A series of Mg/TiO2
photocatalysts were prepared using aqueous wet impregnation method at different Mg loading
followed by calcination at different temperatures for 1 h duration. The photocatalysts were characterized using thermal
gravimetry, Fourier-transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy and
high-resolution transmission electron microscopy. The photocatalysts were investigated for photooxidative-extractive
deep desulfurization of model oil containing dibenzothiophene at room temperature and under visible light irradiation.
The model oil containing 100 ppm S was photooxidized followed by extraction using imidazolium-phosphate ionic liquids
at room temperature. The best performing photocatalyst was 0.25 wt. % Mg/TiO2
calcined at 400°C (0.25Mg400), in
which 98.4% of dibenzothiophene (3.070 mmol DBT per g photocatalyst) was converted to dibenzothiophene sulfone. The
highest extraction efficiency of 97.8% (0.01525 mmol S per mL ionic liquid) was displayed by 1,2-diethylimidazolium
diethylphosphate.
This paper addresses the optimal Dye Solar Cell (DSC) design considering parameters namely TiO2
thickness, surface
area, iodide concentration in electrolyte and TiO2
passivation layer thickness as they have influence on DSC performance.
It aims to do the research of the practical use of Taguchi method in the optimization of DSC design in order to improve
the performance of DSC. This work highlight on the integration of Taguchi method with simulation which showed that the
optimal design of DSC is 10 µm thickness of TiO2
, 90m2
/g of TiO2
photoelectrode surface area, 1 M iodide concentration
in electrolyte and two layers with 20 nm thickness of TiO2
passivation layer with efficiency of 4.59165%. All the features
of the Taguchi-based optimization were also discussed.
We report herewith the study of fingernail clippings obtained from the residents of Tokyo, Japan. A total of 18 participants with no health problems and occupational exposure to metals were recruited to provide fingernails samples for this study. Through the use of instrumental neutron activation analysis (INAA), 18 elements (Ag, Al, As, Ca, Cl, Co, Cu, Fe, Hg, K, Mg, Mn, Na, S, Sb, Se, V, and Zn) were determined. The results showed that the toxic elements in the fingernails are in the lower range when compared to literature values. There were no chronic exposures to toxic elements such as As and Hg found. The level of Hg found is lower than that reported 20 years ago, possibly due to the strict regulation control in Japan on the release of Hg to the environment. The elements Se and Zn are found to be rather uniformly distributed among participants and are in agreement with results from other countries. There were no significant differences in elemental concentrations due to genders and smoking habits. The overall data from this study showed similar concentrations to those of healthy participants from other countries. Thus, the current data could represent the background level of elemental concentrations in fingernails of residents in Tokyo, which could serve as reference values for future study.
Bisphenol A is an endocrine disruptor with widespread applications, especially in the production of polycarbonate and epoxy resins. Dispersive liquid-liquid microextraction based on solidification of floating organic technique has been developed for the extraction of bisphenol A from water and soft drink. The 1-undecanol has been applied as the extraction solvent because of its low density and melting point and high affinity to the analyte. The technique offered rapid and simple analysis as the 1-undecanol was homogeneously dispersed in the sample solution to speed the extraction and the collection of extraction solvent was simplified by centrifugation, cooling and melting steps.
The benefits of using structural lightweight concrete in construction industry, particularly in high rise buildings, over normal weight concrete are numerous. The main method of producing structural lightweight concrete is the use of lightweight aggregates instead of ordinary aggregates in concrete. Due to the limited resources for natural and artificial lightweight aggregates, the alternative sources for lightweight aggregates should be discovered from industrial wastes. Oil palm shell (OPS) and oil-palm-boiler clinker (OPBC) are two solid wastes from palm oil industry and are available in abundance in tropical regimes. The use of just OPS as coarse lightweight aggregate in concrete mixture has some drawbacks for concrete. The aim of this study was to investigate engineering properties of a lightweight concrete containing both of these aggregates. For this purpose, in this study, 50% (by volume) of OPS was replaced with OPBC in an OPS lightweight concrete. The test results showed that when OPS was substituted with OPBC, significant improvement was observed in the compressive, splitting tensile and flexural strengths. In addition, initial and final water absorption as well as drying shrinkage strain of blended coarse lightweight aggregate concrete were significantly less than OPS concrete.
