bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical properties of diamond-like carbon thin films deposited by DC-PECVD
Authors: Deraman Karim , Sarmid Suriany , Ismail Bakar , Ahmad N.E. , Hussin R. , W. Shamsuri W. Nurulhuda , M. Yusof M. Nor , Hamzah Khaidzir
Published: October 2017

Diamond-like carbon (DLC) thin films were deposited at different substrate temperatures using methane gas in DC-PECVD at 1x10-1 Torr. From the lighttransmission using UV-VIS spectroscopy it was found that the optical transition had changed from allowed indirect transition to forbidden directtransition as the substrate temperature increased. The photoluminescence study has shown that the recombination centre occurred at 1.738 eV. Theobservation in the present work shows that the Urbach energy decreases with increasing substrate temperature provides evidence that such films have anarrowed band tail. This decrease in Urbach energy is due to a more ordered structure with lower hydrogen concentration and larger cluster by theincrease in the degree of cross-linking of the C-C network. Distorted cluster which contribute to the broadening of the band tail may also contribute to thePL peak width. As the substrate temperature increases, the cluster size in the tetrahedral hydrogenated amorphous carbon (ta-C:H) increases, resulting insmaller band gap and the structure is more ordered as the decrease in Urbach energy, give the decrease in PL peak energy.
On the theory of metal nanoparticles based on quantum mechanical calculation
Authors: Saion Elias , Gharibshahi Elham
Published: October 2017

Metal nanoparticles have attracted considerable attention owing to their unusual physical and chemical properties from those of their molecular and bulkcounterparts and are fundamental to surface science applications such as catalysts, optics, photonics, sensors, and spectroscopy. Traditionally, the opticalabsorption spectra are derived from the collective oscillations of free electrons of conduction band in metal nanoparticles as a consequence of incidentelectromagnetic radiation polarizing the nanoparticles. This phenomenon, known as the localized surface plasmon resonance, is unique to metallicnanostructures and has been modelled by Gustav Mei in 1908 based on the Maxwell’s equations. It is the most-cited scientific paper of 20th century and thisclassical approach is still used widely. However, the theory cannot account for quantum confinement effects of the electronic structure, the fundamentalphysical properties of metal nanoparticles. More satisfying treatment of photons interacting with metal nanoparticles is by a quantum theory approach.When UV-visible light impinging on a metal nanoparticle, occupied ground-state conduction electrons absorb photons and excite to higher unoccupiedhigher energy-state of the conduction band of the particle. In this development we used time-independent Schrodinger equation of the ground-state energyof Thomas-Fermi-Dirac-Weizsacker atomic model and also the density function in the final Euler-Lagrange equation was algebraically substituted with theabsorption function. The total energy functional was computed numerically for isolated silver and gold nanospheres at various sizes. The electronictransitions within the conduction band are limited only by the Lagrange multiplier and the quantum number selection rules. The calculated absorption peaksfall within the experimental regimes. The results show a red-shift absorption peak increases with the increase of particle diameter corresponds to a decreasein the conduction band energy of metal nanoparticles.
Integral and differential equations for conformal mapping of bounded multiply connected regions onto a disk with circular slits
Authors: Murid Ali H.M. , Kareem Sangawi Ali W. , Nasser M.M.S.
Published: October 2017

Conformal mapping is a useful tool in science and engineering. On the other hand exact mapping functions are unknown except for some special regions.In this paper we present a new boundary integral equation with classical Neumann kernel associated to f f , where f is a conformal mapping ofbounded multiply connected regions onto a disk with circular slit domain. This boundary integral equation is constructed from a boundary relationshipsatisfied by a function analytic on a multiply connected region. With f f known, one can then treat it as a differential equation for computing f .
A facile preparation of nanosized ZnO and its use in photocatalytic decolorization of methyl orange
Authors: Sapawe Norzahir , Jaafar Nur Farhana , Hairom Nur Hanis Hayati , Satar Mohammad Azrul Hisham , Ariffin Md Noor , Triwahyono Sugeng , Abdul Jalil Aishah
Published: October 2017

Nanoparticles zinc metal was prepared by a simple electrochemical method of a N,N-dimethylformamide solution containing 0.1M tetraethylammoniumperchlorate in the presence of naphthalene as a mediator in a one-compartment cell fitted with a platinum plate cathode and a zinc plate anode at 60mA/cm2 of constant current under a nitrogen atmosphere. The prepared zinc oxide (ZnOelec) was characterized by FE-SEM, TEM, XRD, nitrogensorptionand DRUV spectrophotometer, which confirmed that the particles of ZnOelec are composed of pure nanosized ZnO with a large surface area andmajority of particle size was less than 20 nm. The particles size of the ZnOelec affected its photoactivity, which clearly observed when it was tested on adecolorization of methyl orange under UV illumination. By using ZnOelec, 50% of higher removal percentage of MO was achieved compared tocommercial zinc, which only gave 30% after 30 min of contact time. These result shows that ZnOelec has a great potential to be used as a catalyst for thephotocatalytic decolorization of industrial dyes wastewater.
Mechanism of protection of adenosine from tert-butoxyl radicals and repair of adenosine radicals by α-tocopherol in aqueous solution
Authors: Vijayalakshmmi G. , Adinarayanna M. , Jayaprrakash Rao P.
Published: October 2017

