bluuebunny/crossref_metadata_2025 huggingface dataset:
Determine of copper metal in cooking oil by saponification method with atomic absorption spectrophotometer (AAS)
Authors: Handajani Usreg Sri , Harsini Muji , Wicaksono Zaldy
Published: October 2017

A research on the analysis of copper metal in the cooking oil saponification by AAS method. This study aimed to validate analytical methods, including precision and accuracy in the determination of copper metal in cooking oils through saponification and knowing destructed Cu content in cooking oils on the market. This research was done by creating a simulation of cooking oils and then added with a solution with various concentrations of Cu2+, reacted with KOH for saponification, then destructed dried, and absorbance was measured using an atomic absorption spectrometer. Results of accuracy (recovery) be obtained average of 96.88, 97.35, and 97.36% and precision values of 0.8233, 0.3154, and 0.4803%. It can be concluded that this method is very well used to determine the concentration of copper metal contained in cooking oils, and Cu content in cooking oils on the market for bulk cooking oil 1 at 11.5 mg/kg, bulk cooking oil 2 at 10.9 mg/kg, and for branded cooking oil at 7.4 mg/kg.________________________________________GRAPHICAL ABSTRACT
Immobilization of Lipase From Azospirillum sp. PRD1 Using Chitosan Alginate as Supporting Agent
Authors: Zusfahair Zusfahair , Ningsih Dian Riana , Nurhandayani Santi , Lestari Puji , Hermawan Dadan
Published: October 2017

Immobilization of lipase from Azospirillum sp. PRD1 bacteria with trapping method using chitosan alginate has been successfully performed in this study. The study was started by manufacture of the inoculum, followed by the production of enzymes and extraction with centrifugation method. The crude extract obtained was fractionated using ammonium sulphate and the 60% fraction was used for the immobilization of enzymes and determination of its molecular weight. The preparation of chitosan alginate beads were performed using several variations that are chitosan concentration, enzyme volume: chitosan alginate ratio, incubation time and the concentration of TPP. The activity of lipase beads formed was tested using titrimetric methods. The results showed that the fraction of 60% was more pure than the crude extract. The chitosan used has de-acetylation degree of 74.57%. The synthesis of the immobilized lipase beads was optimum at 8.5% chitosan concentration, ratio of enzyme:chitosan alginate of 1:10, 150 min incubation time and 2% TPP concentration with activity of 90 U/mL. SEM results indicated the presence of trapped enzyme in the matrix.
Optimum conditions for the synthesis of high solubility carboxymethyl chitosan
Authors: Kurniasih Mardiyah , Purwati Purwati , Hermawan Dadan , Zaki Muhamad
Published: October 2017

A research on optimizing the synthesis conditions to obtain carboxymethyl chitosan with the highest solubility in 1%(v/v) acetic acid solvent have been performed. Optimization was performed by varying: the concentration of NaOH during alkalizing the chitosan, chitosan: monochloroacetic acid ratio, temperature and reaction time. This study uses a full factorial experimental design. The results showed that the highest solubility was found in 40% (w/v) NaOH concentration, chitosan to monochloroacetic acid ratio of 1:7, reaction temperature of 80°C and reaction time at 4 hours with the solubility up to 63.78 mg /mL. IR and 1H-NMR spectra showed that the synthesis gave result to carboxymethyl chitosan. Results of physical characterization of carboxymethyl chitosan at the highest solubility showed the value of water content, ash content, molecular weight, and swelling effects up to 14.27%, 8.48%, 2,86978 x 105 g/mol; and 884.19%, respectively.
Photoisomerization of n-pentane over nano ZnO/MoO3-ZrO2
Authors: Triwahyono Sugeng , Abdul Jalil Aishah , Mamat Che Rozid
Published: October 2017

A series of nano ZnO/MoO3-ZrO2 catalysts with different ZnO loading (1.0, 2.5, 5.0 wt%) were prepared by impregnation method for n-pentane photoisomerization under hydrogen or nitrogen atmosphere. The properties of the catalysts were characterized with X-ray Diffraction (XRD), Brunauer Emmett Teller (BET), Transmission Electron microscope (TEM) and FTIR. The XRD result showed that the fraction of tetragonal phase of ZnO/MoO3-ZrO2 was about 0.67 for all samples. While, the specific BET surface area was about 24 m2/g. Pyridine adsorbed FTIR results showed that all samples possessed high concentration of strong Lewis acid sites and small concentration of weak Bronsted acid sites. The interaction of hydrogen and surface samples at 298-523 K formed protonic acid sites with the concomitant of the partial elimination of Lewis acid sites. Whereas no changes of the concentration of acid sites were observed in the presence of nitrogen atmosphere. The activity of all samples in the n-pentane photoisomerization was strongly determined by the presence of hydrogen gas. In fact no activity was observed in the absence of hydrogen________________________________________GRAPHICAL ABSTRACT
Chromium oxide zirconia solid acid catalyst for n-pentane isomerization
Authors: Rozali Annuar Nur Hazirah , Abdul Jalil Aishah , Triwahyono Sugeng
Published: October 2017

