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RISS 인기검색어
- 검색키워드
- 저자 : Mehdi Molaei (검색결과 6 건)
- 무료
- 기관 내 무료
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A simple one Step Thermochemical Approach for Synthesis of ZnS:Mn Nanocrystals (NCs)
Molaei, Mehdi,Lotfiani, Ahmad,Karimimaskon, Fatemeh,Karimipour, Masoud,Khanzadeh, Mohammd The Institute of Electronics and Information Engin 2014 Journal of semiconductor technology and science Vol.14 No.1
In this work we have synthesized ZnS:Mn nanocrystals (NCs) using a simple one step thermochemical method. $Zn(NO_3)_2$ and $Na_2S_2O_3$ were used as the precursors and $Mn(NO_3)_2$ was the source of impurity. Thioglycolic acid (TGA) was used as the capping agent and the catalyst of the reaction. The structure and optical property of the NCs were characterized by means of X- ray diffraction (XRD), HRTEM, UV-visible optical spectroscopy and photoluminescence (PL). X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses demonstrated cubic phase ZnS:Mn NCs with an average size around 3 nm. Synthesized NCs exhibited band gap of about 4 eV. Photoluminescence spectra showed a yellow-orange emission with a peak located at 585 nm, demonstrating the Mn incorporation inside the ZnS particles.
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A simple one Step Thermochemical Approach for Synthesis of ZnS:Mn Nanocrystals (NCs)
Mehdi Molaei,Ahmad Lotfiani,Fatemeh Karimi maskon,Masoud Karimipour,Mohammd Khanzadeh 대한전자공학회 2014 Journal of semiconductor technology and science Vol.14 No.1
In this work we have synthesized ZnS:Mn nanocrystals (NCs) using a simple one step thermochemical method. Zn(NO3)2 and Na2S2O3 were used as the precursors and Mn(NO3)2 was the source of impurity. Thioglycolic acid (TGA) was used as the capping agent and the catalyst of the reaction. The structure and optical property of the NCs were characterized by means of X- ray diffraction (XRD), HRTEM, UV-visible optical spectroscopy and photoluminescence (PL). X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses demonstrated cubic phase ZnS:Mn NCs with an average size around 3 nm. Synthesized NCs exhibited band gap of about 4 eV. Photoluminescence spectra showed a yellow-orange emission with a peak located at 585 nm, demonstrating the Mn incorporation inside the ZnS particles.
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Red Florescent Ag2S-CdS Hybrid Nanoparticles Prepared by a One Pot and Rapid Microwave Method
Masoud Karimipour,Mehdi Molaei 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.2
In this work, Ag2S-CdS hybrid composite with novel luminescenceproperty was synthesized using a one pot and rapid microwave method. Structural analysis by means of XRD and TEM obtained the formationof the composite. Optical spectroscopy by means of UV-Vis andPhotoluminescence measurements revealed that the functionalcomposite has an intensive red light emission at 657 nm with a largestocks shift of about 150 nm. The quantum efficiency of the preparedhybrid material in red region is 10% which is comparable with theefficiency of pure CdS (11%) with green emission.
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Saeed Zaka Khosravi,Samira Molaei Ramshe,Mehdi Allahbakhshian Farsani,Saeed Solali,Mohammadreza Moonesi,Majid Farshdousti Hagh 대한혈액학회 2021 Blood Research Vol.56 No.2
Background Acute lymphoblastic leukemia (ALL) is the most common type of leukemia in children. Several environmental and genetic factors are known to be involved in its development and progression. The angiopoietin-Tie system is one of the most critical factors in angiogenesis, and its possible role in solid tumors and leukemia has been previously investigated. In this study, we examined the expression of these genes in ALL patients (early pre-B-ALL and pre-B-ALL) and compared them with normal samples. Methods Bone marrow samples were collected from 40 patients (aged 0‒19 yr) newly diagnosed with early pre-B-ALL or pre-B-ALL using molecular and flow cytometric tests and from 15 control individuals. For molecular tests, RNA extraction and cDNA synthesis were performed, and Ang1, Ang2, Ang4, Tie1, and Tie2 gene expression was examined by real-time polymerase chain reaction. Results Ang2, Tie1, and Tie2 gene expression were significantly increased in patients with ALL, whereas Ang1 gene expression was decreased. The Ang4 gene did not show significant expression changes between the two groups. Conclusion Changes in the expression of the Ang-Tie system indicate a possible role of angiogenesis in ALL prognosis. Moreover, such changes can be considered as potential diagnostic biomarkers or therapeutic targets.
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Dariush Souri,Ali Reza Khezripour,Mehdi Molaei,Masoud Karimipour 한국물리학회 2017 Current Applied Physics Vol.17 No.1
The using of a reliable and accurate new method (called in literature as derivation of absorption spectrum fitting (DASF)) for evaluation of the optical band gap (Eg) and also the exact nature of charge carriers optical transitions, is investigated in ZnSe and ZnSe:Cu nanocrystals (NCs) synthesized by rapid microwave irradiation. This method can be performed by using the output of UVeVisible spectroscopy. The obtained Eg values are within the range of 2.985e3.261 eV, depending to the microwave irradiation time and Cu dopant percentage (decreasing trend with increasing of irradiation time and Cu content). The DASF-based obtained results for ZnSe and ZnSe:Cu nanoparticles, showed the more precise values of band gap, with the same trend of previously qualitative reported data on the same samples. Also, the direct gap nature of their optical transitions was justified. To perform the method, there is no any need to the concentration of solutions and merely one need the direct absorption or transmission spectra. In other word, DASF technique was employed on ZnSe NCs to confirm its validity and to avoid non-precise reports on optical band gap which can affect on the device optimizations based on these samples. Moreover, using the values of Eg, refractive index and dielectric constant of each sample were obtained at the absorption edge. Also, the width of the tailing states in the gap (Urbach energy: ETail) was estimated and were within the range of 0.049e0.122 eV, which their very small values in compare with Eg imply to the sharp valence and conduction band edges; it means the good crystallinity nature of the produced samples.
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Masoud Karimipour,Sara Mashhoun,Mohsen Mollaei,Mehdi Molaei,Nima Taghavinia 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
TiO2 nanotubes were synthesized using a modified autoclave-free thermal method from as-prepared initial powders. The size of initial powders (IP) was found to be critical in determining the morphology and crystal structure of the final product. Oleylamine (OA) was used as the polymer agent in the preparation of initial powders with different mol ratios of OA/Ti: 1, 5, and 10. X-ray diffraction analysis depicted that the increase of mole ratio up to 10 resulted in smaller nanoparticles with the sizes of about 8 nm. It was also deliberated that low temperature thermally treated IP showed the characteristic diffraction pattern of titanate phase of nanotubes. Scanning electron microscope images showed nanorods, short nanotubes, and single-phase long and uniform nanofibers produced from initial powders. SEM cross-section of the anode cell of TiO2 nanofibers demonstrated the presence of uniformly closed net long fibers in the cell. Open circuit voltage measurements of the nanofiber cell demonstrated a several hundreds of seconds in the electron transport decay, which was significantly higher than that of the nanoparticles. IMPS/IMVS measurements of the nanofibers and nanotube solar cells showed electron transport enhancement and long life time compared to their nanoparticle counterparts.
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