http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
FAHEEM AHMED,Nishat Arshi,M. S. ANWAR,Rehan Danish,구본흔 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10
Herein, the effect of different TM (Co, Ni and Cu) doping on structural, optical and magnetic properties of ZnO nanostructures has been studied. Zn1−xTMxO (TM=Co, Ni and Cu) nanostructures were prepared by a microwave assisted chemical route and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy (TEM), Raman spectroscopy, UV-Vis and magnetization measurements. XRD and TEM analyses showed that the TM-doped ZnO nanostructures had single phase nature with the wurtzite structure. Changes in the lattice volume, bandgap energy, morphology and the saturation magnetization of Zn1−xTMxO nanostructures were found to be dependent on the type of TM dopants. Lattice volume, bondlength and bandgap determined from XRD and UV-Vis, respectively, were found to decrease as the atomic number of the dopant increased from Co to Cu. Magnetic studies showed that all the TM-doped ZnO exhibited room temperature ferromagnetism and the decreasing trend of saturation magnetization was observed with the increase of 3d electrons number from Co to Cu.
Ahmed, Faheem,Arshi, Nishat,Anwar, M S,Danish, Rehan,Koo, Bon Heun American Scientific Publishers 2015 Journal of nanoscience and nanotechnology Vol.15 No.2
<P>In this work, pure and 3% TM (Co, Ni, and Cu)-doped ZnO nanostructures were prepared by microwave-hydrothermal method. The striking similarities between changes in the lattice volume, bandgap energy, morphology and saturation magnetization indicated a strong correlation between these properties. XRD, SAED and HRTEM analyses revealed that all the TM-doped ZnO nano-structures have wurtzite structure and no secondary phase was detected. FESEM and TEM results confirmed a higher aspect ratio and highly crystalline nature of nanostructures. Raman spectra revealed that no defect related mode was observed which indicated that the nanostructures have high quality and negligible defects. The value of bandgap was found to decrease with the increase in atomic number of TM dopants. RTFM was observed in all the TM-doped ZnO nanostructures and the value of Ms and Mr were decreased with TM dopants.</P>
A Scalable Data Integrity Mechanism Based on Provable Data Possession and JARs
( Faheem Zafar ),( Abid Khan ),( Mansoor Ahmed ),( Majid Iqbal Khan ),( Farhana Jabeen ),( Zara Hamid ),( Naveed Ahmed ),( Faisal Bashir ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.6
Cloud storage as a service provides high scalability and availability as per need of user, without large investment on infrastructure. However, data security risks, such as confidentiality, privacy, and integrity of the outsourced data are associated with the cloud-computing model. Over the year`s techniques such as, remote data checking (RDC), data integrity protection (DIP), provable data possession (PDP), proof of storage (POS), and proof of retrievability (POR) have been devised to frequently and securely check the integrity of outsourced data. In this paper, we improve the efficiency of PDP scheme, in terms of computation, storage, and communication cost for large data archives. By utilizing the capabilities of JAR and ZIP technology, the cost of searching the metadata in proof generation process is reduced from O(n) to O(1). Moreover, due to direct access to metadata, disk I/O cost is reduced and resulting in 50 to 60 time faster proof generation for large datasets. Furthermore, our proposed scheme achieved 50% reduction in storage size of data and respective metadata that result in providing storage and communication efficiency.
Magnetic, Optical and Structural Property Studies of Mn-Doped ZnO Nanosheets
Ahmed, Faheem,Kumar, Shalendra,Arshi, Nishat,Anwar, M. S.,Kim, Geun Woo,Heo, Si Nae,Byon, Eung Sun,Lee, Sung Hun,Lyu, Nam Jin,Koo, Bon Heun American Scientific Publishers 2012 Journal of nanoscience and nanotechnology Vol.12 No.7
<P>We report the synthesis of pure and Mn doped ZnO in the form of nanosheets using a simple and single step procedure involving a microwave assisted chemical method. As prepared Mn-doped ZnO nanosheets were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible (UV-Vis), Raman spectroscopy and magnetization measurements. The structural studies using XRD and TEM revealed the absence of Mn-related secondary phases and showed that Mn-doped ZnO comprise a single phase nature with wurtzite structure. FESEM and TEM micrographs show that the average diameter of Mn-ZnO assembled nanosheets is about approximately 50 nm, and the length of a Mn-doped ZnO nanosheet building block which is made up of thin mutilayered sheets is around approximately 300 nm. Concerning the Raman scattering spectra, the shift in peak position of E2 (high) mode toward low frequencies due to the Mn doping could be explained well by means of the spatial correlation model. Magnetic measurements showed that Mn-doped ZnO nanosheets exhibit ferromagnetic ordering at or above room temperature.</P>
Ahmed, Faheem,Arshi, Nishat,Anwar, M. S.,Alsharaeh, Edreese,Koo, Bon Heun,Azam, Ameer American Scientific Publishers 2018 Science Of Advanced Materials Vol.10 No.1
<P>In this work, mono-disperse hematite iron oxide (alpha-Fe2O3) nanoparticles with continuously tunable sizes from 2 to 11 nm by using Sb doping in alpha-Fe2O3 were synthesized by a sonication method at room temperature followed by calcination. By varying the concentration of the Sb, precise control on the size of the alpha-Fe2O3 nanoparticles could be established. The X-ray diffraction (XRD), and high resolution transmission electron microscopy (HR-TEM) studies confirmed that the prepared nanoparticles were hematite with high crystallinity. The optical measurements showed that the band gap of the Sb-doped alpha-Fe2O3 nanoparticles increased with Sb doping. Transmission electron microscopy (TEM) results showed that the alpha-Fe2O3 nanoparticles appeared as spherical dots, and the size decreased from 11 to 2 nm with Sb doping. Magnetic studies revealed that all the Sb doped samples were superparamagnetic at 300 K, and the increase in Sb doping can controllably decreased the blocking temperature from 248 K for pure alpha-Fe2O3 nanoparticles to 209 K for 5% Sb doped, respectively. The presented method might be useful for controlling the diverse size of crystalline inorganic materials for a variety of applications.</P>