Red organic light-emitting diodes with high efficiency, low driving voltage and saturated red color realized via two step energy transfer based on ADN and Alq3 co-host system

Khizar-ul Haq,Liu Shan-peng,M.A. Khan,X.Y. Jiang,Z.L. Zhang,Jin Cao,W.Q. Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.1

We demonstrated efficient red organic light-emitting diodes based on a wide band gap material 9,10-bis(2-naphthyl)anthracene (ADN) doped with 4-(dicyano-methylene)-2-t-butyle-6-(1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10(2-benzothiazolyl)quinolizine-[9,9a,1gh]coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA)/ N,N'-bis(naphthalene-1-yl)-N,N0-diphenyl-benzidine (NPB)/[ADN:Alq3]:DCJTB:C545T/Alq3/LiF/Al. It was found that C545T dopant did not by itself emit but did assist the energy transfer from the host (ADN) to the red emitting dopant via cascade energy transfer mechanism. The OLEDs realized by this approach significantly improved the EL efficiency. We achieved a significant improvement regarding saturated red color when a polar co-host emitter (Alq3) was incorporated in the matrix of [ADN:Alq3]. Since ADN possesses a considerable high electron mobility of 3.1 × 10-4 ㎠ V-1 s-1, co-host devices with high concentration of ADN (>70%) exhibited low driving voltage and high current efficiency as compared to the devices without ADN. We obtained a device with a current efficiency of 3.6 cd/A, Commission International d’Eclairage coordinates of [0.618, 0.373] and peak λmax = 620 nm at a current density of 20 mA/㎠. This is a promising way of utilizing wide band gap material as the host to make red OLEDs, which will be useful in improving the electroluminescent performance of devices and simplifying the process of fabricating full color OLEDs. We demonstrated efficient red organic light-emitting diodes based on a wide band gap material 9,10-bis(2-naphthyl)anthracene (ADN) doped with 4-(dicyano-methylene)-2-t-butyle-6-(1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10(2-benzothiazolyl)quinolizine-[9,9a,1gh]coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA)/ N,N'-bis(naphthalene-1-yl)-N,N0-diphenyl-benzidine (NPB)/[ADN:Alq3]:DCJTB:C545T/Alq3/LiF/Al. It was found that C545T dopant did not by itself emit but did assist the energy transfer from the host (ADN) to the red emitting dopant via cascade energy transfer mechanism. The OLEDs realized by this approach significantly improved the EL efficiency. We achieved a significant improvement regarding saturated red color when a polar co-host emitter (Alq3) was incorporated in the matrix of [ADN:Alq3]. Since ADN possesses a considerable high electron mobility of 3.1 × 10-4 ㎠ V-1 s-1, co-host devices with high concentration of ADN (>70%) exhibited low driving voltage and high current efficiency as compared to the devices without ADN. We obtained a device with a current efficiency of 3.6 cd/A, Commission International d’Eclairage coordinates of [0.618, 0.373] and peak λmax = 620 nm at a current density of 20 mA/㎠. This is a promising way of utilizing wide band gap material as the host to make red OLEDs, which will be useful in improving the electroluminescent performance of devices and simplifying the process of fabricating full color OLEDs.

Prion Protein Genotypes in Pakistani Goats

Babar, M.E.,Nawaz, M.,Nasim, A.,Abdullah, M.,Imran, M.,Jabeen, R.,Chatha, S.A.,Haq, A.U.,Nawaz, A.,Mustafa, H.,Nadeem, A. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.7

The PCR-amplified prion protein (PrP) gene was sequenced to determine the frequency of scrapie-associated as well as novel PrP genotypes in 72 healthy goats representing five breeds. A total of six genotypes were detected, resulting from the three reported 143 (H/R), 154 (R/H) and 240 (S/P) and the two novel 39 (S/R) and 185 (I/F) amino acid polymorphisms. Of the four silent mutations 42 (a$\rightarrow$g), 138 (c$\rightarrow$t), 231 (c$\rightarrow$a) and 237 (g$\rightarrow$c) detected in this study, 237 (g$\rightarrow$c) is novel. A genotype (SIP/RFP) harboring three amino acid polymorphisms 39 (S/R), 185 (I/F) and 240 (S/P) was found in few goats. Although both scrapie-associated genotypes with 143 (H/R) and 154 (R/H) polymorphisms and others with 39 (S/R), 185 (I/F) and 240 (S/P) polymorphisms were present in the studied Pakistani goats, their frequency was lower than that of the wild-type genotype SHRIS/SHRIS (34.7%). These results emphasize the need for further sequencing of the PrP gene in a large number of goats representing the five studied breeds, so that overall PrP variability can be assessed in these breeds in research addressing future concerns about scrapie.

