) : Dispersion relation of modulational instability for one-dimensional standing solitary waves in hot ultrarelativistic electron–positron plasmas. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02069-7.

In this paper, the non-linear dispersion relation of the system for interactions between high intensity laser and hot relativistic electron–positron plasma is derived. We restrict the problem to the standing solitons in ultrarelativistic plasmas and apply the quasineutrality condition. The modulational instability growth rate for different values of plasma temperatures, velocities and wave numbers are illustrated numerically. It is shown that, by increasing the unperturbed plasma enthalpy, the modulational instability growth rate decreases for all the values of plasma fluid velocities. It is also found that the growth rate shows an increasing trend with plasma fluid velocity. Furthermore, the impact of wave amplitude on the modulational instability growth rate is investigated explicitly. The growth rate increases with wave number as well as wave amplitude.

6 illus, 21 ref

000392   AHUJA J, GIROTRA P (Post Graduate Government Coll, Chandigarh- 160 011, Email: jyotiahuja1985@gmail.com) : Analytical and numerical investigation of Rayleigh–Taylor instability in nanofluids. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02046-0.

This article is a maiden and naive attempt to formulate, analyse and investigate the Rayleigh–Taylor (RT) instability of two superimposed horizontal layers of nanofluids having different densities. Conservation equations are formulated and linearised by keeping in mind that density of the base fluids as well as nanoparticles is not constant. Linearised perturbed equations are sorted out by using the technique of normal modes and a dispersion relation incorporating the effects of surface tension, Atwood number and volume fraction of nanoparticles is obtained. Stable and unstable modes of RT instability are scrutinised using Routh–Hurtwitz criterion in the presence/absence of nanoparticles and presented graphically. Numerical calculations have been performed to explore the effect of surface tension, Atwood number and volume fraction of the nanoparticles. It is observed that in the presence/absence of nanoparticles, surface tension has a significant impact on stabilising the unstable mode of RT instability whereas Atwood number and volume fraction of nanoparticles hasten this instability. The graphical representations of these numerical investigations confirm the very explanation of RT instability under the effect of different parameters that have significant impact on the intensity of growth rate.

11 illus, 5 tables, 43 ref

000391   EKOSSO M C, FOTUE A J, FOTSIN H, FAI L C (Physics Dep, Dschang Univ, Dschang, Cameroon, Email: fotuea@yahoo.fr) : Information processing and thermodynamic properties of microtubules. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02044-2.

The Shannon entropy dependence on temperature, dipole moment and thermodynamic properties of microtubules (MTs) have been investigated using the Landau–Ginzburg phenomenological theory through continuum Boltzmann distribution function. By minimising the loss in energy, we found that there is a possibility that MTs formed from the heterodimers can process information over a long time at higher temperature. We also found that multiple heterodimers under the influence of dipole moment, has the tendency to process information whenever the amount of information stored or transferred decreases with increasing electronegativity of the system. We analyse the dynamic instability phenomenon that infinitely occurs in polymerisation and depolymerisation processes in MTs. Also, under physiological conditions, temperature dependence of thermodynamic properties was investigated and our results exhibited critical behaviour of heat capacity and chemical potential giving room for phase transitions around 302 K.

9 illus, 28 ref

000386   ABEBE T, MOSISA E, GASHU C (Physics Dep, Adama Science and Technology Univ, Adama, Ethiopia, Email: tam1704@gmail.com) : Generation of entanglement from a two-mode cascade laser. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02049-x.

We analyse the entanglement of the light produced by a three-level laser whose cavity contains a parametric amplifier, with the cavity mode driven by the coherent light and coupled to a squeezed vacuum reservoir. Employing stochastic differential equations associated with the normal ordering resulted from the pertinent master equation, the quadrature variances and entanglement of the two-mode light are obtained and photon statistics of the two-light modes is discussed. It is found that the three-level laser generates squeezed light under certain conditions, with maximum intracavity squeezing being 89.7% below the coherent state level. We also show that the parametric amplifier enhances the mean photon number and photon number correlation.

13 illus, 27 ref

000385   SINGH N S (Physics Dep, Delhi Univ, Delhi- 110 007, Email: 25santacruz@gmail.com) : Some applications of special trans function theory in physics. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02045-1.

Examples of applications of special trans function theory (STFT) which may be useful in obtaining closed-form analytical solutions of certain transcendental equations found in undergraduate physics is presented. The novelty of the method can be of utmost importance to the academia involved in undergraduate physics.

1 illus, 19 ref

000383   RAO P, DEOTA H N, CHAVDA N D (Applied Physics Dep, The Maharaja Sayajirao Univ of Baroda, Vadodara- 390 001, Email: pnrao-apphy@msubaroda.ac.in) : Ordered level spacing distribution in embedded random matrix ensembles. Pramana- J Phys 2021, 95(1), 10.1007/s12043-020-02066-w.

The probability distributions of the closest neighbour (CN) and farther neighbour (FN) spacings from a given level have been studied for interacting fermion/boson systems with and without spin degree of freedom constructed using an embedded Gaussian orthogonal ensemble (GOE) of one plus random two-body interactions. Our numerical results demonstrate a very good consistency with the recently derived analytical expressions using a 3 × 3 random matrix model and other related quantities by Srivastava et al, J. Phys. A: Math. Theor. 52, 025101 (2019). This establishes conclusively that local level fluctuations generated by embedded ensembles (EE) follow the results of classical Gaussian ensembles.

4 illus, 2 tables, 50 ref