New catalyst based on zirconia (ZrO2) supported by chromium oxide (CrO3) for isomerization of n-pentane was studied. CrO3-ZrO2 was prepared with chromium nitrate by the titration and sol-gel technique. The physical properties of the catalysts were characterized by XRD, BET surface area analyzer, and TEM. The acidity and structure of catalysts were determined by pyridine and lutidine preadsorbed FTIR spectroscopy.  The isomerization of n-pentane was carried out at 523 K under hydrogen stream. CrO3-ZrO2 shows the differences in terms of physical properties where the introduction CrO3 partially eliminated the monoclinic phase of ZrO2 and developed new peaks assigned to tetragonal phase of ZrO2. CrO3-ZrO2 also shows a higher specific surface area where it increases in the pore volume of the catalyst compare to its parent zirconia.  The IR results indicated that CrO3-ZrO2 catalyst have strong Lewis and weak Brønsted acid sites. The conversion of n-pentane for CrO3-ZrO2 was 32% respectively, while the selectivity to iso-pentane was 100%. ________________________________________GRAPHICAL ABSTRACT
Weighted Simple and Semi-Simple Splicing Systems
Authors: Yee Siang Gan , Fong Wan Heng , Sarmin Nor Haniza , Turaev Sherzod
Published: October 2017

The modelling of splicing system has been introduced theoretically by Head in 1987.  As time goes on, various splicing systems have been developed, such as one-sided, simple and semi-simple splicing systems.  However, in the investigation on the generative power of splicing system, there are limitations on the generative power of splicing system with finite components.  In order to overcome the limitation of the usual splicing system, one variant of splicing system has been introduced recently, called the weighted splicing system.  In this paper, we associate weights from selected weighting spaces to the axioms of simple and semi-simple splicing systems, thus introducing weighted simple splicing system and weighted semi-simple splicing system.  Some examples are presented for weighted simple and semi-simple splicing systems to illustrate their generative power.  Lastly, relation of the languages generated by weighted simple and semi-simple splicing systems in the Chomsky hierarchy are also investigated.
Improved thermal features and ionic conductivity of lithium-zinc-tellurite glass electrolytes
Authors: Widanarto Wahyu , Sahar M. R. , Ghoshal S. K. , Mashadi Mashadi , Gustiono D. , Effendi M.
Published: October 2017

Synthesizing glass electrolytes with modified ionic conductivity by incorporating Li2O for enhanced secondary battery safety is ever-demanding. Electrolytes based on zinc-tellurite glasses with chemical composition (85-x)TeO2×xLi2O×15ZnO, where x = 0, 5, 10, 15 mol% are prepared using melt quenching method. The temperatures, frequency and Li2O concentrations dependent modifications of structural features, thermal stability, and ionic conductivity are determined. Amorphous nature of electrolytes is verified from X-ray diffraction patterns. Incorporation of Li2O in the electrolytes is found to decrease the glass transtition temperature from 318.41 to 280.63 °C leading to their thermal stability enhancement. Alternating current impedance measurement revealed that the ionic conductivity of the electrolytes is significantly influenced by the temperature and concentration of Li2O and not by the frequency of AC voltage. The glass electrolyte containing 5 mol% of Li2O exhibited good performance with the ion conductivity of 1.72´10-2 S cm-1 and activation energy of 3.85´10-1 eV. These improvements in the conductivity and activation energy are attributed to the alteration in ions vibration and breakage of covalent bonds. This modification allowed the ions to move through un-perfect non-bridging oxygen under the influence of an external electric field (applied voltage) with enhanced mobility. The present glass electrolyte is very promising for secondary Li-ion battery fabrication.
Quantitative determination of ciprofloxacin and levofloxacin antibacterials by Spectrophotometeric and high performance liquid chromatography
Authors: Akram Muhammad , Anwar Jamil , Alshemarya Ammar Z. , Goh Yi-Fan , Sher Awan Ahmed , Farooqi Qamar H.
Published: October 2017

A simple, rapid and sensitive Spectrophotometeric method for the determination of fluoroquinolones; ciprofloxacin and levofloxacin have been performed in pure form and pharmaceutical tablets. Both drugs gave reddish complexes when treated with iron (III) chloride at pH 4.0. The drugs showed maximum absorption at 530 and 545 nm. In both cases linear calibration was obtained up to 0.9 mg/10 mL of the drug. Effect of different parameters like pH, temperature and time was also studied on the stability of the complexes. The percentage recoveries found by described method was in the range of 98.2---100.01 %. Standards were prepared from the pure compounds obtained from sigma-Aldrich Pharm. The method was successfully employed for the Assay of drugs in commercial formulations. Finally determination of the drugs was carried out through HPLC method which showed that there is no appreciable difference between the results of both the methods. Results revealed that proposed method is practically suitable for routine applications in quality control laboratories for the analysis of fluoroquinolones drugs.________________________________________GRAPHICAL ABSTRACT
Simulation of furnace system with uncertain parameter
Authors: W.M. Wan Munirah , Ahmad T. , Ahmad S. , Ashaari A.
Published: October 2017

Energy system in power plants is one of the most frequently mentioned areas in thermal energy. The aim of this study is to model the heat transfer of a furnace in order to minimize energy losses. The furnace system is simulated using fuzzy arithmetic, namely, the uncertain model inputs are represented by fuzzy numbers. The analysis of the model is presented in this paper.
Some fundamental properties for regular element of electroencephalography signals semigroup during epileptic seizure
Authors: Ali Barja Ameen Omar , Ahmad Tahir , Binjadhnan Faisal Abdurabu Mubarak
Published: October 2017