Population genetic structure of Varuna litterata living along the coast of Thailand were examined in this study. The samples were collected from 3 coastal regions: The Andaman sea (Satun, Trang, Phang Nga), the lower Gulf of Thailand (Pattani, Songkhla, Nakhon Si Thammarat) and the upper Gulf of Thailand (Petchburi, Samut Songkram, Rayong, Trat). Intraspecific variation was determined based on partial sequences of the cytochrome oxidase subunits I gene. A total of 182 samples were collected but only 32 haplotypes were obtained from these samples. An excess of rare haplotypes indicated that the female effective population size of V. litterata living along the coast of Thailand is large. Estimated values of haplotype diversity and nucleotide diversity were 0.790 and 0.003, respectively. The AMOVA (analysis of molecular variance) and phylogenetic analysis results showed that based on genetic variation, the population of this organism was found to have 2 genetically different populations: The Andaman sea population and the Gulf of Thailand population. Genetic exchange of V. litterata among populations inhabiting along the coast of Thailand could be described by the stepping stone model. The results of neutrality tests, both Tajima's D and Fu's Fs statistics, yielded negative values (-1.992 and -26.877, respectively) and statistically significant deviation from the neutrality, indicating that the V. litterata living along the Thailand coast had experienced population expansion. Mismatch distribution analysis indicated that a possible expansion occurred 211,428 years ago during the Pleistocene glaciations period.
The Geant4 simulation code was developed to study the Hp
(10) energy response of the LiF:Mg,Cu,P (TLD-100H). Initial
study chose the simulation conditions similar to the work reported by Obryk et al. in year 2011, in which a TLD-100H chip
without filter was used. The work went further to simulate the Hp
(10) results obtained experimentally at SSDL Malaysia.
The experiment used a TLD-100H chip embedded in a TLD card and the card was enclosed in a badge complete with PTFE
filter. Irradiation with eleven photon energies in the range of 24-1250 keV was applied. The simulation code therefore
took into accounts the details of the badge (the materials type and the dimensions of the chip, the card, the badge and
the filters) and the set-up of the experiment (the source distance and the energies). In comparison with Obryk’s work, the
simulation code yielded the mean deviation of 0.59%. For the experimental work, the simulated Hp
(10) curves obtained
were quite similar and comparable and a mean deviation of 13.96% was obtained. As both 0.59% and 13.96% deviations
are within the acceptable limit of ±25%, it was concluded that a satisfactory level of accuracy has been achieved by the
developed simulation code and the selection materials and physics processes that have been adapted in the code were
correct. Sources of uncertainty that has contributed to this deviation are discussed.
Baram Delta Operation had been producing oil and gas since 1960's and serious pipelines failure was reported in the year of 2005. The final investigation has concluded that one of the species of bacteria that has been identified to cause microbiologically influenced corrosion, specifically known as sulfate reducing bacteria (SRB) was found to be one of the potential contributing factors to the incidents. This work investigates the potential use of ultraviolet (UV) radiation to inhibit the SRB consortium that was cultivated from the crude oil in one of the main trunk lines at Baram Delta Operation, Sarawak, Malaysia. The impact of UV exposure to bio-corrosion conditions on carbon steel coupon in certain samples for 28 days was discussed in this study. The samples were exposed to UV radiation based on variations of parameters, namely: time of UV exposure; and power of UV lamp. The significant changes on the amount of turbidity reading and metal loss of the steel coupon were recorded before and after experiment. The results showed that SRB growth has reduced rapidly for almost 90% after the UV exposure for both parameters as compared to the abiotic samples. Metal loss values were also decreased in certain exposure condition. Additionally, field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS) was performed to observe the biofilm layer formed on the metal surface after its exposure to SRB. The evidence suggested that the efficiency of UV treatment against SRB growth could be influenced by the particular factors studied
In this study, magnetic cellulose membranes (MCM) have been prepared by using cotton linter as cellulose source and NaOH/urea as cellulose solvent at different magnetite content. Cellulose was dissolved in pre-cooled NaOH/urea solvent at -13°C to form cellulose solution. The cellulose solution then was mix with magnetite (Fe3O4) nanoparticles synthesized via co-precipitation method of Fe2+ and Fe3+ in the presence of sodium hydroxide (NaOH) to form MCM. The MCMs formed at different percentage of Fe3O4 i.e., 10, 20 and 30%. Analysis from vibrating sample magnetometer (VSM) shows that the saturation magnetization of the MCM increase as the percentages of Fe3O4 nanoparticles increased. However, the addition of Fe3O4 nanoparticles in the regenerated cellulose membrane has decreased the crystallinity index of MCM. The surface morphology of the MCM showed that the Fe3O4 nanoparticles were dispersed in the pore of the membrane. Tensile test showed decreasing in the tensile strength of the cellulose membrane with the addition of Fe3O4 nanoparticle.
