bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Transport Critical Current Density of Tl-1212 Bulk Superconductor Added with Nickel-Zinc Ferrite Nanoparticles
Authors: Kong Wei , Khalid Nurul Auni , Nizam Wani Nadhirah Titingan , Tshai Kim Yeow , Kong Ing , Yap Eng Hwa , Abd-Shukor Roslan
Published: May 2021

High temperature superconductor Tl-1212 with nominal starting composition (Tl0.85Cr0.15)Sr2CaCu2O7-δ was prepared with high purity oxide powders using a solid state reaction method. Small amounts of nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) at compositions 0.01, 0.02, 0.05 and 0.10 wt. % were added into Tl-1212 superconductors. The effect of Ni0.5Zn0.5Fe2O4 nanoparticles’ addition on the critical temperature (Tc), transport critical current density (Jc), phase formation, and morphology was studied. The samples were characterized using electrical resistance measurement, transport critical current density measurement, powder X-ray diffraction method (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Zero-resistance critical temperature (Tc-zero) was found to rise from 97 K to 99 K with increasing Ni0.5Zn0.5Fe2O4 nanoparticles concentration. The highest value recorded for transport critical current density (Jc) was 3,120 mA/cm2 at 77 K, which exhibited by sample with 0.02 wt. % of Ni0.5Zn0.5Fe2O4 nanoparticles. All samples showed a dominant Tl-1212 phase and exhibited tetragonal lattice structure in the P4/mmm space group. SEM micrographs showed close-packed microstructure with low porosity. EDX mapping showed that Ni0.5Zn0.5Fe2O4 nanoparticles were well distributed in the Tl-1212 samples. This study demonstrated that Ni0.5Zn0.5Fe2O4 nanoparticles have functioned as effective flux pinning centers to Tl-1212 superconductors and thus significantly enhanced its Jc.
Synthesis and Characterization of Low Density Bi-2223 Cuprates Superconductor Doped Eu2O3 Nanoparticles
Authors: Suhaimi Nurbaisyatul Ermiza , Hashim Azhan , Kasim Azman , Ibrahim Norazila , Saipuddin Siti Fatimah
Published: May 2021

Bi1.6Pb0.4Sr2Ca2-xEuxCu3Oδ cuprates superconductor doped with Eu nanoparticles (x = 0.0000, 0.0025, 0.0200 and 0.0500) were synthesized through conventional solid state reaction method. Crystalline sucrose was added during pelletization and burn at 400°C for two hours to create low density sample. The effect of doping Eu2O3 nanoparticles on the structural and superconducting properties by means of critical temperature (Tc), critical current density (Jc), X-ray diffraction (XRD) together with Field Emission Scanning Electron Microscopy (FESEM) and Alternating Current Susceptibility (ACS) were studied. Based on XRD analyses, the crystallographic structure has shown slightly changed from tetragonal to orthorhombic. The amount of 2223 phase gradually decreased with the increment of Eu concentration which indicates that Eu nanoparticles substitution favours the growth of 2212 phases. The resistivity measurements show that the highest Tcvalue for doped samples found at 90 K for x = 0.0025. The FESEM images showed that the plate-like grains become smaller and distributed randomly without specific alignment due to the increment of Eu concentration.
Influence of Zr Additive on the Chemical Reduction Behaviour of MoO3 in Carbon Monoxide Atmosphere
Authors: Samsuri Alinda , Latif Mohd Nor , Dzakaria Norliza , Salleh Fairous , Abu Tahari Maratun Ajina , Tengku Saharuddin Tengku Shafazila , Yarmo Mohd Ambar
Published: May 2021

Temperature-programmed reduction (TPR) was used to observe the chemical reduction behaviour of molybdenum trioxide (MoO3) and zirconia (Zr)-doped MoO3 catalyst by using carbon monoxide (CO) as the reductant. The characterisation of catalysts was performed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses. The reduction performance were examined up to 700°C and reduction was continued for 60 min at 700°C in a stream of 20 vol. % CO in nitrogen. The TPR profile showed that the doped MoO­3 catalyst was slightly moved to a higher temperature (580°C) as compared to the undoped MoO3 catalyst, which began at around 550°C. The interaction between zirconia and molybdenum ions in doped MoO3 catalyst led to an increase in the reduction temperature. According to characterisation of the reduction products by using XRD, it revealed that the reduction behaviour of pure MoO3 to MoO2 by CO reductant involved two reduction stages with the formation of Mo4O11 as the intermediate product. Meanwhile, MoO3 catalyst doped with zirconia caused a delay in the reduction process and was proven by the presence of Mo4O11 species at the end of reactions. Physical analysis by using BET showed a slight increase in surface area of 3% Zr-MoO3 from 6.85 m2/g to 7.24 m2/g. As for TEM analysis, black tiny spots located around MoO3 particles revealed that the zirconia was successfully intercalated into MoO3 particles. This confirmed that formation of intermetallic between Zr-MoO3 catalyst will give new chemical and physical properties which has a remarkable chemical effect by disturbing the reduction progression of MoO3 catalyst.
Morphology Studies of SWCNT Dispersed in Conducting Polymer as Potential Sensing Materials
Authors: Sa'aya Nurul Syahirah Nasuha , Demon Siti Zulaikha Ngah , Abdullah Norli , Abdul Halim Norhana
Published: May 2021

