INTERNATIONAL NANO LETTERS (INL)
Year:2013 | Volume:3 | Issue:3|Papers Count:5

Mechanochemical process has attracted a worldwide interest in the synthesis of nanomaterials since reactions can be run in solid state without any organic solvent. Therefore, this method is an environmentally friendly reaction.Cadmium oxide is a category of the practical semiconductor metal oxides, which is widely applied in various scientific and industrial fields because of its catalytic, optical, and electrical properties. In this study, cadmium oxide spherical nanoparticles were successfully synthesized using a facile and effective solid-state process called mechanochemical reaction. This performance was carried out by employing cadmium acetate dihydrate and urea as reactants without any additives at room temperature and an adjusted rate of 30 Hz (1,800 rpm) for 130 min. Due to calcination of the resulting precursor at 500oC for 2 h in a furnace, the organic sections disappeared and only the CdO phase remained. The X-ray diffraction pattern confirmed the formation of the CdO phase with an excellent crystalline structure. Scanning electron microscopy and transmission electron microscopy images indicated that the morphology of the product is spherical nanoparticles with an average particle size of 46 nm and a standard deviation of 1.95. Particle size distribution was concluded using a statistical method and image processing program.Meanwhile, the solid-state diffuse reflectance spectrum of the resulting product was evaluated to study its optical property via measurement of the band gap energy value (Eg).

Cadmium selenide nanoparticle films were deposited on usual glass substrate by chemical bath deposition method.Temperature dependence of dc conductivity of the present samples was studied. In the nanocrystalline materials due to small size of grains and confined charge carriers, the electronic states near the Fermi level are localized.When states are localized, the conduction occurs by hopping of carriers between the occupied and unoccupied localized states. Variable range hopping was identified as a predominant conduction mechanism and occurs above room temperature. The density of localized states near the Fermi level was observed to increase with increase of average grain size in the film.

Highly stable and sensitive detection of trace level (approximately 1 ppm) of NH3 gas at room temperature is demonstrated for single wall carbon nanotube (SWCNT)-based resistive sensor. The sensor device was comprised of two planer Au electrodes deposited on carbon nanotubes (CNTs) by thermal evaporation method followed by patterning with photolithography process. For the growth of high-quality SWCNTs, multiple catalysts were deposited by co-sputtering method, and the yielded CNTs were in the diameter range of 0.8 to 1.5 nm. The CNTs were characterized by various techniques including Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. As-grown SWCNTs-based resistive sensor showed an excellent variation in sensor response in the trace sensing range from 1 to 50 ppm of NH3 where the sensor response linearly increased with NH3 concentration. The sensing mechanism was attributed to the electron transfer to the SWCNTs as a result of NH3 oxidation on the nanotube surface. The sensor was found to have good sensitivity with a response time of a few minutes at room temperature. Sensor recovery posed a great problem at room temperature, and the fast and complete recovery was successfully achieved by using appropriate thermal treatment protocol.

Lung cancer is by far the leading cause of cancer-related mortality worldwide, most of them being active tobacco smokers. Non small cell lung cancer accounts for around 85% to 90% of deaths, whereas the rest is contributed by small cell lung cancer. The extreme lethality of lung cancer arises due to lack of suitable diagnostic procedures for early detection of lung cancer and ineffective conventional therapeutic strategies. In course with desperate attempts to address these issues independently, a multifunctional nanotherapeutic or diagnostic system is being sought as a favorable solution. The manifestation of physiochemical properties of such nanoscale systems is tuned favorably to come up with a versatile cancer cell targeted diagnostic and therapeutic system. Apart from this, the aspect of being at nanoscale by itself confers the system with an advantage of passive accumulation at the site of tumor. This review provides a broad perspective of three major subclasses of such nanoscale therapeutic and diagnostic systems which include polymeric nanoparticles-based approaches, metal nanoparticles-based approaches, and bio-nanoparticles-based approaches. This review work also serves the purpose of gaining an insight into the pros and cons of each of these approaches with a prospective improvement in lung cancer therapeutics and diagnostics.

One-dimensional (1D) nanostructures of Co3O4 were synthesized via a mild hydrothermal route. The results of XRD, IR, and TEM revealed a phase transformation was accompanied by the replacement of NO3-with CO32- throughout the hydrothermal process. The symmetric types and amount of NO3- and CO3 2- intercalated between the brucite layers played an important role in the formation of nanowires from the hydrothermal system. The amount of CO32- increased as the hydrothermal reaction proceeded. The substitution of CO32- for NO3- led to a variation of interlayer forces thus resulted in the instability of intralayer interactions. Therefore, a shape transformation from sheets to wires occurred.Upon calcination, the shapes of precursors were preserved, and 1D nanostructures of Co3O4 resulted.