International Journal of Nanoparticles (10 papers in press)
- Combined Convection Nanofluid Flow and Heat Transfer over Microscale Forward-Facing Step
by AKEEL KHERBEET, Hussein Mohammed, Kannan Munisamy, Bassam Salman
Abstract: Laminar mixed convection flow of nanofluids over a 3D horizontal microscale forward-facing step (MFFS) is numerically investigated by using a finite volume method. Various nanoparticles materials such as SiO2, Al2O3, CuO and ZnO, were dispersed in Ethylene glycol as a base fluid with volume fractions range of 0% ≤ phi ≤4%. The duct has a step height of 650μm and downstream wall length of 50
Keywords: Mixed convection, Microscale forward-facing step, Heat transfer enhancement, Nanofluids.
- Effects of built-in internal fields and Al alloy content on donor binding energy of a hydrogenic impurity in a wurtzite GaN/AlGaN Quantum dot
by John Peter Amalorpavam, Pattammal M
Abstract: Built-in internal field induced donor hydrogenic binding energy of an impurity in a wurtzite GaN/AlGaN quantum dot is investigated. The built-in internal electric field has the contribution from spontaneous and piezo-electric polarization. The computations are carried out with the inclusion of conduction band nonparabolicity through the energy dependent effective mass. It is calculated with a variational approach within the framework of single band effective-mass approximation. A two-parametric trial wavefunction is employed in order to improve the results. The effects of quantum confinement and the strength of internal electric fields on the donor binding energy are discussed. The results show that the strength of the internal field is of the order MV/cm and it has more influence on the geometrical confinement and the composition of Al alloy content in the GaN/AlxGa1-xN quantum dot. These results are in good agreement with the other investigators.
Keywords: Hydrogenic donor impurity; Electronic states; semiconductor nano-structures
- Characterization and Surface Chemical Modification of Starch Nanoparticles with Lactid through Ring Opening Polymerization
by Hasan Namazi, Farzaneh Fathi, Abbas Dadkhah
Abstract: Waxy corn starch nanoparticles were prepared by an acid treatment process. The obtained starch nanoparticles were modified by ring opening polymerization of lactide and the structure of the resulted polymers characterized with FTIR (Fourier transform infrared) spectroscopy. Weight fraction of starch nanoparticles and modified starch calculated by elemental analysis experiment. Thermal characteristic of the modified starch nanoparticles was investigated using TGA (Thermal Gravimetric Analysis) and DSC (Differential Scanning Calorimetry) techniques. By surface chemical modification of starch nanoparticles, the thermal properties of modified starch nanoparticles have improved and starch nanoparticles showed greater thermal stability. Also wettability tests showed that the surface characters of starch nanoparticles have been changed during modification and modified starch nanoparticles have higher affinity toward organic solvents rather than aqueous media. X-ray diffraction studies showed that the starch crystalline structure has not changed during the reaction.
Keywords: nanoparticles; biopolymers; graft; starch nanocrystals; lactide
- Effect of Cross Sectional Geometry on Band Gap of Silicon Nanowires
by sana kausar, shirish joshi
Abstract: The electronic properties of very thin Silicon nanowires of different shapes were studied by ab-initio method using the generalized gradient approximation. We consider four different shapes of nanowires viz triangular, rectangular, pentagonal and hexagonal wire. The geometry optimization and the band gap of all nanowires were investigated. SiNWs exhibiting different patterns at the cross section show significant difference in their band gaps indicating that the electronic structures of SiNWs are much more sensitive to surface modification and the change of cross section. The present study reveals that band gap of a nanowire depends on cross sectional geometry not on cross sectional area.
- Effect of Al doping on electrical properties of Si nanowire
by Sana Kausar, Shirish Joshi, Anurag Srivastava
Abstract: The stability and electronic structure of a single monatomic Silicon nanowire has been studied using density functional theory. The Si nanowire undergoes two structural rearrangements when it undergoes compression, i.e., zigzag configurations . cohesive energy and bond length of Si nanostructures (chains and monolayers) are examined by using Generalized geometry approximation and Local density approximation. The relation between low dimensional 1D structure (chain) to high dimensional 3D bulk Si is estimated
Keywords: GGA, nanowire,castep
- Synthesis, Characterization and Gas Sensing Application of Nano ZnO Material
by Madhavrao Deore, Gotan Jain
Abstract: Zinc oxide (ZnO) nanomaterial was synthesized by hydrothermal method. The formation of ZnO nanoparticles were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV studies. XRD analysis confirmed the powder to be ZnO with wurtzite structure, with crystallite size ranging from 5 to 25 nm. Observation from TEM images confirmed that the grains were nearly hexagonal rod type in nature with sizes from 22 to 56 nm. The thick films of nano ZnO were prepared by screen-printing technique in desired pattern. The surface morphology of the films was studied by scanning electron microscopy (SEM). The gas sensing performance of the materials have been investigated for various interfering gases such as CO, Cl2, NH3 and H2S etc at operating temperature varying from 50oC to 400 oC. The results indicate that the nano ZnO material thick film showed much better gas response than the usual ZnO materials to H2S gas (100ppm) at 250 oC. The nanoshaped hexagonal rod would improve the sensitivity and selectivity of the sensors. The selectivity, response and recovery time of the sensor were measured and presented. ZnO nanomaterial is excellent potential candidates for gas sensors.
