Dry sliding wear of polyester hybrid composites containing carboxylic functionalized multi-walled carbon nanotubes (cNT) and microparticles, silica (Si02) was studied at different sliding distances. An attempt has been made to produce uniform dispersion of nano- and micro- particles in the test samples by ultrasonication. The tribological properties of the hybrid composites were performed by using pin-on-disc (POD) tester against grey cast iron countersurface. The dry sliding wear tests were carried out under pressure-velocity (pv) condition of 0.4 MPa and 4 m/s for total sliding distance of 28800 m and at an interval of every sliding distance of 3600 m, wear properties and behavior were studied. The samples containing 10 wt.% silica (microparticles) with and without CNT always show increase in coefficient of friction at the expense of wear rate. However, samples containing only ci'rr have the lowest wear rate with the increase in coefficient of friction. Sliding distance studies also provide the information on wear rates which were ever changing at different sliding distances whereas average coefficient of friction did not vary throughout the tests. SEM observations of wear surfaces showed different wear morphologies when reinforcement (cNT or Si02) incorporated into the composites either alone or in combination.
Research on the development of lightweight concrete (LWC) utilizing wastes and natural resources as lightweight
aggregates (LWA) is increasingly gaining attention worldwide due to sustainable and environmental concerns. A new
alternative is using palm kernel oil polyol (PKO-p)-based polyurethane (PU) as filler. Rigid PU is a block copolymer
comprised of a monomeric PKO-p and 2, 4-methylene diphenyl diisocyanate (crude MDI). The property of PKO-p, its
ratio with crude MDI and reaction time were determined. The reaction time showed the average of 60 s for cream
time and 95 s for rise time with maximum hardening time of 8 min. The reaction between PKO-p to MDI at 1:1 ratio
resulted in a very short hardening time (within 2 min). The compressive strength of the rigid PU was at 7.0 MPa at a
density of 206 kg/m3
. Further increase in the amount of PKO-p increased the density and compressive strength of the
PU. PU aggregate in the concrete mixture was added at 1 to 5% (w/w) to obtain concrete with density of less than 1800
kg/m3
. The resulting concrete has excellent compressive strength (17.5 MPa) and thermal conductivity (0.24 W/m⋅K).
The results showed that physical properties of PU played the most significant effect on the physical and mechanical
properties of the lightweight concrete
Epoxy shape memory foam (ESM) was produced by an advanced aqueous method. Mixture of epoxy, sodium bicarbonate,
hardener and ammonium chloride was premixed and emulsified in distilled water by using high speed stirring (at 1200
rpm). The content of sodium bicarbonate used was 5, 10, 15 and 20 phr. Besides that, ammonium chloride was used
(based on stoichiometrical content) to also function as acidifying agent in initiating the decomposition process of sodium
bicarbonate at lower foaming temperature. The foam morphology was observed using SEM. It was found that higher
sodium bicarbonate produced more porosity, more cell size, thinner cell wall and more cell interconnection. Epoxy shape
memory foam with 10 phr of sodium bicarbonate exhibited good shape memory property and better compression set.
Shape memory behaviour was measured by the recovered time of the transformed sample to its original shape.
Bioethanol is a very environmentally friendly liquid biofuel that is not only renewable, but also sustainable. It is currently
deemed as a highly suitable additive and substitute energy source to replace fossil based fuel. In this study, bioethanol
was produced from sago hampas by using commercial amylase, cellulase and Saccharomyces cerevisiae via sequential
saccharification and simultaneous fermentation (SSSF), a modified version of the simultaneous saccharification and
fermentation (SSF) process. SSSF was performed on sago hampas at 2.5 and 5.0% (w/v) feedstock load for five days. The
samples taken from the SSSF broths were analysed via high performance liquid chromatography (HPLC) for ethanol, glucose
and acetic acid production. From the results obtained, SSSF with 5.0% sago hampas loading exhibited the highest ethanol
production at 14.13 g/L (77.43% of theoretical ethanol yield), while SSSF using 2.5% sago hampas loading produced
ethanol at 6.45 g/L (69.24% of theoretical ethanol yield). This study has shown that ethanol not only can be produced
from sago hampas using different enzyme mixtures and S. cerevisiae via SSSF, but yields were also high, making this
process highly promising for the production of cheap and sustainable ethanol as fuel.
Two new records of moray eels (Muraenidae), Gymnothorax margaritophorus Bleeker, 1864 and Strophidon sathete (Hamilton 1822), are reported for Malaysia. They are represented by two specimens each, all collected from Sabah waters. The present study also provides the current taxonomic and distributional information of the Malaysian moray eels. To date, there are 33 species belonging to six genera of the Muraenidae in Malaysian waters based on the published records.
