Synthesis and photoluminescence of novel Ca(1-x)MgP2O7:xEu(3+) pyrophosphate phosphor for near ultraviolet light emitting diodes.

Hakeem, A,Shinde, K N,Yoon, S J,Dhoble, S J,Park, K American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.8

<P>We studied the microstructure and photoluminescence properties of Ca(1-x)MgP2O7:xEu(3+) (0.01 x 0.2) phosphors, considering Eu(3+) content. The Ca(1-x)MgP2O7:xEu(3+) phosphors crystallized in the monoclinic structure, belonging to the space group of P2(1)/n. The Ca(1-x)MgP2O7:xEu(3+) phosphors showed a nanocrystalline nature. In the FT-IR and Raman spectra, the stretching vibrations of PO3 and P-O-P groups in (P2O7)(4-) were observed. The amount of Eu(3+) content significantly affected the magnitude of the excitation and emission intensities. The excitation intensity at 393 nm and the emission intensity at 605-628 nm were increased with an increase in Eu(3+) content up to x = 0.1 and then decreased with further increasing Eu(3+) content. The strong emission intensity under near ultraviolet excitation makes it possible red phosphor for generating white light based on LEDs.</P>

Empirically Measuring the Impact of Corporate Social Responsibility on Earnings Management in Listed Banks of the Iraqi Stock Exchange: The Mediating Role of Corporate Governance

Hakeem Hammood Flayyih,Wided Khiari 대한산업공학회 2023 Industrial Engineeering & Management Systems Vol.22 No.3

The current study is based on previous findings, where corporate governance (CG) significantly increased corporate social responsibility (CSR) to enhance transparency while reducing the tendency of corporate management to engage in earnings management (EM). A sample of 11 Iraqi banks listed on the Iraq Stock Exchange from 2010 to 2020 was selected. The CG was included in the board size and board independence apart from the variables of Chief Executive Officer (CEOs) gender, majority shareholder ownership, foreign ownership, and institutional ownership. The CSR in-cluded the wage growth rate, bank contribution growth rate for social security, training programmes, subsidies, envi-ronmental protection, and bank compliance with the law. Specifically, EM practices were revealed from the sample. As bank management was not involved in CSR activities, the significant interaction role of CG was not discovered in the relationship between CSR and EM. An insignificant relationship between CG mechanisms (CGMs) and EM was also demonstrated. Summarily, CSR and CG structures were substandard among underdeveloped countries.

Synthesis and Luminescence Properties of Blue Na(Sr0.97-xCa(x))PO4:0.03Eu2+ Phosphors for White Light Emitting Diode Applications.

Hakeem, D A,Park, K American Scientific Publishers 2015 Journal of nanoscience and nanotechnology Vol.15 No.7

<P>The crystal structure and luminescence properties of Na(Sr0.97_Cax)PO4:0.03Eu(2+) (0 <= x <= 1.0) phosphors were studied, depending on the Ca2+ concentration. All the Na(Sr0.97_xCax)PO4:0.03Eu(2+) phosphors had a hexagonal crystal structure. The excitation spectra of the prepared phosphors showed a broad band ranging from 250 to 420 nm, which arises due to the 4f-5d transitions of Eu2+ ions. Upon the excitation of 334 nm wavelength, the emission spectra showed a broad blue band ranging from 400 to 700 nm peaking at 450 nm. Among the prepared phosphors, the Na(Sr0.72Ca0.25)PO4:0.03Eu(2+) showed the strongest emission intensity and could be applied as a blue emitting phosphor for UV-based w-LEDs.</P>

Crystal structure and photoluminescence properties of novel garnet Y_2-<i>x</i>LaCaGa₃ZrO₁₂:<i>x</i>Ln³⁺ (Ln = Eu and Tb) phosphors

Hakeem, D.A.,Kim, D.H.,Kim, S.W.,Park, K. Elsevier 2019 Dyes and pigments Vol.163 No.-

