bluuebunny/crossref_metadata_2025 huggingface dataset:
The Pumping Parameters for Er-Doped Tellurite Glass
Authors: Sharip N. , Daud M.R. Sahar Y. , Tamuri A.R.
Published: February 2014

Erbium doped tellurite glass rod of the 78.5 TeO2 20 ZnO 1.5 Er2O3 where has successfully been fabricated as lasing medium and have been investigated by means of their properties needed in lasing application. The external triggering method is used to generate high peak current in several microsecond pulse duration. The external triggering circuit design consists of power supply, discharge capacitor, control unit, pulse forming network and ignition circuit. This driver operates in single mode pulse that can be adjusted corresponding to the controller which can vary from 650V to 1000V. The operation is started initially with an external trigger pulse which is the voltage pulse of 8kV with pulse duration 20.0μs. The connection operated by trigger thrystor (SCR) as a switch and ionized gaseous inside the lamp. After the gaseous breakdown, the current from the capacitor flows continuously through the flashlamp. The output current is initially increased proportion in order to the input energy. Maximum value of peak current flashing at 888A with higher input energy, while, the increasing voltage is not linearly increased with the input energy. From the plotted graph of current and voltage, V-I, shows a nonlinear relationship with the electrical input energy. The developed flashlamp driver has produced about 87% in efficiency while another 13% is lost in the circuit resistance. Flashlamp radiation is detected by using spectrometer in the range of 200nm to 1000nm. The beam is used to excite the erbium glass medium and a coherent beam of 1550nm wavelength is produced.
Absorption Spectra of Neodymium Doped Tellurite Glass
Authors: Mat Jan Nur Amanina , Sahar M.R. , Ghoshal Sib Krishna , Ariffin R. , Rohani M.S. , Hamzah K.
Published: February 2014

Modifying the optical and structural properties of tellurite glasses by controlling rare earth doping is an important issue. Neodymium doped magnesium-tellurite glasses of composition TeO2-MgO-Na2O with concentration from 0.5 to 2.5 mol% were synthesized by conventional melt-quenching technique. The amorphous natures of the glass were confirmed from x-ray diffraction (XRD) pattern. The absorption spectra (exhibits five bands) were recorded to determine the optical energy gap and Urbach energy. The values of the optical band gap are found to lie between 3.04-3.20 eV, while the Urbach energy values varies are between 0.21-0.12 eV. The optical energy gap for indirect forbidden transition has increased whereas the values of Urbach energy have decreased with the increasing of Nd2O3 content. The structural and optical properties were found to be strongly affected by the varying concentration of Nd3+ ions.
Fractal Analysis of Morphological Image of Organic Phthalocyanine Tetrasulfonic Acid Tetrasodium (TsNiPc) Film
Authors: Kong Yeo Lee , Muniandy S.V. , Fakir M.S. , Sulaiman K.
Published: February 2014

Surface morphology of thin films can be efficiently characterized using power spectral density method. Spectral based parameters from surface models can then be linked to electrical conductivity of thin films used for fabricating organic photovoltaic devices. In this study, the surface morphologies of the organic thin films phthalocyanine tetrasulfonic acid tetrasodium (TsNiPc) are investigated using atomic force microscopy. The thin film samples are imaged at 40-minutes and 120-minutes after the solvent treatment. The spectral exponent β is determined from the slope of PSD log-log plot and the fractal dimension D of each film is calculated based on fractal relation β = 8 2D. The relationship between surface roughness and fractal dimension with respect to electrical properties of thin film is discussed.
Plasma Pre-Treatment of Polyethylene Terephthalate Substrate Influence on the Properties of ZnO Thin Film
Authors: Tho Seiw Yen , Ibrahim Kamarulazizi
Published: February 2014

In this work, the influences of plasma pre-treatment on polyethylene terephthalate (PET) substrate to the properties of ZnO thin film have been carried out. ZnO thin films were successfully grown on PET substrate by spin coating method. In order to study the effects of plasma pre-treatment, a comparison of treated and untreated condition was employed. Water contact angle measurement had been carried out for PET wettability study prior to ZnO thin film coating. Morphology study of ZnO thin film was performed by scanning probe microscope (SPM). Besides, optical study of the ZnO thin film was done by using UV-vis spectrophotometer. All the measured results show that plasma pre-treatment of PET substrate plays an important role in enhancing the wettability of PET and optical properties of the ZnO thin films. In conclusion, pre-treatment of PET surface is essential to produce higher quality ZnO thin film on this particular substrate in which would pave the way for the integration of future devices.
Calculation of Confined Electron and Hole States in a Strained InAs-GaAs Pyramidal Quantum Dot System Based on Effective Mass Approximation
Authors: Ripan Gregory Henry , Woon Chin Y. , Gopir Geri , Othman Ahmad Puaad
Published: February 2014

Computational studies on zero dimensional semiconductor structure have been centred on typically produced quantum dot of various geometries namely pyramidal and lens with lateral sizes ranging from 10 nm to 24 nm. In the case of an epitaxially grown quantum dot, strain plays another essential role apart from its size and shape in determining its electronic properties [. Among the most studied strained structures is the self-assembled InAs quantum dot capped by a GaAs matrix. A study by [ on InAs pyramidal quantum dot predicted no confined electron states for quantum dot with base lengths 6 nm and below. Nevertheless, a calculation by [3] based on atomistic psedudopotential predicted at most two confined states for both electron and hole in a self-assembled InAs-GaAs quantum pyramid system of base length 6.06 nm.
Magnetic Ground State and Electronic Structure Calculations of PbMnO3 Using DFT
Authors: Subramanian Sathya Sheela , Natesan Baskaran
Published: February 2014