Reduced graphene oxide nanosheet (RGO)/Pt nanocomposite have been successfully prepared through a facile chemical reduction method. The reduction of Pt precursor was carried out using sodium borohydride as the efficient chemical reductant. The morphology of RGO/Pt nanocomposite was investigated using high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). HRTEM analysis showed that platinum nanoparticles were homogenously distributed onto the surface of RGO. The electrochemical study proved that Pt nanoparticles were successfully incorporated onto RGO. Therefore, it can be concluded that the proposed method could provide well-dispersed of Pt nanoparticles onto RGO to form RGO/ Pt nanocomposite.
The effect of graphene content on the structure and conductivity of an eco-friendly cellulose/ graphene (CG) composite was investigated. Different compositions of graphene content from 0 to 70 wt. % were prepared using the sol-gel method. Ionic liquids 1-butyl-3-methyl-imidazolium chloride was used to disperse graphene between the cellulose. The investigation showed that CG composite with higher graphene composition exhibits higher conductivity. The highest conductivity (2.85×10-4 S cm-1) was observed at 60 wt. % graphene composition. Sample without graphene showed the lowest conductivity of 1.77×10-7 S cm-1, which acts as an insulator. The high conductivity of CG composite can be associated with the X-ray diffraction (XRD) patterns. The XRD patterns of α-cellulose exhibits a decrease in crystallinity at peak 15° and 22° due to the depolymerization in CG composite. At 60 wt. % composition, XRD pattern showed the decrease in intensity at peak 26° indicates that graphene is more dispersed in the cellulose mixture. This is supported by Fourier transform infrared spectrum of CG composite where the absorption peaks of C-O stretching are weakened at wavelength of 1163 and 1032 cm-1, suggested dehydration and rupture of cellulose. The dehydration and rupture of cellulose result in the high conductivity of CG composite. This research is believed to provide an eco-friendly method to produce cellulose/graphene composite which is useful in future applications of energy.
The fabrication of high quality graphene has become the main interest in current chemical vapour deposition (CVD) method due to the scalability for mass production of graphene-based electronic devices. The quality of graphene is determined by defect density, number of layers and properties changed such as electron mobility, transparency and conductivity as compared to the pristine graphene. Here, we did a study on the effects of reaction conditions such as methane, CH4 concentration and deposition time towards the quality of graphene produced. We found that by lowering both CH4 concentration down to 20% and deposition time to 5 min, a better quality graphene was produced with higher I2D/IG ratio of 0.82 compared to other reaction condition. Through the analysis, we concluded that there are two important parameters to be controlled to obtain high quality graphene.
The yellowtail scad, Atule mate, forms important fisheries throughout the Indo-Pacific region. To know about the stock status of A. mate in Malaysia, various population parameters were measured, by utilizing length-frequency data, that included asymptotic length (L∞), growth coefficient (K), mortality rates (Z, F and M), exploitation level (E) and recruitment pattern of this species from Marudu Bay, Sabah, Malaysia. Total length and body weight relationship was estimated as W = 0.007TL3.148 (R2 = 0.937). The asymptotic length (L∞) and growth coefficient (K) were estimated 27.80 cm and 1.50 yr−1, respectively. Total mortality (Z), natural mortality (M) and fishing mortality (F) were found to be 4.53, 2.46 and 2.07 yr−1, respectively. The exploitation level (E) was estimated 0.46. It was showed that the recruitment pattern was continuous with two major peaks per year. Relative yield per recruit predicted a maximum exploitation rate (Emax) which was 0.55. The current E value (0.46) is lower than the optimum exploitation (E = 0.50) as well predicted Emax. Therefore, it could be concluded that stock of A. mate in the investigated area of Marudu Bay, Sabah is under exploited.