Ultrafine, cemented tungsten carbide (WC) possesses exceptional hardness, wear resistance and high strength in various applications. In this study, WC was produced through micro powder injection molding (μPIM), which is also applicable for metals and ceramics in producing complex parts with high-dimensional accuracy. Different inhibitors, such as VC, Cr2C3, NbC, or TaC, were added to improve the mechanical properties of WC and control its grain growth. The effects of a grain growth inhibitor were investigated by adding VC in WC–10%Co–nVC, where n = 0 to 1.2 wt. %. The mechanical properties of the sintered part, such as hardness and flexural strength, were determined. The morphology and elemental distribution of the samples were studied by field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. X-ray diffraction was employed to study the phases of the obtained samples. The results showed that the sample with 0.4 wt. % VC (optimal amount) sintered at 1410°C exhibited the highest theoretical density, hardness and flexural strength of 95.2%, 1973±31 HV and 2586±172 MPa, respectively. The average grain size measured was 519±27 nm. VC acted as a grain growth inhibitor during sintering, thereby improving the mechanical properties.
Palm oil mill effluent (POME) treatment has developed in the last decade. Due to the characteristic and volume of POME,
it needed a complete treatment to reduce the pollutant content. Three pre-treatments method, ultrafiltration, adsorption
and decantation were applied prior to nanofiltration (NF) membrane. The polyethersulphone membrane, montmorillonite
as the adsorbent and modern decanter was investigated in this research. Two types of NF membrane, named NF-1 and
NF-ASP30 were used after pre-treatment. The removal of four important parameters were determined i.e. COD, TSS, colour
and turbidity. The results showed that the adsorption and UF is better than decantation pre-treatment. The ultrafiltration
and adsorption can reduce POME content more than 80% for all parameter while decantation varied between 40 and 80%.
The combination of ultrafiltration and adsorption with both of NF membrane can removed almost all the parameter. But
the decantation can only remove the turbidity but not for the rest of the parameters. Besides the POME content, the flux
decline for both of NF membrane was also investigated. The flux of NF-1 membrane was higher than NF-ASP30 membrane
but NF-ASP was more relative stable for the flux decline. Overall, NF-1 has better performance in flux decline.
The aim of this study was to establish a simple, accurate and reproducible method for the identification and quantification of surfactin using high-performance liquid chromatography (HPLC). Previously reported method of identification and quantification of surfactin were time consuming and requires a large quantity of mobile phase. The new method was achieved by application of Chromolith® high performance RP-18 (100 × 4.6 mm, 5 μm) as the stationary phase and optimization of mobile phase ratio and flow rate. Mobile phase consisted of acetonitrile (ACN) and 3.8 mM trifluroacetic acid (TFA) solution of 80:20 ratio at flow rate of 2.2 mL/min was obtained as the optimal conditions. Total elution time of the obtained surfactin peaks was four times quicker than various methods previously reported in the literature. The method described here allowed for fine separation of surfactin in standard sample (98% purity) and surfactin in fermentation broth.
owder injection molding (PIM) is able to produce porous titanium alloy/hydroxyapatite composite through the space holder technique. Thermal debinding and sintering processes were the main challenges due to different properties of metal and ceramic in producing such composite. This study focused on the effect of different space holders on the physical and mechanical properties of debound and sintered porous titanium aloi/hydroxyapatite composite. The feedstock is containing of 80 wt. % of titanium alloy/hydroxyapatite with 20 wt. % of space holders such as sodium chloride (NaCl) and polymethylmethacrylate (PMMA), respectively. The binders were then removed from the injected samples by two stages of debinding; solvent and thermal debinding. The sintering was performed at three different temperatures 1100oC, 1200oC and 1300oC at a heating rate of 10oC /min and holding time of 5 h. It was found that the samples containing PMMA space holder was fractured after sintering. While, the samples containing NaCl space holder successfully formed pores and not fractured. At sintering temperature of 1300oC, the density, compressive strength and porosity volume percentages for the sintered sample containing NaCl space holder were 3.05 g/cm3, 91.7 MPa. and 11.9 vol%, respectively.