Novel electronic nanomaterial, the carbon nanotube (CNT) has emerged in many sensor applications as such its state dispersion has considerable importance to ensure the sustainability of its electronic properties. In this paper, we reported a state of art conductivity mapping on nanostructure surface of single walled carbon nanotubes (SWCNT) and poly(3-hexylthiophene-2,5-diyl), (P3HT) as potential sensing film. This composite is proposed to give selective analyte anchoring across the film as well as improved carrier mobility. The easy solution processing method was chosen to produce non-covalently wrapped conducting polymer onto the surface of SWCNT. We successfully observed high resolution images of the SWCNT walls that indicated increase of the thickness due to polymer wrapping. The image obtained from conductivity atomic force microscopy (CAFM) show the film’s electrical distribution that correlated with the observed nanostructure of film. Supporting optical characteristics of the nanocomposite obtained from UV-Vis spectroscopy and Raman spectroscopy discussed the morphology of the polymer wrapping and the state of dispersion of the polymer and the nanotubes. It is hypothesized the filament structures made by P3HT/SWCNT can give better sensing performance due to modification of π-π electronic band of SWCNT.
Multi-Walled Carbon Nanotubes Functionalized with Carboxyl and Amide for Acetone detection at Room Temperature
Authors: Janudin Nurjahirah , Abdullah Norli , Md Yasin Faizah , Yaacob Mohd Hanif , Ahmad Muhammad Zamharir , Kasim Noor Azilah Mohd
Published: May 2021

The functionalization of multi-walled carbon nanotubes (CNT) with amide group is reported as an alternative to enhance response time, recovery time and sensitivity of detecting acetone gas. We have fabricated an interdigitated transducer (IDT) deposited with amide-functionalized CNT. The elemental compositional analysis was characterized using Energy Dispersion X-ray spectroscopy and CHNOS elemental analyzer. The detection of acetone gas was performed in room temperature and digital multimeter was employed to record the changes of resistivity of IDT upon exposure of acetone. Results showed that amide functional group increases sensitivity, shortens the response time as well as recovery time of the sensor.
Facile Synthesis and Characterizations of Silver Nanoparticles-Reduced Graphene Oxide Hybrid
Authors: Ikhsan Nurul Izrini , Zamri Nurul Ain Mohamed
Published: May 2021

Here, we report the synthesis of silver nanoparticles-reduced graphene oxide (AgNPs-rGO) hybrid for simple and eco-friendly method. Silver nanoparticles (AgNPs) were successfully deposited on reduced graphene oxide (rGO) sheets to form (AgNPs-rGO) hybrid using lemon extract as a reducing and stabilizing agent. The products form a stable aqueous solution without any surfactant stabilizers and this makes it possible to produce (AgNPs-rGO) hybrid on a large scale using low-cost solution processing technique. The synthesis of nanohybrid was examed at different ratio of reducing agent (1:1, 1:2, 1:4) and characterized using UV-Visible (UV-Vis) absorption spectrum, X-ray diffraction (XRD), Raman spectroscopy analyses and transmission electron microscopy (TEM) analyses. From UV-Vis absorption spectrum, the (AgNPs-rGO) (1:1) hybrid result shows the sharp peak at 433 nm indicating the accomplishment formation of AgNPs on the surface of rGO sheets. Crystalline and spherical AgNPs with an average particle size of 21 nm were found in the (AgNPs-rGO) hybrid with the assistance of 1:1 reducing agent. Furthermore, (AgNPs-rGO) (1:1) hybrid exhibit fast electron-transfer kinetics for electrochemical reaction of Fe (CN)63-/4- redox couple compared to other controlled modified electrodes, suggesting the potential applications for electrocatalysis and electrochemical sensor.
In Vivo Toxicity Assessment of Nickel Zinc Carbon Nanotubes in a Living Host Model
Authors: Kong Cin , Azizan Siti Sarah Syahirah , Kakarla Akesh Babu , Kong Ing , Kong Wei
Published: May 2021

