Noriah Bidin

Non‐imaging Focusing Heliostat

A non-imaging focusing heliostat for effective use of thermal solar energy is proposed. The heliostat consists of a number of grouped slave mirrors, which are able to move according to a proposed formula to eliminate the first order aberration. The master mirror tracks the sun by a proposed rotation-elevation mode to project solar rays together with the rest of slave mirrors into a fixed target. The merit of this design is that it may benefit the use of solar energy in high temperature applications by allowing a single stage collector to replace a conventional double stage structure; it may also benefit high concentration applications, e.g., solar powered Stirling engines, solar pumped lasers, etc. The feasibility and a reliability test of the proposed method by a prototype heliostat in the University of Technology, Malaysia is reported.

Synthesis of novel ZnV2O4 spinel oxide nanosheets and their hydrogen storage properties

We report the synthesis of ZnV2O4 spinel oxide novel nanosheets via a template free route to explore its potential hydrogen storage properties for the first time. 2D layered nanostructures are excellent candidates for storage applications. This attracted our interest to synthesize novel spinel oxide nanosheets (NSNs) of ZnV2O4. The maximum value for hydrogen absorption in ZnV2O4 nanosheets at 473 K is 1.36 wt.% and 1.74 wt.% at 573 K, respectively. Our hydrogen storage measurements along ZnV2O4 reveal its superiority over previous reports on hydrogen absorption values concerning oxides, nitrides and chalcogenides. To understand the rate-limiting mechanism, various kinetics models are applied. The calculations show that kinetics is governed by 3D growth with constant interface velocity. The measurements point to ZnV2O4 spinel oxide as a promising hydrogen storage material. PL measurements demonstrate the potential for violet/blue optoelectronic devices.

Characterization of Pollution Indices in Soil Surrounding a Power Plant by Laser Induced Breakdown Spectroscopy

The distribution of pollution indices of copper, iron, lead, and nickel in the soil around a gas fired power plant were determined by laser induced breakdown spectroscopy. A Q-switched Nd:YAG laser operating at 90 mJ and 1064 nm was employed to convert the soil into a plasma that was characterized by optical emission spectroscopy. High concentrations of copper, iron, lead, and nickel were measured near the power station. The enrichment factors for lead, copper, nickel, and iron were 0.38–0.64, 0.2–0.65, 0.49–0.73, and 1.02–1.46 with means of 0.48, 0.37, 0.60, and 1.16. Geo-accumulation was observed to be in class 0 (unpolluted) for all metals except for iron, which was in class 0–1. The ecological risk factor was in the low potential range for all metal concentrations. From the center to the outskirts of power station and from surface to deep soil, the soil quality varied from low polluted to unpolluted for heavy metals due to power plant emission, fuel storage, and station remnants.

Plasma Splashing from Al and Cu Materials Induced by an Nd:YAG Pulsed Laser

Plasma splashing from Al and Cu target materials and the growth of thin films on Cu and Al, respectively, has been studied using a Q-switched Nd:YAG laser with a 1064-nm, 80-mJ, 8-ns pulse width as the source of ablation. The target kept rotating and the substrate, Cu for Al and vice versa, was placed at an angle of 15° with respect to the beam axis. During the laser-matter interaction, the targets absorbed thermal energy within the thermal region depth of 4.7 (1.1) nm, yielding an ablated skin depth of 6.7 (4.2) nm. The surface morphology of the exposed targets was studied by analyzing SEM micrographs obtained using a ZEISS SUPRA 35 VP. The obtained results are explained on the basis of different sputtering/ablation mechanisms. Comparatively severe damage forming a bigger crater is seen on the Al target surface in contrast to the crater on the Cu surface. This observation is correlated with the blustering effect and/or debris formation. Energy dispersive spectroscopy (EDX) of the substrates yielded the deposition of micrometric grain-size particles.

Influence of gold nanoparticles on wound healing treatment in rat model: Photobiomodulation therapy

The aim of this study is to investigate the effect of gold nanoparticles (AuNPs) in photobiomodulation therapy (PBMT) on wound healing process.

Photobiostimulation effect on diabetic wound at different power density of near infrared laser

The photobiostimulation effects of near infrared 808 nm diode laser irradiance on diabetic wound were investigated. 120 rats were induced with diabetes by streptozotocin injection. Full thickness punch wounds of 6mm diameter were created on the dorsal part of the rats. All rats were randomly distributed into four groups; one group served as control group, whereas three groups were stimulated daily with unchanged energy density dose of 5 J/cm(2) with different power density, which were 0.1 W/cm(2), 0.2 W/cm(2) and 0.3 W/cm(2) with different exposure duration of 50s, 25s and 17s, respectively. Ten rats from each group were sacrificed on day 3, 6 and 9, respectively. Skin tissues were removed for histological purpose. The contraction of wound was found optimized after exposure with 0.1 W/cm(2). Based on the histological evidence, laser therapy has shown able to promote wound repair through enhanced epithelialization and collagen fiber synthesis. Generally, irradiated groups were advanced in terms of healing than non-irradiated group.

