Proses penyemperitan merupakan salah satu proses pra-pencampuran yang dapat membantu meningkatkan tahap serakan
bahan pengalir dalam komposit polimer pengalir (CPC). Tahap keberaliran elektrik dilihat tidak begitu memuaskan
walaupun telah melalui proses serakan melalui pengacuan mekanik. Kajian ini dijalankan bagi mengoptimumkan
proses penyemperitan bahan gentian karbon terkisar (MCF) dan polipropilena (PP) iaitu suhu penyemperitan dan halaju
putaran melalui kaedah reka bentuk eksperimen (Taguchi). Susunan orthogonal Taguchi L9 digunakan bagi menentukan
aras yang paling optimum serta menjalankan analisis varian bagi memperoleh nilai keberaliran elektrik yang paling
baik. Pengoptimuman parameter pada suhu penyemperitan 210ºC hingga 250ºC dan halaju putaran 50 hingga 90 rpm
menggunakan komposisi bahan sebanyak 80 % bt. MCF dan 20 % bt. PP dengan tahap keberaliran elektrik meningkat
pada tahap maksimum 3.67 S/cm. Pengoptimuman parameter ini menunjukkan bahawa reka bentuk eksperimen yang
terhasil mampu menghasilkan nilai keberaliran elektrik yang tinggi serta mempunyai sifat mekanik yang baik.
Batuan Formasi Singa yang terdiri daripada batu lumpur dominan, berselang lapis dengan batu lodak, batu pasir dan
juga sedikit unit konglomerat tertabur secara meluas di kepulauan Langkawi. Formasi Singa boleh dibahagikan kepada
sepuluh fasies sedimen dan empat sekutuan fasies. Keputusan kajian menunjukkan Formasi Singa telah terendap di
lautan cetek, iaitu di sub-sekitaran luar pesisir, transisi, muka pesisir serta dalam alur. Lautan cetek Lembangan Singa
dipengaruhi oleh iklim sejuk kerana terdapat sedimen asalan glasier, iaitu fasies batu lumpur berpebel. Kertas kerja ini
akan menjelas dan membincangkan segala aspek sedimentologi formasi batuan ini.
Suatu kajian untuk menilai kesan gabungan aktiviti guna tanah dan perubahan musim terhadap kualiti sumber air telah dijalankan di Terusan Utara, Kedah. Kajian ini dijalankan di lima stesen terpilih selama 12 bulan berdasarkan Indeks Kualiti Air (WQI) dan Piawaian Interim Kualiti Air Kebangsaan (INWQS). Kajian mendapati kualiti air di Terusan Utara berada pada Kelas III dan berlaku peningkatan kualiti air dari hulu ke hilir. Hampir semua stesen berpotensi sebagai punca pencemaran berdasarkan aktiviti guna tanah terutamanya di Pelubang, Jitra serta Tunjang. Kajian menunjukkan terdapat perbezaan yang signifikan ketika perubahan musim pada DO, TSS serta BOD, namun tidak pada ammonia, pH dan COD. Secara amnya, kombinasi aktiviti guna tanah dan perubahan musim boleh mempengaruhi atau memberi kesan terhadap kualiti sumber air. Oleh itu, tindakan segera perlu dilakukan untuk mengawal punca pencemaran bagi memastikan kualiti sumber air di Terusan Utara kekal terpelihara.
Postmenopausal osteoporosis is one of the main health problems in aging women. It was due to several factors including oxidative stress, which can be controlled through intake of antioxidants from food sources. Virgin coconut oil (VCO) is one of the natural product rich in antioxidants and has been proven to protect osteoporotic bone. This study was conducted to gain in-depth understanding on virgin coconut oil’s activity on osteoporosis at molecular level. Thirty two female Sprague-Dawley rats were divided into four groups, namely Sham operated group, ovariectomized control group (Ovx+Ctrl), ovariectomized with VCO treatment (Ovx+VCO), and ovariectomized with estrogen treatment (Ovx+E). All treatments were administered orally for ten weeks. Bone samples were obtained to examine changes on expression of superoxide dismutase (SOD), glutathione peroxidase (GPX), osteocalcin and runt-related transcription factor 2 (Runx2) genes. The results indicated that rats receiving VCO treatment had experienced significant increments in SOD, GPX and osteocalcin gene expressions compared to the ovariectomized control group, besides the gene expressions of Runx2 which also showed an increment pattern. In conclusion, VCO helps to protect bone in osteoporotic rat model by increasing the expressions of antioxidant genes and genes which increase the osteoblast acitivities.