Nickel zinc carbon nanotubes (NiZnCNT) has gained substantial interest among researchers lately due to its wide application in the field of biomedical fields. Nickel zinc (NiZn) is well known for its corrosion-resistant, microware and magnetic properties. On the other hand, carbon nanotube (CNT) is known for its application as biosensor and tissue engineering scaffolds. Despite the excellent properties and diverse applications, the toxicity profile of NiZnCNT remains poorly understood. In this study, the potential toxic effect of NiZnCNT to living organism was evaluated using a nematode Caenorhabditis elegans (C. elegans) model. Adult worms were exposed to NiZnCNT at 50 and 200 μg/mL, followed by the assessment of three physiological parameters, including the effect NiZnCNT on C. elegans feeding behavior, reproductive ability and the overall lifespan of the worms. No significant difference was noted between the feeding rate of worms treated with NiZnCNT at both concentrations and the control population (p>0.05). Furthermore, there was no reduction in the production of progenies in NiZnCNT-treated worms, proposing that the nanoparticles tested does not negatively affect the reproductive system of animal. The mean lifespan of worms for untreated control, 50 μg/mL and 200 μg/mL of NiZnCNT was 10.4, 9.7 and 8.9 days respectively and no significant difference was observed in statistical analysis (p>0.05). In conclusion, this study demonstrated in the context of whole organism that NiZnCNT did not possess harmful toxic effect to living system, at concentration up to 200 μg/mL. The results further support the use of this nanoparticle in the field of biomedicine.
Synthesis of Carbide Lime Derived Strong Base Catalyst for Biodiesel Production
Authors: Hua Lim Hong , Pua Fei Ling , Othman Rohaya , Hin Taufiq Yap Yun , Nabihah Sharifah
Published: May 2021

Carbide lime is a result of acetylene production. Carbide lime made out of calcium hydroxide with minor amount of calcium carbonate. In this study, carbide lime was used as the raw material to synthesize a new base catalyst with high base strength. A strong base catalyst was prepared through calcination and impregnation with potassium fluoride. The structure and morphology of catalyst were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) The base strength was determined by Hammett Indicator test, temperature-programmed desorption of carbon dioxide (TPD-CO2). The surface area of the catalyst was determined by Brunauer-Emmet-Teller isotherm (BET). The catalytic performance was examined through transesterification reaction. Fatty acid methyl ester (FAME) was successfully synthesized with the presence of carbide lime derived catalyst. The highest biodiesel conversion rate for sunflower oil was 95.83% with 6 wt% of catalyst loading while palm oil was 88.07% with 3 wt% of catalyst loading. The presence of the ester functional group was determined by Fourier Transform Infrared Spectroscopy (FTIR) analysis.
Photocatalytic Degradation of Methylene Blue by TiO2- Graphene Composite
Authors: Razak Mohd Fairul Sharin Abdul , Hin Ong Soon , Hamzah Raihan
Published: May 2021

Inappropriate treatments of discharge wastewater from textile industries effluents with high concentrated dye are dangerous to the human and aquatic life due to the carcinogenic effect and chemical toxicity. Therefore, the usage of TiO2 photocatalysis in water treatment has shown a significant impact on the degradation of dye into less carcinogenic and toxicity of the water. Interestingly, the addition of graphene oxide into TiO2 system showed better photocatalytic efficiency of dye degradation as compared toTiO2 photocatalyst alone due to a sufficient amount of radicals supply by the graphene oxide. The oxide radicals reacted with the dye radicals and eliminate the possibility of any chances of recombination of photons and electrons during the photodegradation process. These immobilized graphene/TiO2 films were coated onto the glass substrate under the influence of polymeric polyvinyl aceatate/ polyvinyl chloride (PVA/PVC) mixture act as a binder. The adhesion strength of the immobilized system was fixed at ratio 1:0.025 of PVA/PVC binders. As a result, the immobilized system showed a high degradation rate of methylene blue dye due to the improvement of charge separation and also good adhesion property and sustainability of the film during continuous wastewater treatment.
Comparative Study on Micronsized and Nanosized Carica papaya Seed Modified Pullulan as Biocoagulant in Wastewater Treatment
Authors: Lie Deong Jing , Ahmad Mazatusziha , Azhar Nur Sabrina
Published: May 2021