Preparation of superparamagnetic maghemite (γ-Fe2O3) nanoparticles by wet chemical route and investigation of their magnetic and dielectric properties

Kashif Ali,A.K. Sarfraz,Imran M. Mirza,A. Bahadur,S. Iqbal,A. ul Haq 한국물리학회 2015 Current Applied Physics Vol.15 No.8

Maghemite (γ-Fe2O3) nanoparticles have been synthesized using a wet chemical route, optimizing the reaction time, PH value and size of the crystallite during synthesis. The Powder X-ray diffraction (XRD) measurements confirmed the presence of an impurity free maghemite phase in our sample with an average crystallite size of 16 nm as calculated from the DebyeeScherrer equation. In physical characterization, the room temperature hysteresis (M-H loop) and blocking temperature (as observed from the M-T plot) revealed that the particles are in the superparamagnetic phase at room temperature. Dielectric behaviour of γ-Fe2O3 with respect to the variation of frequency and temperature was also performed. At room temperatures, we observe a decaying behaviour of both dielectric constant (έ) and tangent looses (tanδ) at smaller frequencies while at higher frequencies both saturate to smaller constant values. In temperature dependent dielectric properties we notice that the dielectric constant (both real and imaginary parts) show an increasing trend with increasing temperatures but an overall slower enhancement at elevated frequencies. The former effect can be attributed to the possible delocalization of impurities at higher temperatures while the latter effect can be explained as an inability of the electric dipole moments to respond at higher frequencies.

Thermal energy performance due to convection process of nanofluid in a porous medium due to split lid motion in a right triangular enclosure

Ullah M Zaka,Hussain S T,Haq Rizwan Ul,Alzahrani A Khamis,Mallawi Fouad 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.3

In the current phenomena, a study is carried out for the convection process of nanofluid within the porous media enclosed in a triangular permeable cavity. The heat generation effect within the nanofluid is developed when the two heat sources are applied through the split lids. To analyse the behaviour of nanofluids and steam lines, we have considered an elliptic (cold, adiabatic, and heated)-shaped obstacle that is placed inside the cavity. Mathematical modelling is carried out through continuity, momentum equation, and energy equations in the form of a system of non-linear partial differential equations. These equations are produced after incorporating the relations of viscosity, density, shapes of nanoparticle, and thermal conductivity for nanofluids Constraints are adjusted according to the forced convection due to the upper moving wall of the cavity. Four different cases of the upper double lid-driven wall are considered. All the emerging parameters, namely Reynolds number $( {25 \le {\rm{Re}} \le 750} ),$ heat generation $( { - {{10}^4} \le Q \le 40} ),\ $ nanoparticle volume fraction $\ ( {0 \le \phi \le 0.2} )$, and Darcy number ${10^{ - 5}} \le Da \le {10^{ - 3}}$, are analysed through variation of velocities, temperature profile, isotherms, and streamlines. Various cases at the surface of the inner elliptical obstacle provide significant contributions in the variation of heat transfer rate and velocity profiles. Nanoparticles provide a considerable increase in the heat transfer rate. The Darcy number shows the substantial variation in the formation of the isothermal region. An increase in heat generation parameter Q provides an improvement in temperature distribution inside the cavity and it also caused the formation of a single isothermal region around the heated obstacle.