Keywords: Osteoporosis; ovariectomized rat model; postmenopausal; virgin coconut oil
Countless statistical tools are available to extract information from data. Life time modeling is considered as one of
the most prominent fields of statistics, which is evident from the developments made in this field in the last few decades.
Almost every statistic for life time analysis is based on precise life time observations, however, life time is not a precise
measurement but more or less fuzzy. Therefore, in addition to classical statistical tools, fuzzy number approaches to
describe life time data are more suitable. In order to incorporate fuzziness of the observations, fuzzy estimators for the
three parameter lognormal distribution were suggested. The proposed estimators cover stochastic variation as well as
fuzziness of the observations.
MeSH terms: Biometry; Statistical Distributions; Life
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.
Multiple imputation method is a widely used method in missing data analysis. The method consists of a three-stage
process including imputation, analyzing and pooling. The number of imputations to be selected in the imputation step
in the first stage is important. Hence, this study aimed to examine the performance of multiple imputation method at
different numbers of imputations. Monotone missing data pattern was created in the study by deleting approximately 24%
of the observations from the continuous result variable with complete data. At the first stage of the multiple imputation
method, monotone regression imputation at different numbers of imputations (m=3, 5, 10 and 50) was performed. In the
second stage, parameter estimations and their standard errors were obtained by applying general linear model to each
of the complete data sets obtained. In the final stage, the obtained results were pooled and the effect of the numbers of
imputations on parameter estimations and their standard errors were evaluated on the basis of these results. In conclusion,
efficiency of parameter estimations at the number of imputation m=50 was determined as about 99%. Hence, at the
determined missing observation rate, increase was determined in efficiency and performance of the multiple imputation
method as the number of imputations increased.
MeSH terms: Data Interpretation, Statistical; Models, Statistical; Linear Models
In this article, the general form of Runge-Kutta method for directly solving a special fourth- order ordinary differential
equations denoted as RKFD method is given. The order conditions up to order seven are derived, based on the order
conditions, we construct a new explicit four-stage sixth-order RKFD method denoted as RKFD6 method. Zero-stability of
the method is proven. Comparisons are made using the existing Runge–Kutta methods after the problems are reduced
to a system of first order ordinary differential equations. Numerical results are presented to illustrate the efficiency and
competency of the new method.
Disease frequency is used to measure the situation of the disease with reference to the population size and time period
which is in a fractional form. The lower part of the fraction, known as denominator is the important part as it was used
to calculate a rate or ratio. Since the disease frequency is based on a ratio estimator, the results are highly dependent
upon the value of denominator. Therefore, the main aim of this paper was to propose a new method in calculating the
denominator for the relative risk equation with the application to chikungunya disease data from Malaysia. The new
method of calculating the denominator of the relative risk equation includes the use of discrete time-space stochastic
SIR-SI (susceptible-infective-recovered for human population and susceptible-infective for vector population) disease
transmission model instead of the total disease counts. The results of the analysis showed that the estimation of expected
disease counts based on total posterior means can overcome the problem of expected counts estimation based on the total
number of disease especially when there is no observed disease count in certain regions. The proposed new approach to
calculate the denominator for the relative risk equation is suitable for the case of rare disease in which it offers a better
method of expected disease counts estimation.
In this study, the corn stalk (CS) had been utilized as natural filler in low density polyethylene (LDPE). The effect of CS
loading and coconut oil coupling agent (COCA) on tensile, thermal and water absorption properties of LDPE/CS composites
were investigated. The increases of CS decreased the tensile strength and elongation at break of LDPE/CS composites, but
increased in Young’s modulus. The incorporation of CS also contributed to high water uptake of LDPE/CS composites.
However, the presence of CS has increased the crystallinity of composites and LDPE matrix due to nucleating effect. The
addition of COCA has significantly increased the tensile strength, elongation at break, water resistivity and crystallinity
of LDPE/CS composites, but slightly reduced in Young’s modulus. The scanning electron microscope (SEM) also evidence
the presence of COCA improved the adhesion between CS and LDPE matrix.
The aim of this research was to synthesize zeolite from coal fly ash by hydrothermal method. The effect of aging temperature
and time on zeolite P1 synthesis (Na-P1) from Mae Moh coal fly ash (MFA) without adding any alumina and silica sources
were examined during the synthesized process. The central composite design (CCD) was used for experimental design
to obtain the optimal process parameters of the aging temperature (105-195ºC) and time (12-84 h) where the specific
surface area was used as a response. The chemical and physical properties of Na-P1 such as specific surface area,
crystalline phase, compositions and morphology were examined. The response results showed that the specific surface
area of Na-P1 decreased with an increase of both aging temperature and time, whereas the XRD intensity of Na-P1
increased with an increase of both aging temperature and time. The composition of SiO2
in mass ratio of coal fly
ash was observed, which was suitable to Na-P1 synthesis. The maximum specific surface area of zeolite products was
found at the designed condition of aging temperature of 105ºC and time of 12 h. Thus, zeolite P1 can be prepared by
hydrothermal method without adding any alumina and silica sources.