The rates of oxidation of adenosine and α-tocopherol by tert-butoxyl radicals (t-BuO•) were studied spectrophotometrically. Radicals (t-BuO•) were generated by the photolysis of tert-butyl hydroperoxide (t-BuOOH) in presence of tert-butyl alcohol to scavenge •OH radicals. The rates and the quantum yields () of oxidation of α-tocopherol by t-BuO• radicals were determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine was found to decrease the rate of oxidation of α-tocopherol, suggesting that adenosine and α-tocopherol competed for t-BuO• radicals. From competition kinetics, the rate constant of α-tocopherol reaction with t-BuO• was calculated to be 7.29 x 108 dm3 mol-1 s-1. The quantum yields expt and cal values suggested that α-tocopherol not only protected adenosine from t-BuO• radicals, but also repaired adenosine radicals, formed by the reaction of adenosine with t-BuO• radicals.
The usage of optical coupler and its optimization signal in modified optical time domain reflectometer
Authors: Jahanadan Subramaniam , Munajat Yusof
Published: October 2017

In this study, attention was made to measure the length of the fiber and the coefficient of the fiber attenuation utilizing novel configurations. Laser diodesource with a fundamental wavelength of (808 ± 10) nm with a maximum power of 50 mW was employed. First measurement utilizes a polarized beamsplitter whereas the second measurement utilizes a beam coupler. The laser was launched in pulsed mode with a 75 ns pulse width which deliveredapproximately 15 mW power into the fiber and the laser source was adjusted to operate in continuous mode with a 50 % duty cycle. A preamplified SiPIN photodetector was used to detect the backscattered light. Later these results were compared with a measurement that utilizes a conventional AnritsuOTDR with a 850 nm wavelength. The length of the fiber obtained is 1313.99 m and shows a deviation of 0.46 % for the first measurement and 1303.89m with a deviation of 0.38 % for the second measurement. The attenuation coefficient for that fiber is 2.65 dB.km-1 with a deviation of 16.22 % for thefirst measurement and 2.58 dB.km-1 with a deviation of 13.16 % for the second measurement. An adjustable BK7 glass plate was used for signaloptimization in the system. Results show that maximum coupling and also maximum backscattered signal occurs when the BK7 glass window is rotated35° anticlockwise.
A numerical algorithm for nth root
Authors: Murugesan Natarajan , Ramasamy A.M.S.
Published: October 2017

Presently a direct analytical method is available for the digit-by-digit extraction of the square root of a given positive real number. To calculate the nthroot of a given positive real number one may use trial and error method, iterative method, etc. When one desires to determine the nth root, it is found thatsuch methods are inherent with certain weaknesses like the requirement of an initial guess, a large number of arithmetic operations and several iterativesteps for convergence, etc. There has been no direct method for the determination of the nth root of a given positive real number. This paper focusesattention on developing a numerical algorithm to determine the digit-by-digit extraction of the nth root of a given positive real number up to any desiredaccuracy. Examples are provided to illustrate the algorithm.
Influence of InxGa1-xAs Underlying Layer on the Structural of the In0.5Ga0.5As Quantum Dots Grown by MOCVD
Authors: Aryanto D. , Othaman Z. , Ismail A. K. , Ameruddin A. S.
Published: October 2017

The single layer In0.5Ga0.5As quantum dots (QDs) were grown on a thin InxGa1-xAs underlying layer by metal-organic chemical vapor deposition(MOCVD) via Stranski-Krastanow growth mode. The effect of different indium composition in the InxGa1-xAs underlying layer was investigated usingatomic force microscopy (AFM). AFM images show that the QDs structures were formed on the surface. The dots formation on the surface changes withdifferent composition of InxGa1-xAs underlying layer. Increasing indium composition in the underlying layer resulted to formation of higher density andsmaller size dots. Several large dots were also formed on the surface. Growing of underlying layer reduces the lattice mismatch between In0.5Ga0.5As andGaAs, and decreases the critical thickness of the dots. This strongly influences the dots nucleation on the surface. Growth of quantum dots usingunderlying layer is one way to modify dot formation in order to achieve uniform QDs of right size and high density, which are essential for QDs deviceapplications.
Optimal stopping rules for exponential data
Authors: Nezhad Mohammad Saber Fallah , Modarres Mohammad , Akhavan Niaki Seyed Taghi
Published: October 2017

A problem of sequential sampling from an Exponential Distribution is considered in this research. The problem is formulated in the stochastic dynamicprogramming framework and the objective is to determine a control policy maximizing the total expected reward. It is assumed that under standardassumptions the control limit policy is optimal. Two types of optimal stopping problems are considered. First one is the problem of sampling withoutrecall that once the decision maker cannot return to that observation at a later time, the second type of optimal stopping problems is sampling with recallwhere the decision maker can select any observation which he has taken earlier.
Depth distribution profile of martensite phase observed by transmission electron microscope in ion implanted metals
Authors: Gustiono Dwi
Published: October 2017

In this work, transmission electron microscopy (TEM) observation results from a depth distribution profile of the nano-martensite occuring in titanium implanted austenitic stainless steel is presented. The thickness of 200 keV high-energy ion implantation induced layer until 150 nm as calculated by the TRIM computer simulation based on the Monte-Carlo program. After the implantation, the specimens were attached to thin foil ring to be milled by focused ion beam (FIB). TEM observation on the ion implantation induced layer reveled that nano-martensite is distributed until80 nm under surface. the nano-martensite mostly nucleated at the region near the surface occurred the higher concentration gradient of implanted ion, namely higher stress concentration takes place so that this stress introduced due to the implanted ions act as a driving force for the transformation.
Synthesis of Tungsten Oxide as Visible Light-Driven Photocatalyst for Removal of Salicylic Acid
Authors: Yuliati Leny , Maisarah Mazalan , O. Lintang Hendrik
Published: October 2017

