Zarina Aspanut

Structure deformation of indium oxide from nanoparticles into nanostructured polycrystalline films by in situ thermal radiation treatment

A microstructure deformation of indium oxide (In2O3) nanoparticles by an in situ thermal radiation treatment in nitrous oxide plasma was investigated. The In2O3 nanoparticles were completely transformed into nanostructured In2O3 films upon 10 min of treatment time. The treated In2O3 nanoparticle sample showed improvement in crystallinity while maintaining a large surface area of nanostructure morphology. The direct transition optical absorption at higher photon energy and the electrical conductivity of the In2O3 nanoparticles were significantly enhanced by the treatment.

Measurement of the signal from a cultured cell using a high-Tc SQUID

Stem cells in developing tissues give rise to the multiple specialized cell types that make up the heart, lung, skin, and other tissues. For scientists, it is important to know the stages of stem cell development. We propose a new method to obtain knowledge of the cell development stages by using a high-Tc SQUID magnetometer. In the first step of the research, we used Wister rat myocardial cells incubated for 12–14 days in a culture dish as a sample, which were not derived from stem cells. With the cells we tried to measure the signal using a SQUID magnetometer. We were able to measure the magnetic signals, which may be generated by ion transport through the cell membrane. A beat signal with a period of 0.6 s was observed. The peak-to-peak value was about 400 pT. This showed good agreement with the result of microscopic observation.

A DNA detection system based upon a high Tc SQUID and ultra-small magnetic particles

A high Tc SQUID system for biological molecules (DNA) detection is developed. This system is based on a hybridization process. Two strands in a DNA molecule are held together by hydrogen bonds between base pairs like a ladder. The two strands are referred to as being complementary each other. HPVB 33 (Human Papillomavirus Probes 33) was prepared as a DNA. One strand (Sample DNA) was labeled with Fe/sub 3/O/sub 4/ ultra-small magnetic particles and the other (probe DNA) was anchored on a glass slide. Then they were hybridized each other on the slide. After washing the excess sample DNA, the hybridized DNA was evaluated in the presence of excitation ac field by high Tc SQUID. The signal was initially proportional to the concentration of the sample DNA and then saturated. It means that the hybridization occurred successfully between the sample DNA and the probe DNA.

Effect of Rapid Thermal Annealing Time on the Structural and Optical Properties of Layered Structured SiOx/Au/SiOx Film

In this work, layer structured silicon suboxide/gold/silicon suboxide (SiOx/Au/SiOx) films were prepared by using plasma enhanced chemical vapor deposition assisted with hot wire evaporation technique. Post rapid thermal annealing (RTA) process was done on the as-prepared films for 100, 500 and 700s at constant temperature of 800oC in vacuum ambient. Effects of RTA process on the structural and morphological properties of films were studied using FE-SEM, depth profiling and XRD measurement. While, surface plasmon resonance (SPR) phenomenon exhibited by Au particles was investigated via the optical absorption spectra. SPR signals can be exhibited by sample annealed for longer time duration. Individual Au islands tend to form the spherical shape as a whole. Diffusion of Au particles towards the surface of SiOx film is temperature dependent and crystallite size of Au enlarges with the rapid thermal annealing time.

Fabrication and characterization of co-sputtering Au/SiO 2 thin films prepared by RF magnetron sputtering

An amorphous silicon suboxide was synthesized by co-sputtering of Au and SiO2 using RF magnetron sputtering. The extracted data from XRD, SEM as well as EDX were utilized to characterize the surface of the thin film samples.

3D hyperbranched heterostructures of Ag nanocrystals-decorated ZnO nanopillars: controlled growth and characterization of the optical properties

Herein, the synthesis along with the structural and optical characterization of 3D hyperbranched ZnO nanopillars (NPLs) decorated with Ag nanocrystals (NCs) is reported. This hyperbranched heterostructure, displaying broccoli-like morphology, was prepared via two-step synthesis method, in which freestanding ZnO NPLs were hydrothermally grown onto a Zn foil substrate, followed by scrupulous decoration with Ag NCs using a similar approach. FESEM observations revealed that the reaction time highly influenced the crystallization mechanism, whereby the as-deposited Ag NCs could serve as a catalyst to induce secondary nucleation sites that promote the sprouting of secondary ZnO NPLs branches that grow along the edges of the upper half of the primary ZnO NPLs. HRTEM analysis was conducted to investigate the crystallography structure at the interfaces and elemental mapping was used to probe the elemental distribution. These results were further complemented with both XRD and Raman spectroscopy. Finally, diffuse reflectance and photoluminescence analysis were employed to elucidate the optical behaviour. A possible growth mechanism for obtaining such a unique broccoli-like morphology with a complicated nanoarchitecture is proposed. The present study could assist the development of a crystal engineering process for the preparation and analysis of hybrid nanostructures.

Influence of Nitrogen/Methane Ratio on the Properties of Hydrogenated Amorphous Carbon Nitride Deposited by r.f. PECVD Technique

Hydrogenated amorphous carbon nitride (a‐CNx:H) thin films were prepared in a radio frequency plasma enhanced chemical deposition system with a parallel‐plate electrode configuration. The effects of nitrogen/methane flow rate ratio calculated on the a‐CNx:H thin films are studied in terms of the optical, bonding and photoluminescence (PL) properties. The increase in the flow rate ratio results in a decrease in the deposition rate which corresponds to an increase in ion bombardment effect and gas phase reactions. The optical energy gap E04, decreases while its PL intensity increases as the flow‐rate ratio increases up to 70%, followed by an increase in E04 and a decrease in PL intensity as the ratio is further increased. These are discussed in terms of the bonding and sp2 content in the films.Hydrogenated amorphous carbon nitride (a‐CNx:H) thin films were prepared in a radio frequency plasma enhanced chemical deposition system with a parallel‐plate electrode configuration. The effects of nitrogen/methane flow rate ratio calculated on the a‐CNx:H thin films are studied in terms of the optical, bonding and photoluminescence (PL) properties. The increase in the flow rate ratio results in a decrease in the deposition rate which corresponds to an increase in ion bombardment effect and gas phase reactions. The optical energy gap E04, decreases while its PL intensity increases as the flow‐rate ratio increases up to 70%, followed by an increase in E04 and a decrease in PL intensity as the ratio is further increased. These are discussed in terms of the bonding and sp2 content in the films.

Medical application of small magnetic particles and SQUID magnetic sensor

We have proposed two medical applications using ultra-small magnetic particles. One is a lymph-node detection system and the other is a DNA probing system. In both cases, magnetic particles are detected by a sensitive high Tc SQUID magnetic sensor. We demonstrate that lymph nodes containing particles extracted from the rat were successfully measured by a SQUID system. In the application of DNA detection system, a preliminary experiment has been done. These results are described in this paper.