Eu3+ ion concentration induced 3D luminescence properties of novel red-emitting Ba4La6(SiO4)O:Eu3+ oxyapatite phosphors for versatile applications

Raju, G. S.,Pavitra, E.,Hussain, S. K.,Balaji, D.,Yu, J. Royal Society of Chemistry 2016 Journal of Materials Chemistry C Vol.4 No.5

<P>A series of Eu3+ ions activated (BaLa6)-La-4(SiO4)(6)O (BLSO:Eu3+) phosphors were synthesized by a modified citrate sol-gel process. The structural properties of these phosphors were explored by means of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The XRD patterns confirmed their oxyapatite structure with the space group of P6(3)/m after annealing at 1400 degrees C. The scanning electron microscope image exhibited the irregular morphology of BLSO: Eu3+ particles and the elemental mapping confirmed that the Eu3+ ions were distributed homogeneously on the La3+ ion sites. Photoluminescence (PL) excitation spectra of BLSO: Eu3+ exhibited the charge transfer band (CTB) and intense f-f transitions of Eu3+ ions in the violet and blue wavelength regions. The CTB intensity decreased and the f-f transition of Eu3+ ions increased with increasing the Eu3+ ion concentration due to the presence of defects in the 4f and 6h sites of the BLSO host lattice. This feature facilitates the strong absorption in the near-ultraviolet (NUV) region, which is useful for high color rendering index NUV based white light-emitting diodes for display and lighting applications. The PL spectra displayed intense red emission (D-5(0) -> F-7(2)) along with considerable orange emission (D-5(0) -> F-7(1)) with good asymmetry ratios and chromaticity coordinates, and exhibited better emission performance than that of commercial Y2O3:Eu3+ phosphors. The three-dimensional PL spectra revealed their strong emission characteristics under UV, NUV and visible excitation wavelengths. The cathodoluminescence properties were also similar to the PL results, confirming that the BLSO: Eu3+ phosphors emit stable red emission under different excitation sources as compared to the commercial Y2O3: Eu3+ phosphors.</P>

A Beeline Routing Protocol for Heterogeneous WSN for IoT-Based Environmental Monitoring

Sahitya, G.,Balaji, N.,Naidu, C.D. International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.10

A wireless sensor network (WSN), with its constrained sensor node energy supply, needs an energy-efficient routing technique that maximises overall system performance. When rumours are routed using a random-walk routing algorithm, which is not highly scalable, spiral pathways may appear. Because humans think a straight line is the quickest route between two sites and two straight lines in a plane are likely to intersect, straight-line routing (SLR) constructs a straight path without the aid of geographic information. This protocol was developed for WSNs. As a result, sensor nodes in WSNs use less energy when using SLR. Using comprehensive simulation data, we show that our upgraded SLR systems outperform rumour routing in terms of performance and energy conservation.

Electronic structure studies of nanoferrite Cu(x)Co(1-x)Fe2O4 by X-ray absorption spectroscopy.

Gautam, S,Muthurani, S,Balaji, M,Thakur, P,Padiyan, D Pathinettam,Chae, K H,Kim, S S,Asokan, K American Scientific Publishers 2011 Journal of Nanoscience and Nanotechnology Vol.11 No.1

<P>Pure and mixed cobalt copper ferrites are of great interest due to their widespread application in electronics and medicine. We report on the electronic structure of a nanoferrite Cu(x)Co(1-x)Fe2O4 (0.0 < or = x < or = 1.0) system studied by X-ray absorption spectroscopy. These magnetic nanoferrites (average crystallite size approximately 31-43 nm) were synthesized by an auto combustion method and are characterized by high resolution X-ray diffraction and near edge X-ray absorption fine structure measurements at the O K and Co, Cu, and Fe L-edges. The O K-edge spectra suggest that there is a strong hybridization between O 2p and 3d electrons of Co, Cu and Fe cations and Fe L3,2-edge spectra indicate that Fe ions coexist in mixed valence states (Fe3+ and Fe2+) at tetrahedral and octahedral sites of the spinel structure. Copper and cobalt ions are distributed in the divalent state in octahedral sites of the spinel structure. The origin of high saturation magnetization and coercivity in cobalt-copper ferrites are explained in light of these results.</P>

Sensing properties of polyoxomolybdate doped polyaniline nanomaterials for oxidising and reducing volatile organic compounds