Composition-induced influence on the electronic band structure, optical and thermoelectric coefficients of the highly mismatched GaNSb alloy over the entire range: A DFT analysis

Ul Haq, Bakhtiar,Ahmed, R.,Rhee, Joo Yull,Shaari, A.,AlFaify, S.,Ahmed, M. Elsevier 2017 Journal of alloys and compounds Vol.693 No.-

<P><B>Abstract</B></P> <P>Capable of achieving wide control over energy band gap and following optoelectronic properties; the highly mismatched alloys (HMAs) are considered to be promising materials for solar energy conversion devices. The dramatic restructuring of energy bands and density of states in HMAs caused by the replacement of anions with distinctly-mismatched isovalent constituents could further be an important course in improving their thermoelectric efficiency. In this paper, we attempt to explore and address the composition-induced modifications in the electronic band structure and the resultant effects on optical spectra and thermoelectric coefficients of GaN<SUB>1−x</SUB>Sb<SUB>x</SUB> based HMAs in the framework of density functional theory. We observe, the substitution of N by Sb, considerably affects its band structure and split the conduction band minimum (CBM) into sub-bands. With increasing Sb composition, the lowest sub-band stemmed from N-s electrons has experienced drastic downward shift leading to energy gap narrowing. Interestingly, the energy gap narrowing along R- Γ is found to be faster than that of Γ- Γ point leading to an amazing direct to indirect band gap crossover. On the other hand, the composition-induced energy gap narrowing stimulates the red-shift in fundamental absorption edge in both ultraviolet and the infrared regime, making the GaNSb potentially useful material for photovoltaic applications. In addition, substantial effect on the thermoelectric coefficients of GaNSb is also observed via Sb substitution. We obtain larger Seebeck coefficient, improved power factors and figure of merit (ZT) for GaNSb at low Sb substitution and found diminishing effect with the further increase of Sb composition. With enhanced Seebeck coefficient, power factor and ZT values at modest doping levels, GaNSb alloy could be a promising candidate for near or above room temperature thermoelectric applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Alloying of GaNSb across entire composition in the framework of DFT. </LI> <LI> The striking direct to indirect energy gap cross over. </LI> <LI> Enhanced absorption in ultraviolet, visible and infrared energy regime. </LI> <LI> Comprehensive investigations of thermoelectric properties of GaNSb alloy. </LI> </UL> </P>

Effect of Cotton Leaf Mosaic Disease on Morphology, Yield and FibreCharacteristics of Upland Cotton in Pakistan

Khalid P. Akhtar,M. A. Haq,Wajid Ishaque,M. K. R. Khan,Azeem I. Khan 한국식물병리학회 2005 Plant Pathology Journal Vol.21 No.2

The effect of cotton leaf mosaic disease on morphology,yield and fibre characteristics was examined for a susceptible cotton candidate variety CRIS-168. Plants inoculated at most susceptible growth stage (six week) under screen house showed severe mosaic symptoms.There was a significant reduction in plant height and yield. Cotton leaf mosaic disease was found to produce severe effects on plant morphology with 24.1% reduction in plant height, 25% in internode length and 37.5% in number of sympodia on main stem. However no changes were observed against number of monopodial branches per plant. Inoculated plants showed 82% decrease in yield/plant, 80% in number of boll set/plant, 12.1% in boll weight, 12.8% in lint weight, 10.8% in seed weight, and 6.8% in seed index. Cotton leaf mosaic disease also showed effects on fibre characteristics with 0.8% decrease in GOT and 1.6% in fibre length. In contrast, uniformity ratio, fibre fineness and maturity index was increased by 20.5%, 14.4% and 0.9%, respectively.

Structural and magnetic studies on Zr doped ZnO diluted magnetic semiconductor

G. Murtaza,R. Ahmad,M.S. Rashid,M. Hassan,A. Hussnain,Muhammad Azhar Khan,M. Ehsan ul Haq,M.A. Shafique,S. Riaz 한국물리학회 2014 Current Applied Physics Vol.14 No.2

