Abstract: This study utilized chemical method to reform titania nanopowder into larger surface area titania-based nanotubes (NTs). Various factors, such as reaction temperature, concentration, time, and aging time were investigated to determine their effects toward NT properties. The formation of the titania-based NTs was carried out under the conditions of 10N NaOH reaction medium, at reaction temperature and time of 116°C and 23 hours, respectively. Subsequent aging was done at 40°C for 24 hours. The NTs were further resintered at 400°C for 1 hour to improve their crystallinity and photocatalytic efficiency. Result indicates that aging process is significant for NT synthesis process. The treated titania-based NT has a surface area of 247.91 m2/g with nearly 100% photodecomposition of (MB) in 15 minutes.
Abstract: In this paper, we synthesized the CdSe quantum dots (QDs) about 4.5 nm, and using the in-situ XAFS technique to study the thermal expansion of CdSe QDs from room temperature to 700°C. We find that the thermal expansion of the CdSe QDs is about 2.0×10-5/K, which is bigger than the bulk CdSe (3~8×10-6/K). This can demonstrate that the thermal properties of CdSe QDs is related to the size of the dots, which means the thermal expansion is reducing as the size of the nanoparticles increasing.
Keywords: CdSe quantum dots, thermal expansion, EXAFS technique
Abstract: Metal oxide nanocomposite (ZnO-CuO) was successfully synthesized by one step homogeneous coprecipitation method and further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), X-ray diffraction analysis (XRD) and UV-visible diffuse reflectance spectra. XRD analysis exhibited presence of pure copper oxide and zinc oxide within the nanocomposite. SEM analysis indicated that the ZnO-CuO nanocomposite was consisted of flower shaped ZnO along with leaf shaped CuO. Photocatalytic activity of nanocomposite was evaluated in terms of degradation of methylene blue (MB) dye solution under ultra-violet radiation. Results showed that the photocatalytic efficiency of ZnO-CuO nanocomposite was higher than its individual pure oxides (ZnO or CuO).
Abstract: Silica nanotubes with controlled diameter and length were synthesised by using a novel and modified template-sol-gel method. The consistency and order of silica nanotubes mainly depend on the anodic alumina membrane (AAO) template that was used during the preparation process. The AAO membrane was chemical etched using different concentrations (5, 7 and 10 wt %) of phosphoric acid. The obtained silica nanotubes had diameters in the range of 220-280 nm and thicknesses around 70-90 nm as observed by field emission scanning electron microscopy (FE-SEM). Scanning transmission electron microscopy (STEM) images enable us to view the arrangement of the hollow cylindrical silica nanotubes. Porosity of the silica nanotubes was investigated by nitrogen adsorption-desorption. The mesoporous silica nanotubes show characteristic type IV isotherm behaviour, with double capillary condensation step in the relative pressure range of 0.2-1.0 (p/p0). Thermogravimetric (TGA) and differential thermal (DTA) analyses confirm the thermal stability of the silica nanotubes and their weight changes and endo and exothermic reactions. The structural and functional group analyses of the silica nanotubes were carried out by using X-ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FT-IR).
Abstract: Concepts of the surface excess energy in the present work have been applied to explain the methane formation in Fischer-Tropsch synthesis by iron catalysts. A series of iron oxide particles doped by adding copper and lanthanum were prepared as a catalyst via precipitation by microemulsion method. Size dependent kinetic expressions for methane formation were derived and evaluated using experimental results. Experimental results show that the methane formation is increased by decreasing the catalyst particle size. The value of surface tension energy (σ) for iron catalyst is calculated in range of 0.047-0.015 J/m2 in methane formation mechanism. This value is lower than iron metal and is referred to the presence of iron carbide and gas phase in this catalytic reaction. With a series of complicated mechanisms, methane is produced on the surface of catalyst and in the gas phase as well, this would be elaborated by following paragraphs, thus we can conclude that surface tension of catalyst has less effect on these reactions.
Abstract: Most of mortality worldwide occurs because of cancer diseases. Nanostructures are the new compounds that have become one of the most important technologies for using in different fields over the past two years especially in medicine. In between, nanotechnology has the potential to cancer detection and therapy. This study is a review of prospects in applications of nano-materials for cancer detection and treatment. We have summarized the nano-materials (metal nanospheres, nanorods, nanoshells and nanotubes) in medical applications targeting cancer. We also discuss advances in established nanoparticle technologies such as liposomes, polymer micelles, and functionalization about tumor targeting, controlled release and drug delivery. This paper will discuss the therapeutic applications of different nano-materials with a major focus on their applications for the treatment of cancer. Briefly, the toxicity of conventional nanostructures was also mentioned in this paper.
