bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Gallium Additions on the Microstructure of Lead-Free Solder Materials: A Short Review
Authors: Nazri S.F. , Mohd Salleh Mohd Arif Anuar
Published: August 2018

This paper reviews the results of gallium (Ga) additions on the properties of Lead (Pb)-free solder alloys in terms of the solderability, microstructure and mechanical properties. Throughout the review, it is proven that when 0.5% of Ga is added, the shear force is improved and the grain size of the solder has refined remarkably. Besides, the addition of Ga has significantly suppressed the interfacial intermetallic compounds (IMCs) formation at solder/Copper substrate interface. This is caused by the formation of the Cu2Ga phase around the joint surface during solidification which decrease the growth rate of the IMCs layer. In fact, the enhancement in the mechanical aspect can also be affiliated with the improvement of the IMCs of the solder due to the addition of Ga. Moreover, Ga element also added to act as solid solution strengthening in β-Sn matrix. Furthermore, the addition of Ga element definitely decreases the melting temperature of Pb-free solder in Sn-0.7Cu Pb-free solder. As Ga addition also improve the oxidation resistance and reduce the surface tension of the solder, thus the solderability of the Pb-free solder alloys is slightly improved.
Microstructure Evolution of Sn-Cu Based Solder Paste with Different Cu Concentration Subjected to Multiple Reflows
Authors: Said Rita Mohd , Mohd Salleh Mohd Arif Anuar , Amran Nur Ain Athirah , Ramli Mohd Izrul Izwan
Published: August 2018

The evolution in microstructure of Sn-Cu based solder paste with different copper (Cu) content subjected to multiple reflow cycles was investigated. In this study, the Sn-0.7Cu (SC) solder paste was used as based material. The Cu particles were added into SC solder paste to produce new Sn-4Cu and Sn-10Cu solder paste. After that, the solder paste was then reflowed on Cu-OSP surface finished and subjected to six times reflows. Characterization focuses on the bulk solder microstructure, morphology and intermetallic compound (IMC) thickness after multiple reflows. Results reveal that solder composition significantly affect the microstructure formation and growth of IMC.
Effect of Neutron Irradiation on Electrical Properties of Bi2Sr2CaCu2 (Bi-2212) Phase Superconductor
Authors: Hamid Nasri A. , Mohiju Z.A. , Abdullah Y.
Published: August 2018

The effect of neutron irradiation on superconducting properties of Bi2Sr2CaCu2 (Bi-2212) phase superconductor was studied. TRIGA MARK II research reactor with neutron flux of 2.00 × 1011 /cm2s was used as the neutron source. Results between non-irradiated and irradiated samples have been analyzed from the aspects of microstructure and electrical properties. In this work, the bulk samples were prepared using the conventional solid-state reaction method. Molar ratio of Bi2O3, Sr2CO3, CaCO3 and CuO were mixed according to its ratio into composition of Bi:Sr:Ca:Cu = 2:2:1:2. The samples were sintered at 840°C during the sample preparation process. Some of the fully synthesized samples were irradiated with neutron irradiation. Neutron irradiation has been proved to promote better flux pinning properties by introducing larger defects in various superconductor ceramics. Enhanced flux pinning centers in the superconductor is responsible in enhancing the critical current, Ic and critical current density, Jc of the irradiated samples. The samples were characterized through X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The transition temperature, Tc and the Jc were measured by using a cryogenic four-point probe system. The XRD patterns for the non-irradiated and irradiated samples show well-defined peaks of which could be indexed on the basis of the Bi-2212 phase structure. XRD patterns also indicate that irradiation did not affect the Bi-2212 superconducting phase. However, the enhancement of Jc was observed in the neutron irradiated sample and this indicates the effectiveness of .neutron irradiation in creating defects that acted as effective flux pinning centers for vortices.
Optimization of Anodized Aluminum Oxide for DNA Application Using Taguchi Methods
Authors: Derman Mohd Nazree B. , Zuraidawani C.D. , Razlee N. , Shamsudin S.I. , Jamil Amerul Azree
Published: August 2018

This paper on optimizing the anodised Al oxide for DNA detection by using Taguchi method. One step anodizing is carry out in the mixture electrolyte using phosphoric and oxalic acid. Control factor for this study is voltage, concentration and time. The corrosion tested to measure polarization resistance. The Taguchi methods will be optimize the anodizing parameter for DNA application. These three samples is then undergo DNA immobilization with 10µM DNA with amine-terminated group and leave it in 4h at RT. The cyclic voltammetry used to detect DNA by measure the immobilization current (Iimmo). From the result, anodized part with DNA immobilized have higher immobilized current thanpolarized part with DNA. Scanning Electron Microscope (SEM) is to observe the surface morphology of the anodized and polarize part. The result show anodized part had more particle and dispersed around than the polarize part.
The Effect of Current Densities in Zinc Electroplating Process on Mild Steel for Soil Water Environment Application
Authors: Zainal Farah Farhana , Rahim N.S.Md. , Rajaselan Wardan
Published: August 2018