In this study, Zirconium doped Zn1xZrxO (with x ¼ 0.00e0.10) samples have been prepared by formal solid-state reaction technique. The Zr doped ZnO samples annealed at 1100 C and characterized by different characterization techniques, such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). The Xray diffraction (XRD) used to study the structural properties. XRD pattern showed that lattice parameters, “a”, “c”, unit cell volume and ZneO bond length increase with doping content (x 0.04) where as these decrease with x > 0.04. On the other hand, reverse trend observed with lattice distortion. The crystallite size decreases with increasing doping content of Zr. FTIR employed to investigate functional chemical bonding properties of different elements and compounds present in materials. The low, medium and high frequency absorption bands observed at 630, 1500 and 3435 cm1, which were the common features of ZneO, HeOeH and OeH bond respectively. SEM used to study surface morphology and measured grain size of specimen. The surface becomes dense and grain size decreases with increasing degree of Zr contents. The SEM micrograph also shows the presence of spherical micro size particles and formation of pores in samples. Magnetic properties were obtained using VSM. The samples exhibit room temperature ferromagnetism. The magnetic hysteresis loops show variation in the value of magnetic parameter. The saturation magnetization (Ms) and coercivity (Hc) decrease, while remanence magnetization (Mr) shows gradually increasing trend with Zr content. VSM measurement reveals that sample Zn0.96Zr0.4O show better result as compared to x ¼ 0.06e0.10.

Combining Ability in Mungbean (Vigna radiata (L.) Wilczek) 1 : Agronomic Traits

G.S.S. Khattak,M.A. Haq,M. Ashraf,P. Srinives 韓國作物學會 2001 Korean journal of crop science Vol.46 No.5

Combining ability in mungbean was studied in 15 quantitative traits through a 6 ~times 6 diallel cross. Both additive and non-additive gene effects were found conditioning the inheritane of nodes of the first peduncle, clusters per plant, clusters on main stem and branches, pods per plant, 1000 seed weight, grain yield per plant, biomass, and harvest index. The additive gene action was found significant for nodes on main stem, average internodal length, branches per plant, pods per cluster, pod length, and seeds per pod. The predominace of additive genetic variance was observed in all traits. For grain yield and yield components, the best combiner were VC3902A, VC1560D and ML-5, while the best combinations were the crosses VC3902A ~times ML-5, VC1560D ~times ML-5, and NM 92 ~times VC1560D

Effect of Cotton Leaf Mosaic Disease on Morphology, Yield and Fibre Characteristics of Upland Cotton in Pakistan

Akhtar, Khalid P.,Haq, M.A.,Ishaque, Wajid,Khan, M.K.R.,Khan, Azeem I. The Korean Society of Plant Pathology 2005 Plant Pathology Journal Vol.21 No.2

The effect of cotton leaf mosaic disease on morphology, yield and fibre characteristics was examined for a susceptible cotton candidate variety CRIS-168. Plants inoculated at most susceptible growth stage (six week) under screen house showed severe mosaic symptoms. There was a significant reduction in plant height and yield. Cotton leaf mosaic disease was found to produce severe effects on plant morphology with 24.1% reduction in plant height, 25% in internode length and 37.5% in number of sympodia on main stem. However no changes were observed against number of monopodial branches per plant. Inoculated plants showed 82% decrease in yield/plant, 80% in number of boll set/ plant, 12.1% in boll weight, 12.8% in lint weight, 10.8% in seed weight, and 6.8% in seed index. Cotton leaf mosaic disease also showed effects on fibre characteristics with 0.8% decrease in GOT and 1.6% in fibre length. In contrast, uniformity ratio, fibre fineness and maturity index was increased by 20.5%, 14.4% and 0.9%, respectively.

Combining Ability in Mungbean (Vigna radiata (L.) Wilczek) I. Agronomic Traits

Srinives, P.,Khattak, G.S.S.,Haq, M.A.,Ashraf, M. The Korean Society of Crop Science 2001 Korean journal of crop science Vol.46 No.5

Combining ability in mungbean was studied in 15 quantitative traits through a 6 $\times$ 6 diallel cross. Both additive and non-additive gene effects were found conditioning the inheritane of nodes of the first peduncle, clusters per plant, clusters on main stem and branches, pods per plant, 1000 seed weight, grain yield per plant, biomass, and harvest index. The additive gene action was found significant for nodes on main stem, average internodal length, branches per plant, pods per cluster, pod length, and seeds per pod. The predominace of additive genetic variance was observed in all traits. For grain yield and yield components, the best combiner were VC3902A, VC1560D and ML-5, while the best combinations were the crosses VC3902A $\times$ ML-5, VC1560D $\times$ ML-5, and NM 92 $\times$ VC1560D.