Abstract: Introduction of Mn2+ ions into ZnO in the form of Zn(1-x)MnxO (0.00≤x≤0.25) has been done by means of coprecipitation method at low temperature using Zn(CH3COO)2·2H2O, Mn(CH3COO)2·4H2O, HCl, and NH4OH as starting materials. The XRD analysis showed that the produced Zn(1-x)MnxO (0.00≤x≤0.09) samples were crystallized in single phase of wurtzite with hexagonal structures. Besides the wurtzite, the presence of the secondary phase of hetaerolite ZnMn2O4 with tetragonal structures was detected in the samples having 0.10≤x≤0.25. The nanometer-sized Zn(1-x)MnxO crystals obtained from XRD analysis were well confirmed by SEM and TEM images. The electron diffraction data showed that the secondary phase formed even for 0.01 and 0.10 Mn-doping samples were ZnMn2O4 and MnO2. The VSM data indicate that the paramagnetic properties of Mn doping occurred at 0.00≤x≤0.06 and 0.10≤x≤0.25 as well as superparamagnetic properties occur in Mn doping 0.07≤x≤0.09. The most interesting fact in this study was the formation of secondary phases in all Mn-doped ZnO samples, even for the smallest x of 0.01.
Abstract: TiO2 nanoparticle is one of the most fascinating materials for stimulating germination and growth of various seeds. However, the low capacity of these materials in absorbing sunlight is a challenging issue which should be taken into consideration. Sensitization of TiO2 nanoparticles is already a common strategy for improving its visible light absorption and it is mainly used in dye-sensitized solar cells. In this study, a set of experiments were conducted to investigate the influences of dye-sensitized TiO2 nanoparticles on germination and growth of barley seeds (Hordeum vulgare L.). Fluorescein was used as the sensitizer with high extinction coefficient in the visible regions. It was shown that different growth parameters including seedling fresh and dry weights, root and shoot lengths, chlorophyll-a, and chlorophyll-b were increased by 59.2% and 85.7%, 330%, 100%, 45% and 50% relative to the control, respectively. Moreover, the results confirmed that dye-sensitized TiO2 nanoparticles do not have any negative influence on germination parameters and are beneficial for increasing vigor index I.
Abstract: Tuberculosis is still a major global health concern, causing the estimated death of 1.5 million people per year and being associated with high morbidity. The development of point-of-care diagnostic tools for tuberculosis is mandatory, especially because the fast and accurate detection of the slow-growing Mycobacterium tuberculosis by the conventional diagnostic tests is difficult.The objective of this work was to develop the first steps to achieve a portable method for the diagnosis of tuberculosis, by a sandwich-immunoassay combined with magnetoresistive biochip technology.With the purpose of conjugating 250 nm streptavidin-coated magnetic nanoparticles with anti- M. tuberculosis biotinylated antibodies, Mycobacterium bovis Bacillus Calmette-Guérin was used as a surrogate for M. tuberculosis bacteria. After magnetic capture, target bacteria were brought in contact with the surface of the magnetoresistive biochip previously functionalized with a secondary anti-M. tuberculosis antibody. Magnetically labeled cells were detected by an array of spin-valve sensors, which change their electrical resistance in the presence of the fringe field of the magnetic particles. Optimization studies on the efficiency of the magnetic capture and further recognition of the bacteria by the secondary antibody on the biochip surface were conducted. The results on the magnetoresistive biochip showed a clear difference in the signal between specific and control (non-specific) sensors, suggesting the usefulness of this technique as a potential biorecognition tool for the development of a point-of-care diagnostic method for tuberculosis.
Abstract: Silver nanoparticles (SNPs) are widely invested in nanomedicine and consuming products due to their unique antimicrobial properties. However, little is known about the toxicity of these particles on human health. The present investigation was carried out to investigate the histological alterations induced in the lung tissues by 20±5 nm SNPs. Male albino Wistar rats were exposed to SNPs at a daily dose of 2 mg/kg for 21 days. Lung biopsies from all rats under study were subjected to histopathological examinations. Exposure to 20±5 nm SNPs induced the following pulmonary alterations: thickened alveolar wall, macrophages invasion and inflammatory cells infiltration, lymphatic follicles enlargement, pulmonary edema, alveolar hypersensitivity and interstitial congestion. Occasional atelectasis and fibrocytes proliferation were also detected. The findings of the present work might indicate that SNPs potentially trigger oxidative stress and alterations in the pulmonary tissues that may affect the function of the lungs.