Structural optimization, magnetic ground state and electronic structure calculations of tetragonal PbMnO3 have been carried out using local density approximation (LDA) implementations of density functional theory (DFT). Structural optimizations were done on tetragonal P4mm (non-centrosymmetric) and P4/mmm (centrosymmetric) structures using experimental lattice parameters and our results indicate that P4mm is more stable than P4/mmm. In order to determine the stable magnetic ground state of PbMnO3, total energies for different magnetic configurations such as nonmagnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) were computed for both P4mm and P4/mmm structures. The total energy results reveal that the FM non-centrosymmetric structure is found to be the most stable magnetic ground state. The electronic band structure, density of states (DOS) and the electron localization function (ELF) were calculated for the stable FM structure. ELF revealed the distorted non-centrosymmetric structure. The band structure and DOS for the majority spins of FM PbMnO3 showed no band gap at the Fermi level. However, a gap opens up at the Fermi level in minority spin channel suggesting that it could be a half-metal and a potential spintronic candidate.
DFT Investigations of the Optical Properties of Gallium Arsenide
Authors: Anua N. Najwa , Ahmed R. , Shaari A. , Bakhtiar Ul Haq , Binti Mohamad Mazmira
Published: February 2014

Gallium Arsenide (GaAs) because of having unique characteristics like direct band gap, higher electron mobility and saturated electron velocity etcetera, has wide applications specifically in optoelectronic devices. In this research work we present a comprehensive density functional theory (DFT) based first principles study of optical properties of GaAs. Exchange correlation functional (XC) play a key role in the DFT investigations. A comparative study of the optical properties is presented based upon local density approximation (LDA) by Perdew and wang, Perdew-Burke-Ernzerhof parameterized generalized gradient approximation (GGA-PBE), Wu-Cohen parameterized GGA (GGA-WC) and Engel and Vosko proposed GGA (GGA-EV). Computations in this study have been performed by full potential (FP) linearized augmented plane wave (LAPW) plus local orbitals (lo) approach designed within DFT as realized in the computational code WIEN2k. Our investigations, for the optical properties of GaAs with mentioned XC potentials, cover detailed analysis of dielectric functions, absorption coefficient α (ω), energy loss functions, reflectivity R(ω), refractive index n (ω) and extinction coefficient k (ω). The analysis shows that the optical parameters calculated with GGA-PBE are comparatively reasonable and closer to the experimental results.
Keywords: Density functional theory, local density approximation, gradient and other corrections, APW calculations, Dielectric function, absorption and reflection spectra
PACS: 71.15.Mb, 71.15.Ap, 77.22.Ch, 78.40.Pg
Temperature Dependent DC and RF Performance of n-GaN Schottky Diode: A Numerical Approach
Authors: Munir Tarriq , Abdul Aziz Azlan , Abdullah Mat Johar , Ain Mohd Fadzil
Published: February 2014

This paper reports the temperature dependent DC and RF characteristics of n-GaN Schottky diode simulated using Atlas/Blaze developed by Silvaco. It was found that as the temperature increases from 300K to 900K the forward current decreases due to lowering of the Schottky barrier with an increase in series-resistance and ideality factor. These observations indicates that tunneling behavior dominates the current flow rather than thermionic emission. Furthermore, the breakdown voltage decreases in reverse bias and insertion loss for RF behavior increases with respect to temperature due to the increase in capacitance near diode junction.Keywords: Atlas/Blaze, Schottky barrier, series resistance, ideality factor, insertion loss.
Formation and Optical Studies of Porous GaN Thin Films via UV-Assisted Electrochemical Etching Approach
Authors: Cheah Sook Fong , Ng Sha Shiong , Yam Fong Kwong , Haslan Abu Hassan , Zainuriah Hassan
Published: February 2014

This paper presents the investigation of porous gallium nitride (PGaN) thin films by ultra-violet (UV)-assisted electrochemical etching at various etching durations. The etching process was performed in potassium hydroxide aqueous solution under illumination of 150 W xenon lamp. The surface morphology and cross-section of the PGaN thin films were examined by scanning electron microscopy. Increased etching duration resulted in a more homogeneous pore distribution. Results showed that the etching duration strongly influences the layer characteristic of porous structure. Infrared (IR) and Raman studies were performed to investigate the optical properties of PGaN. IR spectroscopy revealed that the PGaN thin films exhibit distinctive IR spectra as compared to the as-grown GaN thin film. The number of interference fringes in the non-reststrahlen band is correlated to the film thickness of as-grown and PGaN thin films. The Raman measurements clearly reveal two forbidden optical phonon modes observed in all the PGaN thin films. This result indicates the crystal disordering in the films. Additionally, the findings show that the intensity of these forbidden modes becomes stronger with increasing etching duration.
Interface-Induced Modifications of Polarization in Nanoscale Ferroelectric Superlattices
Authors: Lim Kok Geng , Chew Khian Hooi
Published: February 2014

A thermodynamic model to study the effect of interface intermixing on polarization of ferroelectric superlattices composed of a ferroelectric and paraelectric layers is developed. Interface intermixing forms an intermixed layer with property different from its individual layers, leading to inhomogeneous ferroelectric properties in the superlattices. Polarization induces near the interface of paraelectric layers, which extends into the layer over a distance governed by its characteristic length. Dependence of polarization on periodic thickness indicates an interface-induced modification of ferroelectricity in superlattices. Enhancement in polarization of superlattices is shown to be possible, if certain interface property and periodic thickness met.
Morphological Distinctions on CdSe QDs Synthesized via Auto Clave and Organometallic Route
Authors: Ahamefula Ubani Charles , Sulaiman M.Y. , Ibrahim Zahari , Ibrahim N.B. , Othman M.Y. , Lim C.H.
Published: February 2014

