In this study, a simple, selective and sensitive method, for spectrophotometric determination of As(III) with gallocyanine as the sensitive reagent was developed. The wavelength of an analytical measurement, for the determination of As (III), using gallocyanine was at 630 nm with an optimum response at pH 2. The RSD for the reproducibility of 100 ppm As (III) was 2.3%. The LOD was 0.04 ppm with linear dynamic range in As(III) concentration of 0.2 - 1.5 ppm. The developed method has been validated against Atomic Absorption Spectrophotometry (AAS). The interference study of several metal ions was carried out and it revealed that that Mn (II) ion was interfered the most.
The synthesis of carbon nanotubes (CNTs) using a chemical vapour deposition (CVD) method requires the use of hydrocarbon as the carbon precursor. Among the commonly used hydrocarbons are methane and acetylene, which are both light gas-phase substances. Besides that, other carbon-rich sources, such as carbon monoxide and coal, have also been reportedly used. Nowadays, researches have also been conducted into utilising heavier hydrocarbons and petrochemical products for the production of CNTs, such as kerosene and diesel oil. Therefore, this article reviews the different kind of hydrocarbon sources for CNTs production using a CVD method. The method is used for it allows the decomposition of the carbon-rich source with the aid of a catalyst at a temperature in the range 600-1200°C. This synthesis technique gives an advantage as a high yield and high-quality CNTs can be produced at a relatively low cost process. As compared to other processes for CNTs production such as arc discharge and laser ablation, they may produce high quality CNTs but has a disadvantage for use as large scale synthesis routes.
An artificial neural network (ANN) was applied for the determination of V(V) based on immobilized fatty hydroxamic acid (FHA) in poly(methyl methacrylate) (PMMA). Spectra obtained from the V(V)-FHA complex at single wavelengths was used as the input data for the ANN. The V(V)-FHA complex shows a limited linear dynamic range of V(V) concentration of 10 - 100 mg/ L. After training with ANN, the linear dynamic range was extended with low calibration error. A three layer feed forward neural network using backpropagation (BP) algorithm was employed in this study. The input layer consisted of single neurons, 30 neurons in hidden a layer and one output neuron was found appropriate for the multivariate calibration used. The network were trained up to 10000 epochs with 0.003 % learning rate. This reagent also provided a good analytical pedormance with reproducibility characters of the method yielding relative standard deviation (RSD) of 9.29% and 7.09% for V(V) at concentrations of 50 mg/ L and 200 mg/ L, respectively. The limit of detection of the method was 8.4 mg/ L.
A molecularly imprinted polymer (MIP), with the ability to bind Pb(II) ion, was prepared using the non-covalent molecular imprinting methods and evaluated as a sorbent for the Pb(II) ion uptake. 4-vinylbenzoic acid was chosen as the complexing monomer. The imprinted polymer was synthesized by radical polymerization. The template (Pb(II) ions) was removed using 0.1 M HCl. As a result, the efficient adsorption was found to occur at pH 7. The result also showed the applicability of the Langmuir model for the sorption, with the maximum sorption capacity of 204.08 μg/mg.
A novel DNA biosensing platform was designed by the functionalization of iron oxide (Fe3O4)
with the carboxylic group via capping agent, mercaptopropionic acid (MPA) and conjugated
with nanocellulose crystalline (NCC) surface modified with surfactant cetyltrimethylammonium
bromide (CTAB) to assist in the DNA sensing capability. The product of nanocomposites
compound was drop-casted on screen printed carbon electrode (SPCE). Characterization by field
emission scanning electron microscope (FESEM) and energy dispersive X-Ray (EDX)
spectroscopy showing that carboxyl functionalized iron oxide (COOH-Fe3O4) can be hybridized
with NCC-CTA+ via electrostatic interaction.
Molecularly imprinted polymer (MIP) particles for selective extraction of Pb2+ from aqueous media were prepared using non-covalent molecular imprinting methods. 2-vinylpyridine was chosen as the complexing monomer. The imprinted polymer was synthesised by radical polymerisation. The template (Pb2+) was removed by leaching with 0.1 M HCl. The polymer particles (imprinted and non-imprinted) were characterised by IR spectroscopy. The effect of different parameters such as pH, kinetic, adsorption isotherm and selectivity were evaluated. The maximum adsorption capacity is 150 μg Pb2+/mg MIP. The adsorption efficiently occurred at pH 6. The selectivity coefficients of the imprinted polymer particles for Pb2+/Zn2+ and Pb2+/Al3+ were 13.55 and 1.71, respectively.
Normalisation is a process of removing systematic variation that affects measured gene expression levels
in microarray experiment. The purpose is to get a more accurate DNA microarray result by deleting
the systematic errors that may have occurred when making the DNA microarray slid. In this paper,
four normalisation methods of Global, Lowess, Quantile and Print-tip are discussed, tested and their
final results compared in the form of Matrixes and graphs. Ideal and real microarray slides have been
used for this project. It was found that the Print-tip normalisation method showed the closest results to
the real result for an ideal microarray slide and it has a straight median line final graph. The Print-tip
normalisation method uses more than one normalization factor that is divided among intervals which
are dependent on the values of the addition of red and green logarithm.
Despite the continued effort globally made to control the growing case of Tuberculosis (TB), it
continues to be regarded as the second deadliest disease after the HIV. There are various
methods developed to diagnose TB, most of which having the criteria of sensitive, selective,
cheap and portable to be used in robust applications. Even with the advancement in medication,
the important keys including early stage diagnosis is yet to be considered. In diagnosing TB, the
only technique remained as the gold standard method is the culturing method, which is the Acid
Fast Bacilli (AFB) staining. On the other hand, molecular technique utilising Polymerase Chain
Reaction (PCR) assay is preferred as a non-culturing method. Additionally, as molecular
techniques become advanced, real-time PCR or quantitative PCR (qPCR) using multiple probes
in one shot has raised interest among researchers, because it can skip the process of gel
electrophoresis. Recently, researchers have been working on electrochemical DNA sensors
which are sensitive, selective, rapid, cheap and can meet with point of care (POC) testing
requirements to diagnose TB.
The effect of composition on nickel cobaltites prepared by co-precipitation was investigated. Various compositions were synthesised under different heat treatment conditions. The formation mechanism, lattice parameter and crystallite size were determined by various techniques. X-ray diffraction (XRD) analysis revealed that the optimum condition for the formation of single phase nickel-cobalt oxide (NiCo2O4) can be obtained from solution containing Ni: Co ratio of 33.3 mol%: 66.7 mol% with heat treatment at 400 °C. The presence of pure phase NiCo2O4 with the particle size of approximately 34.10 nm was also observed in field emission scanning electron microscopy (FESEM). The crystallinity of the synthesized oxides was improved with the increment of Ni content.