Electroencephalography (EEG) is a record of electrical activity along the scalp. It is measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. EEG is most often used to diagnose epilepsy, which causes understandable abnormalities in EEG readings. The mathematical analysis of EEG signals assists medical specialists by providing a clarification of the brain activity being observed, so increasing the information about the structure and function of the human brain. EEG signals during epileptic seizure can be viewed as a semigroup of square matrices under matrix multiplication, and every element in that semigroup is shown to be regular. In this paper, we will present some main properties of regular element of EEG signals during epileptic seizure.
Performance evaluation of black hole algorithm, gravitational search algorithm and particle swarm optimization
Authors: Aliman Mohamad Nizam , Ibrahim Zuwairie , Naim Fardila , Nawawi Sophan Wahyudi , Sudin Shahdan
Published: October 2017

Particle Swarm Optimization (PSO) and Gravitational Search Algorithm are a well known population-based heuristic optimization techniques. PSO is inspired from a motion flock of birds searching for a food. In PSO, a bird adjusts its position according to its own ‘‘experience’’ as well as the experience of other birds. Tracking and memorizing the best position encountered build bird’s experience which will leads to optimal solution. GSA is based on the Newtonian gravity and motion laws between several masses. In GSA, the heaviest mass presents an optimum solution in the search space. Other agents inside the population are attracted to heaviest mass and will finally converge to produce best solution. Black Hole Algorithm (BH) is one of the optimization technique recently proposed for data clustering problem. BH algorithm is inspired by the natural universe phenomenon called "black hole”. In BH algorithm, the best solution is selected to be the black hole and the rest of candidates which are called stars will be drawn towards the black hole. In this paper, performance of BH algorithm will be analyzed and reviewed for continuous search space using CEC2014 benchmark dataset against Gravitational Search Algorithm (GSA) and Particle Swarm Optimization (PSO). CEC2014 benchmark dataset contains 4 unimodal, 7 multimodal and 6 hybrid functions. Several common parameters has been chosen to make an equal comparison between these algorithm such as size of population is 30, 1000 iteration, 30 dimension and 30 times of experiment.
Intuitionistic fuzzy in spline curve/surface
Authors: Wahab Abd Fatah , Zulkifly Mohammad Izat Emir
Published: October 2017

The uncertainty data problem with intuitionistic information is difficult to deal with through the methodology or approach available. This is because the existing fuzzy geometric modeling can only solve the fuzzy data problem that is  intuitionistic and fuzzy complex in nature as the data have information that is incomplete boundary value (less clear and ambiguous), have meaning and truth value of the range, a lot of value logic values as well as having vague distribution and indistinct. Furthermore, the operation is characteristically minimum or maximum and image together with the range are obscure and complex. To solve this problem, a new model with a redefinition of the control points which   characterized by three important components of intuitionistic fuzzy is developed. These control points will be blended with the basic functions of spline to generate several models in the form of intuitionistic fuzzy spline curve / surface and can be easily understood. With the intuitionistic concept and its relations, then the relevant data can be translated through the production of these models.
Fuzzy linguistic in geometric modeling
Authors: Husain Mohd Sallehuddin , Wahab Abd Fatah , Gobithasaan R.U.
Published: October 2017

Fuzzy Linguistic is an extension of fuzzy set theory was introduced by Zadeh. Normally fuzzy linguistic is often associated with linguistic variables generated by a function modifier is also known as a hedges. This paper discusses the theorems and definitions of fuzzy linguistic perspective geometric modeling to produce Fuzzy Linguistic Control Point (FLCP). Fuzzy Linguistic Control Points have been blended in with the spline basic functions of the model to produce a few splines’s model are characterized by fuzzy linguistics. At the end of this article will discuss some numerical examples of Fuzzy Linguistic Bezier Model.
The multiple intelligence classification of management graduates using two step cluster analysis
Authors: Mohamed Noorazilah , Awang Siti Rahmah
Published: October 2017

In this study, graduates multiple intelligences profile are the main interest in order to enhance the opportunities of the management graduates for employability. In order to measure and classify the multiple intelligences of graduate, Two Step Cluster Analysis is applied. The cluster is based on their demographic background and Gardner’s nine intelligences namely musical, spatial/visual, verbal/linguistic, mathematics/logical, bodily-kinaesthetic, interpersonal, intrapersonal, naturalist and spiritual. The framework and findings of this study are conducted at Faculty of Technology Management and Technopreneurship (FPTT), Universiti Teknikal Malaysia Melaka (UTeM). The nine intelligence types of the 137 management graduates had been successfully clustered into four more meaningful clusters based on their intelligence scores and characteristics that agree with the Gardner’s Multiple Intelligence theory.
Synthesis and characterization of nanocrystalline nickel - cobalt ferrites by co-precipitation Method
Authors: A. Ati Ali , Othaman Zulkafli , Dabagh Shadab , Rosnan R. M. , Zare Samad
Published: October 2017

