Advanced Materials Research Vol. 802

Abstract: In this work the effects of amorphous (glass) and crystalline (Si) substrates on the structural, morphological and adhesion properties of CoFeB thin film deposited by DC Magnetron sputtering were investigated. It was found that the structure of a substrate affects to crystal formation, surface morphology and adhesion of CoFeB thin films. The X-Ray diffraction patterns reveal that as-deposited CoFeB thin film at low sputtering power was amorphous and would become crystal when the power increased. The increase in crystalline structure of CoFeB thin film is attributed to the crystalline substrate and the increase of kinetic energy of sputtering atoms. Atomic Force Microscopy images of CoFeB thin film clearly show that the roughness, grain size, and uniformity correlate to the sputtering power and the structure of substrate. The CoFeB thin film on glass substrate shows a smooth surface and a small grain size whereas the CoFeB thin film on Si substrate shows a rough surface and a slightly increases of grain size. Sticky Tape Test on CoFeB thin film deposited on glass substrate indicates the adhesion failure with a high sputtering power. The results suggest that the crystalline structure of substrate affects to the atomic bonding and the sputtering power affects to intrinsic stress of CoFeB thin film.

Abstract: According to the low efficiency of cell attachment and proliferation on commercial polystyrene (PS) dish, scaffold with porous structure on the polystyrene dish is required to improve the cell attachment and proliferation efficiency on the dish. The scaffold with porous structure was fabricated from a solution of powdered silk fibroin by plasma grafting polymerization technique. Argon plasma was utilized by a 13.56 MHz capacitively coupled discharge (CCP) reactor at working pressure of 100 mTorr. Rf power, plasma treatment time, and the cycle of grafting on the dish were varied. The proper treatment time and rf power set to 10 minutes and 100 W, respectively. The experimental results showed the uniformly and highly distributed of porosity of fibroin scaffold on the PS dish surface. The Ar-treated dish had lower UV-Vis absorbance than the untreated dish indicating the efficiency of grafting between fibroin structure and treated PS surface is better than the untreated surface. The absorbance spectra of phanyalanine at 280 nm affirmed the success of the fibroin amino acid grafting to PS aromatic structure.

Abstract: In this work, we report on the frequency-impedance characteristics of dye-doped organic material. The device structure is glass substrate/indium tin oxide/DCM:Alq₃/Aluminum 100 nm. The influence of doping concentraion has been investigated by impedance spectroscopy. The impedance characteristics of the dye-doped organic material can be modelled by simply adopting the conventional equivalent circuit with the simple combination of resistors and capacitor network. The variation of bulk resistance with applied bias voltage as a result of the Space Charge Limited Conduction (SCLC) mechanism for charge conduction.

Abstract: In this work, X-ray diffraction (XRD), Raman spectroscopy (RAMAN) and vibrating sample magnetometer (VSM) measurements were employed to investigate the crystal structure, chemical bonding and magnetic properties of the nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites (ZnFe₂O₄, NiFe₂O₄ and Ni_0.5Zn_0.5Fe₂O₄) which were synthesized by sol-gel combustion method. Moreover, the composition of elements and the electronic structure including the cation distribution for all ferrite samples were examined through synchrotron X-ray fluorescence (XRF) and X-ray absorption near-edge structure (XANES) spectra. The overall characterization results indicate that the different amount of zinc and nickel ions in ferrites has crucial effect on their physical, magnetism and the site occupancy distribution of Fe³⁺ ions.

Abstract: Tungsten oxide (WO₃) electrochromic thin films were deposited onto F-doped tin oxide (FTO) substrates using DC sputtering of tungsten target in presence of oxygen and argon gas. As-deposited films were prepared with different sputtering power at 50 W, 100W and 200W. The effect of power on structural, surface morphology optical and electrochromic properties of the WO₃ thin films were characterized by X-ray diffractometer, scanning electron microscope, UV-VIS spectrophotometer and Cyclic voltammetry, respectively. The XRD results show that the crystalline of WO₃ can be identified an orientation growth along (222) plane. The average grain size evaluated from SEM image is approximately 200 nm. The films deposited at power of 200 W exhibited better electrochromic properties with greatest optical modulation (∆T) value of ∆T = 31.2 % at l= 550 nm. The cyclic voltammograms (CV) of WO₃ thin films evidently exhibited that the WO₃ films prepared at power of 200 W displayed the superior electrochromic performance, compared to the others.