Plant-based coagulants have been used as an alternative material to replace chemical coagulant in wastewater treatment. So far, limited information was found on the incorporation of plant-based biocoagulant to natural polymers and the effect of particle size upon wastewater treatment application. Thus, this study was conducted to explore the effectiveness of micronsized and nanosized Carica Papaya (CP) seed modified pullulan as biocoagulant. Biocoagulant were prepared at different composition of CP to pullulan, with the CP content range from 1% to 9%. The biocoagulant were characterized via Particle Size Analyzer (PSA), Fourier Transform Infrared Spectroscopy (FTIR) and morphological analysis via Field Emission Scanning Electron Microscopy (FESEM). It was used to treat municipal wastewater. The treated wastewater quality was analyzed by jar test method with dosage of biocoagulant used was 0.6g/L. Result showed that the 10% (D10), 50% (D50) and 90% (D90) distribution of micronsized CP had particle size of 0.3675 µm, 0.8433 µm and 1.9537 µm respectively. The nanosized CP was 0.4473nm (D10), 2.3758nm (D50) and 2.9938nm (D90). Characterization of biocoagulant via FTIR revealed the appearance of O-H, C=O, C-H and C-O-C bond which contribute to particle interaction for turbidity reduction of wastewater. Jar test analysis found that at 3% micronsized CP and 7% nanosized CP were able to reduce turbidity up to 59.65% and 65.27% respectively. Both size of biocoagulant slightly changed the pH of treated wastewater to neutral, increased in dissolved oxygen (DO) and reduced in total suspended solid (TSS). Overall, nanosized CP was found more effective as compared to micronsized CP.
Fatigue Crack Growth of Natural Rubber/Butadiene Rubber Blend Containing Waste Tyre Rubber Powders
Authors: Hassim Dayang Habibah Abang Ismawi , Abraham Frank , Summerscales John , Brown Paul
Published: May 2021

Fatigue crack growth in NR/BR compound and the effect of two different types of recycled rubber powder (RRP) i.e. micronized cryo-ground 74 μm and ambient-ground 400 μm were studied using fracture mechanics approach. Absolute and relative hysteresis losses using single-edge notch tensile (SENT) specimens were determined with a displacement-controlled strain compensating for permanent set of the samples throughout the Fatigue Crack Growth (FCG) experiments. Results indicated a correlation between absolute/relative hysteresis loss and fatigue crack growth rate under specific dynamic strain amplitudes. Differences in relative hysteresis loss showed that additional energy dissipation, due to multiple new crack surfaces at the crack tip, contributes to the FCG of the RRP compounds. At higher tearing energy, beside other factors affecting the FCG performance of the RRP compounds, both higher absolute and relative hysteresis loss are slightly detrimental to the crack growth rates.
Preliminary Study on the Effect of Sulphuric Acid to Nitric Acid Mixture Composition, Temperature and Time on Nitrocellulose Synthesis Based Nata de Coco
Authors: Jori Roslan Nursyafiqah , Jamal Siti Hasnawati , Ong Keat Khim , Wan Yunus Wan Md Zin
Published: May 2021

Nitrogen content is a paramount significance in predicting nitrocellulose. Nitrocellulose with high nitrogen content (>12.5%) can be used for propellant, while low nitrogen content (<12.5%) can be applied for the production of ink, paint and leather finishes. In this preliminary study, the effect of mole ratio of sulphuric acid to nitric acid, reaction temperature and time towards nitrogen content in nitrocellulose was investigated. Nitrocellulose was synthesized using nata de coco as bacterial cellulose source via nitration method. Nitrocellulose with percentage of nitrogen content of 11.74% to 12.75% was obtained when 2 to 4 mole ratio of sulphuric to nitric acid was used with operating temperature and time ranging 20°C to 40°C and 20 minutes to 40 minutes respectively. Analysis of Fourier transform infrared (FTIR) displayed the reduction of hydroxyl group in nitrocellulose proving that several hydroxyl group in cellulose was successfully replaced by nitryl group. Other characterizations such as elemental analyser, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were evaluated to support the result.
Thermomechanical Properties and Thermal Behavior of Poly(Lactic Acid) Composites Reinforced with TiO2 Nanofiller
Authors: Sudin Nur Ain Syafiqah , Daud Norlinda , Mustapa Izan Roshawaty , Zorah Mohammed
Published: May 2021

