Abstract: The manuscript reports wet chemical assisted low temperature synthesis of CTAB stabilized elongated triangular bipyramidal shape nanostructures of ZnO for photocatalytic degradation of methyle blue (MB) and congo red (CR) dyes. Physiochemical characterization has been carried out by X-ray diffraction, scanning electron microscope, transmission electron microscope and UV-visible spectroscope. Pure wurtzite structure of ZnO with crystallite size ~56 nm has been confirmed from X-ray study. Well dispersed particles with elongated triangular bipyramidal morphology have been observed through SEM. Fine resolved particles with varied aspect ratios ~80 X 200 ± 10 nm have been depicted by TEM images. UV-visible absorption analysis confirms the energy band gap of 3.43 eV for synthesized ZnO particles. Molecular composition and functional groups of CTAB were confirmed by FTIR spectroscopy. The potential applicability of the particles for photocatalytic degradation of MB and CR as standard analytical dyes was studied. Time bound study under UV irradiated source depicted more than 95% degradation of both dyes in separate experiments.
Abstract: SnO2 thin films were prepared on glass substrates by sol-gel spin coating method using stannous chloride dihydrate and ethyl alcohol absolute as raw materials at annealing temperature 450-550 °C. The crystal phase was measured by X-ray diffraction (XRD) and showed tetragonal rutile structure with a preferential orientation of (110). Atomic force microscope (AFM) and Scanning Electron Microscope (SEM) images revealed the homogeneous grains distribution, and SEM images showed the obvious rectangular objects corresponding to tetragonal structure. Optical properties were observed by the transmittance in ultraviolet-visible (UV-Vis) region and optical energy gap, which revealed the transmittance over 75% and energy gap between 3.84 eV and 3.89 eV. Finally, I-V characteristics were tested to research electrical properties, and found the gradual non-linear property and the increase of resistance.
Abstract: Carbon nanotube (CNT) interconnects are emerging as the ultimate choice for next generation ultra large scale integrated (ULSI) circuits. Significant progress in precise growth of aligned CNTs and integration of multiwalled CNT interconnects into a test chip make them promising candidates for future nanoelectronic chips. Tremendous research efforts were made on silicon based ultra-low-k dielectrics for Cu interconnects, but, the most recent advancements in polymer based composites as dielectric materials open up fresh challenges in the use of low-k dielectrics for CNT interconnects. This paper reviews the emerging polymer composites like Boron Nitride Nanotubes, Graphene/Polyimide composites, Metal Organic Frameworks and small diameter CNTs. Many reviews are already exists on the synthesis, fabrication, dielectric, mechanical, chemical and thermal properties of these materials. In this review, we have explained the specific properties of these materials and the necessities for integrating them into CNT interconnects to meet the requirements of future IC designers.Keywords: low-k dielectric materials, ultra low-k dielectrics, carbon nanotubes, interconnects, dielectric constant,
Abstract: Nanoscratching and nanoindentation simulations are performed to study the processability of Cu/Ni bilayers with interfaces using molecular dynamics (MD) method. Single crystals Cu and Ni are served as comparisons. In the nanoscratching processes, the interfaces of Cu/Ni bilayers appear as a barrier of dislocations gliding, and lead to larger friction forces and normal forces. For single crystals and bilayers, both their friction forces and normal forces increase with the increasement of scratch velocity at 100-300 m/s. Friction coefficients under scratching processes are calculated, and they are smaller than macrosacle scratching process because of coating effects of nano-chips on the tool. The effects are analyzed by conducting both molecular dynamics simulations in nanoscale and finite element simulations (FES) in macroscale. In the indentation process, the processing properties of Cu-Ni and Ni-Cu bilayers are different from each other, and their indentation forces are both larger than their single crystals. Recovery deformation takes place during the relaxation stage. When the tool is unloading, some workpiece atoms adhere to the tool. The simulation results of the two nanoscale machining processes reveal the strengthening mechanism of interface, and show comprehensive processability of metal bilayers.
Abstract: The sulfonic acid-functionalized KIT-6 magnetite mesoporous silica nanoparticles (Fe3O4@SiO2@KIT-6-SO3H NPs) were prepared as an adsorbent and used for the removal of methyl green from aqueous solutions. Characterization of the obtained adsorbent was done by FT-IR, SEM and EDX instruments. According to the experimental results, about 96.4 % of dye was removed from aqueous solutions at the adsorbent amount of 3.2 g L-1 at pH = 3 and ionic strength = 0 during 10 min. The kinetic results indicated that the pseudo-second-order kinetic model was the best model for describing the adsorption kinetic ( = 0.9999). The isotherm analysis demonstrated that the equilibrium data were well fitted to the Freundlich isotherm model, showing a multilayer adsorption of the dye on the adsorbent surface. The maximum adsorption capacity for methyl green was obtained 196 mg g-1. Furthermore, the Fe3O4@SiO2-KIT-6-SO3H NPs could be simply recovered by external magnet and it exhibited recyclability and reusability for six cycles. The results showed that the Fe3O4@SiO2-KIT-6-SO3H NPs are appropriate adsorbent for removal of methyl green from real wastewater samples.