Abstract: Flavonoid biomaterials have a protecting function from various stresses. We examined the flavonoid biosynthesis in plant treated under visible light (VL) and additional UV-A light. The transgenic tobacco containing PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) cDNA, involved in flavonoid biosynthesis from Arabidopsis thaliana, were used for studying the flavonoid biosynthesis under both light conditions comparing to non transgenic tobacco. The flavonoid biomaterials were extracted with acidic methanol and water solvent from treated plant leaves. The absorbance of each biomaterial in the extract was measured under specific wavelength using a spectrophotometer. Additional UV-A radiated to non transgenic and transgenic tobacco affect the increasing of p-coumaric acid, naringenin, apigenin and kaempherol biomaterials from themselves grown under VL (approximately 120-130%). However, PAP1 transgenic tobaccos under additional UV-A radiation enhance the accumulation of these biomaterials up to160-180% higher than non transgenic tobaccos grown under VL condition. Moreover, PAP1 transgenic tobacco radiated with UVA light also significantly increased pelargonidin biomaterial. PAP1 transgenic tobaccos had a similar phenotype with non transgenic tobaccos but the color of fully expanding flower was more pink intensity than non transgenic.

Abstract: Dissolved Poly (methyl methacrylate) (PMMA) in Dimethylformamide solution was fabricated as thin films on different substrates, glass, poly (ethylene naphthalate) and Si wafer, using spin coating technique. The effect of different substrates on electrical performances of the PMMA films was investigated. For an acceptable organic thin-film transistor (OTFT) performance, uniform thickness with low defect density of the PMMA thin-films was required. A parallel plate capacitor structure was used to test electrical properties of the PMMA dielectric layers. Good dielectric properties were obtained on glass and PEN at film thicknesses of 95 nm. An optimal condition for the OTFT preparation was used to fabricate an OTFT with the PMMA dielectric layer on glass substrate. Measured results showed that the OTFT achieved a mobility of 0.16 cm²/V.s, a threshold voltage of -3.6 V, and on/off current ratio of 1×10⁵.

Abstract: The microwave-assisted solution combustion synthesis was applied to the initial synthesizing of Ca₃Co₂O₆ powder using glycine as a fuel and nitrate as an oxidant. The as-synthesized powders were calcined at 700-1,000^ºC for 4h. Product characterization was performed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The fuel-to-oxidizer molar ratio was found to affect the combustion reaction and character of the powder obtained. The phase composition of powder after calcination at various temperatures has shown that the formation of Ca₃Co₂O₆ occurs directly. The calcined powder possesses a rhombohedral crystal structure with an X-ray diffraction pattern that could be matched with the Ca₃Co₂O₆JCPDS: 89-0629. This method is a simple way of synthesizing fine Ca₃Co₂O₆ powder with a low calcination temperature.

Abstract: In this work, series of CuO/ZnO functional nanocomposites were synthesized through co-precipitation method using CuCl₂×H₂O and ZnCl₂ as starting materials with various molar ratio of copper:zinc, followed by annealing process at 600 °C for 2 hours to obtain CuO/ZnO nanocomposites. The structures of the composites were analyzed using X-ray diffraction and field emission scanning electron microscopy. For XRD result, diffraction peaks of the composites reveal the well-crystalline characteristic indicating the mixture phase of CuO and ZnO. SEM results show different morphologies of CuO, ZnO and Cu-Zn oxide nanocomposites appearing in quasi spherical structure.The composites were used for antifungal activity via agar disk diffusion method. It is found that the composite with certain ratio of Cu:Zn exhibits superiority in partial inhibition of strain AspergillusflavusTrichoderma comparing to either pure CuO or ZnO.

Abstract: A chemosensor based on a cyanoacrylic (DTP-C) consists of dithieno[3,2-b;2’,3’-d]pyrrole(DTP) as a chromophore and a cyanoacrylic moiety as an ionophore which linked by aromatic system. DTP-C demonstrates the response of complex with Fe(II) in dimethylformamide (DMF) solution. The binding mode of Fe(II)/DTP-C complex was characterized using UV-Visible and fluorescence spectroscopy. In addition, the effect of various MES buffer was then studied at 5%, 10%, 15% and 20% v/v in Fe(II)/DTP-C complex which the appropriate ratiomatric of MES buffer is 10%. The enhancement of Fe(II) concentration indicate a decrease emission intensity while the addition of buffer concentrations found to increase in the intensity. Moreover, quantum chemical calculations were used to study the electronic and optical properties of the molecular structure of DTP-C under the density functional theory.