فهرست مطالب

Nano Letters - Volume:1 Issue: 2, 2011
  • Volume:1 Issue: 2, 2011
  • تاریخ انتشار: 1390/03/05
  • تعداد عناوین: 10
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  • Zohreh Ahadi, Muhammad Shadman, Amir Vahid Page 62
    Sorption of drugs in nano-scale materials such as single-wall carbon nanotubes is a very interesting research in nanomedicine. Nitroglycerin is one of drugs that can be used medically as a vasodilator to treat heart conditions. It is one of the oldest and most useful drugs for treating heart disease by shortening or even preventing attacks of angina pectoris. Nitroglycerin can be used to help destroy prostate cancer as well as being used as a heart medicine. Therefore, the study of capability of delivery of nitroglycerin as a drug may be useful in nano-sacle medicine. We apply Monte Carlo simulations to predict the sorptivity of single-wall carbon nanotubes for nitroglycerin at room temperature and varying pressure. The isotherm diagrams for nitroglycerin sorption report to find mechanism of this fluid sorption in single-wall carbon nanotubes. The sorption isotherms show that nitroglycerin can diffuse inside the single-wall carbon nanotubes while their diameter is larger than 10 Å. Also, these results can be verified with energy sorption plots. The density field and the distribution energy diagram were prepared to verify the sorption isotherms of nitroglycerin inside single-wall carbon nanotubes.
  • Mohammad Ghaem Tajgardoon, Marzieh Jafari, Ezzat Rafiee, Mostafa Faizi, Mohammad Joshaghani Page 69
    Bismuth(III) salophen as a new catalyst has been synthesized. Structural properties of this complex have been studied by FTIR, XRD, DSC and TG analyses. The average of crystalline size of Bi-salophen particles was 86 nm. Thermal analyses show that the complex is stable over 300 °C. Catalytic activity of this catalyst has been investigated in oxidation of sulfides. Different kinds of sulfides have been oxidized to the corresponding sufoxides efficiently in the presence of sodium periodate as oxidant in glacial acetic acid as solvent at room temperature. These sulfides were selectively and completely converted into their corresponding sulfoxides in very short reaction times. Selectivity of this method was excellent which is another advantage of this method.
  • Kamellia Nejati, Zolfaghar Rezvani, Rafat Pakizevand Page 75
    Nanorods of ZnO have been selectively produced in a simple aqueous system prepared by mixing Zn(NO3)2 and NaOH solutions. Also, semi-spherical ZnO nanoparticles have been obtained by adding KNO3 and K2SO4 solutions to the Zn(NO3)2/NaOH mother solutions at different molar ratios of KNO3/Zn(NO3)2 and K2SO4/Zn(NO3)2, but with using LiNO3 at different molar ratios, the nano particles shape was different and not semi-spherical. The products have been characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. The XRD patterns of samples were in agreement with that of the typical wurtzite structure ZnO and the sharp diffraction peaks indicated good crystallinity of the ZnO nanoparticles. The morphologies of the particles have been studied with a scanning electron microscope (SEM) and a transition electron microscope (TEM), and their average size has been determined by means of an X-ray line-broadening method using the Scherrer equation. The results showed that the presence of K2SO4, KNO3 or LiNO3 led to the formation of slightly smaller ZnO nanoparticles. Chemical component analysis by energy-dispersive spectroscopy (EDS) showed that the ZnO nanoparticles were free from impurities.
  • Rostam Moradian, Sahar Nazeri Page 82
    Nano sensing properties of Hydrogenated edges Armchair Grephene Nano Ribbons (HAGNR) are investigated. Using Non-equilibrium Green's Function (NGF) method in the tight binding approach, effects of hydrogen and oxygen adsorption on current-voltage (I-V) characteristics and also electrical conductivity of these systems are calculated. We found that I-V curve of these systems change by adsorption of hydrogen or oxygen molecules. Also we found conductivity of these systems at low adsorption concentrations increases while at high adsorption concentrations decrease. This could be explained in terms of semiconducting or metallic properties of the adsorbed system which is obtained from electronic properties of our clean HAGNR system. On the other hand, LDOS of some sites have a metallic behavior while the other sites have a semiconducting behavior. Note that our results are investigated at the fixed temperature of T=300K, i.e. room temperature. By calibration of conductivity in terms of adsorbed gas molecules one can make a gas nano sensor.
  • Sanjeev Raghuwanshi, Virendra Kumar, Rsdha Raman Pandey Page 91
    In this paper, we try to optimize the substrate-radiation/substrate-cladding (cover) radiation modes in terms of their performance parameters. It is well known that the guided modes can only be normalized. However the radiation modes can also be normalized by using the Delta/Dirac function. We try to optimize the waveguide design parameters for the known cases to achieve performance as good as guided modes. The formal electromagnetic theory is applied to study the radiation modes. The normalization condition on radiation mode has been taken care in to analysis. The results are found satisfactory. It has been concluded that we can modify the performance of radiation modes according to our requirements. The performance is compared with guided mode. The paper discusses guidelines to optimize the radiation modes for various constraints.