In the present study, tungsten oxide (WO3) was prepared using mesoporous carbon nitride (m-C3N4) as a template. Based on the results obtained from X-ray diffraction (XRD) and diffuse reflectance (DR) UV-Visible spectroscopy, it was confirmed that WO3 can be successfully prepared at all investigated calcination temperatures, even at low temperature of 200°C. It was found that the WO3 prepared at 700°C using m-C3N4 showed higher photocatalytic activity than the WO3 commercial for salicylic acid removal under visible light irradiation. With the optimum loading amount of platinum as cocatalyst, 80.6% of salicylic acid removal was obtained on the prepared WO3. It was suggested that the small particle size and the high crystallinity of the prepared WO3 played important role in giving high photocatalytic activity.
Effect of acidic aqueous alcohol solution on template sol-gel synthesis of phosphorescent hexagonal mesoporous silica film nanocomposite
Authors: O. Lintang Henrik , Kinbara Kazushi , Aida Takuzo
Published: October 2017

Here novel mesoporous silica film nanocomposite with a hexagonal structure is successfully synthesized by using phosphorescent columnar assembly of a trinuclear gold(I) pyrazolate complex bearing amphiphilic side chains [Au3Pz3], formed via a weak AuI-AuI metallophilic interaction, as a functional template in the sol-gel synthesis. By controlling the molar ratios of alcohol to acid in an acidic aqueous alcohol solution, the sol-gel synthesis of columnar assembled [Au3Pz3] with a silica source can provide highly ordered hexagonal mesoporous silica film composite [Au3Pz3]/silicahex consisting one-dimensional molecular assembly in the nanoscopic channels. The as-fabricated silica film nanocomposite [Au3Pz3]/silicahex with red emission have phosphorescent properties with luminescence emission centered at 693 nm (ext = 276 nm; Stokes shift,  = 417 nm) and lifetime at 7.8 s (ext = 266 nm, em = 690 nm).
Statistical Convergence of n-Sequences and eta-Dual of Some Classical Sets of n-Sequences
Authors: Dutta Hemen , Reddy B Surender , H. Jebril Iqbal , Kumar Vijay
Published: October 2017

In this paper we introduce the notion of n-sequence and extend the notion of statistical convergence to n-sequences. Further we define the notion of eta-dual as a generalization of Köthe-Toeplitz dual for subsets of n-sequence spaces and compute eta-duals of some classical sets of n-sequences.
Enantioseparation of enilconazole using cyclodextrin-modified MEKC
Authors: Hermawan Dadan , Ahmad Kamali Ahmad Nor Shafiq , Wan Ibrahim Wan Aini , Sanagi Mohd Marsin
Published: October 2017

Enantiomeric separation of enilconazole has been successfully achieved using cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method with HP-γ- CD as chiral selector. Two parameters which were HP-γ-CD concentration and SDS concentration have been optimized by investigating their effects on resolution and analysis time. Enantioresolution of enilconazole was achieved by the optimized CD-MEKC system containing 40 mM HP-γ- CD, 40 mM SDS and 20 mM phosphate buffer (pH 8) with resolution (Rs = 1.3) and analysis time within 9 min. Good repeatabilities were obtained in term of RSD% (n = 3) for migration time, peak area and peak height ranging from 0.07 to 6.1 %. The optimized CD-MEKC method was a simple, less solvent used, and able to perform enantiomeric separation of enilconazole with a good resolution and relatively short analysis time.
Covalent Immobilization of Tyrosinase onto Multi-walled Carbon Nanotubes and Its Potential Use In Phenol Biosensing
Authors: Shahir Shafinaz , Kai Tai Boon , Abdul Majid Zaiton , Buang Nor Aziah
Published: October 2017

The possibility of modifying the surface properties of multi-walled carbon nanotubes (MWCNTs) has stimulated increasing interest in their application as components in biosensors. In this sense, it is possible to employ surface modified MWCNTs as support to immobilize biomaterials such as enzymes. In this study the enzyme tyrosinase was immobilized onto functionalized MWCNTs (fMWCNTs) via covalent bonding and activity of immobilized tyrosinase was measured via electrochemical detection of phenol. MWCNTs were first treated with sulphuric acid and nitric acid with ratio 1 : 3 at 70ºC to introduce carboxylated groups (-COOH). The carboxyl moieties were then activated by treatment with a cross-linker, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to enable tyrosinase immobilization via amide bonding. FTIR spectra of tyrosinase immobilized fMWCNTs showed the presence of peaks attributing to aliphatic C-N (1382 cm-1) and amide carbonyl (1639 cm-1) vibrations which confirmed successful covalent immobilization of tyrosinase onto fMWCNTs. Electrochemical measurements using tyrosinase-fMWCNTS-CPE revealed increasing limiting current values of reduction peak with increasing phenol concentrations at -200mV. The appearance of the reduction current indicates that the immobilization process retained the biological activity of the covalently bonded tyrosinase on fMWCNTs surface. This study has demonstrated the potential of using MWCNTs as support for enzyme immobilization and their application in biosensor technology.
Synthesis and characterization of Fe3O4 nanoparticles by electrodeposition and reduction methods
Authors: Salamun Nurrulhidayah , Xin Ni How , Triwahyono Sugeng , Abdul Jalil Aishah , Karim Ainul Hakimah
Published: October 2017