P. Chithra lekha,M. Balaji,S. Subramanian,D. Pathinettam Padiyan 한국물리학회 2010 Current Applied Physics Vol.10 No.2

The polyoxomolybdates encapsulated PAni hybrid materials are prepared by interfacial polymerisation. In P12MPA, the crystal structure of 12MPA is not modified on doping with PAni. However, P11MPA have the polycrystallinity due to the presence of vanadium in the dopant molecule. Though, the hybrids prepared by interfacial polymerisation are in emaraldine salt form, there is a blue shift in the absorption spectra due to dopant induced decrease in conjugation length and over-oxidation. Interfacially polymerised PAniPOM hybrid materials are exposed with various concentrations of vapours of different volatile organic compounds (VOC) such as acetone, methanol, chloroform and carbon tetrachloride. The oxidising VOCs like acetone and methanol on exposure to PAni decrease the resistivity by hydrogen bonding with the redox cites of the polymer. Among these two, the sensitivity towards acetone is more in PAni and its hybrids which can be linked with the vapour pressure of the analyte. Due to the weak acidic characteristics of chlorinated hydrocarbons which are reducing vapours, the resistivity of PAni and its hybrids increases on exposure to chloroform and CCl4. Here, the chlorinated hydrocarbons interact with the redox sites of PAni and reduce it to base form. Bridging of polymer chains is also proposed for the reduction of conductivity on exposure to the analyte. The sensitivity is higher for the reducing analytes than that of the oxidising one.

Drain Current Characteristics of 6 H-SiC MESFET with Un-Doped and Recessed Area under the Gate: A Simulation Study

Pydimarri Padmaja,Radhamma Erigela,D. Venkatarami Reddy,SK Umar Faruq,A. Krishnamurthy,B. Balaji,M. Lakshmana Kumar,Sreevardhan Cheerla,Vipul Agarwal,Y. Gowthami 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.2

In this paper, we have investigated the impact of the un-doped and recessed gate structure on the performance of the 6 H-SiC Metal Semiconductor Field Effect Transistor. The performance of the 6 H-SiC MESFET analyzed using TCAD simulations. The proposed un-doped gate structure made of high-k dielectric materials and low-k dielectric materials being hafnium oxide (HfO2) and silicon dioxide (SiO2) and it has minimized ionized impurity scattering, leading to increased electron mobility and improved carrier concentration. One of substrate layer of this device grown on Silicon (Si) and β-gallium oxide (β-Ga2O3). Performance metrics such as drain current, transconductance, subthreshold slope, and cutoff frequency are evaluated and compared with conventional SiC MESFET structures. The proposed device exhibits superior current driving capabilities, enhanced transconductance, and reduced leakage currents, leading to improved power efficiency. Moreover, the recessed gate structure contributes to a significant reduction in short channel effects, making the device more suitable for low power applications. The simulation parameters are calculated and compared with conventional MESFET structure with the length of source and drain in submicron technology. Therefore the drain current of this proposed device is improved 68%.

Performance enhancement of a doublepass solar air heater with a shot-blasted absorber plate and winglets

P. Ganesh Kumar,D. Sakthivadivel,K. Balaji,Mohammed Salman,Sung Chul Kim 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

A double-pass solar air heater (DPSAH) with shot blasting and winglets in the air passage is a recommended cost-effective design development to enhance thermal performance. Three different absorber plate configurations for DPSAHs were experimentally tested: (a) V-corrugation with shot blasting, (b) V-corrugation with shot blasting and a 4-3 winglet pattern, and (c) V-corrugation with shot blasting with a 3-2 winglet pattern. Furthermore, aluminum winglets were welded to the DPSAH absorber plate to increase the channel turbulence to enhance the heat transfer performance. The pressure drop and thermal performance of the DPSAHs with and without winglets were investigated using meteorological parameters such as ambient temperature, wind speed, solar irradiance, and interior temperature at regular time intervals. V-corrugation with 4-3 winglets has a maximum thermal efficiency and pressure drop of 49.5 % and 230 Pa, respectively, at a mass flow rate of 0.02 m/s. Results showed that the thermal efficiency of V-corrugation with 4-3 winglets was improved by a maximum of 7 % compared with the V-corrugation air heater. Finally, increasing the mass flow rate from 0.01 kg/s to 0.02 kg/s increases the pressure drop by 1.22 times for the V-corrugation and 1.3 times for the V-corrugation with 4-3 winglets. Furthermore, a complete economic study of DPSAHs for India is examined in this article.

High-energy ion induced physical and surface modifications in antimony sulphide thin films

S. Subramanian,M. Balaji,P. Chithra Lekha,K. Asokan,D. Kanjilal,Indra Sulania,Jai Prakash,D. Pathinettam Padiyan 한국물리학회 2010 Current Applied Physics Vol.10 No.4

Sb2S3 thin films prepared by electrodeposition on indium tin oxide coated glass substrate were irradiated with 150 MeV Ni11+ ions for various fluence in the range of 1011–1013 ions/㎠. The modifications in the structure, surface morphology and optical properties have been studied as a function of ion fluence. X-ray diffraction (XRD) analysis indicates a shift in the (2 4 0) peak position towards lower diffraction angle and a decrease in grain size with increase in ion fluence. Presence of microcracks due to irradiation induced grain splitting effect has been observed from the SEM micrograph at higher ion fluence. The optical absorbance spectrum revealed a shift in the fundamental absorption edge and the band gap energy increased from a value of 1.63 eV for as-deposited films to 1.80 eV for the films irradiated with 1013 ions/㎠.

