Often, fluoride based electrolyte was applied to synthesize highly ordered titanium dioxide nanotubes. However, in the present work, bundled titanium dioxide nanotubes were fabricated in chloride based electrolyte through electrochemical method. Structural and morphological investigations were carried out on the nanotubes synthesized under different anodization parameters. The growth mechanism of such nanotubes was elucidated and illustrated. The estimated diameter of the as-anodized nanotube was less than 150 nm while the length varied from hundreds of nanometer to microns. X-ray diffraction patterns and Raman spectra have showed anatase and rutile phases of titanium dioxide within the thermally treated samples.
This research explores the possibility of using fluorescence technique to detect the presence of volatile organic compounds based on a single sensing material. The material used was TiO2 nanoparticles coated with porphyrin dye. The TiO2 nanoparticles colloid is in a sol-gel form synthesized from titanium (IV) ethoxide in ethanol with addition of kalium chloride (KCl) as stabilizer. TiO2 nanoparticles were then coated with porphyrin dye, Manganase (III) 5,10,15,20 tetra (4-pyridyl)-21H, 23H porphine chloride tetrakis (metachloride). The coated nanoparticles were deposited on quartz substrate using self-assembly through dip coating technique. The sensing properties of the thin film toward volatile organic compounds; ethanol, acetone, cyclohexane and 2-propanol were studied using luminescence spectrometer. It was found that the thin film produced different emission spectra peaks for different volatile organic compounds (VOCs). Hence, it eases chemical identification process and potentially be use as fluorescence gas sensor.
In this study, group acceptance sampling plan (GASP) proposed by Aslam et al. (2011) is redesigned where the lifetime of
test items are following Pareto distribution of 2nd kind. The optimal plan parameters are found by considering various
pre-determined designed parameters. The plan parameters were obtained using the optimization solution and it also
concludes that the proposed plan is more efficient than the existing plan as it requires minimum sample size.
Time series analysis and forecasting has become a major tool in many applications in air pollution and environmental management fields. Among the most effective approaches for analyzing time series data is the model introduced by Box and Jenkins, ARIMA (Autoregressive Integrated Moving Average). In this study we used Box-Jenkins methodology to build ARIMA model for monthly ozone data taken from an Automatic Air Quality Monitoring System in Kemaman station for the period from 1996 to 2007 with a total of 144 readings. Parametric seasonally adjusted ARIMA (0,1,1) (1,1,2)12 model was successfully applied to predict the long-term trend of ozone concentration. The detection of a steady statistical significant upward trend for ozone concentration in Kemaman is quite alarming. This is likely due to sources of ozone precursors related to industrial activities from nearby areas and the increase in road traffic volume.
CCUS (Carbon Capture, Utilization and Storage) now is a lead way to reduce greenhouse effect such as carbon dioxide emission in the world. This paper presents an integrated overview of seismic monitoring technology when CO2 injection process. Mainly is time-lapse seismic method .Time-lapse seismic method is a feasible way to monitor CO2 injection process when CO2 interaction with minerals, which is proved an effective method in CCUS experiments. AVAZ (Amplitude versus Azimuth) seismic method is proved a useful tool to indentify CO2 injection process, which can detect fluid-induced seismic anisotropic response and locating where CO2 flow to in reservoirs, therefore, it’s an effective way to monitor CO2 flow in CO2 monitoring process. Since we develop AVAZ modelling experiment base on rock physics theory to modeling the time-lapse AVAZ seismic reservoir response. The research show fluid saturation and pressure behave two main factors influence modeling seismic AVAZ response. Meanwhile the AVAZ response can also be detect by seismic AVAZ data.