  • Kazi Hanium Maria, Saadni Islam, Shamima Choudhury, Mohammad Abdul Hakim, Dilip Kumar Saha, Shiekh Manjura Hoque Page 97
    A thorough study has been performed on FINEMET type of ribbons with nominal composition of Fe70.5Cr3Cu1Nb3Si13.5B9 synthesized by rapid solidification technique. X- ray diffraction studies have been performed to identify the phases and to determine the grain size using Scherrer’s formula. Grain size increased with increasing annealing time and annealing temperature when the amorphous ribbon is annealed close to the crystallization temperature. The soft magnetic properties of this nanocrystalline alloy annealed at 425-560°C for 1 to 60 minutes at regular interval are investigated. Annealing time has great influence on permeability. The permeability increases gradually from 1 to 25 minutes then decreases. Curie temperature of the amorphous sample was found to be 276°C, which increased to 292°C gradually with increasing annealing temperature up to 475°C and then decreases for further increases. The results of the experimental observations are explained on the basis of existing theories of nanocrystalline amorphous metallic ribbons.
  • Md. Shahzad Khan, Mohd. Shahid Khan Page 103
    We have investigated the potassium-decorated boron nitride nanotubes for hydrogen storage using semi-empirical AM1 method. The ultra narrow (3,3) and (5,0) boron nitride nanotubes of same diameter but of different chirality have been used. Both of them show hydrogen storage greater than 8% by weight. Density of States have been calculated and it is found that the presence of alpha density of state of potassium results in smaller energy gap as a result of which the conductivity of the potassium decorated boron nitride nanotubes is enhanced compared to pristine boron nitride nanotubes. Charge decomposition analysis showed that there is significant transfer of charge from adsorbate potassium to boron nitride nanotubes; the same is also confirmed by Mulliken Population analysis. For the same diameter, due to different electronic configurations, zigzag tube is found to be slightly more favourable for hydrogen adsorption. The results of the present simulation study suggest that the potassium decorated boron nitride nanotubes are good candidates for hydrogen adsorption.
  • Shamima Choudhury, Mahabub Alam Bhuiyan, Sheikh Manjura Hoque Page 111
    Polycrystalline NiFe2O4 was prepared by solid state reaction from nano size powders of NiO and Fe2O3 which were synthesized by wet chemical method. Enhancement of apparent density of the sample has been observed with the increase in sintering temperature and has great influence on the transport properties of NiFe2O4. Decrease in resistivity with increasing temperature confirms the semiconducting behavior of the prepared ferrites. Also it was found that the value of resistivity at room temperature decreased with the increase in sintering temperature. Variation of activation energy has been found for different sintering temperatures. Dielectric constant shows the normal behavior of the ferrite materials which can be explained on the basis of Koop’s two-layer model and Maxwell-Wagner polarization theory. Also the increased value of dielectric constant (κ) has been observed with the increase in sintering temperature.
  • Deepak Prasad Subedi, Dinesh Kumar Madhup, Ashish Sharma, Ujjwal Man Joshi, Andrzej Huczko Page 117
    Al-doped and un-doped ZnO thin films deposited on quartz substrate by the nebulized spray pyrolysis method were studied to investigate the wettability of the surface. The main objective of the present study was to investigate the wettability of ZnO thin film by changing the concentration of Al doping. Microstructure and water contact angles of the films were measured by SEM and contact angle goniometer. SEM studies revealed that the grain size within the film increases with the doping concentration. The contact angles were studied to see the effect of aluminum doping on the hydrophilicity of the film. ZnO films were found to be hydrophobic in nature. A good correlation was observed between the SEM micrographs and contact angle results. The nature of the film was found to change from hydrophobic to hydrophilic after the treatment in low pressure DC glow discharge plasma, which, however, was reversible with the storage time.
  • Talaat M. Hammad, Naser K. Hejazy Page 123
    Antimony-doped tin oxide ATO thin films were prepared by dip coating method. The effect of antimony doping on the structural, electrical and optical properties of tin oxide thin films were investigated. Tin(II) chloride dehydrate (SnCl2•4H2O) and antimony(III) chloride (SbCl3) were used as a host and a dopant precursor. X-ray diffraction analysis showed that the non-doped SnO2 thin film had a preferred (211) orientation, but as the Sb-doping concentration increased, a preferred (200) orientation was observed. The lowest resistivity (about 5.4 ×10-3 Ω.cm) was obtained for the 2 at.% Sb-doped films. Antimony-doping led to an increase in the carrier concentration and a decrease in Hall mobility. The transmittance of ATO films was observed to increase to 96% at 2 at. % Sb-doping, and then it was decreased for a higher level of antimony doping.