For more environmental friendly study, commonly undesired natural process which is corrosion will present. Thus, in this century there is a serious effort in ongoing analysis in order to prevent this phenomenon occurring. The challenge of corrosion in manufacturing and domestic sector is enormous. Thus, corrosion can be defined as the deterioration and destruction of a material because of reaction with the environment. Replacing a corroded pipeline can cost about $643,000 per kilometer. The application of the traffic sign or a road sign that embedded in soil usually can withstand for two to three years until it will corrode and then fracture. The main objectives of this study is to increase the protection on the surface of the materials towards corrosion and to improve the appearance of the product or serves as an effective undercoat for paints which can reduce the cost of using expensive material by using the other method; electroplating process. The samples were plated with zinc at 2, 4 and 6 A/dm2 for 20 minutes for every sample. Then, the samples were immersed in the artificial soil solution for 30 days, then the testing to measure the corrosion rate, phase analysis, morphological analysis and hardness test were conducted. From all the tests, sample with 6 A/dm2 got the best results with 5.2059 mpy and 80.6 HV hardness strength. It is because by increasing the current density, the thickness will then increase the zinc plating will not easily peel off and attack by corrosive agent.
Electrochemical Impedance Spectroscopy (EIS) Evaluation of Hydroxyapatite-Coated Magnesium in Different Corrosion Media
Authors: Zaludin Mohd Amin Farhan , Jamal Zul Azhar Zahid , Derman Mohd Nazree B. , Kasmuin Mohd Zaheruddin
Published: August 2018

Magnesium corrosion has been identified as the main challenge that limits the implementation of this material into various applications, including biomaterials. Simple chemical conversion coatings have been employed in order to minimize the corrosion problems. In this paper, hydroxyapatite-coated magnesium were fabricated by using chemical conversion coatings and the corrosion behaviour of the coated samples were evaluated inside different corrosion media (Ringers, SBF, and PBS) by using electrochemical impedance spectroscopy (EIS). EIS reveals the electrical properties of the coatings towards corrosion attack by the corrosion media. The corrosiveness of the tested solutions was given by (from least to the most aggressive): PBS ˂ SBF ˂ Ringers.
Effects of Dynamic Vulcanization on Properties of Polypropylene/Natural Rubber/Thermoplastic Starch Blends
Authors: Hazwan S.M. , Ab Wahab Mohamad Kahar
Published: August 2018

The effects of thermoplastic starch (TPS) loading on polypropylene (PP)/natural rubber (NR) blend vulcanized with N, N’-m-phenylene bismaleimide (HVA-2) were investigated. Thermoplastic starch ratios was varied at 5%,10%,20% and 30% weight percentage in order to imparted biodegradable properties into PP/NR blends. The study has focused on the thermoplastic starch loading and blend’s modification on the mechanical properties, morphology and biodegradable properties of PP/NR blends. This study showed that the tensile properties of the PP/NR blends were deteriorated with increasing in TPS content. The dynamic vulcanization by using HVA-2 crosslinker was applied on the blends in order to compensate the deterioration properties caused by incorporation of TPS. According to the results, the HVA-2 crosslinker showed the increasing in tensile properties as well as better morphology analysis as compared to unvulcanized counterparts. On top of that, the scanning electron microscopy (SEM) studied also found that the interfacial adhesion and dispersion of TPS was improved upon HVA-2 vulcanized in PP/NR blends. Microscope images after soil burial test show that the HVA-2 crosslinker has delayed the biodegradability of PP/NR/TPS blends.
Effect of Annealing Temperature on Silver Doped Titanium Dioxide (Ag/TiO2) Thin Film via Sol-Gel Method
Authors: Razak Kamrosni Abdul , Che Halin Dewi Suriyani , Al Bakri A.M. Mustafa , Mohd Salleh Mohd Arif Anuar , Mahmed Norsuria , Danial N.S.
Published: August 2018

This study is conducted to investigate the effect of different annealing temperature on the growth of Silver doped Titanium Dioxide (AgTiO2) nanocrystalline thin films.AgTiO2 nanocrystalline thin films on silicon wafer have been prepared by sol–gel spin coating. The thin films were characterized for surface morphology and phase analysis by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 ± 0.5 and with annealing temperature of 300, 400, 500 and 600°C for 2h soaking time. X-Ray diffraction shows that only Ag/TiO2 thin film annealed at 600°C have anatase TiO2 phase. From SEM micrograph, there are cracks and pulled out thin film from the substrate, which were gradually minimize as the annealing temperature increase.
The Influence of Sodium Bicarbonate Loading as Blowing Agent on the Properties of Epoxy Foam
Authors: Hussein Mohamad Saed , Teh Pei Leng , Rahmat Abdul Razak , Zainuddin Firuz , Yeoh Cheow Keat
Published: August 2018

This research studied the effect of sodium bicarbonate content on the properties of epoxy. Sodium bicarbonate (SB) was used as foaming agent to improve the properties of thermosetting epoxy resin. The samples of epoxy foam were produced using mixing method. Sodium bicarbonate was selected as blowing agent by reason of the environmental friendly and low cost concern. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15, 20 and 25 part per hundred (phr), respectively. It can be highlighted that the optimum content of the SB was selected at 15 phr and it gave the moderate porosity percentage (%), and moderate value in mechanical and density properties, higher SB content exhibited lower flexural properties.
A Review on Effect of Nanoreinforcement on Mechanical Properties of Polymer Nanocomposites
Authors: Ervina Efzan M.N. , Siti Syazwani N.
Published: August 2018