The effect of turbulent fluctuations on the threshold criteria for incipient grain motion over a wide range of sediment size is investigated. In this work, attention is paid to the comparison of the critical Shields parameter θc profile obtained when the near-bed fluid forces induced sediment motion are oscillating-grid turbulence and a single idealised eddy of vortex ring. For experimental work, near-spherical monodisperse sediments were used throughout with relative densities of 1.2 and 2.5 and mean diameters d ranging between 80 and 1087 μm. The measured values of θc on a horizontal bed α = 0 (hence denoted as θc0), were compared to the θc0 profiles obtained by grid turbulence and vortex ring experiments. Although different in magnitude, the θc0 profiles were comparable, that is the θc0 were seen to increase monotonically for hydraulically smooth bedforms and to be approximately constant for hydraulically rough bedforms. However the limit of hydraulically smooth region was found to vary between the oscillating-grid turbulence experiments, where wider smooth region was found when the turbulent fluctuations used to calculate θc0 is not the near-bed velocity.
Eurycoma longifolia is one of the well-known herbal plants in Southeast Asian region due to its remarkable properties, especially the root part that can be used as aphrodisiac, anti-cancer, anti-malaria and anti-ulcer agent. Uncontrolled harvesting of this plant has reduced its population. Thus, an efficient protocol involving the induction of direct somatic embryogenesis from cotyledon culture of E. longifolia has been developed. 15% explants forming embryos were achieved on Modified Murashige and Skoog’s (MMS) medium supplemented with 0.1 mg/L zeatin plus 0.2 mg/L indole-3-butyric acid (IBA). However, the addition of 0.12 mg/L thidiazuron (TDZ) has increased the percentage up to 22.0%. The maturation phase occurred in the same medium, thus decreased the frequency of subculture and the genetic instability of the embryos. Secondary somatic embryogenesis growth of 20%, which was the highest percentage of growth, was achieved from the primary embryos that were cultured in the MMS medium with the treatment of 2.0 mg/L IBA plus 0.075 mg/L TDZ. The results indicated that the direct somatic embryogenesis obtained can be further used to develop a protocol for plantlet regeneration of E. longifolia.
Moldability of metal injection molding (MIM) is dependent on the outward appearance of the resultant feedstock. Properties of the binders used will influence the properties of the feedstock. Stainless steel powder 316L with mean size 22 μm and the binder system consists of three major fractions of paraffin wax, thermoplastic natural rubber and stearic acid with a powder loading of 65 vol. % was investigated. Comparison was also made with existing palm stearin in the binder system replacing the paraffin wax. Kinetic solvent extractions were done to determine the differences between the binder systems. The feedstock was then injected into tensile bar using vertical injection machine. The results showed that there is a slightly time extension during the solvent extraction as a comparison. The feedstock has been successfully injection molded at 190-200°C. Study of thermal analysis such as DSC and TGA has been done as a preparation for the thermal debinding and sintering process. This study demonstrated that a backbone polymer; thermoplastic natural rubber performs best in term of flow stability and compact quality and also saves in processing time.
The non-linear refractive index of Ag nano-fluids prepared by γ-radiation method was investigated using a single beam z-scan technique. Under CW 532 nm laser excitation with power output of 40 mW, the Ag nano-fluids showed a large thermal-induced non-linear refractive index. In the present work it was determined that the non-linear refractive index for Ag nano-fluids is -4.80×10-8 cm2/W. The value of Δn0 was calculated to be -2.05×10-4. Our measurements also confirmed that the non-linear phenomenon was caused by the self-defocusing process making them good candidates for non linear optical devices.
A nanofluid is a suspension of nano-sized particles dispersed in a base fluid. It is very much obligatory to know more about stability and thermal characteristics of such a nanofluid for their further use in practical applications. In this research, multiwalled carbon nanotubes (CNT) is dispersed in water. CNT dispersed in water is highly unstable and it sediments rapidly due to the Vander Waals force of attraction. Therefore, to overcome this limitation, xanthan gum (XG) was added which behave as a promising dispersant followed by 4 h water bath sonication. Experimental work includes stability studies using UV Vis spectroscopy with respect to CNT concentration (0.01 and 0.1 wt. %) and XG concentration (0.04 and 0.2 wt. %). The thermal conductivity of the most stable suspensions was measured using KD 2 Pro as a function of temperature (25-70°C) and CNT concentration. The optimum XG concentration was found for each CNT concentration studied. Thermal conductivity was observed to be strongly dependent on temperature and CNT concentration. The dispersion state of the CNT-water nanofluid is further examined using scanning electron microscope (SEM). In short, CNT nanofluids are found to be more suitable for heat transfer applications in many industries due to their enhanced thermal conductivity property. This work provides useful insight on the behavior of CNT nanofluids.