<P><B>Abstract</B></P> <P>A series of novel garnet Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB>:<I>x</I>Ln<SUP>3+</SUP> (0 ≤ <I>x</I> ≤ 0.12; Ln = Eu and Tb) phosphors was prepared by a solid-state reaction. Their structural and photoluminescence properties were characterized by X-ray diffraction, Rietveld refinement, and photoluminescence spectroscopy. The studied Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB>:<I>x</I>Ln<SUP>3+</SUP> phosphors crystallized in a cubic garnet crystal structure and Ia 3 ¯ d space group. The Eu<SUP>3+</SUP>- and Tb<SUP>3+</SUP>-doped Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB> phosphors exhibited strong red and green light emissions, respectively, and high emission color purity. With increasing Tb<SUP>3+</SUP> content, the emitting color of the Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors shifted to the green spectral region because of cross-relaxation among Tb<SUP>3+</SUP> ions. The Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB>:<I>x</I>Ln phosphors are suitable for applications in white light-emitting diode and other optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB> was explored as a host material of phosphors for white-light-emitting diode (WLED) applications. </LI> <LI> Eu<SUP>3+</SUP>- and Tb<SUP>3+</SUP>-doped Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB> phosphors showed red and green light emissions, respectively. </LI> <LI> Y<SUB>2-<I>x</I> </SUB>LaCaGa<SUB>3</SUB>ZrO<SUB>12</SUB>:<I>x</I>Ln (0 ≤ <I>x</I> ≤ 0.12; Ln = Eu and Tb) phosphors are suitable for WLED applications. </LI> </UL> </P>

Structural and photoluminescence properties of La_1-<i>x</i>NaCaGa₃PZrO₁₂ doped with Ce³⁺, Eu³⁺, and Tb³⁺

Hakeem, D.A.,Pi, J.W.,Jung, G.W.,Kim, S.W.,Park, K. Elsevier 2019 Dyes and pigments Vol.160 No.-

<P><B>Abstract</B></P> <P>In this work, LaNaCaGa<SUB>3</SUB>PZrO<SUB>12</SUB> was explored as a host material of phosphors for white-light-emitting diode (WLED) applications for the first time. Rare-earth metal ions (Ce<SUP>3+</SUP>, Eu<SUP>3+</SUP>, and Tb<SUP>3+</SUP>) doped garnet LaNaCaGa<SUB>3</SUB>PZrO<SUB>12</SUB> phosphors were fabricated by a solid-state reaction method. The structural and photoluminescence properties of the prepared garnet phosphors were investigated. The Ce<SUP>3+</SUP>-, Eu<SUP>3+</SUP>-, and Tb<SUP>3+</SUP>-doped LaNaCaGa<SUB>3</SUB>PZrO<SUB>12</SUB> phoshors emitted blue, red, and green light, respectively, and are promising for WLED device applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LaNaCaGa<SUB>3</SUB>PZrO<SUB>12</SUB> was explored as a host material of phosphors for white-light-emitting diode applications. </LI> <LI> The structural and photoluminescence properties of the prepared garnet phosphors were investigated. </LI> <LI> The Ce<SUP>3+</SUP>-, Eu<SUP>3+</SUP>-, and Tb<SUP>3+</SUP>-doped LaNaCaGa<SUB>3</SUB>PZrO<SUB>12</SUB> phoshors emitted blue, red, and green light, respectively. </LI> </UL> </P>

“Inspiring the Future” to counter violent extremism in Pakistan

Saba HAKEEM 이화여자대학교 아시아여성학센터 2018 이화여자대학교 아시아여성학센터 학술대회자료집 Vol.2018 No.1

Violent extremism is multifaceted and multilayered phenomenon which is the biggest threat destructing Pakistan in given magnitude of the issues. Initially it was considered that the problem is primarily attracting youth from Madrassah’s (Religious Institutes) but many incidents depicts involvement from reputable educational institutes. These cases underscore the concern that the violent extremism and radicalization is not limited to the disenfranchised and uneducated youth rather highly educated are gravitating towards radical ideology. This segment of the society is basically exposed to violent extremism. So there is a need to take concrete measure to Counter Violent Extremism and delink youth from the attraction towards Violent Extremism. For this Civil Society needs to play its part by educating them with the counter narrative. The most important stakeholders in reaching to this vulnerable segment is the university as they are the crucibles to refine the talents of diverse intellects. So to engage youth in explaining the counter narrative the most significant contributors are the professors. They are the ones who inspire and influence the future of the nation that is youth by this the likelihood of having peaceful nation increases. Through this initiative “Inspiring the Future” professors were oriented on Countering Violent Extremism so that they could reach out to the students and make them realize of the importance of their role in peace promotion regardless of the discipline they belong to.

Triazenoindazoles and Triazenopyrazolopyridines: Design, Synthesis, and Cytotoxic Activity

Maha Abdel-Hakeem 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.6

Several triazenoindazoles 3a-e and triazinopyrazolopyridines 6a-i were prepared through the reaction of the corresponding 3-amino-4-chloroindazole and 3-aminopyrazolopyridine diazonium salts 2 and 5 with a number of secondary amines. All compounds were evaluated for their in vitro cytotoxic activity on three cell lines, HepG2, MCF7, and HeLa. Most compounds inhibited cell growth with IC50 less than 0.1 μM. Compound 6d was the most potent, with an IC50 of 0.03 μM against HepG2 and 0.05 μM against MCF7 and HeLa cells.

