Photoluminescence and cathodoluminescence properties of Sr₂Gd₈Si₆O₂₆:RE³⁺(RE³⁺=Tb³⁺or Sm³⁺) phosphors

Hussain, Sk.K.,Rao, G.M.,Raju, G.S.R.,Krishna Bharat, L.,Subba Rao, P.S.V.,Yu, J.S. Elsevier [etc.] 2016 Journal of luminescence Vol.178 No.-

<P>Trivalent terbium (Tb3+) or samarium (Sm3+) ions individually activated green and orange emitting Sr2Gd8Si6O26 (SGSO) phosphors were synthesized by a citrate sol-gel method. The X-ray diffraction patterns of SGSO:Tb3+ and SGSO:Sm3+ phosphors exhibited the characteristic diffraction peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence (PL) properties at ultraviolet (UV) or near-UV excitation wavelengths were measured for Tb3+ or Sm3+ ions doped SGSO phosphors as a function of its respective concentration. The PL spectra of SGSO:Tb3+ phosphors revealed the characteristic emission peaks of both Gd3+ and Tb3+ ions which are associated with 4f-4f transitions under 274 nm of excitation wavelength. When the concentration of Tb3+ ions increased over 0.05 mol (5 mol%), the emission intensities of D-5(3) transitions decreased due to the well-known cross-relaxation process. However, based on the intensities of D-5(4) transitions, the optimum concentration of Tb3+ ions was found to be 0.05 mol. Under 404 nm of excitation wavelength, the SGSO:Sm3+ phosphors exhibited the characteristic orange emission at 600 nm due to the (4)G(5/2) -> H-6(7/2) electronic transition. The optimum concentration of SGSO:Sm3+ phosphors was found to be 0.02 mol. The decay curves of the optimized SGSO:Tb3+ and SGSO:Sm3+ phosphors were well fitted to single exponential functions and their lifetimes were calculated. Furthermore, the optimized phosphor samples showed good thermal stability. Likewise, cathodoluminescence properties were also studied for the optimized samples as a function of filament current and accelerating voltage. The Commission International de I-Eclairage chromaticity coordinates were calculated for the SGSO:Tb3+ and SGSO:Sm3+ phosphors. (C) 2016 Elsevier B.V. All rights reserved.</P>

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>

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>

Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) composite membranes with controlled silver ion release for antibacterial and water treatment applications

Haider, M.S.,Shao, G.N.,Imran, S.M.,Park, S.S.,Abbas, N.,Tahir, M.S.,Hussain, M.,Bae, W.,Kim, H.T. Elsevier 2016 Materials Science and Engineering C Vol.62 No.-

<P>The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to form AgNPs-APES. The properties of the obtained membrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm x 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag+ leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag+) release to enhance the lifetime of the membranes. (C) 2016 Elsevier B.V. All rights reserved.</P>

Dielectric and Piezoelectric Properties of Ta-modified (K0.53Na0.47)(Nb0.8Ta0.2)O3 Ferroelectric Ceramics

Kim, J.S.,Kim, M.-H.,Hussain, A.,Park, T.G.,Park, J.,Chung, S.T.,Lee, H.S. Taylor Francis 2014 Ferroelectrics Vol.458 No.-

<P>Ta-substituted Na0.53K0.475Nb0.8Ta0.2O3 ceramics were prepared through the solid-state reaction method. The crystallized single phases were confirmed by X-ray diffraction. The temperature dependences of the dielectric and piezoelectric properties were investigated. Ta substitution in Na0.5K0.5NbO3 enhanced the piezoelectric property, and the corresponding piezoelectric coefficient was estimated to be d(33) = 160 pC/N. With increasing temperature, the planar electromechanical coupling coefficient (k(p) ) increased linearly up to the orthorhombic-tetragonal phase-transition temperature (TO-T ) and decreased as the temperature comes closer to the Curie temperature (T-c ).</P>

Structural and Morphological Properties of Zn1−xZrxO with Room-Temperature Ferromagnetism and Fabricated by Using the Co-Precipitation Technique

M. Hassan,R. Irfan,S. Riaz,S. Naseem,S. S. Hussain,G. Murtaza 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.5

In this study, ZnO was doped with various concentrations of zirconium (xZr = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn1−xZrxO was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents (xZr < 3%); however, impurity peaks belonging to ZrO2 appeared at high impurity contents (xZr 3%). The calculated ZnO lattice constants ‘a’ and ‘c’ were found to be 3.256 °A and 5.203 °A, respectively, which are in close match to the values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 °A. The residual strains and the secondary phases of ZrO2 were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the otherhand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

Fermentation, a feasible strategy for enhancing bioactivity of herbal medicines

Hussain, A.,Bose, S.,Wang, J.H.,Yadav, M.K.,Mahajan, G.B.,Kim, H. Published on behalf of the Canadian Institute of F 2016 Food Research International Vol.81 No.-

