Performance of a surface plasmon resonance (SPR) sensor based on Kretchmann configuration for silver (Ag) film is evaluated via theoretical simulation. The film thickness and incident angle are varied to obtain the SPR wavelength in the range of 500-550 nm. Shift of SPR wavelength with refractive index of the dielectric defines the sensitivity whereas the resolution is obtained from the ratio of the instrumental resolution to the sensitivity. The SPR sensor shows increasing sensitivity for thicker film however the absorption magnitudes of such films are high and unfavourable for data acquisition. Film thickness of 45 nm and 50 nm which has good sensitivity and resolution with high absorbance magnitude of the SPR wavelength is the best thickness to be employed for sensing purpose.

One of the major challenges of our present society is the protection of the environment. Some of the important elements in this respect are the reduction of the consumption of energy, natural raw materials and the utilisation of waste materials. The used of waste is showing prospective application in construction as alternative to conventional materials. It conserves natural resources and reduces the space required for the landfill disposal. Palm kernel shell is a byproduct of the production of palm oil. Previous works indicate that palm kernel shell performs satisfactorily as an aggregate for lightweight concrete. This research therefore was carried out in an attempt to evaluate the performance of sisal fiber in palm kernel shell concrete. The palm kernel shell used for this research was determined to have a specific gravity of 1.36, bulk density of 574 kg/m3 and was therefore classified as lightweight aggregate. Values of water absorption and porosity of the shell were found to be 11.43% and 14.70% respectively. A mix proportion of 1:2:4 and water-cement ratio of 0.63 was adopted for all the concrete mixes. A total 36 concrete cubes of size 150mm x 150mm x 150mm were cast with 1%, 2% and 3% sisal fiber and were crushed to obtain the compressive strength at 7, 14 and 28 days of curing, 12 concrete beams were also produced and tested for flexural strength. An increase in compressive strength by 51.2% was observed at 3%. It was concluded that 3% sisal fiber can be adopted for lightweight concrete work.

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The aim of this paper is to evaluate the peak tracking method for determination of optical path difference of a fibre interferometer. This study narros the scope for Mach-Zehnder configuration with neutral white LED as its light source. The peak tracking method is then applied on the interference spectrum recorded from the output port of the interferometer using a spectrometer, allowing the optical path difference to be computed. Accuracy of this method is greatly affected by the wavelength resolution of the detector, where the uncertainty of the result is smaller with higher wavelength resolution and the maximum measurable path difference was found to be about 0.6 mm.

LIBS is a very reliable technique for both qualitative and quantitative purposes. Detection of minerals composition is important to help consumer choose the right variety of rice. In this paper, an ungated Laser-Induced Breakdown Spectroscopy (LIBS) system was used to detect calcium in rice. An experimental setup was designed using Nd:YAG laser operating at 1064 nm (60 mJ per pulse) and a spectrometer connected to a fiber optic in order to collect the atomic emission which is displayed on a computer. Twelve samples of rice were purchased from local market which offered differences with regard to their rice varieties, grain size and polishing rate. The calcium concentration of each sample was initially evaluated by using Flame Atomic Absorption Spectroscopy (AAS) after acid digestion. Pellets of approximately 5 mm thick and 40 mm diameter were prepared by transferring 10 g of ground rice sample to a 40 mm die set and applying 40 MPa. For the LIBS analysis, Nd:YAG laser was used to ablate the surface of each pellets. Fifty spectra from different spots of the pellets were collected by the spectrometer from each sample. The spectra were then averaged and analyzed using OriginPro 8.5 for baseline removal and peak findings. Two calcium (Calcium II) lines with high intensity were observed at the wavelength of 393.37 nm and 396.85 nm. The study shows that LIBS can be an excellent tool for detecting calcium in rice.________________________________________GRAPHICAL ABSTRACT