Magnetite (Fe3O4) nanoparticles have been studied extensively due to their good magnetic, optic and electric properties which offer a great potential of applications in many field especially in removal of heavy metals such as the adsorption of poisonous Cr(VI) ion in water. In addition, Fe3O4 is the only material that has up to now been use in human because it is the only material which is known to be biocompatible, without relevant toxicity in the applied dosage. In this study Fe3O4 nanoparticles were prepared by reduction of ferric oxide (Fe2O3) precursor at 598 K for 10, 20, 30 and 40 min. While, ferric oxide (Fe2O3) precursor was prepared by electrodeposition of iron plate in the N,N-dimethylformamide solvent and tetraethylammonium perchlorate and naphthalene as mediators at 263 K. Reduction of Fe2O3 was carried out with an isothermal heating at 598 K under hydrogen atmosphere. Fe2O3 and Fe3O4 were characterized with XRD, BET Surface area, FTIR, FESEM-EDX and TEM. The surface area of both Fe2O3 and Fe3O4 was 38 - 45 m2/g with the average particle size was 40 - 60 nm. The XRD result showed that the crystallinity of Fe3O4 increased with reduction time. The activity of Fe2O3 and Fe3O4 nanoparticles were tested on the adsorption of chromium (VI) at room temperature in which 30-40 % of Cr(VI) ion was adsorbed on the Fe2O3 and Fe3O4 nanoparticles.
Efficient Synthesis Of Alkyl And Aryl 2,3-Unsaturated Glycopyranosides via Ferrier Rearrangement
Authors: Abang Kamal Dayang Halimatulzahrah , Ngaini Zainab
Published: October 2017

The reactions of 3,4,6-tri-O-acetyl-D-glucal with phenolic and aliphatic alcohol in various Lewis acid catalysts (namely La(NO3)3.6H2O, InCl3, ZnCl2 and BF3•OEt2) have furnished the corresponding alkyl and aryl 2,3-unsaturated glycopyranosides via Ferrier rearrangement. BF3•OEt2 showed the best Lewis acids catalysts with excellent yields and minimum reaction times. The reactions performed in CH3CN gave better yields and shorter reaction times compared to CH2Cl2. The electron withdrawing properties of aromatic ring resulting lower yields of aryl 2,3-unsaturated glycopyranosides compared to alkyl 2,3-unsaturated glycopyranosides under this condition. This study is significant in the preparation of O-glycosides via Ferrier rearrangement.
Relationship between Wheatstone Bridge Circuit and Femtogram Particles Attached on Piezoresistive Microcantilever in Biosensor Application
Authors: Nuryadi Ratno
Published: October 2017

This paper describes basic calculations that are used in a piezoresistive microcantilever for the biosensor application. The working principle of the sensor is generally based on piezoresistance change due to the change of stress in the microcantilever. Such stress change is caused by the microcantilever deflection induced by the adsorption of the ultrasmall particles (virus, glucose, micro-organism, etc) on the microcantilever surface. In this work, two piezoresistors embedded in the microcantilever and two external resistors are used to build the Wheatstone bridge circuit for detecting the stress change. Basic equations in stress analysis and in Wheatstone bridge are considered in order to explain the relationship between the Wheatstone bridge and the particles attached on microcantilever surface. Calculation results show that the particles with the mass of femtogram results in piezoresistance change in the order of μΩ and the voltage output in the order of μV.
A study on the interaction of feldspar and quartz with mixed anionic/cationic collector
Authors: Ibrahim Ismail , Hussin Hashim , Mohd Azizli Khairun Azizi , Alimon Md Muzayin
Published: October 2017

Interaction studies of feldspar and quartz with a mixed cationic/anionic collector namely N-tallow 1,3–propylenediamine-dioleate (duomeen TDO) were carried-out. The interaction between collector and minerals has potential to change the surface properties from hydrophilic to hydrophobic. In this study the adsorption behaviour of duomeen TDO on feldspar and quartz was assessed through zeta potential (ζ) and contact angle (Ө) measurement as well as with Fourier transformed infra-red (FTIR) spectroscopy. The sample was collected from Apex Granite, Muar, Johor and thus sample characterization were also carried out such as X-ray diffraction (XRD) was used for qualitative analysis and field emission scanning electron microscopy (FESEM) in order to yield useful microscopic information. Zeta-potential results between pH 2 and pH 10 for feldspar and quartz were measured. When the zero negative value of quartz reached pH 2 the separation process of feldspar from quartz was more significant. By gradually adding duomeen TDO, the contact angle of feldspar and quartz were increased leading to enhance hydrophobicity, but decreasing its free energy and components (Lifshitz-van der Waals γsLW, Lewis electron-donor γs-, and Lewis electron-acceptor γs+). FTIR results showed that at various dosages of duomeen TDO, this collector adsorbed on feldspar and quartz surfaces in the bands characteristic of alkyl chains, vas (CH3), vas (CH2) and vs (CH2) groups between region of 3000-2800 cm-1. Moreover the intensity of the alkyl chain bands increased slightly higher for feldspar compared to quartz with increasing initial duomeen TDO concentration. Finally single mineral flotation tests using Hallimond tube were performed and it has been found that feldspar floatability increased with increasing concentration of duomeen TDO.
Fermentation of Prawn Waste by using Effective Microorganism (EM) for Protein Production
Authors: Zulkeple Nor Masdiana , Zakaria Zainoha , Hamdan Salehhuddin , Abdul Manaf Mohammed Suhaimee
Published: October 2017