This paper reports the preparation of the dual layer ceramic hollow fiber membrane that made of alumina and a mixed
ion electron conducting (MIEC) material for simultaneous reaction and separation applications. Alumina hollow fiber
membrane was prepared using the phase inversion process followed by a sintering technique at elevated temperature. The
alumina hollow fiber membrane was used as membrane support onto which a thin and dense layer of lanthanum strontium
cobalt ferrite (LSCF) was deposited. The main objective of this study was to investigate the LSCF coating formulations
used in the deposition of LSCF layer onto alumina substrate membrane. The sintering temperature of thin LSCF layer was
varied to investigate gas-tightness properties of LSCF membrane. A series of characterizations were conducted for both
the support and the LSCF membrane. The result showed that the thin layer membranes with thicknesses ranging from 3
to 20 µm were successfully deposited on the surface of alumina hollow fiber support. The sintering process improved the
gas-tightness properties but the sintering temperature above 1150o
C caused defects on the surface of LSCF membrane.
The increasing demands of natural gas pushes energy industries to explore the reservoirs contain high CO2 concentration
and impurities including heavy hydrocarbons. High efficiency of using membrane technology in CO2
-natural gas separation
has extended its potential application to offshore environment. Due to the limited studies related with the separation of
under offshore conditions, the present work has investigated the separation performance of a commercial membrane
in removing bulk CO2
from methane at elevated pressure condition. A wide range of offshore operating conditions
including pressure from 10 to 50 bar, CO2
concentration from 25 to 70% and temperature of 30o
C and 50o
studied. High relative CO2 permeance and relative CO2
selectivity were observed when the pressure and the CO2
concentration increased. This work, therefore substantial is to bridge the gap and facilitates the application of membrane
technology for offshore operating conditions.
The composite polymer electrolytes (CPEs) composed of polyacrylonitrile (PAN) as host polymer, lithium tetraflouroborate
) as dopant salt, dissoÅlved in the mixture of ethylene carbonate (EC) and dimethyl phthalate (DMP) as plasticizing
solvent, with the addition of silica (SiO2
) as inorganic filler were prepared by the solution casting technique. The CPE films
were prepared by varying the concentrations of SiO2
from 1 to 5 wt. %. The CPE film containing 3 wt. % of SiO2 exhibits
the highest ionic conductivity of 1.36 × 10-2 S cm-1 at room temperature while for temperature dependence studies, the
plot obtained obeyed Arrhenius rule and the calculated activation energy was 0.11 eV. The ionic conductivity of the CPEs
was found to depend on the concentration of ion pairs of dopant salt as showed by FTIR spectra. The calculated value of
lithium ions transport number, tLi+ for the highest conducting CPE film was 0.15. This result indicates that anionic species
are the main contributor to the total conductivity of the CPE. The CPE film has an electrochemical stability higher than
the non-filler film.
The development of a non-thermal plasma jet with a capillary configuration working at atmospheric pressure is reported
in this paper. The plasma jet is powered by a power source with frequency of several kilohertz. The working gas is
argon. The plasma obtained has been characterized by optical emission spectroscopic measurements and electrical
measurements of the discharge using voltage and current probes. The electron temperature has been estimated by using
the modified Boltzmann plot method utilizing the Ar 4p-4s transition. The electron temperatures at various positions
along the plasma jet length have been obtained and it is found that the electron temperature decreases at position further
from orifice. The electron density has been estimated from current and voltage measurements using the power balance
method. The effects of gas flow rate, applied voltage and frequency on the characteristics of the plasma jet have also been
investigated. The applications of the atmospheric pressure plasma jet (APPJ) developed to modify the surface properties
of Polyethyleneterephthalate (PET) and polycarbonate (PC) have been tested. Our results showed that the atmospheric
pressure non-thermal plasma jet can be effectively used to enhance the surface wettability and surface energy of the
PET and PC. The plasma jet has also been tested for inactivation of prokaryotic cells (Escherichia coli, Staphylococcus
aureus). In the case of E. coli, better than 4 log10 reduction can be achieved. The effect of plasma jet on the pH of cell
culture medium has suggested that the plasma species, particularly the electrons, are solely responsible for the effect
of inactivation of living cells.