Nano crystalline powders of Co-Ni ferrite compounds having the chemical formula Co(x)Ni(1-x) Fe2O4( x = 0.0, 0.2 and 1.0) have been successfully synthesized by co-precipitation technique. These synthesized compounds are characterized by X-ray diffraction (XRD), field emission scan electron microscopy (FESEM), fourier transformed infrared (FTIR) spectrum, energy dispersive X-ray diffraction (EDX) and TGA-DTA. The XRD analyses of the samples sintered at 600 °C clearly show the formation of single cubic spinel structure. XRD patterns are further analyzed to calculate the lattice constant and jump length of charge carriers. Average crystalline sizes for ferrite powders are determined from XRD line using Debye-Scherrer's formula is found to be in the range of 16 to 19 nm with narrow size distribution. The Fourier transformed infrared (FTIR) spectrum characterization of the  spinel ferrite structure sintered at 600 °C shows two fundamental strong band in the range 385-600 cm-1, which is attributed to different main metal-oxygen bands.
Unsteady boundary layer flow of a casson fluid past an oscillating vertical plate with constant wall temperature
Authors: Khalid Asma , Khan Ilyas , Shafie Sharidan
Published: October 2017

The unsteady boundary layer flow is presented for non-Newtonian fluid flow past an oscillating vertical plate with constant wall temperature. The Casson fluid model is used to distinguish the non-Newtonian fluid behavior. The governing partial differential equations corresponding to the momentum and energy equations are transformed into dimensionless forms, by using suitable transformations. Laplace transform method is used to find the exact solutions of these equations. The expressions for shear stress in terms of skin friction and the rate of heat transfer in terms of Nusselt number are also obtained. Numerical results of velocity and temperature profiles with various values of embedded flow parameters are shown graphically and their effects are discussed in detail.
Interactive graph dynamics for fuzzy autocatalytic set of fuzzy graph of type-3 for combustion process in a circulating fluidized bed boiler
Authors: Hashim Hazwani , Abu Bakar Sumarni
Published: October 2017

Dynamical changes of chemical reactions which occurred during combustion process in Circulating Fluidized Bed boiler (CFB) has been modelled using adjacency matrix of Fuzzy Autocatalytic Set (FACS) of fuzzy graph type-3. Analysis of sequence of changes in the reactions at time t through Perron-Frobenious eigenvector (PFE) of the matrix in the Graph Dynamic Algorithm (GDA) shows that end-product of the combustion process in the CFB namely Water and Hydrogen is not really potrayed the real process.  Therefore, in this study, transition matrix of FACS is utilized to analyse the dynamical changes of the reactions and the GDA is modified and improvised and known as Interactive Graph Dynamics (IGD) is subsequently use to facilitate the analysis. The result shows that by using the transition matrix of FACS, the end-product of the combustion process in CFB is in accordance to the real process. Whilst the IGD is able to reduced computer running time as compared to the existing GDA. This paper describes the development of IGD and the analysis of sequence of changes of chemical reactions during combustion process in CFB by using transition matrix with the helped of MATLAB.
Fuzzy state space model for a pressurizer in a nuclear power plant
Authors: Ashaari A. , Ahmad T. , Shamsuddin Mustaffa , Zenian S.
Published: October 2017

In this paper, Fuzzy State Space Model (FSSM) for a nuclear power plant is proposed. Pressurizer is used to control pressure and temperature in a nuclear power plant. In order to maintain the pressure and the temperature of the system, the effectiveness of the system needs to be monitored frequently. Hence, fuzzy state space approach is used to model the pressurizer. The influence of input to output of the pressurizer is established and presented in this paper. The result from the model is then verified against published data.
Multiple intelligence prioritization for people with epilepsy
Authors: Rezaie Vahideh , Ahmad Tahir , Awang Siti Rahmah , Khanmohammadi Masumeh , Maan Normah
Published: October 2017

This study uses the data envelopment analysis (DEA) interval efficiency to determine the priorities of eight perceived intelligence parameters skills by considering the people with epilepsy (PWE)'s demographic background. The results of this study help the PWE to identify their strengths and weaknesses where to improve the chances of employability in the job market and to improve their inherent skills for suitable employment. The ranking of PWE's intelligence parameters would describe the status quo of epilepsy sufferers with respect to their intelligence level. Gardner had introduced related activities, products, and suitable careers to each of eight intelligence parameters. Therefore, training the various recommended activities for an epileptic sufferer is paramount in order to be successful in the workplace.
Tabu search algorithm for solving waste collection vehicle routing problem
Authors: Hassan Siti Asnor Faraien , Nordin Syarifah Zyurina
Published: October 2017

This study considers a Waste Collection Vehicle Routing Problem where the situation happens when vehicle must make a complete trip to make disposal operation per day. The Waste Collection Vehicle Routing Problem objective is to decide the best solution where a vehicle should make the collection first between the customers since there exist larger number of customers. The method proposed to solve the Waste Collection Vehicle Routing Problem is by using Tabu Search Algorithm.
Some properties of fuzzy quasi-metric space for FACS of fuzzy graph type-3
Authors: Obaid Umilkeram Qasim , Ahmad Tahir
Published: October 2017

In this paper, we investigate some properties and characteristics of fuzzy quasi-metric space of Fuzzy Autocatalytic Set (FACS) of fuzzy graph Type-3. These properties are used to justify an aperiodicity of a graph.
Influence of the sintering temperature on the morphology and structural properties of Ni-Mg substituted of cobalt ferrites
Authors: Rosnan R. M. , Othman Zulkafli , Ati A. A.
Published: October 2017