Quantum dots (QDs) semiconductors exhibit size-dependent Opto-electronic properties and customizable bandgaps that can be engineered to match the solar spectrum [. Organometallic synthetic approach relies on the injection of organometallic precursor into a pyrolyphic mixture at elevated temperature sufficient enough to initiate particle growth. This approach entails precise control of temperature gradient [. Organometallic reagents injected into a heated non-coordinating octadecene (ODE) were compatible with oleic acid (OA) that was used to protect the CdSe QDs against oxidation and emission loss. ODE is stable in air and has a low melting point (below 20 oC) making it easier to be handled at room temperature. Its high boiling point (about 360 oC) coupled with its inert nature, less toxicity, low cost and good dissolving power makes it an ideal solvent for the growth of CdSe QDs [3,4,5 and 6]. However, QDs synthetic methods differ and relies on how the thermodynamic properties of the reactant mixtures are varied. QDs nucleation growth depicted the underlying processes occurring in aqueous solution and the need to control thermodynamic variables such as reaction time and temperature of the reactants as well as non-thermodynamic variable such as stirring speeds.
Nanoscale Growth of CdS and PbS Semiconductor within Calix[4]Arene Langmuir-Blodgett LB Film for Ion Sensing Application
Authors: Supian Faridah Lisa , Richardson Tim H. , Nabok Alexei V. , Deasy Mary , Azmi M. Syahriman M.
Published: February 2014

The characteristics of cadmium sulphide (CdS) and lead sulphide (PbS) nanoparticles, grown inside Langmuir-Blodgett (LB) multilayer films of 5,11,17,23-tetra-tert-butyl-25,27-dicarboxymethoxy-26,28-dihydroxycalix [arene (I), have been studied using ellipsometry, UV-visible spectroscopy, and transmission electron microscopy (TEM). Multilayer films were formed by transferring a floating Langmuir monolayer of I onto substrates using LB deposition and water subphase containing Pb2+ or Cd2+ ions. The nanoparticles were fabricated by exposing cadmium-or lead-containing multilayer films of I (20-80 monolayers thick) to hydrogen sulphide (H2S) gas for 12 hours. By Gaussian fitting of the absorbance - energy spectra, the size of the clusters and their dispersion were found to be 1.43±0.18 nm and 1.21±0.05 nm for CdS and PbS respectively. This is the first time that such thick LB films of an amphiphilic compound possessing such high thermal stability (m.pt. ~270°C) have been used as the vehicle for the formation of CdS and PbS semiconductor particles.
Theoretical Studies of InGaN/GaN Multiple Junction Solar Cell with Enhanced Tunneling Junction Diode
Authors: Hussain Shahzad , Ali Ghulam , Mehmood Haris , Omar Muhammad , Zaidi Tahir
Published: February 2014

Recent developments in the growth of InGaN layers made it possible to grow a heavily doped p-type layer with Indium concentration up to 40%. In this work, a tunnel junction based on these developments has been designed with the use of Silvaco TCAD. This diode introduces a low resistive path to the current carriers, effectively adds voltages and encounters the parasitic effects of the stacked sub-cells. A double-junction solar cell is designed based on our interfacing tunnel diode and simulated results are presented in this paper. Remarkable results are achieved comparing to the existing InGaN based multijunction solar cells. A high Voc of ~3.1V and conversion efficiency greater than 17.5% has been achieved under AM 1.5. This paper also highlights and discusses the challenges in fabrication of such a highly efficient solar cell.
Properties of Pt Schottky Contact on Porous In0.27Ga0.73N Thin Film Revealed from I-V Measurements
Authors: Abud Saleh H. , Hassan Zainuriah , Yam F.K. , Ahmad Mohd Anas
Published: February 2014

The electrical properties of a Pt Schottky contact on porous In0.27Ga0.73N/GaN/AlN/Si (111) thin film that was grown via the plasma-assisted molecular beam epitaxy technique were reported. Porous film nanostructure was synthesized using the electrochemical etching technique at a current density of 25 mA/cm2. The formed pores were dissimilar in terms of size and shape. The effects of annealing temperature and applied bias on Schottky contact for porous sample were investigated by current-voltage (IV) measurements in ambient illumination. The barrier height and ideality factor were determined. The Pt Schottky contact exhibits thermal stability during annealing. Schottky barrier height increased when each of the annealing temperature and bias voltage were increased.
Effects of Nitridation Temperatures on Gallium Nitride Thin Films Formed on Silicon Substrates
Authors: Fong Chee Yong , Ng Sha Shiong , Yam Fong Kwong , Haslan Abu Hassan , Zainuriah Hassan
Published: February 2014

In this article, GaN thin films were successfully grown on p-type silicon (p-Si) substrates with orientation (100) through spin coating method followed by nitridation in ammonia ambient at various temperatures (750 °C, 850 °C, and 950 °C). The morphology of the GaN thin films were performed by using field-emission scanning electron microscopy. The results showed that the grain size increases with increasing nitridation temperature from 750 °C to 950 °C. Optical analysis of the GaN thin films was performed using Fourier transform infrared spectroscopy. It was confirmed from the results that the reflectance intensity of the transverse optical and longitudinal optical phonon modes of wurtzite GaN increases with increasing nitridation temperature. All the measured results show that nitridation temperature plays a very important role in improving the quality of the GaN thin films. Finally, the results revealed that the 950 °C was the optimal growth nitridation temperature for synthesizing GaN thin film.
Nonsurfactant Surface Modifications of Monodispersed Si-Cu Core-Shell Nanocomposite
Authors: Salim Musdalilah Ahmad , Misran Halina , Othman S.Z. , Shah N.N.H. , Razak N.A.A. , Mahbor K.M.
Published: February 2014