Effective microorganisms or EM has been actively used for various reasons but mainly in the waste water treatment, as plant growth initiators and fertilizers. In this study, fermentations of local tiger prawn waste (Panaeus monodon) by EM were conducted at laboratory scale at different fermentation conditions for protein recovery. Fermentations were conducted at various temperature conditions (250C, 370C and 600C) and various level of inoculum and carbohydrate source (5%, 10%, 15% and 20%) and their pH values compared over 72 hours. Results showed that the pH rapidly decreased to pH 5.0 and the fermentation profiles were similar when different types of carbohydrates were used during fermentation. However, temperatures affect fermentations considerably where the pH did not rapidly decrease at 600C. The fermentation products or silage formed is also stable over a period of 60 days. In addition, acid production was dependent on glucose concentration but not on the inoculum level. For protein production, approximately 86% of protein can be recovered after fermentation process. Therefore, it can be suggested that fermentations were successful using EM on palm brown sugar and fermentation done at either 250C or 370C due to its better acid production.
Mussel Shell and Waterworks Sludge as Sorbent Materials for the Removal of Cu(II) from Aqueous Solution
Authors: Awab Hanim , Paramalinggam Thanalechumi
Published: October 2017

Waterworks sludge generated from water treatment plants and mussel shells generated from the mussel cultivation industry contribute to the problem of solid waste in the environment. Reusing them as sorbent materials for the removal of heavy metals from water systems not only reduces the problem of solid waste management but also solves the problem of heavy metal pollution. In this study, the properties and capability of mussel shells (MS), waterworks sludge (AS), mussel shell-bentonite clay mixture (MSBC) and mussel shell-alum sludge mixture (MSAS) to remove copper from aqueous solutions were investigated. The bulk density, particle density, porosity and pH were determined to discern the physical properties of the sorbents. The addition of MS into BC and AS increased the sorption capability for Cu(II). The order of removal of copper ions by each sorbent was MSBC > MSAS > AS > BC which was established in 300-360 minutes. The maximum sorption capacities were in the range of 9.0-11.8 mg/g, with mixed sorbents exhibiting higher capacity. Kinetic studies showed that the pseudo second-order kinetics correlated well with experimental data. In addition, the removal of Cu(II) were well described by the Langmuir isotherm.
Measuring the Performance of an Eigenvalue Control Chart for Monitoring Multivariate Process Variability
Authors: Mohd Noor Aishah , Djauhari Maman Abdurachman
Published: October 2017

In manufacturing process, it is very important to control and monitor the stability of a process such that a high quality product will be produced. The most common statistical tool used for monitoring the stability of a process is the control chart. In recent applications of control charting methods, there is a need to construct a control chart that is able to represent the behaviour of a multivariate process since in many manufacturing processes; quality of a product is determined by the joint-level of several quality characteristics. For this reason, in this paper, a new control chart is introduced for monitoring the stability of multivariate process in terms of the process variability. The proposed method is based on charting each of the eigenvalues of a covariance matrix. To show the efficiency of the proposed method, we conduct a simulation study and compare the performance of the proposed method with the existing method. A real example will be presented to illustrate the advantage of our proposed method.
QM/MM Study for the Reaction Mechanisms of Benzyl Alcohol with Dimethyl Carbonate over a Faujasite Zeolite Catalyst
Authors: Xian Chong Shu , A. Wahab Habibah , Abdallah Hassan Hadi
Published: October 2017

Benzyl methyl ether (BME) compounds are largely synthesized by the industry for use as a starting material for the synthesis of other organic compounds. In order to achieve the target of green chemistry, BME can be synthesized from benzyl alcohol and dimethyl carbonate (DMC) using a zeolite catalyst. DMC is a non toxic compound and a good methylating and carboxymethylating agent. The methylation and carboxymethylation reactions of benzyl alcohol over a 36T extended framework was investigated by ONIOM(HF/3-21g:UFF). Two pathways for the methylation reaction were found, where the first involving two transition states (TS) and the second only a single TS. Methylation via the two-TS pathway has a lower activation energy compared to the single-transition state pathway. Also, the methylation reaction is kinetically more favorable than the carboxymethylation reaction and this finding agrees well with the previous experimental results. The rate constant for the studied reactions were calculated by using the transition state theory and the rate determining step was determined.
Magnetic Neutron Scattering Investigation and Kondo Effect in paramagnetic crystals
Authors: Farzaneh Azadeh , Abdi Mohammad Reza , Ebrahim Saraee Khadije Rezaee
Published: October 2017

Paramagnetic inelastic neutron scattering have been considered to investigate the crystal of rare earth of cerium. In rare earth crystals The hybridization of the f electrons with electrons in the conduction band gives rise to a variety of interesting phenomena. In particular, magnetic form factor can use to help in the understanding of the wave functions of localized electrons, and the energy scales of magnetic fluctuations and characteristic temperatures will be analysed in inelastic neutron scattering . At high temperature, the magnetic scattering can be described by two coherent broad peaks. At low temperatures, one narrow inelastic peak indicates dynamic magnetic correlation and paramagnetic effective moment in cerium ions. These results allow us to establish that in Ce+3 ions, at low T, inelastic scattering is contribution of the Kondo effect.
Photodecomposition of methylene blue over EGZrO2/HY in aqueous alkaline solution
Authors: Sapawe N. , A. Jalil A. , Triwahyono S.
Published: October 2017