Polymer nanocomposites represent a new class of materials that offer an alternative to the conventional filled polymers. In this new class of materials, nanosized reinforcement are dispersed in polymer matrix offering tremendous improvement in performance properties of the polymer. The combination of nanoscale reinforcement and polymer matrix possess outstanding properties and functional performance which play an important role in many field of applications. This review addresses the types of nanoscale materials reinforced in polymer matrix such as nanocellulose, carbon nanotubes (CNTs), graphene, nanofibers and nanoclay followed by the discussion on the effect of these nanoscale reinforcement on mechanical properties of polymer nanocomposites. Besides, the potential use of polymer nanocomposite reinforced with those nanoscale reinforcements in various field of applications also discussed.
Radiation Induced Grafting of Acrylic Acid on to Polyaniline Nanofiber
Authors: Kamarudin Sabariah , Mohammad M. , Mohammed N.
Published: August 2018

This study aims to explore modification of polyaniline nanofiber through grafting polymerization to increase its solubility and processability for application in aqueous environment. Grafting via electron beam radiation procedure is extremely productive in terms of time consumption and environmental friendliness. In this work, acrylic acid was grafted on to polyaniline nanofiber using electron beam irradiation. The influence of altering the electron beam power from 2-3 MeV, radiation dosage from 5-25 kGy, acrylic acid concentration from 10-100% and soaking time from 2-24 hours during graft polymerization were studied over the grafting percentage (%G). Grafting parameter was determined by weight changes before and after grafting procedure. Grafted polyaniline is characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA). Formation of new peak at 1700 cm-1 for FTIR spectroscopy analysis of grafted polyaniline confirmed grafting has taken place during irradiation.
Characterization and Properties of Biodegradable Thermoplastic Cassava Starch/Chitosan Films
Authors: Ab Wahab Mohamad Kahar , Wahab Mohd Kahar A.
Published: August 2018

The chitosan starch film was produce through solution casting with different carboxylic acid for acid treatment. Several testing were conducted such as tensile test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), moisture absorption and soil burial. The optimum ratio for the chitosan/starch was 70:30. This ratio shows the highest tensile strength which is 11.84 MPa for the control film. The acid used for chemical modifications were citric acid and ascorbic acid. This acid modificationsexhibited higher tensile strength, Young's modulus, and less weight loss in soil burial and lower percentage of moisture absorption. SEM shows the better solubility of the starch in film with acid treatment. Moisture absorption and weight loss in the soil burial test was lower in the film with acid treatment than thefilm without acid treatment.
Effect of Vacuum and Non-Vacuum Packaging on Total Phenolic Content of Encapsulated Orthosiphon stamineus Spray-Dried Powder during Storage
Authors: Razak N.A. , Hamid Nasri A. , Shaari Abdul Razak
Published: August 2018

The experiment was conducted to determine the effects of vacuum and non-vacuum packaging on the total phenolic content of encapsulated O. stamineus spray-dried powder when stored under different temperatures (10 and 25 °C) for 4 weeks of storage period. The total phenolic compound was measured using the Folin-Ciocalteu method and was analyzed using UV/VIS spectrophotometer. The results showed that both vacuum and non-vacuum packing affected the consistency of capsulated O. stamineus spray-dried powder during storage. The total phenolic content of the samples significantly increased for both vacuum and non-vacuum packaging when stored at 10 °C. However, the total phenolic content of the samples for both vacuum and non-vacuum packaging decreased after 2 weeks of the storage period when the samples stored at room temperature, 25 °C. Thus, it is suggested to keep the encapsulated O. stamineus spray-dried powder under low temperature (10 ˚) with vacuum packaging to sustain the medicinal properties quality and to prolong the shelf-life of the encapsulated products.
The Mechanical Properties of Carboxymethyl Cellulose (CMC) Filled Halloysite Nanotube (HNT) Bio-Nanocomposite Films: Effect of Sodium Dodecyl Sulfate (SDS)
Authors: Suppiah K. , Teh Pei Leng , Husseinsyah S. , Rahman R. , Yeoh Cheow Keat
Published: August 2018

In this study, carboxymethyl cellulose (CMC) used as matrix, while halloysite nanotube (HNT) used as nanofiller to produce bio-nanocomposite films via solvent casting method. The effect of sodium dodecyl sulfate (SDS) on tensile properties and morphology study of CMC/HNT bio-nanocomposite films have been investigated. The results showed that the mechanical properties of treated CMC/HNT bio-nanocomposite films using SDS enhanced the tensile strength, elongation at break and modulus of elasticity compared to untreated CMC/HNT bio-nanocomposites. Besides, the tensile fracture surface of treated bio-nanocomposites demonstrated by field emission scanning electron micrograph (FESEM) indicates that the presence of SDS improved the interfacial interaction between CMC matrix and treated HNT nanofiller.
Characterization of Several Microcrystalline Cellulose (MCC)-Based Agricultural Wastes via X-Ray Diffraction Method
Authors: Sainorudin Muhammad Hanif , Mohammad Masita , Kadir Nurul Huda Abd , Abdullah Nur Athirah , Yaakob Zahira
Published: August 2018