Light-based therapy on wound healing: A review

Wound healing is a complex matrix and overlapping process. In order to accelerate the healing process and minimize bacterial infection, light-based therapy was applied to stimulate bio-reaction to improve healing. The aim of this paper is to review the effects induced by light source (laser and incoherent light like LED) on different biological targets. The light-based therapy techniques were categorized according to the wavelength, energy density, type of irradiance and activity of tissues in the healing process. Out of 80 cases, 77% were animal studies, 5% were human studies and 18% were cell studies. Around 75% of light-based therapy has an advantage on tissue interaction and 25% has no effect or inhibition on the healing process. The appropriate dose appears to be between 1 and 5 J cm−2. At shorter wavelength, photobiostimulation would be effective with a high frequently administrated low-energy dose. On the other hand, for longer wavelength it is the reverse, i.e., more effective with a low frequent treated schedule and a high-energy dose.

Crystallization of poly-silicon film by different annealing techniques

Poly-Silicon is widely used in semiconductor devices especially in TFTs technology. Performance of silicon thin film depends on the degree of crystallization. Enhancing the crystalline is the ultimate goal in this annealing process. The best annealing process will be identified. Initially Al doped Si film was prepared via PVD technique. Three different annealing processes were investigated. The first two techniques dealing with a single step annealing process, that were conventional heat treatment CHT and an excimer laser annealing ELA. The third technique, involved two-step annealing processes which combination from two techniques. The structural surface of the annealed poly-silicon thin film was characterized via AFM. The crystallization was measured based on the grain size. The result showed that the crystallization was extremely small with single step annealing process. In contrast, two step annealing process induced fine nanostructure and maximum crystallization. The optimum grain size was obtained as 129 nm at super lateral growth energy of 356 mJcm−2.

Plasma Diagnostics and Determination of Lead in Soil and Phaleria Macrocarpa Leaves by Ungated Laser Induced Breakdown Spectroscopy

ABSTRACT Laser induced breakdown spectroscopy (LIBS) is an excellent technique that may be more convenient and less expensive by the elimination of the time gating operation. In this study, ungated single pulse LIBS was explored for the determination of lead in leaves and soil at various ambient air pressures. Ground Phaleria Macrocarpa and soil were utilized for this investigation. Matrix matched, laboratory prepared calibration samples were ablated with a Nd:YAG (1064 nm, 100 mJ, 10 ns) laser and spectra were recorded using a spectrometer equipped with a CCD detector. The pressure was optimized for the highest signal-to-noise ratio and moderate background signal. Calibration curves were drawn at the optimized ambient pressure of 500 mbar. Linear calibration curves were obtained with regression coefficients exceeding 0.98 using the lead I 363.95 nm line. The maximum relative errors in lead concentrations were 10.69% and 18.59% from Phaleria Macrocarpa and soil, respectively. Relative standard deviations of 14.99% and 3.42 were obtained for lead in Phaleria Macrocarpa and soil. The results demonstrate that ungated LIBS may be used for the determination of lead in leaves and soil with reasonable accuracy.

Performance of a New Bundle Fiber Sensor of 1000 RF in Comparison With 16 RF Probe

The comparison of bundle sensor performance between 16 concentric receiving fiber (RF) and 1000 hemicircular RF probes is reported. A theoretical analysis is developed for 1000 RF to support the experimental findings, which uses an electromagnetic Gaussian beam approach to determine the transfer function of the probe. Three linear ranges of the displacement profile can be obtained from each probe, namely, the front slope, the first back slope, and the second back slope. The highest sensitivity obtained by the 16 concentric RF at the front slope range is 5.8148 mV/mm with a resolution . Its lowest sensitivity at the second back slope region is 0.06 mV/mm with an initial resolution of 26 μm. The 16 RF probe produces a better sensor performance both at the front slope and the first back slope region, whereas at the second back slope region, the 1000 RF exhibits a higher sensitivity. Furthermore, a wider linear range is realized through the 1000 RF whereby the front slope and the first back slope are 1.45 and 4.75 mm, respectively. The second back slope of the 16 RF, however, provides a longer linear range 3.0 mm. The latter sensor probe has many potential applications in the longer displacement range, such as position control, micro-displacement sensing in hazardous regions, and automated monitoring control.