The photodecomposition of methylene blue (MB) in an aqueous alkaline solution over EGZrO2/HY catalyst was investigated. The prepared catalyst was examined using X–ray diffraction (XRD) and transmission electron microscopy (TEM). The MB was completely decolorized under visible light at pH 11 after 432 h over 1 wt% EGZrO2/HY photocatalyst. Photolysis almost did not occurs even the MB was kept for the same reaction time but when the system was kept under dark condition in the absence of catalyst the MB converted into methylene violet (MV) after 30 h of reaction.
Mathematical Modelling of Some Null-Context and Uniform Splicing Systems
Authors: Lim S. J. , Fong W. H. , Sarmin N. H. , Karimi F.
Published: October 2017

The mathematical modelling of splicing system which involves recombination of DNA molecules was first introduced by Head in 1987. Splicing of DNA involves cutting of DNA molecules using the restriction enzymes and re-associating different fragments of DNA molecules using the ligase under some specific chemical conditions. A splicing language, L is generated if there exists a splicing system S for which L = L(S). There are different types of splicing systems which have been discussed by various researchers. Among them are the persistent splicing system, null-context and uniform splicing system. In this paper, some molecular examples on null-context splicing system and uniform splicing systems with different initial strings and combination of restriction enzymes will be discussed. Applications of automata theory on some molecular examples of null-context and uniform splicing languages will also be presented in this paper.
Multiple Linear Regression to Forecast Balance of Trade
Authors: Omar Gan Sarimah , Ahmad Sabri
Published: October 2017

The main objective of this study is to build a regression model by using multiple linear regression (MLR) analysis. MLR will be used when there are two or more controlled variables involved in the relationship. There are four general steps in building a regression model which are checking assumptions, selecting suitable methods of MLR, interpreting the output and selecting the best MLR model. The objective will be evaluated by using a time series data that have been obtained from Monthly Statistical Bulletin Sabah, Department of Statistics Malaysia, Sabah which is from year 2003 to 2009. The monthly data of external trade in Sabah in term of import and export totals for seven years will be analysed by using Statistical Package for the Social Sciences (SPSS) Statistics Version 17.0. Balance of trade for year 2011 and above can be forecasted through the regression model that has been developed by using MLR analysis.
Synthesis and Characterization of alumina nanofiber reinforced Poly ether ether ketone (PEEK)
Authors: Tg Kamaruddin Tg Mahizatulazwa , Kong Yong Liew , Noordin Mohd Ridzuan
Published: October 2017

The effects of reinforcing Poly ether etherketone (PEEK) with alumina nanofiber have been studied. The nano-composites were prepared by first dispersing the fibre in solvent and then undertaking the synthesis of PEEK. Nanocomposite materials with 1wt.%, 2.5wt.% and 5wt.% of alumina nanofiber have been prepared successfully by dispersing the alumina nanofiber in Sulfolane as solvent and upon sonication for 30 minutes. Transmission electron microscopy and scanning electron micrographs indicated excellent dispersion and interactions between PEEK matrixes with the added alumina nanofibers. Differential scanning calorimeter shows changes in melting and crystallization point and degree of crystallinity for 1wt.% nanocomposites. The result also indicated that alumina nanofiber serves as nucleating agents in PEEK nanocomposites. The X-ray diffractogram data indicated that the crystallinity of the PEEK nanocomposites was highest for 1wt.% alumina nanofiber. The thermogravimetry analysis, shows that thermal stability for alumina nanofiber/PEEK nano-composites was enhanced compared to that of the pure PEEK.
Molecular Dynamics Folding Simulation of β-hairpin Protein (1E0Q)
Authors: Mazlan Nur Shima Fadhilah , Ahmad Khairudin Nurul Bahiyah
Published: October 2017

The structure and trajectories of the mutant peptide of ubiquitin (PDB ID: 1E0Q) has been studied using Molecular Dynamics (MD) simulation. The simulation was performed using AMBER 11 utilizing force field 99 for 50 ns at constant temperature 325 K. The purpose of this study is to investigate the protein folding pathway of protein 1E0Q. In this simulation, the protein 1E0Q has folded into its near native β-hairpin structure within 5 ns. The RMSD value as compared to the NMR structure from the first residue to 17 residues is 2.17 Å. It has been observed that Gly 10 had been responsible to promote β-turn which caused the structure to turn into β-hairpin. In secondary structure analysis, it is shown that the residue from Thr 6 to Lys 11 has formed a bend in the structure. Two beta strands has also been found comprising residues Glu 2 to Lys 5 and Ile 13 to Glu 16.
Antioxidant Activity, Phenolic, Flavonoid and Tannin Content of Piper Betle and Leucosyke Capitella
Authors: Sundang Murni , Syed Nasir Sharifah Norfarahani , Sipaut Coswald Stephen , Othman Hasnah
Published: October 2017

Piper betle and Leucosyke capitella are plants that are commonly used as traditional medicine. In this study, antioxidant Activity, Phenolic, Flavonoids and Tannin content of these plants were evaluated. The plants were extracted using petroleum ether, acetone and methanol. The total phenolic, flavonoid and tannin extract of both plants is in the order of acetone > methanol > petroleum ether. The result shows that the total phenolic, flavonoid content for Piper Betle and Leucosyke Capitella is in the range of 31.25 to 47.48 mg/g and 1.68 to 7.19 mg/g, respectively. For Piper betle, the total flavonoid content is in the range of 29.58 to 46.08 mg/g and for Leucosyke capitella is in the range of 1.08 to 6.83 mg/g. It is also found that Piper betle extracted with methanol has higher antioxidant activity than vitamin E, butylated hydroxytoluene (BHT) and catechin but lower than quercetin.
Field-induced Director Alignment of MCM-41/liquid crystals
Authors: Wai Loon Leaw , Mamat Che Rozid
Published: October 2017