This study evaluates the morphology and structural properties of Ni-Mg substituted Cobalt ferrite samples prepared through the co-precipitation method. The nominal composition of Co0.5Ni0.5−xMgx Fe2O4 in the range x = 0.1 have been synthesized and then were sintered at temperature 700 and 1000°C for 10 hour with a heating rate of 5°C/min. The prepared nano-ferrites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). XRD confirmed formation of single phase spinel ferrite with average crystalline size in the range of 40–120 nm. Further information about the structure and morphology of the nanoferrites was obtained from FESEM and results are in good agreement with XRD.
Effect on silicon nitride thin films properties at various pressure of R.F. magnetron sputtering
Authors: Majeed Uzair , Mustafa Mohd. Kamarulzaki , Nayan Nafarizal
Published: October 2017

Silicon nitride is a well-known kind of material with numerous applications such as gate dielectrics and etch-masks in semiconductor device fabrication, anti reflective coatings in solar panel manufacturing and optical waveguides in biosensing fields. In this work, Silicon nitride thin films were prepared using radio frequency (R.F.) magnetron sputtering technique at room temperature. The properties of thin films were investigated with respect to sputtering-gas pressure during film deposition. The produced thin films were characterized with spectral reflectance, AFM, FTIR and FE-SEM techniques for growth rate and optical properties, surface roughness and morphology, chemical bonding information and surface micro structures respectively. Spectral reflectance results showed that there existed an optimum value of sputtering-gas pressure for increase in growth rate and beyond that value the growth rate started decreasing. Refractive index was found to increase with increased pressure confirmed the films were Si-rich. AFM results revealed the increment in surface roughness is in direct proportion with working pressure. FTIR results showed the overlapping of Si-N and Si-O characteristic bands and its shift toward higher wave number due to increasing Si content in deposited films. FE-SEM results showed prominent changes in surface micro structure with higher sputtering-gas pressures.
Hydrolysis of eichhornia crassipes (eceng gondok) to glucose over sulfonated active carbon catalyst
Authors: Dwi Anggoro Didi , Rispiandi Rispiandi , Purwanto Purwanto
Published: October 2017

Enzimatic process and acid hydrolysis process are common process for conversion of cellulose to glucose. Unfornately, the two processes are expensive process and korosif process. Hence, the new process, that use sulfonaned active carbon catalyst is important to developing. The sulfonated active carbon is made from carbonated coconut sheel under temperature at 350oC. After carbonation, sulfonated active carbon soaked under sulphate acid 96% at 150oC until 15 hours. The result is then washed and dried, and tested catalyst characteristics in the form of H+ capacity, pore size catalysts by used BET surface area, functional groups by used FTIR, and morphology catalyst structure by used SEM. Catalyst performance was tested in an autoclave reactor through a hydrothermal process with difference of the catalyst amount and temperature. The results showed that the test characteristics of H+ capacity is 2.95 mmol/g, the pore size is 29 m2/gr. FTIR analyze showed that the presence of sulfonate groups read at a wavelength of vibration 1750 cm-1 and 1379 cm-1. By SEM analyze showed that the morphological structure of sulfonated active carbon is more open than other catalyst. By testing catalyst, the highest conversion of glucose is 87.2 %.
Photocatalytic removal of cyclohexane on visible light-driven gallium oxide/carbon nitride composites prepared by impregnation method
Authors: Chin Lee Shu , Shern Chew Wee , O. Lintang Hendrik , Yuliati Leny
Published: October 2017

Carbon nitride is a material of interest for photocatalytic reactions due to its catalytic and visible light absorption properties. However, the photocatalytic activity is still low. Hence, modifications must be carried out to improve the photocatalytic activity of carbon nitride. In this work, a series of gallium oxide/carbon nitride composites with various gallium to carbon ratios (Ga/C = 1-50 mol%) was prepared by impregnation method for removal of cyclohexane under visible light irradiation for the first time. The successful preparation of gallium oxide/carbon nitride composites was supported by several characterization techniques. X-ray diffraction (XRD) patterns and diffuse reflectance UV-visible (DR UV-vis) spectra revealed that the increased Ga/C ratio resulted in the increased formation of Ga2O3. Furthermore, all the prepared composite samples also showed visible light absorption up to about 430 nm. In the photocatalytic removal of cyclohexane under 6 h of visible light irradiation, sample with low loading of 1 mol% Ga/C improved the photocatalytic activity of carbon nitride for two times. The high activity obtained on the gallium oxide (1 mol%)/carbon nitride composite clearly suggested the presence of synergic effect between small amount of gallium oxide and carbon nitride when they were combined. This study showed that a visible light-driven gallium oxide/carbon nitride composite could be prepared by impregnating a small amount of gallium oxide on carbon nitride and the composite is a potential photocatalyst for removal of cyclohexane under visible light irradiation.
Copper modified TiO2 and g-C3N4 catalysts for photoreduction of CO2 to methanol using different reaction mediums
Authors: Oluwatobi David Adekoya , Tahir Muhammad , Saidina Amin Nor Aishah
Published: October 2017