Monodispersed silica spheres with particles size of ca. 450 nm were successfully synthesized using modified Stöber method. The synthesized monodispersed silica spheres were successfully coated with copper through modified sol-gel method employing nonsurfactant template and catalyst. A renewable nonsurfactant template, decyl-alcohol (C10) and catalyst were used to modify the silica surfaces prior to coating with copper. In order to study the effect of catalyst on copper deposition onto silica surfaces, ammonia was used as catalyst in various amounts. The X-ray diffraction patterns of Si-Cu core-shell exhibited a broad peak corresponding to amorphous silica networks and exhibited monoclinic CuO phase. It was found that samples modified in the presence of 1 ml catalyst exhibited relatively homogeneous deposition. The surface area of uncoated core (SiO2) was at ca. 7.04 m2/g and coated samples 1 ml catalyst was at ca. 8.21m2/g.
Electrical Resistivity of Fe-Bearing Sn1Ag0.5Cu Lead-Free Solder Alloys
Authors: Mohd Amin Nur Aishah Aminah , Shnawah Dhafer Abdul Ameer , Mohd Sabri Mohd Faizul , Said Suhana Binti Mohd
Published: February 2014

This paper reports on the effect of Fe addition in the range of 0.1 wt.% to 0.5 wt.% on the electrical resistivity of the Sn-1Ag-0.5Cu (SAC105) solder alloy. The electrical resistivity is characterized by the four-point probe technique. Results showed that the Fe-bearing SAC105 solder alloys exhibit lower electrical resistivity compared with the standard SAC105 solder alloy. Moreover, the electrical resistivity further decreases with increasing the amount of Fe addition. As Fe is a low-cost and non-hazardous element, along with the high mechanical reliability, the Fe-bearing SAC105 solder alloys also demonstrate good electrical characteristics, and hence may be an attractive candidate for a low cost, reliable formulation for lead free solders in electronics packaging.
Properties of Calix4-Lead(Pb) Films Using Langmuir-Blodgett (LB) Technique as an Application of Ion Sensor
Authors: Azahari Noor Azyyati , Supian Faridah Lisa , Richardson Tim H. , Malik Syed Abdul
Published: February 2014

Calixarenes are promising compounds to be used as ionophores and for molecular recognition. Their ability to form Langmuir and Langmuir-Blodgett (LB) films is of great interest in order to obtain small sensor devices which incorporate an active nanometric film. Calix[4]arene (Calix4) has been used in this work and its ability to form Langmuir films has been shown. Calix4 forms monolayers but at higher compressions tends to form multilayers. The presence of ions in the subphase, as lead chloride salt solutions, leads to some changes in the surface pressure-area (П-A) isotherms and surface potential-area (ΔV-A) isotherms. The effective dipole moments (μ) of the calixarene molecules in the uncomplexed and complexed states has been calculated from the ΔV values by using Helmholtz equation. Some characteristics of the films and mean molecular area have been deduced from the isotherms graph.
Properties of Rare-Earth Substitution in Bi(Pb)-2223 Superconductor Prepared by Coprecipitation Method
Authors: Hawa Jamil Siti , Hashim Azhan , Yahya S.Y.S. , Kasim Azman , Hidayah Hassan Nurul , Norazidah Abd Wahab
Published: February 2014

The superconducting and structural properties of pure and rare-earth elements substituted in Bi (Pb)-2223 samples were investigated. All samples were fabricated by the oxalate coprecipitation (COP) method using metal acetates and oxalic acid as starting materials. The electrical and resistivity were measured by using the four-probe method, while phase purity and microstructural examination were performed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM). The pure sample has a critical temperature of (Tc zero) 100 K, which decreased to 98, 96 and 97 K for the Eu, Dy and Yb samples, respectively. At 77 K, the un-doped sample gives the highest Jc, which gradually decreases with rare-earth substitution as one move towards the right in the lanthanide series. XRD results reveal two main phases (Bi-2223 and Bi-2212) with decreased amounts of Bi-2223 phases by rare-earth substitution. SEM micrographs showed flaky grains but Yb showed better grain alignment compared with the other substitutions.
Effect of Pr-Substitution in Eu1-xPrxBaSrCu3O7-δ on the Superconductivity and Transport Properties
Authors: Nik-Jaafar Nor Azah , Abd-Shukor Roslan , Kong Wei
Published: February 2014

The effect of Pr-substitution at the Eu-site on the superconductivity and transport properties in Eu1-xPrxBaSrCu3O7-d (x = 0.0, 0.1, 0.2, 0.4, 0.5) has been investigated. Tc onset for x = 0.0, 0.1, 0.2, 0.4, 0.5 are 86 K, 75 K, 65 K, 38 K, 27 K, respectively. The critical temperature (Tc) decreased linearly with increase in Pr concentration x indicating a magnetic pair-breaking mechanism. The transport critical current density (Jc) decreased with increasing x. Analysis of the structure of the samples via X-ray powder diffraction (XRD) technique showed transformation from orthorhombic to pseudo-tetragonal structure at x = 0.2. Scanning electron microscope (SEM) showed no variation in the microstructure.
Optical Properties of Zn-Doped CeO2 Nanoparticles as a Function of Zn Content
Authors: Nurhasanah Iis , Sutanto Heri , Futikhaningtyas Ririn
Published: February 2014