Abstract: In this study, cellulose nanofibers (CNF) was used as a reinforcing material to improve mechanichal strenght of chitosan nanofibrous scaffold. Chitosan scaffolds with different amount of CNF ranging 5.0-20.0 Wt.% were fabricated by adding CNF to chitosan solutions before electrospinning. Both the tensile strength and tensile modulus of the scaffolds were increased as a result of CNF addition. An increase of 4.3 fold (from 2.9±0/02 to 12.7±0/4 MPa) in tensile strength and 4.04 fold (from 86.5±1.7 to 349.5±19.4 P) in Young's modulus were observed after addition of 15 wt. % CNF. The microscopy studies showed that the diameter of the electrospun fibers decreased with the addition of CNF. The diameter decreased from 175± 7 nm to 100±29 nm when 15 wt% CNF were added. Evaluation of cell adhesion by SEM showed that fibroblast cells not only can attachment on the surface of NFC reinforced scaffolds but also can infilterate inside the scaffolds. In addition, the nanocomposite schaffols dose not show any cytotoxic effect using MTT assay.
Abstract: The object of our research is to combine the properties of Mangalloys and nanoscale advantages in order to enhance the performance and extend the range of applications in the field of work-hardening parts such as railroad components, armor, and modern auto components. We have produced a high-manganese austenitic steel nanomaterial containing more than 12 wt% Mn, which is the level of Mn in Hadfield steel. This study experimentally determined the process of phase transitions involved in Fe–13 wt% Mn–1.2 wt% C alloy during mechano-synthesis and after subsequent annealing. The milling time ranged from 0.5 to 24 h. The unique features of the nanocrystalline structure and the changes in microstructure as a function of milling time were investigated by X-ray diffraction analysis, differential scanning calorimetry, and scanning electron microscopy coupled with EDX. The grain sizes and microstrain of the milled powder were determined. A thorough study has been done on the sample where a new phase fcc (at 24h of MA) was formed.The object of our research is to combine the properties of Mangalloys and nanoscale advantages in order to enhance the performance and extend the range of applications in the field of work-hardening parts such as railroad components, armor, and modern auto components. We have produced a high-manganese austenitic steel nanomaterial containing more than 12 wt% Mn, which is the level of Mn in Hadfield steel. This study experimentally determined the process of phase transitions involved in Fe–13 wt% Mn–1.2 wt% C alloy during mechano-synthesis and after subsequent annealing. The milling time ranged from 0.5 to 24 h. The unique features of the nanocrystalline structure and the changes in microstructure as a function of milling time were investigated by X-ray diffraction analysis, differential scanning calorimetry, and scanning electron microscopy coupled with EDX. The grain sizes and microstrain of the milled powder were determined. A thorough study has been done on the sample where a new phase fcc (at 24h of MA) was formed.
Abstract: Magnetic cobalt nanostructured was synthesized by a two-stage method. First, a solution of cobalt precursor droplets was prepared by an ultrasonic nebulizer. Second, the arc discharge method between two electrodes in an inert gas at atmospheric pressure is used to obtain the nanostructured cobalt powder. The sample obtained was characterized by X-ray diffraction (XRD). Scanning electron microscope (SEM), High Resolution Transmission Electron Microscope (HR-TEM), UV-Vis Spectrophotometry, zeta potential (ZP) and vibrating sample magnetometer (VSM). The dielectric constant, and AC conductivity of the prepared sample was determined in the frequency range of 4 Hz to 8 MHz. The investigations showed that the Co nanoparticles prepared in this way have smaller and homogeneous nanoparticles with spherical shape morphology with good stability and unique magnetic properties as compared with the bulky one. The dielectric properties analysis shows an enhancement in the dielectric constant and the AC conductivity of the Co nanoparticles.
Abstract: In this study, we report the effect of ZnO film thickness on its optical and structural properties. The sol solution was synthesized by sol-gel method and deposited on silicon substrates by spin coating technique. The ZnO films thickness was varied from 60 to 180 nm. The ZnO films obtained showed a highly preferred orientation along the (002) plane. It was also observed that the crystallite size was not affected by increasing thickness. Transmittance measurements indicated that the ZnO films have a high transparency in the visible range (~90 %), which remained constant with thickness. Morphological evolution measurements confirmed that the thinner ZnO film consist mostly of a porous layer which became homogeneous and compact to increase the thickness. Photoluminescence measurements exhibit a strong ultraviolet (UV) emission, and the emission intensity was improved with thickness due to crystallinity enhancement.
Abstract: The copper nanoparticles (CuNPs) were developed in two different reaction media (distilled water (DW) and ethylene glycol (EG)) by chemical reduction method using two different stabilizers (polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP)). We carried out a careful examination of the time evolution of surface plasmon resonance (SPR) bands (specifically, peak positions and intensities) of colloidal CuNPs so as to evaluate their stability. In addition, the changing pattern of SPR peak positions and intensities during the stability time period was also investigated. Effects of stabilizer materials, stabilizer concentration, Ag capping and reaction medium on the stability of CuNPs colloids have been highlighted. The maximum stability of CuNPs is 4 hours with stabilizer PEG and is 4 days with PVP in DW. They, with PVP, extend up to 10 days in the different reaction medium (EG). The stability time of CuNPs in EG is further lengthened to 20 days in the presence of Ag capping (Cucore AgshellNPs). Thus a proper selection of the stabilizing/capping agent and the reaction medium is critical in determining the stability of CuNPs colloids. The benefits of stabilization of CuNPs for real world applications are immense and this study would help in examinning the stability of other novel plasmonic metal nanostructures.