In this study, microcrystalline cellulose (MCC) was extracted from various types of local agricultural wastes. Four types of agricultural waste such as coconut coir, banana stem, sugarcane bagasse and pineapple leaves were collected, extracted and hydrolyzed into microcrystalline cellulose, using pre-treatment (alkaline and bleaching) and acid hydrolysis, respectively. The extracted MCC were analyzed and compared with those of commercially available MCC. The study of crystallinity behaviors of the obtained MCC was performed by X-Ray Diffraction (XRD) analysis. The XRD of MCC revealed that the crystallinity of pineapple leaves has the highest crystallinity index with 75% in value and closest compared to commercial MCC, 81.25%. The value of crystallinity index for banana stem is 74.55% followed by coconut coir, 72.73% and sugarcane bagasse, 66.50%. All of the MCC samples showed the similar pattern with the typical crystalline structure of cellulose I. The crystallite size of all MCC samples was calculated and found in the range of 4.04 – 5.14 nm. These extracted MCC that obtained from several agricultural wastes was supposed to have a high potential as value-added products in industrial applications.
Optimization of Methyl Ester Production from Waste Palm Oil Using Activated Carbon Supported Calcium Oxide Catalyst
Authors: Wan Zuraida , Hameed Bassim H. , Nor N. Mohammad , Ali Bashah Nur Alwani
Published: August 2018

In this study, methyl ester (ME) was produced by transesterification of waste cooking palm oil (WPO) using activated carbon supported calcium oxide as a solid base catalyst (CaO/AC). Process optimization using response surface methodology (RSM) was applied to study the effect of reaction time, molar ratio of methanol to oil, reaction temperature and catalyst amount to produce highest ME content. The optimum reaction condition was at 5.5 wt% catalyst amount, 170 °C temperature, 15:1 methanol to oil molar ratio and 2 h 22 min reaction time. The predicted and experimental ME content were found to be 80.02% and 77.32%, respectively.
Thermal Conductivity of Water Based Magnetite Ferrofluids at Different Temperature for Heat Transfer Applications
Authors: Haiza H. , Yaacob Iskandar , Azhar Ahmad Zahirani Ahmad
Published: August 2018

Magnetic magnetite, Fe3O4 nanoparticles produced by Massart’s procedure were used to prepare water based magnetite, Fe3O4 ferrofluids without addition of any stabilizing agent or surfactant. The thermal properties and suspension stabilization of the ferrofluids were investigated by varying the magnetite, Fe3O4 nanoparticles concentration in the ferrofluids prepared. The thermal conductivity of water based ferrofluids prepared using five different volume fraction of magnetite, Fe3O4 suspension (0.1, 0.05, 0.02, 0.01 and 0.005) were measured at five different temperature, 25°C, 30°C, 40°C, 50°C and 60°C in order to evaluate its potential application as heat transfer fluid. The results shows that the thermal conductivity of the ferrofluids are higher than the base fluid, and the thermal conductivity of the ferrofluids increased as the magnetite concentration in the ferrofluids decreased however reached its optimum for ferrofluids prepared using 0.01 volume fraction of magnetite suspension over 0.99 volume fraction of water. Accordingly, the thermal conductivity of the ferrofluids significantly increased as the temperature increased where 49.4% enhancement with respect to water were observed at temperature 60°C.
Study of Cassava Starch Filled with Different Loading of Kenaf Core Fiber
Authors: Walster R.J. , Rozyanty A.R. , Ab Wahab Mohamad Kahar , Musa Luqman
Published: August 2018

Cassava starch (CS) films filled with different loading of kenaf core fiber (KCF) were prepared and tested. Three testing were carried out; tensile test, water absorption test, and oil absorption test. The tensile test showed an increase in stiffness of the modulus as the loading of KCF increased. Additionally, the increase of KCF loading also increased the amount of water and oil absorbed by the films.
Oil and Water Absorption Behavior of TPU/Natural Fibers Composites
Authors: Ahad Nor Azwin , Rozali Fatin Zalila , Rosli Nurul Husna , Hanif Nur Idzwan Hafizi , Parimin Noraziana
Published: August 2018

Fruit skins are waste and natural fibers which are processed from it can be used as filler material in polymer composites. These natural fibers are surely inexpensive, non-toxic and environmentally friendly. In the other hand, natural fibers are chemically hydrophilic and absorb water. Their nature which are rich cellulose making it hydrophilic in nature. Besides their nature to water, the ability of natural fibers to absorb oil also interesting to be studied. In this paper, natural fibers from several types of fruit skin were used as filler in thermoplastic polyurethane (TPU) composites. The fibers from pineapple skin, coconut shell, coconut husk, corn cob, rambutan, mangoesteen and banana with the percentage of 15% and 20% were incorporated with TPU through melt mixing technique. Every type of natural fiber will absorb oil and water at different rate, as well as the effect of filler content in the composite. Overall, the absorption of water and oil increased its percentage when the filler content increases. Rambutan, pineapple and banana absorb more water than others at 20% filler content in the TPU. Pineapple and rambutan also tend to absorb more engine oil.
Influence of Morphology of Cathode-Ray Tube Glass as Coarse Aggregates on Compressive Strength and Water Absorption of Concrete
Authors: Mohd Pauzi Nurul Noraziemah , Jamil Maslina , Hamid Roszilah , Zain Muhammad Fauzi Mohd
Published: August 2018

The study on the substitution for natural coarse aggregates using waste CRT funnel glass in spherically shapes is still limited. In this paper, the waste CRT glass has been processed to form a spherical CRT glass (GS) and crushed CRT glass (GC), which were used as a coarse aggregate in concrete production. Results indicated that the inclusion of GS and GC has lower the compressive strength and decreased the rate of capillary water absorption of concrete. It was demonstrated that the morphology properties of GS and GC (shape, surface texture, size, grading) is significantly affected the concrete properties.
Mechanical Properties of Biocomposite Films Based on Poly(Lactic Acid) Reinforced with Cellulose Fibers
Authors: Jamnongkan Tongsai , Boonjuban N. , Sangkhachat J. , Wattanakornsiri Amnuay , Mongkholrattanasit Rattanaphol
Published: August 2018