CeO2 and Zn-doped CeO2 nanoparticles were synthesized by simple precipitation method in water/isopropanol mixed solvent from cerium nitrate and zinc nitrate with various mole ratios. The precipitates were then calcined at 300°C for 4 hours and characterized by X-ray diffraction (XRD) and uv-vis spectroscopy. Characterization by x-ray diffraction shows that high crystallinity of cubic fluorite structure of CeO2 with crystallite size in the range 6 12 nm depending on Zn content. CeO2 nanoparticles exhibits tranparent in the visible region and strong absorbance in the ultra-violet region. It was also found that significant effect of Zn content on transmittance and optical band gap. In addition, Zn substitution into Ce suppressing photocatalytic activity of pure CeO2 nanoparticle under sunlight irradiation. These results suggest that Zn-doped CeO2 nanoparticle is more prommising for safer optical UV-absorbers.
Copper-Zinc-Titania Nanocomposite as Catalyst for CO2 Photo-Reduction: A Surface Deactivation Study
Authors: Zuas Oman , Krisnandi Yuni Krisyuningsih , Wibowo Widayanti , Kim Jin Seog , Gunlazuardi Jarnuzi
Published: February 2014

In this paper, a surface deactivation study of Cu1.0-Zn0.5-Ti98.5 oxide nanocomposite (CZT-ONC) as catalyst for photo-reduction of CO2 in aqueous solution is reported. The photo-reduction experiments were conducted through five experimental cycles. The results demonstrated that the activity of the CZT-ONC decreased by increasing the number of testing cycle. The causes for declining the activity of the CZT-ONC catalyst was studied by investigating the surface condition of the catalyst before and after used by mean X-ray photoelectron spectroscopy (XPS) and field emission-scanning electron spectroscopy (FE-SEM) techniques and the results are discussed. It was found that the surface conditions (chemical state of the elements and morphology) of the CZT-ONC catalyst have been critically altered. Change in surface condition pointed that the deactivation process on the surface of the CZT-ONC was occurred and it could be considered to be the reasons for declining of the activity.
Enrichment of Indonesian Low Rank Coal's Surface Oxygen Compounds (SOCs) Using Hydrogen Peroxide and its Adsorptive Properties
Authors: Yuliani Galuh , Noviyana Imas , Setiabudi Agus
Published: February 2014

Cheap and highly abundant low rank coal from Banten, West Java, Indonesia, was utilized as an adsorbent for a cationic dye. The previous reports show that raw low rank coal has low adsorption capacity when compared to activated carbon. It is also indicated that the coals surface oxygen compounds played a major role in the adsorption mechanism. This research aimed to enrich the oxygen compounds on the coals surface by a straightforward oxidation process using hydrogen peroxide and to investigate the adsorption capacities of raw and treated coals using cationic dye solutions. The oxidation process was conducted by adding the raw coal in hydrogen peroxide solutions having concentrations of 5%, 10%, and 20%, followed by stirring for 10 minutes to 60 minutes. After a serial of washing processes and air-drying, the adsorption capacities of the treated coals for a cationic dye were investigated using batch tests. The batch tests were conducted by adding 0.1 to 0.3 g of coals to 50 mL of methylene blue solutions followed by stirring the solutions for 5 hours. The experimental data were plotted using Langmuir adsorption isotherm model. The adsorption capacity of a treated coal when plotted using Langmuir isotherm was found to be 103 mg/g, significantly higher than that of the raw coal, which was only 52 mg/g. The FTIR spectra showed new absorption of carboxylates at 1700 cm-1 indicating increases in the oxygen containing groups, whilst the surface area measurement indicated an increase in surface area from 0.097 m2/g to 0.232 m2/g. It is concluded that the treatment using hydrogen peroxide solution has significantly improved the surface oxygen compounds of the low rank coal, increased its surface area and also its adsorption capacity for a cationic dye.
Characteristics of Water-ZrO2 Nanofluids with Different pH Utilizing Local ZrO2 Nanoparticle Prepared by Precipitation Method
Authors: Syarif Dani Gustaman
Published: February 2014

Changing water as the conventional nuclear reactor coolant with nanofluid in order to increase the efficiency of heat transfer in the nuclear reactors becomes a strong need. In this work, a study of synthesis and characterization of ZrO2 nanoparticle and water-ZrO2 nanofluid was done. The ZrO2 nanopowder was synthesized using a precipitation method from ZrOCl2.8H2O (ZOC) that was prepared from local zircon (ZrSiO4) using caustic fusion method with calcination temperature of 800°C. The ZrO2 nanoparticle contained two phases namely cubic and monoclinic with crystallite size of 12 nm measured using Debye Scherrer method. Stability of nanofluids that prepared by mixing the ZrO2 nanoparticle with water depended on pH. The nanofluids with pH less than 5 and larger than 8 were stable. Sedimentation test showed that the Water-ZrO2 nanofluid produced in this study was very stable until at least 9 days. A typical basic nanofluid has zeta potential of about-41 mV and a typical acidic one has zeta potential of +45 mV. Thermal conductivity of the nanofluids was 4-9 % larger than that of water.
Corrosion of Carbon Steel in Nanofluid Containing ZrO2 Nanoparticle at Different Temperature
Authors: Prajitno Djoko Hadi , Syarif Dani Gustaman
Published: February 2014