Titanium dioxide (TiO2
) nanorods and nanoparticles had been successfully done by hydrothermal method and spray
pyrolysis deposition technique, respectively. Form XRD results, crystallite structure for TiO2
nanorods is rutile phase
at 2θ degree 27.5° which corresponded to  orientation. Whereas, TiO2
nanoparticles produced anatase phase at
2θ degree 25.3° which corresponded to  plane. The structure of nanorods and nanoparticles were characterized
using FESEM. The size of nanorods was in the range of 80 to 100 nm. While, the nanoparticles size was ranging from
25 to 35 nm. The HeLa cells were grown on those TiO2
and were observed under fluorescence microscope. The cells
showed healthy sign of growth on TiO2
nanorods and nanoparticles substrates. Thus, TiO2
nanorods and nanoparticles
are biocompatible to HeLa cells.
Titanium dioxide (TiO2
) with various morphologies has been successfully synthesized by a simple hydrothermal method
C for 10 h using titanium butoxide (TBOT) as a precursor, deionized (DI) water and hydrochloric acid (HCl) on
a fluorine-doped tin oxide (FTO) substrate. The influences of HCl volume on structural and morphological properties
have been studied using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM),
respectively. The result showed that several morphologies such as microsphere, microrods, nanorods and nanoflowers
were obtained by varying the volume of hydrochloric acid. The crystallinity of titanium dioxide enhanced with the
increasing of hydrochloric acid volume.
Incorporation of silver nanomaterial into polymer matrix can further accomplished their potential usage in real life
applications. In our previous study, silver nanoparticles (AgNPs) and silver-graphene oxide nanocomposites (AgGO)
were prepared via a rapid microwave-assisted method. Hereby, the as-synthesized AgNPs or AgGO was dispersed in a
chitosan solution. Subsequently, the resultant mixture solution was further coagulated in a coagulation bath containing
sodium hydroxide via a neutralization process. This resulted in the formation of spherical-shaped chitosan beads.
The structure of the beads showed that the chitosan beads embedded with AgGO exhibited a more porous structure as
compared to the plain chitosan beads. Furthermore, the chitosan beads containing AgNPs or AgGO were tested for
their antibacterial activity against Escherichia coli and Staphylococcus aureus. The antibacterial results indicated that
the silver nanomaterial contained chitosan beads could effectively inhibit the growth of both E. coli and S. aureus as
compared to the bare chitosan beads. The produced chitosan nanocomposite envisioned that can be potentially employed
for water disinfection purpose.
This paper demonstrates the performance experiment and numerical prediction of the copper based hair cell for
underwater sensing. Generally, the hair cell consists of the single cantilever that attached perpendicular to the substrate
and integrated with strain gage (Kyowa type: KFG-1N-120-C1-11). The hair cell sensor was simulated using different
flow rates to study the pressure and the strain distribution acting on the sensor by using computational fluid dynamic
and finite element analysis approach. High performance sensor can be achieved by increasing the length of the hair cell
and also using low Young Modulus material. The hair cell has been fabricated for dimension of 8000 μm length, 2000
μm width and 100 μm thickness, where the copper was chosen due to its mechanical properties. The response time for
a sensor to respond completely to a change in input is about 50 m/s and the sensitivity in terms of output voltage and
input flow rate is 0.2 mV/ms-1. Also, the result obtained in the simulation is aligned with the experimental result. The
experiment for moving object detection proved that this sensor is able to detect the moving object and it is necessary for
underwater applications, especially for monitoring and surveillance.
Chemical and thermal properties of pure lignin are depending on the plant origin, extraction method and type of
lignocellulosic. In this study, lignin from oil palm empty fruit bunch (EFB) and kenaf core were recovered from soda black
liquor by two steps of acid precipitation with hydrochloric acid and followed by soxhlet with n-hexane. The XRD analysis
of purified EFB lignin (EAL) and purified kenaf core lignin (KAL) exhibited amorphous properties, similar to the standard
alkali lignin (SAL). The FTIR and Raman spectra showed that all samples consist of HGS unit. In FTIR, the syringyl unit is
assigned at (1125 cm-1), (1327 and 1121 cm-1) and (1326and 1117 cm-1) meanwhile the guaicyl unit is assigned at (1263,
1212 and 1028 cm-1), (1271, 1217 and 1028 cm-1) and (1270, 1211 and 1030 cm-1) for SAL, EAL and KAL, respectively.
The peak around 1160 cm-1 represents C-O stretching of conjugated ester group present in HGS lignin. As for Raman, the
HGS unit exists in the range of 1100-1400 cm-1. Among the purified samples, the TGA result showed that KAL has a better
thermal stability with the residue of 36.49% and higher Tg value which is 152.69°C.