Carbon nano-materials (CNMs) derived from biomass for energy storage applications: a review

Rajeshkumar L.,Ramesh M.,Bhuvaneswari V.,Balaji D. 한국탄소학회 2023 Carbon Letters Vol.33 No.3

In today’s world, carbon-based materials research is much wider wherein, it requires a lot of processing techniques to manufacture or synthesize. Moreover, the processing methods through which the carbon-based materials are derived from synthetic sources are of high cost. Processing of such hierarchical porous carbon materials (PCMs) was slightly complex and only very few methods render carbon nano-materials (CNMs) with high specific surface area. Once it is processed, which paves a path to versatile applications. CNMs derived from biological sources are widespread and their application spectrum is also very wide. This review focuses on biomass-derived CNMs from various plant sources for its versatile applications. The major thrust areas of energy storage include batteries, super-capacitors, and fuel cells which are described in this article. Meanwhile, the challenges faced during the processing of biomass-derived CNMs and their future prospects are also discussed comprehensively.

Light scattering effect of ITO:Zr/AZO films deposited on periodic textured glass surface morphologies for silicon thin film solar cells

Hussain, S. Q.,Kwon, G. D.,Ahn, S.,Kim, S.,Balaji, N.,Le, A. H.,Park, H.,Shin, C.,Razaq, A.,Kim, S. Springer Science + Business Media 2015 APPLIED PHYSICS A MATERIALS SCIENCE AND PROCESSING Vol.120 No.3

<P>Various SF6/Ar plasma-textured periodic glass surface morphologies for high transmittance, haze ratio and low sheet resistance of ITO:Zr films are reported. The SF6/Ar plasma-textured glass surface morphologies were changed from low aspect ratio to high aspect ratio with the increase in RF power from 500 to 600 W. The micro- and nano-size features of textured glass surface morphologies enhanced the haze ratio in visible as well as NIR wavelength region. Micro-size textured features also influenced the sheet resistance and electrical characteristics of ITO:Zr films due to step coverage. The ITO:Zr/AZO bilayer was used as front TCO electrode for p-i-n amorphous silicon thin film solar cells with current density-voltage characteristics as: V (oc) = 875 mV, FF = 70.90 %, J (sc) = 11.31 mA/cm(2), eta = 7.02 %.</P>

Epidemiology and trends in the antibiotic susceptibilities of Gram-negative bacilli isolated from patients with intra-abdominal infections in the Asia-Pacific region, 2010-2013

Chang, Y.T.,Coombs, G.,Ling, T.,Balaji, V.,Rodrigues, C.,Mikamo, H.,Kim, M.J.,Rajasekaram, D.G.,Mendoza, M.,Tan, T.Y.,Kiratisin, P.,Ni, Y.,Barry, W.,Xu, Y.,Chen, Y.H.,Hsueh, P.R. Elsevier Science Publishers ; Elsevier Science Pub 2017 International Journal of Antimicrobial Agents Vol.49 No.6

This study was conducted to investigate the epidemiology and antimicrobial susceptibility patterns of Gram-negative bacilli (GNB) isolated from intra-abdominal infections (IAIs) in the Asia-Pacific region (APR) from 2010-2013. A total of 17 350 isolates were collected from 54 centres in 13 countries in the APR. The three most commonly isolated GNB were Escherichia coli (46.1%), Klebsiella pneumoniae (19.3%) and Pseudomonas aeruginosa (9.8%). Overall, the rates of extended-spectrum β-lactamase (ESBL)-producing E. coli and K. pneumoniae were 38.2% and 24.3%, respectively, and they were highest in China (66.6% and 38.7%, respectively), Thailand (49.8% and 36.5%, respectively) and Vietnam (47.9% and 30.4%, respectively). During 2010-2013, the rates of ESBL-producing E. coli and K. pneumoniae isolates causing community-associated (CA) IAIs (collected <48@?h after admission) were 26.0% and 13.5%, respectively, and those causing hospital-associated (HA) IAIs were 48.0% and 30.6%, respectively. Amikacin, ertapenem and imipenem were the most effective agents against ESBL-producing isolates. Piperacillin/tazobactam displayed good in vitro activity (91.4%) against CA ESBL-producing E. coli. For other commonly isolated Enterobacteriaceae, fluoroquinolones, cefepime and carbapenems exhibited better in vitro activities than third-generation cephalosporins. Amikacin possessed high in vitro activity against all GNB isolates (>80%) causing IAIs, except for Acinetobacter calcoaceticus-baumannii (ACB) complex (30.9% for HA-IAI isolates). All of the antimicrobial agents tested exhibited <45% in vitro activity against ACB complex. Antimicrobial resistance is a persistent threat in the APR and continuous monitoring of evolutionary trends in the susceptibility patterns of GNB causing IAIs in this region is mandatory.