Corrosion of carbon steel in nanofluid containing 0.1 gpl of ZrO2 nanoparticle at temperature from 25 to 55°C was investigated by using potentiodynamic polarization techniques. The open circuit potential measurements, cathodic and anodic polarization were used to characterize the corrosion behavior of carbon steel. Metallurgical techniques such as optical microscopy and X-ray diffraction (XRD) were used to characterize the alloys before and after corrosion testing. The microstructures of the as received carbon steel exhibited equaxed morphology. While corrosion specimens showed that microstructure of carbon steel alloys relatively unchanged after polarization testing. X ray diffraction examination of carbon steel before polarization represent γ phase and after polarization is still γ phase with minor Fe2O3. The open circuit potentials of carbon steel increase to positive displacement with increasing temperature nanofluids. The results of polarization technique show that corrosion currents increase and therefore corrosion rates become faster with the increase of nanofluids temperature.
Effect of Growth Temperature on Cobalt-Doped TiO2 Thin Films Deposited on Si (100) Substrate by MOCVD Technique
Authors: Saripudin Aip , Saragih H. , Khairurrijal Khairurrijal , Khairurrijal Khairurrijal , Arifin Pepen
Published: February 2014

Co:TiO2 (cobalt-doped titanium dioxide) thin films have been deposited on the n-type Si (100) substrate at the temperatures range of 325°C 450°C using MOCVD (metal organic chemical vapor deposition) technique. We investigated the effect of growth temperature on the structural and morphological quality of Co:TiO2 thin films. The structure of Co:TiO2 thin films were characterized by XRD while the morphology and the thickness of films were characterized by SEM. The XRD results reveal that all films show the anatase structure and the dominant orientation of anatase phase depends on the growth temperature. The grain size of crystal increases as the growth temperature increases. We also reveal that the growth rate of Co:TiO2 film has a maximum value at the growth temperature of 400°C.
Mass Production of Stacked Styrofoam Nanofibers Using a Multinozzle and Drum Collector Electrospinning System
Authors: Munir Muhammad Miftahul , Nuryantini Ade Yeti , Iskandar Iskandar , Suciati Tri , Khairurrijal Khairurrijal
Published: February 2014

Electrospinning offers the unique ability to produce fibers with very small diameters down to a few tens of nanometers and an attractive mechanical appearance as well as the controllability of morphology, surface and pores structure. However, the main drawback of the conventional electrospinning technique is its low productivity. In order to produce high yield nanofibers, the production rate of nanofibers must be improved. The multinozzle and drum collector electrospinning system was then developed to overcome the problem. The multinozzle sub-system was used to increase the production rate of nanofibers while the drum collector was utilized to maintain the uniformity and thickness of stacked nanofibers. A solution prepared by dissolving waste styrofoam in the mixture of tetrahydrofuran (THF), citronella oil and cajuput oil was the precursor to produce the stacked styrofoam nanofibers.
Er2O3-Al2O3 Doped Silica Preform Prepared by MCVD-Chelate Vapor Phase Delivery Technique
Authors: Anuar Khairul M.S. , Muhd-Yasin S.Z. , Zulkifli M.I. , Hanif S. , Yusoff A. , Aljamimi S.M. , Zubair Hassan Tarif , Yusoff Z. , Abdul-Rashid H.A. , Tamchek N.
Published: February 2014

Development of rare earth doped silica fibre fabrication using MCVD furnace chelate vapor phase delivery is presented. In this study, erbium and aluminium is used as the dopant with precursor erbium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionate) and aluminium chloride respectively. The preform was designed for 10 layers of SiO2-P2O3 doped silica (clad structure) and 5 layers of SiO2-Al2O3-Er2O3 (core structure). Preform is analysed for the properties of layer structure i.e. refractive index profile using preform index profiler and EPMA (SEM-EDX) for dopant distribution. Results show good longitudinal uniformity despite condensation of metal organic precursor during the fabrication process. Maximum incorporation of Er2O3 is about 0.1 mole % with 1.5 mole% of Al2O3 in the core.
Wettability Study Using O2 and Ar RIE Gas Treatment on Aluminium Surface
Authors: Retnasamy Vithyacharan , Sauli Zaliman , Palianysamy Moganraj , Taniselass Steven , Ehkan Phaklen , Fuad Fairul Afzal Ahmad
Published: February 2014

Wettability is one of the most important aspects in microfluid technology. The effect of surface roughness on the wettability by a liquid has been studied experimentally using Design of Experiment(DOE). Sixteen samples were etched using Reactive Ion Etching (RIE) technique with different combination of parameters. RIE parameters concerned in this experiment are ratio of Oxygen, Argon, ICP power and BIAS power. Reactive Ion Etching influences surface morphology which is correlated with the contact angle produced. This preliminary study is to gain information on the how does RIE affects the aluminum bondpad in terms of surface roughness and contact angle.
Room-Temperature Deposition of ZnO Thin Films by Using DC Magnetron Sputtering
Authors: Marwoto Putut , Sulhadi Sulhadi , Sugianto Sugianto , Aryanto Didik , Wibowo Edy , Wahyuningsih Kiki
Published: February 2014

