Azizah Hanom Ahmad

Electrical Properties of Plasticized Chitosan-Lithium Imide with Oleic Acid- Based Polymer Electrolytes for Lithium Rechargeable Batteries

Solid polymer electrolytes (SPEs) were prepared and their electrochemical characteristics were characterized. The composition of SPEs containing chitosan, lithium trifluoromethane sulfonimide (LiN(CF3SO2)2) and oleic acid (OA) was optimized employing ac impedance measurements at various temperatures. The electrical conductivity of the SPEs with OA shows the highest value and the presence of OA does not change the structure of the polymer.

XRD, conductivity and FTIR studies on LiI-Li2WO4-Li3PO4 prepared by low temperature sintering

Different amounts of Li3PO4 were mixed to a fixed ratio of LiI:Li2WO4, ground and pelletised before subjected to sintering at 70°C for 7 days. XRD shows that the product formed after sintering process is most likely Li6P4W8O32 due to peaks present at 10.6°, 22.4°, 24.0°, 24.4, 26.2°, 32.4° and 34.0°. Conductivity studies show that the sample with 25 wt.% Li3PO4 exhibits the highest room temperature conductivity of 3.42×10−3 Scm−1. Conductivity is expected to occur through channel-like structures which could have formed due to corner or edge sharing of polyhedra. FTIR studies have shown the existence of WO4 tetrahedra and WO6 octahedral at 850 cm−1 and 952 cm−1, and phosphate tetrahedral at 564 cm−1, 700 cm−1, 890 cm−1 and 1030 cm−1.

Structural studies and ionic conductivity of lithium iodide-lithium tungstate solid electrolytes

Solid mixtures of calcined lithium iodide - lithium tungstate (LiI -Li2WO4) have been found to be potential solid electrolytes for practical applications with high conductivities of about 10−3 S·cm−1 at room temperature. The highest ionic conductivity was recorded for the sample containing 20 wt.-% of lithium iodide. The ionic conductivity was related to the structure of the material using X-ray diffraction (XRD) and infrared techniques (FTIR). These experiments confirm the evidence of interaction between LiI and Li2WO4. FTIR spectroscopy revealed the existence of a band at 1505 cm−1 which is formed as a result of this LiI -Li2WO4 interaction. The new phase acts as a conducting pathway for the ions to migrate through the material. Lithium ionic conduction was confirmed by measuring the transference number by Wagners polarization technique. The ionic transference number of this solid electrolyte was found to be 1 within the limits of error.

Conductivity study and fourier transform infrared (FTIR) characterization of methyl cellulose solid polymer electrolyte with sodium iodide conducting ion

Sodium ion (Na+) based solid polymer electrolyte (SPE) has been prepared using solution cast technique with distilled water as solvent and Methylcellulose (MC) as a polymer host. Methylcellulose polymer was chosen as the polymer host due to the abundance of lone pair electrons in the carbonyl and C-O-C constituents, which in turn provide multiple hopping sites for the Na+ conducting ions. Variable compositions of sodium iodide (NaI) salt were prepared to investigate the optimum MC-NaI weight ratio. Results from Electrical Impedance Spectroscopy (EIS) technique show that pure methylcellulose has a low conductivity of 3.61 × 10−11 S/cm.The conductivity increases as NaI content increases up to optimum NaIcomposition of 40 wt%, which yields an average conductivity of 2.70 × 10−5 S/cm.

Solid state proton battery using plasticised cellulose-salt complex electrolyte

Abstract Plasticised cellulose–salt complex films were prepared as solid state electrolytes in proton battery. Cellulose acetate (CA)–ammonium triflate (NH4CF3SO3) salt complexes were plasticised with ethylene carbonate (EC). The film of CA–35 wt-%NH4CF3SO3 with 50 wt-%EC had the highest conductivity of ∼10–4 S cm–1. The highest conductivity film was then applied in battery fabrication by configuration of Zn||CA : NH4CF3SO3+EC||MnO2. The highest open circuit voltage of this cell was ∼1·6 V and is stabilised at ∼1·4 V for 24 h of storage.