The effect of thermal dispersion on the steady free convection flow of a nanofluid in a vertical channel is investigated numerically using a single phase model. Considering the laminar and fully developed flow regime a simplified mathematical model is obtained. In the particular cases when solid phase and thermal dispersion effects are neglected the problem was solved analytically. The numerical solution is shown to be in excellent agreement with the close form analytical solution. Nusselt number enhancement with the Grashof number, volume fraction and thermal diffusivity constant increasing has been found.
This study utilized the incorporation of nanoparticle filler into an epoxy system to study the effect of different nanosized
montmorillonite (MMT) fillers on the thermal stability and mechanical properties of epoxy. The sample was prepared
using diglycidyl ether of bisphenol A (DGEBA) with different surface treatments of montmorillonite filler by mechanical
stirring. The results of thermal stability and mechanical properties of epoxy/clay system obtained from thermal gravimetric
analyzer (TGA), universal testing machine (UTM) and scanning electron microscopy (SEM) were discussed. With the same
amount of filler introduced into the system, different thermal stability of epoxy composite can be observed. Bentonite,
which contained other contaminant components, can downgrade the enhanced properties of the filler.
We give details about how a surface plasmons with phase singularities can be produced when a Bessel beam light is totally reflected internally at the planar surface of a dielectric on which an infinitesimally thin film has been deposited. The characteristic property of such a light is the exponential decay with distance in a vacuum which can basically provide a two-dimensional surface plasmons with phase singularities with attractive enhancements. Such a phenomenon is governable by altering the incident angle and the order of the Bessel beam.
Polarized infrared (IR) reflectance spectrum studies of bulk wurtzite ZnO are presented. The features of the polarized IR reflectance spectra and the optical characteristics of ZnO were investigated. Based on the anisotropic dielectric function model, the experimental IR reflectance spectra were numerically fitted by the theoretical IR reflectance spectra. The obtained transverse optical (TO) and longitudinal optical (LO) frequencies, i.e., ωTO⊥(ωTO||) and ωLO⊥(ωLO|| ) are 411 cm-1 (384 cm-1) and 589.8 cm-1 (572 cm-1), respectively. These results are compared with the reported values measured from the other techniques. Good agreement has been obtained.
Longitudinal water quality trends were assessed in the Tengi River system, Selangor, Malaysia, as the water moved from a peat swamp forest, through different agricultural land uses and finally through a town and then to the Straits of Malacca. Water draining from the peat swamp forest was dark in color due to its organic content and low in dissolved oxygen, pH, E. coli, calcium, nitrate and ammonia. The normal diurnal pattern for water temperature was observed for the peat swamp forest drainage, but there was no clear diurnal pattern evident in the dissolved oxygen data. The E. coli levels increased monotonically from the peat swamp forest waters (0 colonies/100 mL) through the agricultural areas (100-2000 colonies/100 mL) and town (7100 colonies/100 mL) and similarly pH increased along the same continuum. Dissolved oxygen increased from the peat swamp forest through the agricultural areas, but was lower in the town-impacted reach of the Tengi River.
The growth of residential and commercial areas threatens vegetation and ecosystems. Thus, an urgent urban management
issue involves determining the state and the quantity of urban tree species to protect the environment, as well as controlling
their growth and decline. This study focused on the detection of urban tree species by considering three types of tree
species, namely, Mesua ferrea L., Samanea saman, and Casuarina sumatrana. New rule sets were developed to detect these
three species. In this regard, two pixel-based classification methods were applied and compared; namely, the method of
maximum likelihood classification and support vector machines. These methods were then compared with object-based
image analysis (OBIA) classification. OBIA was used to develop rule sets by extracting spatial, spectral, textural and color
attributes, among others. Finally, the new rule sets were implemented into WorldView-2 imagery. The results indicated
that the OBIA based on the rule sets displayed a significant potential to detect different tree species with high accuracy.