In this paper, we intended to study and improve the mechanical properties of poly (lactic acid) (PLA) composites with cellulose fibers from recycled newspapers. The influence of cellulose fiber content on tensile mechanical properties and swelling behavior of biocomposite films were investigated. In addition, the morphological property of biocomposite films was determined by scanning electron microscopy (SEM). It was found that the cellulose fibers have directly affected to the swelling behavior of biocomposite films. In addition, it was found that the cellulose fibers were found embedded between PLA matrices, which resulting to the improvement and increase the mechanical properties of biocomposite films. These findings illustrate that the cellulose fibers from recycled newspaper possesses good fillers and could be a good alternative reinforcement for biopolymer composites.
Characteristic and Morphology of Palm Waste Filled Thermoplastic Composites
Authors: Zakaria Muhammad Salihin , Ghazali Che Mohd Ruzaidi , Kamarudin Hussin , Wahab Mohd Kahar A. , Halim Khairul Anwar Abdul , Yevon L.
Published: August 2018

This paper presents the characteristic and morphology of palm waste (palm slag and palm ash) filled thermoplastic (high density polyethylene (HDPE) and recycled HDPE) composites. Two different particle sizes were used which are in the range from 150 μm to 300 μm defined as coarse and less than 75 μm defined as fine. The palm waste of HDPE and recycled HDPE with 8 different types of sample were prepared using a twin screw extruder with 10 % of filler loading was chosen to produce the composite. The XRF result indicated that palm slag has higher SiO2, but lower CaO content as compared to palm ash. Median particle size analysis showed that fine size palm ash demonstrated lowest d50 and coarse size palm slag showed a comparable value of d50 with coarse size palm ash. The scanning electron microscopy studies showed that coarse size palm slag illustrated better matrix interaction with HDPE and recycled HDPE. The overall result indicated that coarse size palm slag shows comparable characteristic and morphology compared with fine size palm ash in HDPE and recycled HDPE composite.
Characterisation of Reduction of Iron Ore with Carbonaceous Materials
Authors: Najmi N.H. , Yunos Nur Farhana Mohd , Othman Norinsan Kamil , Asri Idris Muhammad
Published: August 2018

An investigation on the reduction of iron ore with carbonaceous material as a reductant was carried out at 1550°C. Iron ore was mixed with biochar from palm shell and coke as a reference at C/O molar ratio of 1.0. Characterisation of raw materials was performed using X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET), Fourier Transmittance Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM-EDX). The samples after reduction were characterised to study the phase transformation and structural properties. The XRD results revealed the iron ore contained hematite as its main composition. After reduction at high temperature, the hematite has been successfully reduced to metallic iron using biochar as a reductant. It was found that the reaction proceeded in a stepwise reduction of iron oxide. The SEM micrographs proved the formation of metallic iron in the sample after reduction at 1550°C. Through characterisation, the biochar from palm shell has physical properties suitable to be an alternative carbon reductant to replace coke.
Minerals Characterization of Magnetic and Non-Magnetic Element from Black Sand Langkawi
Authors: Khuzaima Nur , Ahmad Khairel Rafezi , Ahmad Zaidi Nur Hidayah , Hashim M.K.R. , Rezan Sheikh Abdul
Published: August 2018

Valuable minerals are defined as mineral which having good opportunities to economic and consireable important. The most commonly occurring sand mineral deposits are ilmenite, rutile, magnetite, cassiterite, monazite, tourmaline, zircon, kyanite, silimanite, and garnet. In Malaysia, mineral sand deposits is found in Langkawi which known as black sand Langkawi. Langkawi black sand having high amount of valuable minerals that is very crucial in the industrial and construction products. Characterizations of black sand acquire different techniques to concentrate and separate valuable minerals. These techniques utilize different in physical or chemical properties of the valuable and gangue (wastes) minerals. For magnetic is based on natural or induced differences in magnetic susceptibility or conductivity of the minerals.. They are used to distinguish and extract magnetic, slightly magnetic and non-magnetic components present in the heavy fraction (Rutile, Ilmenite, Magnetite, Garnets, Zircon and Monazite). All minerals will have one of three magnetic properties: ferromagnetic, paramagnetic and diamagnetic. Ferromagnetic minerals (i.e. Magnetite and Ilmenite) are magnetic and easily attracted to the poles of magnet. Paramagnetic and diamagnetic minerals in the group magnetic, but if the mixture of paramagnetic and diamagnetic minerals are passed through a magnetic field, the paramagnetic minerals will be pulled into the field and diamagnetic minerals separated from the field. By varying the intensity of the magnetic field, it is also possible to separate different paramagnetic minerals from each other. In this study, techniques used to separate valuable minerals from black sand are magnetic separator.
The Effect of Different Sand Gradation with Ultra High Performance Concrete (UHPC)
Authors: Hamiruddin N.A. , Razak R. Abd , Muhamad K. , Zahid M.Z.A. Mohd , Aziz C.N.S. Che Ab
Published: August 2018