Effects of Sodium Iodide (NaI) on Electro-Conductivity with Polyurethane-Diol Organic Electrolyte for Dye-Sensitized Solar Cell (DSSC)

Dye Sensitized Solar Cells (DSSC) technology using inorganic electrolytes post problem in solvent evaporation and iodine sublimation (corroding contacts) causing instability of cells. Application of low molecular oligomers is progressing recently for an improved performance. The electrolyte system was aimed for improving electrochemical stability using quasi-solid-state electrolytes from organic capped polymers. A photo-electrochemical cell was developed from bio-based polyurethane diol (PU) polymer electrolyte with Sodium iodide (NaI) as conducting electrolyte transport material. In this study, polyurethane-diol was modified with NaI cations in the hydrothermal chemical reaction to form modified polyurethane-diol electrolyte. The chemical structure of polyurethane-diol and NaI have achieved highest conductivity of 8.06x10-5 S.cm-1 where structural of polyurethane-diol with NaI shown redox Fermi vectorial energy transfer evaluated for performance of efficiency. Stable cell for DSSC system require material properties to be invidually optimized in views of various elemential performances and solar cell of FTO/TiO-Pc/PU-NaI-I2/Ac give a response under light intensity of 100 mW cm−2 and indicated efficiency of power generation of 4 mW where photovoltaic effect of current density, Jsc of 0.04 mA.cm−2 and open circuit voltage, Voc of 0.4 V respectively.

Slot Radial Array Design on Hollow Pyramidal Microwave Absorber

This paper will introduce the new technique to design new type of microwave absorber. Microwave absorbers are used in anechoic chamber to diminish the unwanted RF signal, so that the measurement obtain have perfect and good results. The basic theories of slot antenna combining with the theory of microwave absorber are used in this paper. As a result of studies, the new design called as the slot radial array design on hollow pyramidal microwave absorber. The design of pyramidal microwave absorber and the slot was introducing in this paper. The simulation process was done by using CST software. The new design of the absorber was measured to make sure it can be compared in terms of the performance. Lastly, the performance of new slot radial array design pyramidal microwave absorber will be analysed by identifying the characteristics performance. The Slot Radial Array proved to be as one of the way to improve the performance.

Review on significant parameters in water quality and the related artificial intelligent applications

This paper presents a review on significant parameters and techniques in water quality assessments used for drinking, domestic purposes and recreational purposes. To ensure water in good quality there are several parameters that have to be considered. Water quality index (WQI) is one of the most effective tools to an attempt to ascertain the water quality. There are many techniques on water quality assessments and some of them are regression analysis, fuzzy reasoning, support vector machine (SVM) and Artificial Neural Network (ANN). The objectives of this review paper are to determine the parameters and ideal technique for water quality assessment.

Rheology behaviour of modified silicone-dammar as a natural resin coating

Modified silicone-dammar (SD) was prepared by various weight percent from 5 – 45 wt% of dammar added. The n-value (viscosity index) of silicone with 5 and 10 % were turn to be 1.6 and 1.3 of viscosity index. While 15, 20, 25 and 30 wt% of dammar added gave 0.7, 0.3, 0.2 and 0.1 of viscosity index. On the other hand, 35, 40 and 45 wt% of dammar gave a fixed value of viscosity index of 0.03. This n-value shows the dispersion quality of paint mixture indicates that the modified silicone-dammar was followed the Bingham’s Model. The rheology measurement of SD mixture was analysed by plotting ln shear stress vs shear rate value. Analysis of the graph showed a Bingham plastic model with regression R2 equivalent to 0.99. The linear viscoelastic behaviour of SD samples increased in parallel with increasing dammar content indicate that the suspension of dammar in silicone resin could flow steadily with time giving a pseudoplastic behaviour.

Performance of Hybrid Radial Basis Function network: Adaptive Fuzzy K-Means versus Moving k-Means Clustering as centre positioning algorithms on cervical cell precancerous stage classification

Cervical cancer been known to be the cause of many deaths each year. Screening tests, such as the Pap smear test used for the detection of the precancerous stage are able to avoid the occurrence of cervical cancer. However, the Pap smear test does have some disappointing disadvantages such as the fact that it has less effective slide preparation and also that it is laden with human error. Therefore, a computer-aided diagnosis system is introduced as a solution to the problem. Recently, artificial neural networks have been widely implemented as a cervical cancer diagnosis system i.e. to classify cervical cancer into normal and abnormal cells. In this recent study, neural network architecture i.e. the Hybrid Radial Basis Function (HRBF) network with Adaptive Fuzzy K-Means Clustering (AFKM) asa centre positioning algorithm is used to diagnose cervical cancer. Four extracted features of cervical cell are used as input data to the networks, which are the size of nucleus and cytoplasm and its grey level. Cells from normal, Low-grade Squamous Intraepithelial Lesion (LSIL) and High-grade Squamous Intraepithelial Lesion (HSIL) categories are used as the training as well as the testing data. The data are fed randomly into the neural networks via 5-folds cross validation techniques. The network performance is compared with the HRBF network with the Moving K-Means algorithm as the centre positioning algorithm. The proposed network produces better accuracy, sensitivity and specificity which illustrates the promising capability of the network to be implemented as cervical cancer diagnosis system for Pap test performance improvement.