The present study was conducted to evaluate the potential of green water meal (GWM) as an alternative dietary ingredient
for juvenile Pacific white shrimp, Litopenaeus vannamei. Five isoproteic and isolipidic diets were formulated with 0%
(GWM0, control diet), 10% (GWM10), 20% (GWM20), 30% (GWM30) and 40% (GWM40) of GWM replacing fishmeal protein
and fed five times daily to triplicate groups of shrimp with an average initial weight of 6.42±0.02 g. In general, growth
performance and feed utilization of shrimp fed with GWM10 did not show any significant differences with the control
diet. Survival rate was above 88% and not affected by the dietary treatments. The whole-body protein and lipid of the
shrimps decreased with the increasing GWM level in the diets. The shrimps fed with the GWM-based diets (GWM10, GWM20,
GWM30 and GWM40) presented more intense red/orange colour and contained higher total carotenoid concentration
compare with the control diet. The present findings suggested that GWM is an excellent source of carotenoid for shrimp
pigmentation and able to replace fishmeal protein at up to 10% replacement level.
Oil-palm-boiler clinker (OPBC) is an agricultural solid waste sourced from the palm oil industry in tropical regions. This study investigates the use of OPBC as coarse aggregate instead of conventional coarse aggregates to produce a greener concrete, which will help in implementing sustainable construction practices by reducing the usage of raw materials. For this purpose, normal weight coarse aggregates was substituted with dry OPBC aggregates up to 75% (by volume) in a high strength normal weight concrete. The effectiveness of this substitution on the properties of the concrete such as workability, density, compressive strength, splitting tensile strength and modulus of elasticity was studied. The slump test results showed that using OPBC in dry condition reduced the workability of the concrete and therefore can be used up to 50% of the total volume of coarse aggregate. Concrete containing 50% OPBC can be considered as semi-lightweight concrete with high strength. Using OPBC in concrete reduced the splitting tensile strength and modulus of elasticity, however, the reduction was not significant.
This study aimed to optimize the condition of silica-supported nanoscale zero valent iron (NZVI/SiO2) synthesis by colloidal impregnation method. Box-Behnken design (BBD) was used as a tool to create and analyze the 17 synthesized conditions of NZVI/SiO2 samples. The independent variables included ethanol concentration (0-100 vol%), amount of silica (0.025-0.125 g) and agitation speed (100-400 rpm). In addition, analysis of variance (ANOVA) for a response surface quadratic model was used to approximate statistical relationship of independent variables. The reducing performance of the synthesized NZVI/SiO2 was examined through removal of Cr(VI) contaminated in water. The optimum of NZVI/SiO2 synthesis was validated with 100 vol% of ethanol concentration, 0.075 g of silica amount, and 100 rpm of agitation speed. The materials were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and nitrogen adsorption/desorption which showed the existence of NZVI phase, composition, and morphology. The Cr(VI) removal efficiency of the NZVI/SiO2 was tested further at the solution pH 4, 7 and 10 in comparison with that by pristine NZVI and silica-unsupported NZVI (NZVI + SiO2). Among the three materials, NZVI/SiO2 presented the highest Cr(VI) removal, especially at pH 7 and 10 with 98 and 94.41%, within 60 min. This was due to the adsorption of Cr(OH)3 and Fe(OH)3 precipitates over SiO2 resulting in availibilty of NZVI/SiO2’s active sites. The proposed mechanism of Cr(VI) removal by NZVI/SiO2 was also described.
A simple and green method was presented to embed TiO2 on regenerated cellulose membranes via cellulose dissolution-regeneration process. The physical, chemical and mechanical properties of the composite membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier- Transform Infrared (FTIR), ultraviolet (UV) - visible spectroscopy and tensile test. The results indicated that cotton linter has been converted from cellulose I to cellulose II after the regeneration process, while the TiO2 nanoparticles embedded inside the membrane maintaining its original crystal structures. The TiO2 composite membranes possessed high ability of water absorption with total pore volume ranged from 0.45±0.01 to 0.53±0.02 cm3/g. The elongation at break of the prepared membranes increased 29% averagely from dry state to wet state. The tensile strength of the membranes remained at a minimum value of 0.50±0.03 MPa in wet state thus enabled the films to withstand in wet for long period of time under weak UV irradiation. The regenerated cellulose membranes with TiO2 performed well in photocatalytic activity while exhibiting distinct absorption abilities. This study provides a potential application in energy-saving decomposition system in which the dye compound can be easily removed via two simultaneous pathways: Absorption and photocatalytic decomposition.