Advances in concrete material research has introduced to development the new class of concrete which is known as Ultra High Performance Concrete (UHPC). Due to the most exceedingly awful on nature coarse aggregate quality, UHPC was delivered to success in concrete. This study investigated the effect of differentsand gradation (63-300μm, 300-600μm, 600-1180μm, and normal sand) on compressive strength and ultrasonic pulse velocity (UPV) of UHPC. The rheology of UHPC mixtures was determined by flow test conducted according to ASTM C1611 and the compression testwas performed to measure concrete compression strength at 7 and 28 days according to BS 1881-116 (1983). To determine the quality of concrete, UPV test were conducted according to BS 1881 part 201 (1986).From the experimental results, the results indicated that sand grading with 600-1180μm obtained the highest in compressive strength and UPV.The compressive strength at 28 days achieved 100 MPawith direct transmission of UPV 4.5% higher than semi direct.
Comparison of Structural and Electrical Behaviour of Phospho-Olivine LiNiPO4 and LiNi0.8Mn0.1Co0.1PO4 for High Voltage Rechargeable Li-Ion Batteries
Authors: Tan T.Q. , Idris Mohd Sobri , Osman Rozana Aina Maulat , Hambali Nor Azura Malini Ahmad , Reddy M.V.
Published: August 2018

Phase pure olivine LiNiPO4 and doped LiNi0.8Mn0.1Co0.1PO4 powders have been prepared by conventional solid state route. X-ray diffraction (XRD) combined with Rietveld refinements analysis reveals the formation of LiNiPO4 and doped LiNi0.8Mn0.1Co0.1PO4 with high crystalline nature at high temperature of 950 °C and 1000 °C. The lattice parameters of doped LiNi0.8Mn0.1Co0.1PO4 are significantly larger than LiNiPO4. It has been found out that the estimated crystallite size is in the order of nanometres for both samples. SEM analysis confirms that the particles have connected with each other in random shape and sub-microns size. The particle size has increased as small amount of Mn and Co are doped into LiNiPO4. The AC impedance spectroscopy measurements have revealed that the conductivity of LiNiPO4 is enhanced by around one order of magnitude by doping Mn and Co.
Tungsten Oxide (WO3) Films Prepared by Sol-Gel Spin-Coating Technique
Authors: Au B. Wen Cheun , Chan Kah Yoong , Pang Wai Leong , Lee Chu Liang , Mustafa Abd Hamid
Published: August 2018

Tungsten oxide (WO3) is a transition metal oxide with a wide range of applications such as displays, rear-view mirrors, electrochromic (EC) smart windows and gas sensors. Many techniques were adopted for the fabrication of WO3, namely magnetron sputtering, spray pyrolysis and sol-gel synthesis techniques. In this work, WO3 films were deposited on indium tin oxide (ITO) coated glasses by sol-gel spin-coating method. The film thickness was varied by depositing different number of layers. The WO3 film thickness and optical transmittance were determined using step profilometer and ultraviolet-visible (UV-Vis) spectrophotometer, respectively. WO3 film thicknesses increased from 38 nm to 606 nmwith increasing number of deposited layers.The optical transmittance of the WO3 films in visible range decreased with increasing film thickness. The optical transmittance were at least 70 % up to 10 deposited layers.WO3is a promising EC material in the application ofEC devices (ECDs).The application of WO3 in the EC devices will be discussed.
Assessing organisational justice as a predictor of job satisfaction and employee engagement in Windhoek
Authors: Pieters Wesley R.
Published: August 2018

Orientation: Working in the service industry with similar products and services requires organisations to be proactive and efficient. Enhancing employees’ levels of organisational justice is likely to influence job satisfaction and employee engagement.Research purpose: The purpose of this study was to investigate the dimensions of organisational justice that best predict job satisfaction and employee engagement among employees in Windhoek, Namibia.Motivation for the study: Poor service delivery is a concern within the service industry and this includes the banks and universities that operate in Windhoek. Having engaged employees is most likely going to improve the quality of service and customer satisfaction.Research approach/design and method: A cross-sectional survey design was used, employing a questionnaire to collect data on the biographical details, organisational justice, job satisfaction and employee engagement of employees at a bank and university in Windhoek. The sample consisted of employees from a bank, Bank A (n = 106), and administrative staff at a university (n = 97).Main findings: Significant predictors of employee engagement (work energy) were interpersonal organisational justice and intrinsic job satisfaction. Regarding employee engagement (work focus), intrinsic job satisfaction and extrinsic job satisfaction were the significant predictors.Practical/managerial implications: Managers and supervisors need to regularly assess, monitor and enhance employees’ perception of organisational justice, job satisfaction and employee engagement. Improving organisational justice within the workplace is likely to result in an increase in job satisfaction and employee engagement, resulting in increased productivity and customer satisfaction.Contribution/value-add: The novelty of this study in Namibia will add to already existing knowledge within industrial and organisational psychology, pave the way for future research and guide the development of interventions aimed at keeping employees satisfied and engaged in their work.
Конусы функций с условиями монотонности для обобщенных
потенциалов Бесселя и Рисса
Authors: Bokayev Nurzhan Adilkhanovich , Gol'dman Mikhail L'vovich , Karshygina Gulden Zhumabekkyzy
Published: August 2018

Рассматриваются вопросы порядкового накрывания и порядковой
эквивалентности для конусов функций со свойствами монотонности,
связанных с убывающими перестановками обобщенных потенциалов
Бесселя и Рисса.
Библиография: 8 названий.
О ядерности операторов Ганкеля, возникающих
в теории уравнения Кортевега-де Фриза
Authors: Grudskii Sergei Mikhailovich , Rybkin A V
Published: August 2018