In this study, Cu/TiO2 and Cu/g-C3N4 catalysts were tested for CO2 reduction to methanol. The catalysts were prepared by the wet impregnation method and, characterized by XRD and FESEM. The product identification and yield were determined using a GC with FID. The CO2 photoreduction process was performed in each of the following reaction mediums: H2O, NaOH, KOH, Na2CO3, K2CO3, NaHCO3 and KHCO3. The efficiency was studied by comparing the methanol yield for each. A slurry type photoreactor with a UV lamp of 365 nm wavelength was used. CO2 photoreduction to methanol using NaOH as the reaction medium registered the highest yield of 431.65 μmole/g-cat•hr. This is due to the higher solubility of CO2 in the alkali as compared to that of the other reaction mediums, the ability of NaOH to serve as a hole scavenger owing to the formation of OH•ions and the higher selectivity of NaOH solution for CO2 photoreduction to methanol. It was obvious the choice of reaction medium affected the photoreduction of CO2 to methanol. The trend of results indicated the use of NaOH as a reaction medium improved the efficiency of the photoreduction process. The findings from this research could promote research in the field of photocatalysis by improving the yield which will encourage the support for methanol economy.
Synthesis and characterization of nitrogen-doped titania nanomaterials of homogeneous particle size
Authors: Zainal Nurul Diyana , Nur Hadi , Siew Ling Lee
Published: October 2017

Modification of sol-gel method was used to synthesize homogeneous particle size nitrogen-doped titania (N-TiO2) nanomaterials using tetraethyl ammonium hydroxide (TEAOH) as N source. XRD analysis showed that these N-TiO2 (1-5 % N concentration) crystallined in anatase structure. The crystallinity of the samples decreased with increasing of N content. The calculation using Scherrer equation showed that the particle size of the synthesized N-TiO2 ranged 15.02 - 26.85 nm, strongly suggesting attainment of nanomaterials. DR UV-Vis results indicated that the band gap energy of 5% N doped TiO2 was only 2.58 eV, implying the sample could be a potential photocatalyst under visible light irradiation.  Homogeneous particle size of the synthesized nanomaterials was evidenced through FESEM images. Meanwhile, the EDX analysis confirmed the homogenous distribution of elements Ti, N and O in 5% N doped titania sample.
Nitrogen-doped-TiO2 nanocatalyst for selective photocatalytic CO2 reduction to fuels in a monolith reactor
Authors: Tahir Beenish , Tahir Muhammad , Saidina Amin Nor Aishah
Published: October 2017

In this study, photocatalytic CO2 reduction with H2 over nitrogen (N)-doped TiO2 nanocatalyst in a monolith photoreactor has been investigated. The N-doped TiO2 nanocatalyst was synthesized by sol-gel method, dip-coated over the monolith channels, and characterized by XRD, SEM and N2 adsorption-desorption. Highly crystalline and anatase phase TiO2 was produced in the N-doped TiO2 samples with increased surface area and reduced crystallite size. The N-doped TiO2 nanocatalyst demonstrated excellent photoactivity for selective CO2 reduction to CO in a continuous monolith photoreactor. The 3 wt. % N-doped TiO2 was found to be the most optimal, giving maximum CO yield rate of 56.30 µmole g-catal.-1 h-1 with selectivity of 96.3% at CO2/H2 feed ratio 1 and feed flow rate 20 mL/min. The performance of monolithic N-doped TiO2 nanocatalyst for selective and continuous CO production was 4.7 fold higher than un-doped TiO2. The significantly enhanced TiO2 activity was evidently due to hindered charges recombination rate due to N2 doping. The N-doped TO2 gave prolonged stability for continuous CO and CH4 production over the irradiation time.
Improved photocatalytic activity of anatase titanium dioxide by reduced graphene oxide
Authors: Alim Nor Shuhada , O. Lintang Hendrik , Yuliati Leny
Published: October 2017

Reduced graphene oxide (rGO) has been one of the most investigated carbon based materials due to its great electronic conductivity that make it able to accept and transport electron easily. In order to study the effect of rGO, anatase titanium dioxide-reduced graphene oxide (TiO2-rGO) composite was prepared by UV-assisted photocatalytic reduction method using the anatase TiO2 as a photocatalyst and various different loadings of graphene oxide (GO). The characterizations of the prepared samples were investigated by X-ray diffractometer (XRD), Fourier transform infrared (FTIR), and fluorescence spectroscopies. The XRD patterns and FTIR spectra confirmed that all the TiO2-rGO composites samples were successfully synthesized without disrupting the structure of the anatase TiO2. Fluorescence spectroscopy revealed the role of the rGO to reduce the electron-hole recombination on the anatase TiO2. In the photocatalytic removal of phenol, all the TiO2-rGO composites showed better photocatalytic activities than the bare anatase TiO2 under UV light irradiation. The activity of the anatase TiO2 was enhanced by more than four times with the addition of the GO with the optimum amount (3 wt%). It was proposed that the good photocatalytic performance obtained on the composites were caused by the successful suppression of electron-hole recombination by the rGO on the TiO2.
Novel oxidative-acidic bifunctional catalyst of tungsten-phosphate modified silica-titania
Authors: Che Mi Salasiah , Nur Hadi , Siew Ling Lee
Published: October 2017

A novel oxidative-acidic bifunctional catalyst of silica-titania supported tungsten-phosphate was successfully synthesized and characterized. Different tungsten amount was impregnated into silica-titania followed by phosphoric acid treatment via sol gel method. The impregnation of WO3 and PO43- into TiO2-SiO2 followed by drying and calcination gave the white colour to the samples. X-ray diffractograms of the samples showed the structures of TiO2-SiO2 remained as amorphous structure after loading of WO3 and PO43-. The catalytic performance of the samples of PO43-/xW/TiO2-SiO2, (x = 1 and 5 wt %) as bifunctional catalyst in the formation of 1,2-octanediol through conversion of 1-octene to 1,2-epoxyoctane using aqueous H2O2 as an oxidant was evaluated. It has been demonstrated that PO43-/5W/TiO2-SiO2 was an active bifunctional oxidative-acidic catalyst in producing 1,2-octanediol from 1-octene.
Correlation of fluorescence and photocatalytic activity of Co-doped TiO2
Authors: Pei Wen Koh , Yuliati Leny , Siew Ling Lee
Published: October 2017