Photoluminescence properties of Sr6-xBP5O20 : xEu2+ phosphors for white LED applications

D. A. Hakeem,K. Park 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.5

Sr6-xBP5O20:xEu2+ (0.005 ≤ x ≤ 0.08) bluish-green phosphors are prepared by solution combustion method. Thephotoluminescence excitation spectra show a broad band covering 250-450 nm with a maximum intensity at 353 nm, whichmatches well with the emission of ultraviolet LED chips. Upon 353 nm excitation, the photoluminescence emission spectracontain two distinct broad emission bands at 408 and 480 nm, which originate from the 4f65d1 → 4f7 transitions of Eu2+ ionsin Sr3(PO4)2 : Eu2+ and Sr6-xBP5O20 : xEu2+, respectively. The emission intensities at 408 and 480 nm increase with increasingEu2+ contents up to 5 and 2 mol%, respectively, and then decreased with further its contents.

Synthesis and structural properties of thermoelectric Ca_3−<i>x</i>Ag_<i>x</i>Co₄O_9+<i>δ</i> powders

Park, Kyeongsoon,Hakeem, Deshmukh Abdul,Cha, Jae Sung The Royal Society of Chemistry 2016 Dalton Transactions Vol.45 No.16

<P>A series of Ca3-xAgxCo4O9+delta (0 <= x <= 0.2) powders is prepared by the Pechini sol-gel method. The effect of dispersants on the size and morphology of the Ca2.9Ag0.1Co4O9+delta powders is investigated. The desired powders are obtained after calcinations of the dried powders at 800 degrees C for 12 h. The structural and morphological properties are studied with the help of XRD patterns, FE-SEM images, FT-IR spectra, Raman spectra, and XPS spectra. It is found that a mixed valence (+ 3 and + 4) of Co exists in a CdI2-type CoO2 layer, while a mixed valence (+ 2, + 3, and + 4) exists in the CoO of a rock salt-type Ca2CoO3 layer. The mixed-valence state in the CoO2 layer can improve the high-temperature thermoelectric properties of Ca3Co4O9 systems.</P>

Emission enhancement of Eu³⁺-doped ZnO by adding charge compensators

Park, K.,Hakeem, D.A.,Pi, J.W.,Jung, G.W. Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.772 No.-

<P><B>Abstract</B></P> <P>Zn<SUB>0.99</SUB>O:0.01Eu<SUP>3+</SUP>, Zn<SUB>0.985</SUB>O:0.01Eu<SUP>3+</SUP>, and Zn<SUB>0.98</SUB>O:0.01Eu<SUP>3+</SUP>, 0.01M<SUP>+</SUP> (M = Li, Na, and K) phosphors were prepared by solid-state reaction at 900 °C and 1000 °C. The structural and photoluminescence (PL) properties of the prepared phosphors were studied with through X-ray diffraction, ultraviolet (UV)-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and PL spectroscopy. To improve the PL properties of Zn<SUB>0.99</SUB>O:0.01Eu<SUP>3+</SUP> phosphor, the effects of charge compensators, such as Li<SUP>+</SUP>, Na<SUP>+</SUP>, and K<SUP>+</SUP> ions, and annealing temperature on the PL properties of Zn<SUB>0.99</SUB>O:0.01Eu<SUP>3+</SUP> phosphor were investigated. An intense red emission peak at 612 nm was observed under 467 nm excitation. This peak corresponded to the <SUP>5</SUP>D<SUB>0</SUB> → <SUP>7</SUP>F<SUB>2</SUB> transition of Eu<SUP>3+</SUP>, and its intensity was significantly improved by adding charge compensators. Among the prepared phosphors, Zn<SUB>0.98</SUB>O:0.01Eu<SUP>3+</SUP>, 0.01Li<SUP>+</SUP> phosphor prepared at 1000 °C showed the strongest emission intensity and highest color purity. Thus, adding Li<SUP>+</SUP> ions and controlling the annealing temperature were highly effective in enhancing the PL properties of Zn<SUB>0.99</SUB>O:0.01Eu<SUP>3+</SUP> phosphor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zn<SUB>0.98</SUB>O:0.01Eu<SUP>3+</SUP>, 0.01M<SUP>+</SUP> (M = Li, Na, and K) were prepared by solid-state reaction. </LI> <LI> Zn<SUB>0.98</SUB>O:0.01Eu<SUP>3+</SUP>, 0.01M<SUP>+</SUP> phosphors can be effectively excited by blue LED chips. </LI> <LI> Addition of Li<SUP>+</SUP> was highly effective for enhancing PL properties of ZnO:Eu<SUP>3+</SUP> phosphor. </LI> </UL> </P>