Мы изучаем свойство принадлежности оператора Ганкеля (и его производных
по параметру) с сильно осциллирующим символом классу ядерных операторов.
Наш подход базируется на критерии Пеллера о ядерности операторов Ханкеля
и точном анализе, возникающего при этом тройного интеграла с помощью
метода перевала. Полученные результаты представляются оптимальными. Мы
применяем их к изучению проблемы Коши для уравнения Кортевега-де Фриза.
Именно, устанавливается связь гладкости решения со скоростью убывания
начальных данных на плюс-бесконечности.
Библиография: 30 названий.
О фредгольмовости одного класса операторов типа свертки
Authors: Kamalian Armen G , Spitkovsky Ilya Matveevich
Published: August 2018

Заменой в определении оператора свертки преобразования Фурье спектральным
преобразованием самосопряженного оператора Штурма-Лиувилля на
оси $\mathscr L$ введены понятия оператора $\mathscr L$-свертки
и оператора $\mathscr L$-Винера-Хопфа. Введенные операторы в случае
нулевого потенциала совпадают соответственно с оператором свертки
и с интегральным оператором Винера-Хопфа. Выявлена связь оператора
$\mathscr L$-Винера-Хопфа с сингулярными интегральными операторами.
В случае кусочно-непрерывного символа в терминах символа и компонент
матрицы рассеяния оператора $\mathscr L$ получены критерий фредгольмовости
и формула для индекса оператора $\mathscr L$-Винера-Хопфа.
Библиография: 18 названий.
Описание пространства риссовых потенциалов функций
из гранд-пространства Лебега на $\mathbb{R}^n$
Authors: Umarkhadzhiev Salaudin Musaevich
Published: August 2018

Рассматриваются потенциалы Рисса $I^\alpha f$, $0<\alpha<\infty$,
в рамках гранд-пространств Лебега $L^{p),\theta}_a$,
$1
0$, по $\mathbb{R}^n$ с грандизаторами
$a\in L^1(\mathbb{R}^n)$, в случае $\alpha\geqslant n/p$
понимаемые в терминах распределений на основных функциях
из пространства Лизоркина. Исследуется образ оператора $I^\alpha$
функций из подпространства гранд-пространства,
удовлетворяющих так называемому условию зануления.
При некоторых предположениях о грандизаторе дается описание
этого образа в терминах сходимости
усеченных гиперсингулярных интегралов порядка $\alpha$
в этом подпространстве.
Библиография: 23 названия.
Connecting regional aerosol emissions reductions to local and remote precipitation responses
Authors: Westervelt Daniel M. , Conley Andrew J. , Fiore Arlene M. , Lamarque Jean-François , Shindell Drew T. , Previdi Michael , Mascioli Nora R. , Faluvegi Greg , Correa Gustavo , Horowitz Larry W.
Published: August 2018

Abstract. The unintended climatic implications of aerosol and precursor
emission reductions implemented to protect public health are poorly
understood. We investigate the precipitation response to regional changes in
aerosol emissions using three coupled chemistry–climate models: NOAA
Geophysical Fluid Dynamics Laboratory Coupled Model 3 (GFDL-CM3), NCAR
Community Earth System Model (CESM1), and NASA Goddard Institute for Space
Studies ModelE2 (GISS-E2). Our approach contrasts a long present-day control
simulation from each model (up to 400 years with perpetual year 2000 or 2005
emissions) with 14 individual aerosol emissions perturbation
simulations (160–240 years each). We perturb emissions of sulfur dioxide
and/or carbonaceous aerosol within six world regions and assess the
significance of precipitation responses relative to internal variability
determined by the control simulation and across the models. Global and
regional precipitation mostly increases when we reduce regional aerosol
emissions in the models, with the strongest responses occurring for sulfur
dioxide emissions reductions from Europe and the United States.
Precipitation responses to aerosol emissions reductions are largest in the
tropics and project onto the El Niño–Southern Oscillation (ENSO).
Regressing precipitation onto an Indo-Pacific zonal sea level pressure
gradient index (a proxy for ENSO) indicates that the ENSO component of the
precipitation response to regional aerosol removal can be as large as 20 %
of the total simulated response. Precipitation increases in the Sahel in
response to aerosol reductions in remote regions because an anomalous
interhemispheric temperature gradient alters the position of the
Intertropical Convergence Zone (ITCZ). This mechanism holds across multiple
aerosol reduction simulations and models.
Zero to moderate methane emissions in a densely rooted, pristine Patagonian bog - biogeochemical controls as revealed from isotopic evidence
Authors: Münchberger Wiebke , Knorr Klaus-Holger , Blodau Christian , Pancotto Verónica A. , Kleinebecker Till
Published: August 2018

Abstract. Peatlands are significant global methane (CH4) sources, but processes governing CH4 dynamics have been predominantly studied on the northern hemisphere. Southern hemispheric and tropical bogs can be dominated by cushion-forming vascular plants (e.g. Astelia pumila, Donatia fascicularis). These cushion bogs are found in many (mostly southern) parts of the world but could also serve as extreme examples for densely rooted northern hemispheric bogs dominated by rushes and sedges. We report highly variable summer CH4 emissions from different microforms in a Patagonian cushion bog as determined by chamber measurements. Driving biogeochemical processes were identified from pore water profiles and carbon isotopic signatures. An intensive root activity within a rhizosphere stretching over 2 m depth accompanied by molecular oxygen release created aerobic microsites in water-saturated peat leading to a thorough CH4 oxidation (
Carbon balance of a restored and cutover raised bog: Comparison to global trends
Authors: Swenson Michael M. , Regan Shane , Bremmers Dirk T. H. , Lawless Jenna , Saunders Matthew , Gill Laurence W.
Published: August 2018