We report on the random disorder effect of MCM-41 on the order of the 3β-DOXYL-5α-cholestane (CLS) spin probe in the ZLI-4792 liquid crystal using Electron Spin Resonance (ESR) technique. In different MCM-41 concentrations, the temperature dependence of the director orientational order parameter,
Removal of Lead from Aqueous Solution by Adsorption using Magnesium Aluminium Hydrogenphosphate Layered Double Hydroxides
Authors: Hamzah Zaini , Ab Rahman Mohd Najif , Yasin Yamin , Sumari Siti Mariam , Saat Ahmad
Published: October 2017

Layered double hydroxide with molar ratio of 4 (MAN 4) was synthesized by co-precipitation and followed by hydrothermal method. The compound was then later going through ion exchange with K2HPO4 for 48 hours to produce MgAlHPO4 (MAHP 4). The solid produced were characterized using X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). Adsorption of lead solution by MAHP 4 was carried out using batch experiment by mixing the lead solution and the solid of layered double hydroxide. The effects of various parameters such as contact time, pH, adsorbent dosage and initial concentration were investigated. The optimum pH for lead removal was found to be at pH of 5 and the optimum time of lead removal was found at 2 hours. The isotherm data was analysed using Langmuir and the correlation coefficient of 0.998 was obtained. The maximum adsorption capacity, Qo (mg/g) of 500 mg/g was also recorded from the Langmuir isotherm. The remaining lead solution was determined by using EDXRF (Energy Dispersive X-Ray Fluorescence spectrometry) model MiniPal 4 (PAN analytical). The results in this study indicate that MAHP 4 was an interesting adsorbent for removing lead from aqueous solution.
Depth Profile of 137Cs Fallout in Soil in Cameron Highlands
Authors: Hamzah Zaini , Amirudin Che Yasmin , Saat Ahmad
Published: October 2017

137Cs is one of the important man-made radionuclide introduced into the environment through nuclear weapons testing and nuclear accidents. In Cameron Highlands meaningful activity concentration of 137Cs radionuclide has been measured. The present study embarked on the determination of 137Cs activity concentration in soils of the sloping area. This would enable the distribution profile in the soil be investigated. Soil profile samples were collected by using scrapper plate in the sloping area which covers top, centre and bottom of the hills and a core in the forest for comparison purpose. The scrapper is 40 cm long and able to obtain slice of 2 cm interval of soil with diameter of 15.2 cm. Soil samples were oven dried, ground, sieved, homogenize and seal properly into a plastic container. The 137Cs activity concentration was measured by using low background coaxial hyper pure germanium detector gamma spectrometer based on 137Cs 661.66 KeV gamma ray. Results showed there were trend of low activity on the top of the hill and subsequently increases downhill. In all location, two trends of profiles were observed starting from the depth of 0 cm to 18 cm and 18 cm to 30 cm which indicating the presence of two sources of 137Cs. The 137Cs activity concentrations range detected at top location was from 0.05 Bq/kg to 1.53 Bq/kg, centre was 0.22 Bq/kg to 2.11 Bq/kg, bottom was from 0.00 Bq/kg to 2.03 Bg/kg and forest was 0.00 Bq/kg to 0.96 Bq/kg. The basic parameters of the soil such as pH (top; 3.72, centre; 4.26, bottom; 4.02), density (top; 1.45 g/m3, centre; 1.41 g/m3 , bottom; 1.59 g/m3 ) and organic matter content (top; 17.08 %, centre; 16.75 %, bottom; 20.32 %) also being tested. These results show that the relative activity concentration of 137Cs at the top is lowest, while at the bottom is highest, representing the presence of downward transport. However, identical pattern of profiles were observed at the three points of the slopes.
Numerical Conformal Mapping of Unbounded Multiply Connected Regions onto Circular Slit Regions
Authors: Yunus A.A.M. , Murid A.H.M. , Nasser M.M. S.
Published: October 2017

This paper presents a boundary integral equation method for conformal mapping of unbounded multiply connected regions onto circular slit regions. Three linear boundary integral equations are constructed from a boundary relationship satisfied by an analytic function on an unbounded multiply connected region. The integral equations are uniquely solvable. The kernels involved in these integral equations are the classical and the adjoint generalized Neumann kernels. Several numerical examples are presented.
Effect of porosity on GaN for hydrogen gas sensing
Authors: Zarzali Shah Aishah , Mohd Noor Nurul Huda , Hassan Zainuriah , Mahmood Ainorkhilah , Kwong Yam Fong
Published: October 2017

