Explore the vast range of titles available.

This work investigates the surface plasmon resonance (SPR) response of 50-nm thick nano-laminated gold film using Kretschmann-based biosensing for detection of urea and creatinine in solution of various concentrations (non-enzymatic samples). Comparison was made with the presence of urease and creatininase enzymes in the urea and creatinine solutions (enzymatic samples), respectively. Angular interrogation technique was applied using optical wavelengths of 670 nm and 785 nm. The biosensor detects the presence of urea and creatinine at concentrations ranging from 50-800 mM for urea samples and 10-200 mM for creatinine samples. The purpose of studying the enzymatic sample was mainly to enhance the sensitivity of the sensor towards urea and creatinine in the samples. Upon exposure to 670 nm optical wavelength, the sensitivity of 1.4°/M was detected in non-enzymatic urea samples and 4°/M in non-enzymatic creatinine samples. On the other hand, sensor sensitivity as high as 16.2°/M in urea-urease samples and 10°/M in creatinine-creatininase samples was detected. The enhanced sensitivity possibly attributed to the increase in refractive index of analyte sensing layer due to urea-urease and creatinine-creatininase coupling activity. This work has successfully proved the design and demonstrated a proof-of-concept experiment using a low-cost and easy fabrication of Kretschmann based nano-laminated gold film SPR biosensor for detection of urea and creatinine using urease and creatininase enzymes.

This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of noble metal nanostructures. The techniques and protocols for producing desirable shapes of noble metal nanoparticles are discussed through introducing the critical parameters which can influence the nucleation and growth mechanisms. Nucleation rate plays a vital role on the crystallinity of seeds while growth rate of different seeds’ facets determines the final shape of resultant nanoparticles. Nucleation and growth rate both can be altered with factors such as absorbed dose, capping agents, and experimental environment condition to control the final shape. Remarkable physical and chemical properties of synthesized noble metal nanoparticles by controlled morphology have been systematically evaluated to fully explore their applications.

SiO2 compound was introduced into zinc ferrite using formula (1-x)ZnFe2O4 – xSiO2 synthesized by sol-gel method where distilled water and citric acid was used as a solvent and binder agent. The produced samples were annealed at 450 °C for 1h. The AFM result analysis show that the average surface roughness and particle size decreased as the compositions of x was increased. XRD results analysis confirmed the formation of spinel structures with crystallite size within range 11.27 – 4.72 nm. UV-Vis analysis to determine the energy band gap of the (1-x)ZnFe2O4 – xSiO2 samples. It shows that the energy band gap increased as the composition of SiO2 was increased due to the dielectric properties of silicon dioxide. FTIR results analysis exhibit common band in the range of 400 – 4000 cm-1. The observed band near 2350 cm-1 shows the presence of oxygen-oxygen bond in the face centered cubic (fcc) crystal lattice of oxygen atoms. The addition of SiO2 into ZnFe2O4 will help to enhance the morphological structures and optical properties. This new proposed dielectric material can be used as dielectric substrate microstrip patch antenna.

PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300°C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS). The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm–424 nm and 426 nm–464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.

Conducting polymers are excellent host materials for nanoparticles of metals and semiconductors. PANI-Ag-Co nanocomposite was prepared by chemical oxidative polymerization of aniline monomer in the presence of nitric acid. PANI-Ag-Co thin films were deposited on the glass substrate using spin-coating technique. The films were characterized by UV-Vis spectroscopy, XRD, AFM and TEM to analyze the internal structure and surface morphology. The performance of the sensor was conducted using I–V measurement to obtain the changes in the current before and after the incubation with E. coli bacteria in water. In UV-visible absorbance bands, a single peak appears at 421.6 nm in each band indicating the Ag-Co alloy nanoparticles were formed. The peaks in the XRD patterns show the crystals are oriented along (111) planes for Ag while (200) plane for Co. AFM images indicate the surface roughness of the PANI-Ag-Co films decreases when the concentration of Co increased. TEM image shows spherical shaped of Ag-Co alloy particles with diameter in the range of 6 – 10 nm. I–V measurements show that the current change of the films increased when incubated in E. coli. The sensitivity on E. coli increases as we increase the Co concentration. PANI-Ag-Co nanocomposite thin films can be explored further for microbial sensor application in future study.

9-channel Arrayed Waveguide Grating (AWG) demultiplexer for conventional and tapered structure were simulated using beam propagation method (BPM) with channel spacing of 20 nm. The AWG demultiplexer was design using high refractive index (n~3.47) material namely silicon-on-insulator (SOI) with rib waveguide structure. The characteristics of insertion loss, adjacent crosstalk and output spectrum response at central wavelength of 1.55 μm for both designs were compared and analyzed. The conventional AWG produced a minimum insertion loss of 6.64 dB whereas the tapered AWG design reduced the insertion loss by 2.66 dB. The lowest adjacent crosstalk value of -16.96 dB was obtained in the conventional AWG design and this was much smaller compared to the tapered AWG design where the lowest crosstalk value is -17.23 dB. Hence, a tapered AWG design significantly reduces the insertion loss but has a slightly higher adjacent crosstalk compared to the conventional AWG design. On the other hand, the output spectrum responses that are obtained from both designs were close to the Coarse Wavelength Division Multiplexing (CWDM) wavelength grid.