<P>Herbal drugs, which possess immunomodulatory, anti-inflammatory, anti-diabetic, anti-infective, and anti-allergic activities, encompass various therapeutic areas, and have been used as traditional medicines for thousands of years. Fermentation is an indispensable traditional technology for the improving the efficacy or reducing adverse effects of herbal medicines. The fermentation process has been shown to improve biological properties of plants, vegetables, and herbs. More specifically, fermentation causes decomposition and/or biotransformation of complex substrates into compatible components, thereby modulating product properties or changing the quantity of certain bioactive compounds. Accumulating evidence indicates the valuable contribution of probiotics and their fermented food products to health. In recent years, considerable attention has been paid to fermentation technology across the globe for improving herbal drugs through production and enrichment of additional bioactive metabolites of medicinal importance including isoflavones, saponins, phytosterols, and phenols. For example, the phenolic contents of the herbal preparation can be increased as a consequence of fermentation and a positive correlation between polyphenols and the anti-oxidant activities of herbs has been well demonstrated. This is in agreement with evidence showing fermentation-mediated enhancement of the pharmacological properties and therapeutic efficacies of herbal formulations against a number of diseases including obesity and inflammation. The subject of fermentation of herbal preparations has been maturing and gaining considerable attention of scientific and technical communities worldwide. In the current review we have addressed these issues in detail with emphasis on understanding the contribution of fermentation-derived bioactive substances to therapies against a number of diseases. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Genome-wide analysis of Family-1 UDP-glycosyltransferases in soybean confirms their abundance and varied expression during seed development

Mamoon Rehman, H.,Amjad Nawaz, M.,Bao, L.,Hussain Shah, Z.,Lee, J.M.,Ahmad, M.Q.,Chung, G.,Yang, S.H. G. Fischer 2016 Journal of plant physiology Vol.206 No.-

<P>Family-1 UDP-glycosyltransferases (EC 2.4.1.x; UGTs) are enzymes that glycosylate aglycones into glycoside-associated compounds with improved transport and water solubility. This glycosylation mechanism is vital to plant functions, such as regulation of hormonal homeostasis, growth and development, xenobiotic detoxification, stress response, and biosynthesis of secondary metabolites. Here, we report a genome-wide analysis of soybean that identified 149 putative UGTs based on 44 conserved plant secondary product glycosyl-transferase (PSPG) motif amino acid sequences. Phylogenetic analysis against 22 referenced UGTs from Arabidopsis and maize clustered the putative UGTs into 15 major groups (A-O); J, K, and N were not represented, but the UGTs were distributed across all chromosomes except chromosome 04. Leucine was the most abundant amino acid across all 149 UGT peptide sequences. Two conserved introns (C-1 and C-2) were detected in the most intron-containing UGTs. Publicly available microarray data on their maximum expression in the seed developmental stage were further confirmed using Affymetrix soybean IVT array and RNA sequencing data. The UGT expression models were designed, based on reads per kilobase of gene model per million mapped read (RPKM) values confirmed their maximally varied expression at globular and early maturation stages of seed development. (C) 2016 Elsevier GmbH. All rights reserved.</P>

Maslinic Acid Protects Against Isoproterenol-Induced Cardiotoxicity in Albino Wistar Rats

Althaf Hussain Shaik,S.N. Rasool,M. Abdul Kareem,G. Saayi Krushna,P. Mohammad Akhtar,Kodidhela Lakshmi Devi 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.8

The present study aimed to evaluate the protective effect of maslinic acid (MA) on body weight, heart weight, lipids, lipoproteins, lipid peroxidation (LPO), cardiac marker enzymes, and paraoxonase (PON) in normal control and isoproterenol (ISO)-induced myocardial infarcted albino Wistar rats. After treatment with MA (15 mg/kg) for 7 days, myocardial infarction was induced by subcutaneous injection of ISO (85 mg/kg) for two consecutive days. ISO caused a considerable decrease in body weight and increased the heart weight. The concentrations of total cholesterol, triglycerides, very low-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol were higher, whereas that of high-density lipoprotein-cholesterol was lower, in the serum of ISO-administered rats. The activities of the cardiac marker enzymes creatine kinase, alanine transaminase, aspartate transaminase, and γ-glutamyl transferase and levels of malondialdehyde were elevated in the serum of ISO-treated rats. ISO-administered rats also exhibited a decline in the activity of PON. Pretreatment of rats with MA reduced the effects of ISO on all parameters tested. This is the first report of the protective effect of MA on ISO-induced cardiotoxicity and of an association between PON status and MA supplementation. The observed cardioprotective effects may be due to the antihyperlipidemic potential of MA, inhibition of LPO, and antioxidant activity.

Thickness dependent magnetic and ferroelectric properties of LaNiO3 buffered BiFeO3 thin films

Shahzad Hussain,S.K. Hasanain,G. Hassnain Jaffari,S. Ismat Shah 한국물리학회 2015 Current Applied Physics Vol.15 No.3

BiFeO3 (BFO) thin films with thickness increasing from 40 to 480 nm were successfully grown on LaNiO3 (LNO) buffered Pt/Ti/SiO2/Si(100) substrate and the effects of thickness evolution on magnetic and ferroelectric properties are investigated. The LNO buffer layer promotes the growth and crystallization of BFO thin films. Highly (100) orientation is induced for all BFO films regardless of the film thickness together with the dense microstructure. All BFO films exhibited weak ferromagnetic response at room temperature and saturation magnetization is found to decrease with increase in film thickness. Well saturated ferroelectric hysteresis loops were obtained for thicker films; however, the leakage current dominated the ferroelectric properties in thinner films. The leakage current density decreased by three orders of magnitude for 335 nm film compared to 40 nm film, giving rise to enhanced ferroelectric properties for thicker films. The mechanisms for the evolution of ferromagnetic and ferroelectric characteristics are discussed.