ZnO thin films have successfully been deposited using DC magnetron sputtering at room temperature by means of plasma power variation. XRD results show that films were grown at a plasma power of 30 W and 40 W are polycrystalline, while at 20 W is considered as amorphous. The optical bandgap of films are shrinkage by increasing the plasma power. The broadest transmittance range is belongs to ZnO film growth at plasma power of 40 W. The electrical conductivity of ZnO films increase from 4.02x10-7 (Ωcm)-1 to 8.92x10-7 (Ωcm)-1 once the plasma power is increased. Based on the electrical and optical properties of the films it clearly be seen that ZnO film grown at plasma power of 40 W has highest transmittance and lower electrical resistivity therefore it appropriate for transparent conductive oxide (TCO).
Effects of Sputtering Coating Factors on Elastic Modulus of MoN Coatings
Authors: Srisattayakul Parinya , Saikaew Charnnarong , Wisitsoraat Anurat , Intanon Naphatara
Published: February 2014

Surface quality of an upper hook, an important fishing net-weaving machine component manufactured from stainless steel, was improved by systematically investigating the effects of sputtering coating factors using experimental design. Three factors of MoN coating on upper hooks including DC current, operating pressure, and Ar/N2 ratio were studied and optimized for maximum elastic modulus. It was found that the three coating factors affected the elastic modulus of the MoN coating on upper hooks. In addition, the optimal operating condition for MoN coating that produced a maximum elastic modulus was obtained at DC current of 0.35 A, operating pressure of 0.01 mbar, and Ar/N2 ratio of 1.5.
Effect of Anodizing in Surface Finishing on Speed Boat Impeller Made of Aluminum
Authors: Soekrisno Soekrisno , Anggoro Budy
Published: February 2014

Aluminum alloy have been used for machine components in many functions and sizes. Every part need to be strong and long life, but when wear should be considered, then one have to hardened the surface, usually the harder the surface, the longer the life. One of the components that mention above is speed boat impeller. The sea water may cause the surface of the impeller eroded. Base on that reason the impeller should be hardened to extend its life. The anodizing process was chosen to improve the surface quality of the aluminum to reduce abrasion/erosion. Aluminum is a special material, other metal will be damaged or being worse when corroded, but Aluminum oxide is harder then the pure aluminum. In this process we use H2SO4 solution and the range of the anodizing temperature were changed gradually. This process was using single electrical force 20 Volt, to serve the anodizing for several minutes. All specimens finally were tested in Vickers micro hardness tester, also in Ogoshi High Speed Universal Wear Testing Machine. The last but not least, we cuts the specimens to see the thickness of the oxide layer by SEM. The result shows that for both hardness and wear, the quality of the surface increase with the increase of the solution of H2SO4, and also better for longer anodizing time. The thickness of the oxide layer was measured using SEM, at five places, and the average of the thickness is 2.662 mm.
Biomimetic Creation of Surfaces on Porous Titanium for Biomedical Applications
Authors: Mediaswanti Kun , Wen Cui E , Ivanova Elena P. , Malherbe Francois , Berndt Christopher C. , Pham Vy Thi Hong , Wang James
Published: February 2014

Titanium and titanium alloys have been extensively studied for many applications in the area of bone tissue engineering. However, dense titanium is prone to lead into aseptic loosening due to their high elastic modulus compared to natural bone. One way to lower the elastic modulus is to produce a porous structure of the metallic alloy by adjusting its porosity. Another concern is the bioinertness of titanium that have no direct chemical bonding with surrounding tissue. One approach to improve the healing process is the application of a calcium phosphate coating onto the surface of biomedical devices and implants. Biomimetic creation of surface using alkali heat treatment with silica addition was employed in this study. The porosity of the samples ranges from 60% to 70%. It was demonstrated that the biomimetic methods are suitable for inducing apatite on the titanium alloys surface.
The Effect of Repeated Impingement on UHMWPE Material in Artificial Hip Joint during Salat Activities
Authors: Jamari J. , Ismail Rifky , Saputra Eko , Sugiyanto S. , Anwar Iwan Budiwan
Published: February 2014

In Indonesia, a country with largest Muslim population in the world, the necessity to study the artificial hip joint which allows Muslim patients with total hip replacement to have normal Salat becomes important issues. This paper discusses the effect of impingement which occurs during one of the Salat movements. i.e. last tashahhud sitting motion. An artificial hip joint model, proposed by previous researcher from developed country, is simulated using finite element analysis to perform last tashahhud sitting motion. The result shows that impingement occurs and causes the plastic deformations and plastic strains in the acetabular liner component which is manufactured from UHMWPE material. The repetition of Salat movement induces repeated impingements and higher plastic deformation. It experiences dimensional change in the liner lip and has a potency to cause clinical failure of total hip replacement. A new design of the artificial hip joint is required to be proposed to avoid the repeated impingement and deformations.
Simple and Easy Method to Synthesize Chicken Eggshell Based Hydroxyapatite
Authors: Tri Wahyudi Setyanto , Utami Dewi Setia , Anggraeni Ajeng , Dahlan Kiagus , Akhmaloka Akhmaloka , Ali Zulfikar Muhammad , Hertadi Rukman
Published: February 2014

Hydroxyapatite is a common material applied in orthophedia and dentistry. The application of this material is currently expanded to biotechnology field, such as to be used as support materials for enzymes immobilization. Hydroxyapatite can be synthesized by utilizing chicken eggshell waste in household and food industries. This work is aiming to provide a simple and easy method to synthesize hydroxyapatite from chicken eggshell. The synthesis of hydroxyapatite was firstly carried out by reacting chicken eggshell powder (calcium precursor) with (NH4)2HPO4 via modified precipitation at room temperature and normal atmospheric pressure. The mixture was then stirred variably for 1, 2, 3, and 24 hours. X-ray diffraction (XRD) analysis suggests that hydroxyapatite powder derived from this procedure formed a single-phase crystal and it was completely formed after the reaction has run for 1 hour. The scanning electron microscopy (SEM) image showed that the synthesized hydroxyapatite forms a rice-like pattern. The size of hydroxyapatite crystal measured at (002) plane was about 45 nm. Our result showed that simple modified precipitation at room temperature and normal atmospheric pressure in one hour reaction has successfully synthesized hydroxyapatite from chicken eggshell.
Synthesis of Hydroxyapatite Nanoparticle from Tutut (Bellamya javanica) Shells by Using Precipitation Method for Artificial Bone Engineering
Authors: Herawaty Lenita , Rohaeti Eti , Charlena Charlena , Sukaryo Sulistioso Giat
Published: February 2014