Porous wide bandgap semiconductors have been widely studied in the last decade due to their unique properties compared to the bulk crystals. The high surface area, shift of bandgap, luminescence intensity enhancement and efficient photoresponse when porosity is formed can be tailored to fabricate new sensing devices. In this work, porous GaN was prepared by ultraviolet (UV) assisted electroless chemical etching method. The commercial Si doped n-type GaN film grown on two inches diameter sapphire (0001) substrate with GaN thickness of 5.5 μm was used in this study. The wafer was then cleaved into few pieces, and these samples were etched in HF:H2O2:CH3OH under UV illumination for 60 minutes. The structural properties was characterized using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Hydrogen sensor was subsequently fabricated by depositing Pt Schottky contact onto the porous GaN sample. The effect of sensing dilute H2 gas with different concentration which is 1% and 2% H2 in a N2 gas ambient was analyzed. The Schottky barrier height of the gas sensor samples was reduced upon exposure to gas. The porous GaN resulted better sensitivity compared to the as grown GaN sample in H2 gas sensing
Hydrophobic silica thin films by sol-gel processing and spin coating technique at low temperature
Authors: Abu Bakar Nurul Huda , Deraman Karim , Hussin R. , W. Shamsuri W. Nurulhuda , Mansor Faizal , Ibrahim Zuhairi , Ismail Bakar
Published: October 2017

Hydrophobic silica thin films were prepared by sol-gel processing and self-assembly by chemical vapor reaction with Trimethylchlorosilane (TMCS) at low temperature. The sols were divided into Sol A with ethanol, Polyethylene glycol (PEG) and water (H2O) while Sol B were contain precursor of silica Tetraethylorthosilicate (TEOS) hydrolyze with ethanol which was stirred for 15 minutes. HCl was added into the mixture and stirred for another 10 minutes. After deposition on 1 x 1 cm corning glass using spin coating technique (two-step timer), the films were heated at 60˚C for 10 minutes and finally annealed at 150°C for 1 hour. The films were characterized by using Rudolph/Auto EL Ellipsometer, Shimadzu Spectrophotometer, Perkin Elmer Fourier Transform Infrared (FTIR) and Atomic Force Microscope (AFM). The results showed that the films thickness and refractive index were in the range of 105.2 to 112.4 nm and 1.35 to 1.38, respectively. The films were transmitted 70-80% of light (in visible range) with various bondings of C-H, Si-O-Si, Si-C and Si-OH. Surface roughness of the films was increased from 30.6 nm (silica thin film) to 140.5 nm (hydrophobic silica thin films) after modification have been done on the films by using TMCS (heated at 40˚C). It was found that the water contact angles increased when time of reaction increased from 109° to 124°.
Worker’s behaviour in manufacturing industry: An evidence from a minimum spanning tree
Authors: Sharif Shamshuritawati , A. Djauhari Maman
Published: October 2017

A manufacturing industry contributes around 10% Malaysian economic. It provides economic opportunities for related industries and business. However, the number of accidents in manufacturing sector, including fatal accidents, has been increased from time to time. We analyze worker’s behaviour to understand the real situation. The method developed in econophysics has been used to transform the correlation structure into sub-dominant ultrametric structure. Its corresponding minimum spanning tree and the centrality measure are performed in order to identify the most influential variables.
Stock Networks Analysis in Kuala Lumpur Stock Exchange
Authors: Siew Lee Gan , Abdurachman Djauhari Maman
Published: October 2017

This paper deals with an analysis of correlation structure among stocks traded in Kuala Lumpur Stock Exchange (KLSE) by using network analysis approach. The minimum spanning tree (MST) related to that correlation structure will be presented to have a better understanding about stocks topological network. An overall centrality measure will be introduced to filter the economic information contained in the MST. This measure will give additional economic information that cannot be delivered by the conventional centrality measures such as degree centrality, betweenness centrality, closeness centrality and eigenvector centrality.
The Precise Value of Commutativity Degree in Some Finite Groups
Authors: Moradipour Kayvan , Sarmin Nor Haniza , Erfanian Ahmad
Published: October 2017

The commutativity degree of a finite group
Estimating Proportional Hazards Model Using Frequentist and Bayesian Approaches
Authors: Mohamed Ismail Noraslinda , Mohd Khalid Zarina , Ahmad Norhaiza
Published: October 2017

In statistics, the proportional hazards model (PHM) is one of a class of survival models. This model estimates the effects of different covariates influencing the time-to-event data in which the hazard function has been assumed to be the product of the baseline hazard function and a non-negative function of covariates. In this study, we investigate the hazard function, also known as the risk function or intensity function, which is employed in modelling the survival data and waiting times. The model parameters can be estimated via frequentist or Bayesian approach. However, the Bayesian approach is well known to have the advantages over frequentist methods when the data are small in size and involve censored individuals. In this paper, the PHM for right-censored data from Bayesian perspective will be discussed and the Markov Chain Monte Carlo (MCMC) method will be used to estimate the posterior distributions of the model parameters using Leukemia data.
Splicing Systems over Permutation Groups of Length Two
Authors: Hamzah N.Z.A. , Mohd Sebry N.A. , Fong W.H. , Sarmin N.H. , Turaev S.
Published: October 2017

The first theoretical model of DNA computing, called a splicing system, for the study of the generative power of deoxyribonucleic acid (DNA) in the presence of restriction enzymes and ligases was introduced by Head in 1987. Splicing systems model the recombinant behavior of double-stranded DNA (dsDNA) and the enzymes which perform operation of cutting and pasting on dsDNA. Splicing systems with finite sets of axioms and rules generate only regular languages when no additional control is assumed. With several restrictions to splicing rules, the generative power increase up to recursively enumerable languages. Algebraic structures can also be used in order to control the splicing systems. In the literature, splicing systems with additive and multiplicative valences have been investigated, and it has been shown that the family of languages generated by valence splicing systems is strictly included in the family of context-sensitive languages. This motivates the study of splicing systems over permutation groups. In this paper, we define splicing systems over permutation groups and investigate the generative power of the languages produced.