Surface water quality monitoring is an important tool for enhancing the water body management system. This study focuses on the water quality of a lake based on rehabilitation work completed in 2014. This lake suffers from eutrophication and water quality degradation due to the increase in pollution rates and water source scarcity. Nine points were selected to represent the water quality status for the study area. Two river tributaries that pass through the University Malaya (UM) campus have been considered due of its potential as a water source for the lake. Field and laboratory analysis were conducted to understand the transport of water quality parameters. The data variations were analyzed using a multivariate statistical method to determine the significant differences between the lake and river. Based on the Malaysian Water Quality Index (WQI) and cluster analysis, the results indicated that the lake and river have different physico-chemical characteristics and the lake water has a better quality than the river. Comparison of the concentration for BOD, TSS, PO43- and NO3- between year 2009 and current study proved that the water quality has improved by 99.8% proving that the lake remediation is effective.
A one-pot green sonochemical process assisted by ascorbic acid as the reducing agent to produce highly reduced graphene oxide (rGO) decorated with silver nanoparticles (AgNPs) is demonstrated. A complete removal of oxygen-containing group in the GO sheets was confirmed by no observation of the peak corresponds to C-O, C=O and -OH bond. The unexpected decrease of peak intensity corresponds to sp2 hybridized C=C group is explained by a so-called bond polarity effect. The peak observed at ~400 nm seems to show the presence of AgNPs and the red shifting of C=C peak to ~270 nm after the introduction of ascorbic acid indicates the formation of highly reduced GO. The increase of AgNPs size and the crumpled silk-like morphology after the introduction of ascorbic acid also indicate the aggressive reduction of both AgNPs and GO. The increase of ID/IG ratio after the introduction of ascorbic acid seems to indicate the increase of the number of small sp2 domains, the presence of unrepaired defects and the restoration of the sp2 network. This work provides the promising green sonochemical approach by utilizing non-toxic and environmental-friendly reducing agent to produce highly reduced GO decorated with AgNPs for various applications.
Forecasting a multiple seasonal data is differ from a usual seasonal data since it contains more than one cycle in a
data. Multiple linear regression (MLR) models have been used widely in load forecasting because of its usefulness in the
forecast a linear relationship with other factors but MLR has a disadvantage of having difficulties in modelling a nonlinear
relationship between the variables and influencing factors. Neural network (NN) model, on the other hand, is a good
model for modelling a nonlinear data. Therefore, in this study, a combination of MLR and NN models has proposed this
combination to overcome the problem. This hybrid model is then compared with MLR and NN models to see the performance
of the hybrid model. RMSE is used as a performance indicator and a proposed graphical error plot is introduce to see the
error graphically. From the result obtained this model gives a better forecast compare to the other two models.
Tujuan kajian ini adalah untuk mengenal pasti kesan rawatan suhu yang berbeza terhadap kebioaktifan wolastonit
yang disintesis menggunakan teknik sol gel. Abu sekam padi dan batu kapur digunakan sebagai bahan awalan untuk
menghasilkan wolastonit. Nisbah campuran kalsium oksida dan silika dioksida CaO/SiO2 ditentukan pada 55:45 dan
dimasukkan ke dalam autoklaf pada suhu 135°C dengan tekanan 0.26 MPa selama 8 jam. Campuran serbuk CaO dan
SiO2 tersebut disinter pada suhu yang berbeza (1150°C dan 1250°C) dan diuji sifat kebioaktifan secara rendaman
dalam larutan cecair badan tersimulasi (SBF) selama 1,3,5,7 dan 14 hari secara in vitro. Sifat fizikal dan kebioaktifan
wolastonit sebelum dan selepas direndam dalam larutan SBF dan beberapa pencirian telah dijalankan menggunakan
teknik analisis XRD, FESEM, EDX dan FTIR. Campuran serbuk CaO-SiO2 yang telah diautoklaf dan disinter pada suhu
1250°C menghasilkan puncak tunggal pseudowolastonit. Ujian kebioaktifan menunjukkan lapisan amorfus kalsium
fosfat (ACP) dengan julat nisbah Ca/P 1.9-1.51 terbentuk lebih pantas pada sampel wolastonit yang disinter pada suhu
1250°C berbanding pembentukan ACP pada sampel tersinter 1150°C.
Getah asli cecair (LNR) dihasilkan daripada proses penyahpolimeran getah asli yang menghasilkan rantaian polimer
lebih pendek dan berat molekular kurang daripada 105
. Namun, LNR masih mempamerkan tahap degradasi dan ketahanan
termal yang rendah seperti getah asli, disebabkan oleh kehadiran ikatan karbon ganda dua pada rantaian polimer.