Dye-sensitized solar cell (DSSC) using multiwalled carbon nanotube/titanium dioxide (MWCNT/TiO2) was successfully synthesized using sol-gel method. In this method, it has been performed under various acid treatments MWCNT concentration level at (a) 0.00 g, (b) 0.01 g, (c) 0.02 g, and (d) 0.03 g. Atomic force microscopy (AFM) was used to study surface roughness of the MWCNT/TiO2 thin films. The average roughness results for 0.00 g, 0.01 g, 0.02 g, and 0.03 g were 10.995, 18.308, 24.322, and 25.723 nm, respectively. High resolution transmission electron microscopy (HR-TEM) analysis showned the inner structural design of the MWCNT/TiO2 particles. The TiO2 nanoparticles covered almost all the area of MWCNT particles. Field emission scanning electron microscopy (FESEM) gave the morphological surface structure of the thin films. The thin films formed in good distribution with homogenous design. The DSSC with MWCNT/TiO2 electrode containing 0.03 g MWCNT were resulted in the highest efficiency of 2.80% with short-circuit current density Jsc of 9.42 mA/cm2 and open-circuit voltage Voc of 0.65 V.

Macrobends are optical fiber structures suitable for detecting motion changes. This structure has been developed using single-mode fibers and a combination of single-mode and multimode fibers called hetero-core. In this study, a new macrobending structure was designed and developed by adding a nano-ZnO element to the fiber optic core based on Revolution 4.0. The addition of nanomaterial elements involves an etching process that uses harmful chemicals or high-cost laser technology. Therefore, hetero-core was applied in this study to replace the etching process. The ZnO-coated fiber optics with 10 (ZnO1), 20 (ZnO2), and 30 (ZnO3) times of dip coating were developed using the dip-coating method and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Sensitivity measurement was conducted with glued optical fiber in the form of bending using a tape with a bending dimension of 2.5 cm × 1.5 cm and a wavelength of 1,550 nm. Morphological characterization using SEM proves that nanoparticles are attached to the optical fiber, and the EDX characterization confirms that the nanoparticles are ZnO elements. Optical fiber sensor sensitivity using core sizes 9, 50–9–50, 50–9–50 (ZnO1), 50–9–50 (ZnO2), and 50–9–50 (ZnO3) achieved sensitivity values of 0.91, 1.61, 2.98, 3.34, and 3.51, respectively. This study successfully produced ZnO-coated optical fiber sensors with a hetero-core structure without performing the etching process and successfully increased the sensitivity of the sensors.

In this research, the CNT/TiO2 nanocomposite solution was prepared using sol-gel method process. Definite amounts of CNT (0.06 g) were sonicated in 30 ml anhydrate 2-propanol. The measured quantities of Titanium (IV) Tetraisopropoxide (TTIP) – 5 ml were introduced into the CNT/2-propanol solution. The CNT/TiO2 paste was doctor-bladed onto the FTO glass and consequently annealed at 250 °C, 350 °C and 450 °C for 30 min. The effect of annealing temperatures on the CNT/TiO2 thin films was discussed. The CNT/TiO2 thin films were characterized for morphological and electrical performance by Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Incident Photon to Charge Carrier Efficiency (IPCE) and IV-Curve Efficiency analysis. The XRD patterns show the thin films major peak at (101) with average anatase phase crystallite size. The CNT/TiO2 thin film's morphological structure composed of compressed and porous distributed composition. The crystal structures were changed upon increasing the annealing temperature. The IV measurement shows that the dye-sensitized solar cell (DSSC) at 450 °C produced highest photoelectric conversion efficiency (η) with 3.88 %. IPCE graph shows the solar cell absorb light within the UV spectrum region. It is revealed that annealing temperature has influence toward photovoltaic performance of the assembled DSSC.

Zinc oxide (ZnO)–single-walled carbon nanotubes (SWCNTs) nanocomposite thin films have been grown by chemical bath deposition method. The changes in structural and chemical properties were studied by means of x-ray diffraction, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The average crystallite size of ZnO doped with 0.1 and 0.5 wt% SWCNTs was measured about 14.69 and 17.76 nm, respectively. Texture coefficient of the carbon peak (002) was investigated as more than 3.2995 for ZnO mixed with 0.5 wt% SWCNTs. SEM images revealed the ZnO and SWCNTs entangled between the particles. TEM images estimated the inner and outer diameters of SWCNTs to be about 4.86 and 11.32 nm, respectively. FTIR analysis proved the formation of Zn–O and C bonding in the thin films. The performance of the dye-sensitized solar cells (DSSCs) was found to depend on the loading of SWCNTs. The power conversion efficiency increased from 0.078 to 0.684% after loading with 0.1 wt% SWCNTs. Higher amount of SWCNTs (0.5 wt%) was determined as ineffective in improving the performance of ZnO-based DSSCs.