Sagittal otolith morphometric measurements from Malaysian Mugilidae species were selected to investigate their possible
role in species identification, due to the Mugilidae species’ morphological similarities, and age determination. Fish
standard length (cm), otolith length (μm), width (μm) and mass (g) measurements were taken from eight species: Chelon
macrolepis, C. melinopterus, C. subviridis, Ellochelon vaigiensis, Moolgarda cunnesius, M. seheli, Mugil cephalus and
Valamugil engeli. Otolith aspect ratio, OAS (otolith length divided by width), was calculated and compared between
species. The four homogenous groups based on their OAS were C. melinopterus (mean=1.65) and V. engeli (1.66) and M.
cunnesius (1.89) and E. vaigiensis (1.89); M. seheli (2.08), C. macrolepis (2.14) and M. cephalus (2.17); and the latter
two with C. subviridis (2.43). The relationships between fish standard length and otolith length/mass showed positive
correlations for both, with otolith length providing the stronger correlation (rs
= 0.897, P < 0.001) than otolith mass (rs
= 0.795, P < 0.001). It is concluded that the more morphologically similar species have similar otolith aspect ratios,
related to head shape; however, otolith shape is also affected by a variety of other environmental factors that have to
be taken account of
According to the classical theory of viscoelasticity, a linear viscoelastic (LVE) function can be converted into another viscoelastic function even though they emphasize different information. In this study, dynamic tests were conducted on different conventional penetration grade bitumens using a dynamic shear rheometer (DSR) in the LVE region. The results showed that the dynamic data in the frequency domain can be converted into the time domain functions using a numerical technique. This was done with the aid of the non-linear regularization (NLREG) computer program. The NLREG software is a computer program for solving nonlinear ill-posed problem and is based on non-linear Tikhonov regularization method. The use of data interconversion equation is found suitable for converting from the frequency domain into the time domain of conventional penetration grade bitumens.
Rainfall intensity is the main input variable in various hydrological analysis and modeling. Unfortunately, the quality of rainfall data is often poor and reliable data records are available at coarse intervals such as yearly, monthly and daily. Short interval rainfall records are scarce because of high cost and low reliability of the measurement and the monitoring systems. One way to solve this problem is by disaggregating the coarse intervals to generate the short one using the stochastic method. This paper describes the use of the Bartlett Lewis Rectangular Pulse (BLRP) model. The method was used to disaggregate 10 years of daily data for generating hourly data from 5 rainfall stations in Kelantan as representative area affected by monsoon period and 5 rainfall stations in Damansara affected by inter-monsoon period. The models were evaluated on their ability to reproduce standard and extreme rainfall model statistics derived from the historical record over disaggregation simulation results. The disaggregation of daily to hourly rainfall produced monthly and daily means and variances that closely match the historical records. However, for the disaggregation of daily to hourly rainfall, the standard deviation values are lower than the historical ones. Despite the marked differences in the standard deviation, both data series exhibit similar patterns and the model adequately preserve the trends of all the properties used in evaluating its performances.
A comparative leaf micromorphological study of Melastoma malabathricum, M. malabathricum var. alba and M.
sanguineum (Melastomataceae) was carried out by scanning electron microscope. Characters such as epidermal cell
shape, trichomes and stomatal type and distribution were observed. Non-glandular trichomes are present in all species
examined. The stomata are all of paracytic type and dispersed randomly over the whole abaxial surface. The patterns of
surface sculpturing and outer stomatal rim are unique in all the species examined. Leaf micromorphology has significant
taxonomic value in the genus Melastoma and the present study has added some new taxonomic information for the genus
Melastoma.