Co-doped TiO2 (0.5-4 mol%) photocatalysts were synthesized via sol-gel method and their physical and chemical properties were investigated. Addition of Co oxide dopant induced anatase to rutile phase transition and reduced the band gap energy of TiO2. The fluorescence result indicated that the electron-hole recombination rate was reduced with the presence of Co oxide dopant. The best photocatalyst obtained was 3Co-TiO2 which enhanced the photocatalytic activity of TiO2 by 12 folds to 26.6%. The importance of fluorescence properties of Co-doped TiO2 towards its photodegradation of Congo Red was presented.
Synthesis and characterization of Ag/TiO2 plasmonic photocatalyst supported on stainless steel webnet
Authors: Khani Mojtaba , Saidina Amin Nor Aishah , Zakaria Zaki Yamani , Alias Hajar , Hosseini Seyed Nezamedin
Published: October 2017

Plasmonic nanostructures present substantial function in the advancement of modern materials science and technology. Plasmon-enhanced solar light is harvested to enhance the solar-to-fuel energy conversion efficiency. Both organic and inorganic semiconductor materials often serve as photocatalysts for the direct conversion of solar energy into fuels, owing to their superior stability, environmental compatibility and photocatalytic activity. However, semiconductor efficiency can be hindered by their inability to absorb visible light due to the vast band gap. More recently, a number of research has been performed to enhance photocatalyst and photovoltaic device efficiency by integrating plasmonic nanoparticles (NPs) with semiconductor materials. The presence of plasmonic NPs causes greater semiconductor absorption cross sections due to robust field enhancement, light absorption at longer wavelengths and enhanced electron–hole charge separation in semiconductor media, thus maximizing the efficiency of photocatalytic devices.  In this study, we have prepared a new visible-light-driven Ag/TiO2 nanoparticles plasmonic photocatalyst coated on webnet stainless steel by the dip-coating method to enhance the visible light plasmonic photocatalyst. FESEM, EDX and UV–vis spectra analyses were carried-out to characterize the prepared catalysts. According to these tests, the Ag/TiO2 coated on the stainless steel webnet functioned quite well. In addition, the maximum conversion of carbon dioxide was achieved at about 20%. This study may provide new insight into the design and preparation of advanced visible-light photocatalytic materials.
Preparation of highly active zinc oxide for photocatalytic removal of phenol: Direct calcination versus co-precipitation method
Authors: Hussin Faisal , O. Lintang Hendrik , Siew Ling Lee , Yuliati Leny
Published: October 2017

Photocatalytic removal of phenol under UV light irradiation was studied on zinc oxide (ZnO) photocatalysts, which were prepared via direct calcination (DC), and co-precipitation (CP) methods. The XRD patterns revealed that all of the prepared ZnO samples showed wurtzite structure, in which the ZnO-CP showed higher intensity of the diffraction peaks than the ZnO-DC sample. Optical and fluorescence properties of the prepared ZnO samples were similar to each other as confirmed by DR UV-Vis and fluorescence spectroscopy, respectively. The Stern-Volmer plot was investigated to study the interactions between the emission sites and the phenol. It was obtained that the emission sites of the ZnO-CP gave better interactions towards phenol molecules as compared to the ZnO-DC. After 6 hours reaction under UV light irradiation, the ZnO-CP sample showed two times higher photocatalytic activity for removal of phenol (10%) than that of the ZnO-DC (5%). It was suggested that the high activity observed on the ZnO-CP sample would be due to high crystallinity and good interactions with phenol. These results clearly suggested that the co-precipitation method was a good approach to prepare the highly active ZnO for the photocatalytic removal of phenol.
Study on quenching effect of nitrite ions on zinc oxide modified by polyvinylpyrrolidone
Authors: Hua Tang Ing , Mohd So’ad Siti Zarina , O. Lintang Hendrik , Yuliati Leny
Published: October 2017

Zinc oxide (ZnO) is appeared to be an attractive material for application for multidisciplinary fields, owing to its unique physical and chemical properties. In this study, ZnO was synthesized using the co-precipitation method, where the zinc acetate was used as the precursor. The ZnO was further modified by adding different amounts of polyvinylpyrrolidone (PVP) via simple physical mixing method to obtain PVP/ZnO composites. The ZnO and the PVP/ZnO composites were characterized using Fourier transform infrared (FTIR), diffuse reflectance ultraviolet-visible (DR UV-Vis), and fluorescence spectroscopy. The FTIR spectra detected the presence of ZnO group and the functional groups from the PVP. The PVP peaks become more apparent with the increase of the PVP amount. From the DR UV-Vis spectra, no significant change was observed after modification with the PVP, and all composites showed similar broad absorption band to that of the ZnO. The fluorescence spectra showed that the addition of PVP decreased the emission intensity and red shifted the peak wavelength, indicating certain interactions between the ZnO and the added PVP. Quenching study was investigated in the presence of nitrite ions (NO2-) with various concentrations (2-10 mM). A linear Stern-Volmer plot was observed and the highest quenching constant rate (KSV) was obtained on the PVP/ZnO sample with PVP content of 0.1 wt%. This study demonstrated that the addition of the PVP on the ZnO improved the interaction between the ZnO and the NO2-, which will be one of the important factors for sensing and catalytic applications for detection and conversion of NO2-.
Predicting growth of gold nanoparticle by photochemical reduction process associated with mathematical modelling
Authors: A. Hamlan Hazidatul , Alias Norma , Cherng Chong Jia , Hong Ley Hood , Bidin Noriah , Rahmat Hamisan
Published: October 2017