Dalam kajian ini, penurunan diimida menggunakan pengoksidaan hidrazin hidrat dengan hidrogen peroksida dijalankan
untuk menghidrogenkan unit tidak tepu LNR. LNR terhidrogen (HLNR) dicirikan menggunakan spektrometer infra-merah
(FTIR) dan spektrometer resonans magnetik nuklear (NMR). Pengoptimuman parameter tindak balas dilakukan dengan
memanipulasi parameter masa dan suhu tindak balas berdasarkan kaedah rangsangan permukaan (RSM) dengan
5-aras-2-faktor reka bentuk komposit putaran tengah (CCRD). Satu model kuadratik yang signifikan telah dihasilkan
untuk menghubungkan dua parameter tersebut dengan nilai R2 adalah 0.9986, menunjukkan bahawa model yang terhasil
adalah sangat sepadan dengan data uji kaji. Keputusan kajian menunjukkan bahawa peratus penghidrogenan boleh
ditingkatkan sehingga 91.2%. Seterusnya, berdasarkan RSM, parameter yang optimum bagi penurunan diimida LNR ini
didapati pada suhu 55.9o
C selama 6.7 jam, menghasilkan 80.2% HLNR. Kajian ini telah menunjukkan reka bentuk uji kaji
secara statistik yang novel bagi menghidrogenkan LNR. Pelbagai variasi peratus penghidrogenan produk HLNR dalam
kajian ini menyumbang kepada lebih banyak aplikasi produk yang memerlukan peratusan ketepuan unit yang tertentu.
Kaedah rangsangan permukaan (RSM) dengan reka bentuk komposit putaran tengah (CCRD) telah digunakan untuk
mengoptimumkan parameter bagi penghidrogenan getah asli cecair (LNR) dalam sistem hidrazin hidrat (HH) dan hidrogen
peroksida (H2
O2
) dengan kehadiran selenium sebagai mangkin. Parameter yang dikaji bagi tindak balas ini adalah
nisbah mol HH:LNR (1.25-2.25), nisbah mol H2
O2
:LNR (1.25-2.25), suhu (40-80°C) dan masa tindak balas (4-8 jam).
Berdasarkan data yang diperoleh, penghasilan getah asli cecair terhidrogen (HLNR) sesuai dijelaskan dengan model
kuadratik. Model kuadratik ini mempunyai nilai pekali penentuan (R2
) sebanyak 0.9596 yang menunjukkan korelasi yang
tinggi antara peratus penghidrogenan sebenar dengan peratus yang telah diramalkan. Berdasarkan plot permukaan
tindak balas 3D, suhu tindak balas memainkan peranan penting dalam penghidrogenan LNR. Keadaan optimum yang
diperoleh melalui RSM bagi kajian ini adalah nisbah mol HH:LNR pada 1.50, nisbah mol H2
O2
:LNR pada 2.00, suhu tindak
balas pada 53.34°C dengan masa tindak balas selama 5.21 jam yang memberikan peratusan penghidrogenan HLNR
sebanyak 68.98%. Persamaan polinomial kuadratik yang diperoleh daripada RSM ini berguna untuk menghasilkan HLNR
dengan peratusan penghidrogenan yang dikehendaki.
According to the basic rules and characteristics of the gold-polymetallic deposits of Beiya gold mine area in terms of mineralization and ore controlling, it is concluded that skarn deposit is the main ore deposit type in this area and the geological conditions are analyzed by the statistics of the physical parameters. Then, the tectonic, rocks, stratum, ore geophysical models have been treated by the forward modeling numerical simulation and the results are analyzed comprehensively. Based on the forward modeling results, combined with the relevant physical differences, the principle and exploration method test and research for the comprehensive geophysical exploration technology has been carried out, covering the induced polarization and magnetic prospecting for the ore body as well as the indirect geophysical exploration method by means of plane gravity data, audio-magnetotelluric sounding for rock mass and tectonics, the mineralization mode-physical forward modeling - geophysical exploration mode has been established and good results have been achieved. Therefore, a location forecast method has been put forward for the concealed skarn type Fe-Au deposit which is adaptive to the mineralized geological background of Beiya and other similar areas.