The synthesis and characterization of both structural and microstructure of hydroxyapatite (HAp) nanoparticles by using precipitation method have been performed. Orthophosphoric acid solution (H3PO4) 0.3 M was dropped into the suspension of Ca(OH)2 from tutut (Bellamya javanica) shells at pH 10 and added by NH4OH 1 M at the final deposition process. The precipitate was filtered and then heated in a furnace at temperature of 1000 °C for 3 hours. The result of elemental analysis showed that the Ca/P ratio of HAp sample was 1.71. X-ray diffraction patterns showed that the sample was a single phase of Ca10(PO4)6(OH)2 with hexagonal structure (P63/m) and lattice parameters of a = b = 9.418(3) Å, c = 6.885(2) Å, a = b = 90o, g = 120o, V = 528.9(4) Å3, and r = 3.084 g cm-3. The as-synthesized HAp has crystallite and particle sizes of 16.1055 and 89.15 nm, respectively. The TEM image revealed that the HAp particles have spherical-polygonal shape with an average diameter particles of around 10-20 nm. It was concluded that the synthesis of HAp nanoparticles from tutut (Bellamya javanica) shells by using a wet precipitation method has been successfully carried out and the as-synthesized HAp was potential to be applied as materials for artificial bone engineering.
Effect of Deacetylation on Characterization of pH Stimulus Responsive Chitosan-Acrylamide Hydrogels Using Radiation
Authors: Basuki Kris Tri , Swantomo Deni , Sigit Sigit , Megasari Kartini
Published: February 2014

Smart hydrogels which can change their swelling behavior and other properties in response to environmental stimuli such as temperature, pH, solvent composition and electric fields, have attracted great interest as chemical sensor material and controlled release system. The pH stimulus responsive hydrogels were synthesized by gamma-irradiation graft copolymerization of chitosan-acrylamide. In this research the influence of deacetylation process on the hydrogels characterization were investigated by measuring grafting efficiency, gel fraction, swelling degree, and crosslink density. Evidence of grafting was confirmed by FTIR spectroscopy. X-ray diffraction showed reduction in the crystallinity of chitosan with different deacetylation process also after the graft copolymerization reaction. The results showed that decreasing acetyl group of chitosan increase the grafting efficiency, gel fraction and swelling degree. While crystallinity decreased. The hydrogels indicated pH-dependent swelling behaviour.
The Role and Prospect of Nanomaterials in Polymeric Membrane for Water and Wastewater Treatment: A State-of-the-Art Overview
Authors: Ismail Ahmad Fauzi , Goh Pei Sean
Published: February 2014

The efforts and attempts made in the past decades have witnessed a considerable amount of research interest in potential of various inorganic nanomaterials for the development and innovative environmental applications. Inorganic nanofillers such as metal oxides nanoparticles, carbon nanotubes and silver nanoparticles are incorporated into polymeric membranes to render the desired properties, i.e high flux, high rejection and enhanced fouling resistance to suitably applied in liquid-based filtration for waste and wastewater applications. This brief review highlights the state-of-the-art overview in the recent progress and advancement made in the utilization of nanofiller/polymer nanocomposite to remediate the current bottlenecks and issues that stumble the further development of the conventionally used polymeric membranes.
Impact and Thermal Properties of Unsaturated Polyester (UPR) Composites Filled with Empty Fruit Bunch Palm Oil (EFBPO) and Cellulose
Authors: Surya Elmer , Michael Michael , Halimatuddahliana Halimatuddahliana , Maulida Maulida
Published: February 2014

In this research, the impact properties of unsaturated polyester (UPR) composites filled with empty fruit bunch palm oil (EFBPO) and cellulose were investigated. The composites were made by hand-lay up method by mixing UPR with the content of each fillers (EFBPO and cellulose) of 5,10,15,20 wt.%. The parameter which was carried out on the prepared samples was impact test. It was found that the addition of fillers to the matrix caused the impact strength of composites increased at 10% addition of EFBPO and 5% addition of cellulose. The results were confirmed by fourier transform infra-red (FTIR) and supported by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM).
The Treated Rice Straw as Potentially Feedstock of Wood and Rice Straw Fiber Blend for Pulp and Paper Making Industry
Authors: Juwono Ariadne Lakshmidevi , Handoko Subawi
Published: February 2014

The study aimed to describe the alkaline treatment advantage to remove ash component from natural rice straws. Most of the ash component in the rice straw is silica. High ash content is particularly harmful to cutting tools and to chemical to recovery systems in the pulp paper industry. In this study, the silica content has been removed simply through by immersion process in the 5% sodium hydroxide solution to obtain de-silicated rice straw. The study revealed the effectiveness of this alkaline process and the compatibility in commercial practice. The rice straw pulping is considered competitively to complement the global demand of raw material in paper production. Therefore, the treated rice straw plays an important role in providing raw material in the form of wood and rice straw blend feedstock for pulp and paper industry.