Abstract. All major aspects of the carbon balance – net ecosystem exchange (NEE), CH4 flux, losses of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC), and open water CO2 evasion – were measured for several distinct ecotypes in a restored unharvested raised bog and an adjacent historically abandoned cutover bog over a two year period. The average annual ecotype carbon balance at the Sub-Central ecotype, with eco-hydrological characteristics most similar to a high quality raised bog, was the largest net carbon sink of −32 ± 65 g C m−2 yr−1 while the Calluna Cutover ecotype, with the characteristics of a well-drained peatland site was the largest net carbon source of 239 ± 83 g C m−2 yr−1. The annual carbon balance from all ecotype study locations was found to be controlled by mean annual water table (MAWT). Also, significant negative correlation was observed between the plot global warming potential and percent Sphagnum moss cover, highlighting the importance of regenerating this keystone genus as a climate change mitigation strategy in peatland restoration. The data from this study was then compared to the rapidly growing number of peatland carbon balance studies across Boreal and Temperate regions. The trend in NEE and CH4 flux with respect to MAWT was compared for the five ecotypes in this study was and literature data from degraded/restored peatlands, intact peatlands, and bare peat sites.
Global sea-level budget 1993–present
Authors:   WCRP Global Sea Level Budget Group
Published: August 2018

Abstract. Global mean sea level is an integral of changes occurring in the climate system in response to unforced climate variability as well as natural and anthropogenic forcing factors. Its temporal evolution allows changes (e.g., acceleration) to be detected in one or more components. Study of the sea-level budget provides constraints on missing or poorly known contributions, such as the unsurveyed deep ocean or the still uncertain land water component. In the context of the World Climate Research Programme Grand Challenge entitled Regional Sea Level and Coastal Impacts, an international effort involving the sea-level community worldwide has been recently initiated with the objective of assessing the various datasets used to estimate components of the sea-level budget during the altimetry era (1993 to present). These datasets are based on the combination of a broad range of space-based and in situ observations, model estimates, and algorithms. Evaluating their quality, quantifying uncertainties and identifying sources of discrepancies between component estimates is extremely useful for various applications in climate research. This effort involves several tens of scientists from about 50 research teams/institutions worldwide (www.wcrp-climate.org/grand-challenges/gc-sea-level, last access: 22 August 2018). The results presented in this paper are a synthesis of the first assessment performed during 2017–2018. We present estimates of the altimetry-based global mean sea level (average rate of 3.1 ± 0.3 mm yr−1 and acceleration of 0.1 mm yr−2 over 1993–present), as well as of the different components of the sea-level budget (http://doi.org/10.17882/54854, last access: 22 August 2018). We further examine closure of the sea-level budget, comparing the observed global mean sea level with the sum of components. Ocean thermal expansion, glaciers, Greenland and Antarctica contribute 42 %, 21 %, 15 % and 8 % to the global mean sea level over the 1993–present period. We also study the sea-level budget over 2005–present, using GRACE-based ocean mass estimates instead of the sum of individual mass components. Our results demonstrate that the global mean sea level can be closed to within 0.3 mm yr−1 (1σ). Substantial uncertainty remains for the land water storage component, as shown when examining individual mass contributions to sea level.
Identifying rainfall-runoff events in discharge time series: A data-driven method based on Information Theory
Authors: Thiesen Stephanie , Darscheid Paul , Ehret Uwe
Published: August 2018

Abstract. In this study, we propose a data-driven approach to automatically identify rainfall-runoff events in discharge time series. The core of the concept is to construct and apply discrete multivariate probability distributions to obtain probabilistic predictions of each time step being part of an event. The approach permits any data to serve as predictors, and it is non-parametric in the sense that it can handle any kind of relation between the predictor(s) and the target. Each choice of a particular predictor data set is equivalent to formulating a model hypothesis. Among competing models, the best is found by comparing their predictive power in a training data set with user-classified events. For evaluation, we use measures from Information Theory such as Shannon Entropy and Conditional Entropy to select the best predictors and models and, additionally, measure the risk of overfitting via Cross Entropy and Kullback–Leibler Divergence. As all these measures are expressed in bit, we can combine them to identify models with the best tradeoff between predictive power and robustness given the available data. We applied the method to data from the Dornbirnerach catchment in Austria distinguishing three different model types: Models relying on discharge data, models using both discharge and precipitation data, and recursive models, i.e., models using their own predictions of a previous time step as an additional predictor. In the case study, the additional use of precipitation reduced predictive uncertainty only by a small amount, likely because the information provided by precipitation is already contained in the discharge data. More generally, we found that the robustness of a model quickly dropped with the increase in the number of predictors used (an effect well known as the Curse of Dimensionality), such that in the end, the best model was a recursive one applying four predictors (three standard and one recursive): discharge from two distinct time steps, the relative magnitude of discharge in a 65-hour time window and event predictions from the previous time step. Applying the model reduced the uncertainty about event classification by 77.8 %, decreasing Conditional Entropy from 0.516 to 0.114 bits. Given enough data to build data-driven models, their potential lies in the way they learn and exploit relations between data unconstrained by functional or parametric assumptions and choices. And, beyond that, the use of these models to reproduce a hydrologist's way to identify rainfall-runoff events is just one of many potential applications.