Sifat isoterma dan kinetik penjerapan formaldehid ke atas komposit serbuk serat kelapa sawit-TiO2 yang melibatkan sistem gas-pepejal adalah dikaji. Komposit serbuk serat kelapa sawit-TiO2 dihasilkan dengan mencampurkan serbuk kelapa sawit dan serbuk TiO2 dengan nisbah 8:2 menggunakan teknik pengisaran mekanik. Pengujian dijalankan di dalam kebuk ujian dengan komposit serbuk kelapa sawit-TiO2 dibiarkan untuk menjerap dan mengurangkan nilai kepekatan formaldehid secara pasif. Didapati nilai penjerapan maksima dan sifat kinetik penjerapan bergantung kepada kepekatan awal formaldehid. Kepekatan awal, Ci, 2.1 ppm dan 0.5 ppm masing-masing diwakili oleh pseudo-tertib pertama dan pseudo tertib kedua, manakala Ci = 0.75 dan 0.9 ppm diwakili oleh model Elovich. Isoterma penjerapan formaldehid diwakili oleh isoterma Freundlich dengan nilai korelasi tertinggi R2 = 0.9397 berbanding nilai korelasi isoterma Langmuir (R2 = 0.8692) dan isoterma Temkin (R2 = 0.8756). Parameter keseimbangan, 0
Zinc oxide (ZnO) utilization in advanced oxidation process (AOP) via solar-photocatalytic process was a promising method for alternative treating wastewater containing phenol. The ZnO photocatalyst semiconductor was synthesized by sol-gel method. The morphology of the ZnO nanostructures was observed by using scanning electron microscope (SEM) and the crystallite phase of the ZnO was confirmed by x-ray diffraction (XRD). The objective of this study was to synthesis ZnO nanoparticles through a sol-gel method for application as a photocatalyst in the photodegradation of phenol under solar light irradiation. The photodegradation rate of phenol increased with the increasing of ZnO loading from 0.2 until 1.0 g. Only 2 h were required for synthesized ZnO to fully degrade the phenol. The synthesized ZnO are capable to totally degrade high initial concentration up until 45 mg L-1 within 6 h of reaction time. The photodegradation of phenol by ZnO are most favoured under the acidic condition (pH3) where the 100% removal achieved after 2 h of reaction. The mineralization of phenol was monitored through chemical oxygen demand (COD) reduction and 92.6% or removal was achieved. This study distinctly utilized natural sunlight as the sole sources of irradiation which safe, inexpensive; to initiate the photocatalyst for degradation of phenol.
The development degree of fissure water in underground rock is a great trouble to the construction of railway tunnel, which will cause a series of environmental geological problems. Take the surrounding rock-section of the typical red clay in Lvliang-Mt. railway tunnel below the underground water level as an example, several aspects about the red clay surrounding rock will be researched, including pore water pressure, volume moisture content, stress of surrounding rock, vault subsidence and horizontal convergence through the field monitoring. Taking into account the importance of railway tunnel engineering, the large shear test of red clay was carried out at the construction site specially and the reliable situ shear strength parameters of surrounding rock will be obtained. These investigations and field tests helped to do a series of work: Three dimensional finite element numerical model of railway tunnel will be established, the deformation law of the red clay surrounding rock will be investigated, respectively, for the water-stress coupling effect and without considering it, the variation of the pore water pressure during excavation, the influence degree about the displacement field and stress field of water-stress coupling on red clay-rock will be discussed and the mechanism of the surrounding rock deformation will be submitted. Finally, the paper puts forward the feasible drainage scheme of the surrounding rock and the tunnel cathode. The geological environment safety of tunnel construction is effectively protected.
Over many years, forested land transformation into urban, agriculture and mining areas within Tasik Chini Catchment become more intense. These activities have negatively affected the catchment through soil erosion and increased the amount of sediments that deposited into the lake. Hence, the present study aimed to estimate soil erosion risk within Tasik Chini Catchment integrating the Revised Universal Soil Loss Equation (RUSLE) model and remotely sensed geospatial data. The multispectral imagery from LANDSAT 8 was used to provide up to date information on land cover within the catchment. The result shows the majority of Tasik Chini Catchment is classified at very low class (< 10 ton ha−1 yr−1) about 4835.34 ha (92.38%), followed by the low class (10-50 ton ha−1 yr−1) with total area of 175.47 ha (3.35%), moderate high class (50-100 ton ha−1 yr−1) with total area of 65.11 ha (1.24%), high class (100-150 ton ha−1 yr−1) with total area of 38.37 ha (0.73%) and very high class (> 150 ton ha−1 yr−1) with total area of 120.04 ha (2.30%). Tasik Chini Catchment is very susceptible to soil erosion especially on northwest and southeast regions, where the main sources of soil loss come from the agricultural, new settlements and mining activities. To conclude, the estimation of soil erosion model using remotely sensed data can be used to build sustainable development strategy within Tasik Chini Catchment in the future.