Keywords: Hydrothermal; ZnO; Particle size; Thick film; H2S gas.
- A Review: Applications of iron nanomaterials in bioremediation and in detection of pesticide contamination.
by Tejomyee Bhalerao
Abstract: Agricultural pesticide contamination results from the use and or misuse of agricultural pesticides. It proved that pesticides adversely affect the human health and the environment. These pesticides tend to bind tightly to the soil, most often in the surface layer and are persistent in the environment and thus may be present in the soil long after they have been applied. rnNanotechnology has great potential in performing chemical and physical processes The potential impact area of nanotechnology could be divided into three categories: treatment and remediation, sensing and detection, and pollution prevention. Nanoscale iron particles and their derivatives offer more alternatives to many remediation technologies. Many of the pollutants can be removed from environment in shorter period by application of different form of iron nanoparticles. It is extremely important that these processes be developed and investigated to ensure that nonmaterial are as safe as possible, while reaching their full potential. rn
Keywords: Bioremediation, contamination, Nanoscale iron nanoparticles, pesticides.
- Structural and optical properties of undoped and Mn-doped SnO2 nanoparticles by hydrothermal method
by Gajendiran jayapal, V. Rajendran
Abstract: Abstract: Undoped and Mn-doped tin oxide (SnO2) nanoparticles were synthesized, using precursors such as tin salt, and alkali hydroxide as a mineralizer via a simple hydrothermal method. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), High-resolution TEM (HR-TEM), Energy dispersive X-ray spectra (EDX), UVvis absorption spectra and photoluminescence (PL) spectra were used to characterize the undoped and Mn-doped SnO2 samples. The confirmation of the nanoparticles size and the nanocrystalline nature of SnO2 samples was carried out, using TEM and Selected Area Electron Diffraction (SAED), respectively. The EDX analysis proved the presence of Mn ions into the SnO2 sample. The band gap energy of the undoped (3.90eV) and Mn-doped SnO2 (3.95eV) samples is estimated from the UV-visible absorption spectra, and may be used in optoelectronic devices. The mechanism for the hydrothermal synthesis of the SnO2 nanoparticles is also discussed.
Keywords: Nanostructures, Semiconductors, X-ray diffraction, Optical properties
- CALORIMETRIC STUDY OF NANOCOMPOSITES OF EPOXY NETWORK DGEBA n=0/m-XDA WITH GOLD NANOPARTICLES
by Francisco Fraga-López, Eugenio Rodríguez-Núñez, Adrian Martínez, Javier Miragaya
Abstract: The optimization of cure conditions for epoxy system diglicidil ether of bisphenol A (DGEBA n=0)/ meta-xylylenediamine (m-XDA) has been made using experimental design. A quantitative analysis by Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) as well as making of nanocomposites of epoxy system with gold nanoparticles have been carried out. The knowledge of the optimum values for the variables of experimental design obtained with DSC in the system BADGE/m-XDA allows to study the adequate conditions of the nanocomposites curing process. DSC was used to measure the glass transition temperture (Tg) and the degree of conversion (α). The FTIR method should be a more precise indicator of degree of conversion than DSC and it was used to corroborate the degree of conversion.
Keywords: differential scanning calorimetry (DSC); diglicidil ether of bisphenol A (DGEBA); gold nanocomposites
- A promising approach to enhanced thermal stability of DC conductivity of Polyaniline- Functionalised multiwalled carbon nanotube composites
by Sobha. A.P, Sunil Narayanankutty
Abstract: Nanocomposites of Polyaniline and 4-aminobenzoyl functionalised Multiwalled Carbon Nanotubes (PANI-FMWCNT) were synthesised through interfacial polymerisation of aniline in presence of FMWCNT and protonating with inorganic acids like Hydrochloric acid (HCl), Sulfuric acid (H2SO4) and organic sulfonic acids like Paratoluenesulphonic acid (TSA), Naphthelene-2-sulfonic acid(NSA). Samples of neat polyaniline were also synthesised. The composites were characterised by scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The high temperature DC conductivity stability was investigated through cyclic accelerated ageing and isothermal ageing studies. The morphology studies indicated that pure PANI had a nano fibrillar structure while composite had a core shell structure consisting of carbon nanotube having an ordered, uniform encapsulation of polyaniline. Composites exhibited improved thermal stability over neat PANI. Covalent grafting and strong interaction between polymer chains and nanotubes resulted in additional thermal stability of composites. On thermal cyclic treatment up to 150Â°C, after fifth cycle, electrical conductivity of samples of PANI rapidly dropped to 42-59% of their initial values, while PANI-FMWCNT samples showed only negligible decrease to 80-87%. Study of electrical properties in terms of DC electrical conductivity retention under isothermal conditions showed that the PANI samples started degradation at 110Â°C whereas nanocomposites achieved conductivity stability even at 140Â°C. Both neat PANI and composites containing NSA and TSA had a higher thermal stability of electrical properties than polyaniline doped with HCl and H2SO4. The role of FMWCNTs in stabilising the DC conductivity of composites at elevated temperature is discussed.
Keywords: DC conductivity; Functionalised multiwalled carbon nanotubes; Interfacial polymerisation; Polyaniline; Thermal stability; cyclic ageing; Isothermal ageing