Kertas ini mengkaji teknologi pengelupasan untuk menghasilkan grafin, grafin oksida (GO) dan grafin oksida terturun
(rGO). Empat teknologi pengelupasan yang utama dikenal pasti dalam tinjauan ini iaitu pengelupasan mekanik,
pengelupasan cecair, interkalasi-pengelupasan dan pengoksidaan-pengelupasan-penurunan. Setiap teknologi ini
dibincangkan daripada segi kualiti grafin, grafit nanoplat, GO dan rGO yang dihasilkan dan langkah utama proses
termasuk bahan kimia yang digunakan. Kami juga membuat satu kajian kemudah-capaian dan analisis sensitiviti untuk
menubuhkan satu kilang penghasilan grafin yang berasaskan teknologi pengelupasan, saiz pasaran grafin dan bahan
mentahnya iaitu grafit. Berdasarkan kitar gemburan Gartner, teknologi dan produk yang berasaskan grafin terletak di
tiga lokasi iaitu lembah kekecewaan, cerun pencerahan dan dataran tinggi produktivit
Superkapasitor MEMS khususnya dengan reka bentuk elektrod antara digit (IDE), telah menarik minat pada masa kini dalam bidang seperti bioMEMS, bioperubatan implan, peranti kuasa elektronik dan aplikasi berkuasa tinggi disebabkan kapasiti pengecasannya yang tinggi. Kajian ini membentangkan superkapasitor MEMS dengan lapisan nano grafin tumbuh di atas elektrod. Superkapasitor MEMS terdiri daripada silikon dioksida (SiO2), nikel, grafin, polipirol (Ppy) dan lapisan alkohol polivinil (PVA). Tumpuan diberikan kepada fabrikasi struktur lapisan nano grafin atas elektrod superkapasitor MEMS melalui beberapa proses seperti pemendapan wap kimia secara peningkatan plasma (PECVD), penyejatan alur e dan salutan pusing. Grafin tumbuh melalui proses PECVD selama 10 minit pada kuasa 40 Watt dan pada suhu antara 400°C dan 1000°C. Spektrum Raman menunjukkan puncak pada 1340 dan 1580 cm-1 mewakili jalur D dan G. Puncak 2D wujud dalam julat 2600 - 3000 cm-1. Nisbah bagi keamatan puncak 2D terhadap puncak G pada 1000°C adalah 0.43 menunjukkan kualiti yang baik bagi banyak lapisan grafin
In this article, the effect of heating duration on the synthesis of silicon carbide nanotubes (SiCNTs) was reported. SiCNTs were synthesized from blend of silicon dioxide (SiO2) and multi-walled carbon nanotubes (MWCNTs) in the ratio of 1:3 by using the microwave heating at 1400°C and maintained at duration of 20, 40 and 60 min, respectively. SiCNTs synthesized at heating duration of 40 and 60 min showed the presence of single phase β-SiC in X-ray diffraction patterns. Meanwhile, field emission scanning electron microscope images showed that SiCNTs were formed and no residual of SiO2 and MWCNTs was observed for SiCNTs formed at heating duration of 40 and 60 min. Transmission electron microscopy images showed the SiCNTs have inter-planar spacing of 0.263 nm and tubular structure of nanotube were retained. The peak corresponded to β-SiC was observed at wavelength of 465 nm from the photoluminescence spectroscopy and associated with energy band gap of 2.67 eV. Absorption bands of Si-C bond were detected at 806.23 cm-1 from the fourier transform infrared spectra. High purity SiCNTs was obtained at 40 and 60 min as indicated by low weight loss by thermo-gravimetric analysis. 40 min is the most suitable heating duration for the synthesis of single phase β-SiCNTs.