Nowadays, to develop new generation of nanodevices, most researchers such as chemists, physicists, biologists, even the engineers are focusing their studies towards the uniqueness as well as the chemical properties of metal nanoparticles. Even, the mathematician also has governed the appropriate mathematical modelling regarding of properties of nanoparticles such as gold nanoparticles. In this paper, some experiment regarding the photochemical and photocatalytic processes for predicting the growth of gold nanoparticles from previous studies has been reviewed. Besides that, in observing the growth rate of gold nanoparticles, a mathematical modelling has been governed. Where, ultraviolet, UV radiation with wavelength of 366 nm and 253.7 nm has been fixed as the constant parameters. The governing equation is then solved numerically using some iterative method known as Jacobi and Gauss Seidel. The convergence of both methods is discussed in detail and the numerical analysis is presented in table form to justify and validate the convergence as well as the performance of the proposed iterative methods.
Copper oxide supported on graphene for phodegradation of rhodamine B
Authors: Hassan Nurul Sahida , Roslani Nurul Jamilah , Abdul Jalil Aishah , Triwahyono Sugeng , Salleh Nur Fatien , Jaafar Nur Farhana
Published: October 2017

In recent years, dyes are one of the major sources of the water contamination that lead to environmental problems. For instance, Rhodamine B (RhB) which was extensively used as a colorant in textile industries is toxic and carcinogenic. Among many techniques, photocatalytic degradation become the promising one to remove those dyes from industrial wastewater. Recently, graphene has shown outstanding performance in this application due to its intrinsic electron delocalisation which promotes electron transport between composite photocatalyst and pollutant molecules. While, copper oxide (CuO) is well-known has a lower bandgap energies compared to other semiconductors. Therefore, in this study, copper oxide supported on graphene (CuO/G) was prepared and its photocatalytic activity was tested on degradation of RhB. The catalysts were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The results showed that the interaction between copper and graphene support could enhance the photocatalytic activity. The 5 wt% CuO/G was found to give the highest degradation (95%) of 10 mg L-1 of RhB solution at pH 7 using 1 g L-1 catalyst after 4 hours under visible light irradiation. The photodegradation followed the pseudo first-order Langmuir-Hinshelwood kinetic model. This study demonstrated that the CuO/G has a potential to be used in photocatalytic degradation of various organic pollutants.
Anatomical data analysis and normal femur bone reconstruction for designing titanium alloys total hip joint femoral stem
Authors: Suhendra Nandang , Gustiono Dwi , Masmui Masmui , Nastia Gina
Published: October 2017

The purpose of the work is to obtain size and geometry numerical data of femur bone for designing femoral stem of total hip joint arthroplasy to fit for Indonesian patient with normal hip joint structure. Geometry data of femur bone was taken by both  X-ray and CT scan methods. The X-Ray anatomy digital objects were taken from different angles at certain intervals as input data to reconstruct anatomical objects. Slicing of femur bone imaging taken by CT scan has a constant interval. Data obtained from both CT scan and X-ray were compared. A solid model of bone is used as a visual-tactile representation, planning surgery (surgical) and simulation tool for physicians. In this work the data input was used for design of a total hip joint arthroplasty (THA) femoral stem. The work reported in this article is considered as a preliminary stage of the development of total hip joint arthroplasty devices for being fit to local (Indonesian) patients with hip joint disorders. The preliminary designs developed in this work is suit for many kind materials, however, for the implementation into manufacturing works, the use of Titanium Alloys need to consider for appropriate femoral stem designs by taking into account the available of tools and effectiveness of femoral stem production, made of the materials.
Immobilization of metalloporphyrin on functionalized SBA-15 nanoporous silica
Authors: Saadon Nurafiqah , Endud Salasiah , Bakar Mohd Bakri , Yazdi Mahsa Khoshkhooy
Published: October 2017

SBA-15 nanoporous silica was prepared by cooperation assembly of tetraethylorthosilicate  precursor in the presence of poly (ethylene glycol)–block- poly (propylene glycol)–block- poly (ethylene glycol) copolymer surfactant and functionalized with (3-aminopropyl) triethoxysilane (APTES) via sol-gel reaction to obtain APTES-SBA-15. Tetra-(p-chlorophenyl) porphyrin (TClPP) was synthesized using modified Alder- Longo method. Zinc was inserted into the TClPP using zinc acetate as a metal source The existance of zinc in porphyrin was confirmed by the appearance of Soret band and Q band in UV- vis spectra. ZnTClPP was also characterized using FTIR and NMR spectroscopy SBA-15 was modified with APTES to immobilize the metalloporphyrin on SBA-15 surface. The product (NH-SBA-15 ZnP) can be used as a heterogenous catalyst in various reactions. The formation of this material was confirmed by FTIR spectroscopy, XRD and BET adsorption.