The reinforcement effect of nanofiller in polymer enhanced the thermal stability, physical and mechanical properties of poly (lactic acid) (PLA) composites with good reinforcing capabilities for bio-based polymers. In this paper, the effect of reinforcement of titanium dioxide (TiO2) nanofiller on the mechanical properties and thermal behavior of PLA matrix are reported. PLA/TiO2 nanocomposites with different percentages of 2.0, 3.5, 5.0 and 7.0 %∙w/w were prepared by using solvent casting method and hot press machine. TiO2 were dispersed in PLA matrix using mechanical mixer and ultrasonication technique. The mechanical properties and thermal behavior of PLA nanocomposites were characterized using dynamic mechanical analysis (DMA) and differential scanning calorimeter (DSC). The increased in storage modulus by the addition of nanofiller with the highest increment provided by 2.0 %·w/w TiO2 indicated a strong influence and better interfacial bonding between nanofiller and PLA matrix. An increased in storage modulus started at 100 °C that linked to the cold crystallization (Tcc) of PLA composites is in agreement with DSC result. The Tcc shifted to higher temperature as the content of nanofiller increased and this result were observed at 2.0 %·w/w of the nanofiller content. Reinforcement of nanofiller increased the melting temperature from lower filler loading until 5.0 %·w/w. The incorporation of TiO2 nanofiller as the reinforcement agent for PLA has a potential in biopolymer medical engineering and packaging industry, a highly competitive application with a great demand of cost and performance.
The Impact of Zr Substitution on the Crystal Structure of Yb Doped BaCeO3 Solid Solution Prepared by a Sol-Gel Method
Authors: Osman Nafisah , Mazlan Nurul Waheeda , Hassan Oskar Hasdinor , Mohamed Zakiah
Published: May 2021

A modified sol-gel method using metal nitrate salts was adopted to synthesis proton conductor of Ba(Ce1-xZrx)0.95Yb0.05O2.975 where x=0.2, 0.3, 0.4, 0.5 and 0.6 ceramic powders. The aim of this work is to study the crystal structure of Yb-doped barium cerate solid solution at different Zr concentrations. The powder was calcined at 1100°C for 12 hours and pressed at 5 tons to become a pellet by a dry pressing technique. The pellet was sintered at 1400°C in air for 6 hours and ground to powder form prior to the X-ray diffraction measurement. The raw diffraction data of the sample at room temperature was analyzed using Rietveld refinement method in X’pert Highscore software. Cubic crystal structure was observed by software with goodness of fit in average 2.82. Phase formation, structure analysis and the empirical rule which holds the linear relation between lattice parameters at different Zr concentrations using Vegard’s Law were also presented and discussed.
The Effect of Ammonium Bromide on Methylcellulose Biopolymer Electrolytes for Electrical Studies
Authors: Abd Majid Siti Nurhaziqah , Ishak Afiqah Qayyum , Nik Ali Nik Aziz , Daud Muhamad Zalani , Salleh Hasiah
Published: May 2021

The development of biopolymer electrolytes based on methylcellulose (MC) has been accomplished by incorporating ammonium bromide (NB) to the polymer-salt system. The biopolymer electrolytes were prepared via solution-casting method. The conductivity and permittivity characteristics of the material were studied. The biopolymer-salt complex formation have been analysed through Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The conductivity of the sample was measured by EIS HIOKI. Upon addition of 20 wt.% of NB, highest conductivity of 3.25×10-4 μScm-1 was achieved at ambient temperature. The temperature dependence of the biopolymer electrolytes exhibit Arrhenius behaviour. This result had been further proven in FTIR study.
Properties of Gel Polymer Electrolyte Based Poly(Vinylidine Fluoride-сo-Hexafluoropropylene) (PVdF-HFP), Lithium Perchlorate (LiClO4) and 1-Butyl-3-Methylimmidazoliumhexafluorophosphate [PF6]
Authors: Mohd Noor Siti Aminah , Wong Chow Peng , Dzulkipli Mariah Zuliana , Su'ait Mohd Sukor , Tian Khoon Lee , Hassan Nur Hasyareeda
Published: May 2021

This study reported the preparation and characterization of gel polymer electrolyte (GPE) using poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), lithium perchlorate (LiClO4) and 1-butyl-3-metilimmidazoliumhexafluorophosphate [PF6]. The GPE were prepared by solution casting technique. [Bmim] [PF6] ionic liquid is used as an additive for the purpose of increasing the ionic conductivity of GPE. Morphological analysis showed that the electrolyte gel polymer sample had a smooth and flat surface with the addition of [Bmim] [PF6] and no phase separation effect was observed. This shows the compatibility between PVdF-HFP and [Bmim] [PF6]. ATR-FTIR analysis showed that C-F bond related peaks experienced peak changes in terms of intensity and peak shifting. This proves the interaction of the imidazolium ion with the fluorine atom through the formation of coordinate bonds. Ionic conductivity analysis showed that PVdF-HFP-[Bmim][PF6] samples reached a maximum room temperature ionic conductivity value of 2.44 × 10-4 S cm-1 at 60 wt.% [Bmim] [PF6]. When 20 wt.% of LiClO4 added to the system, the ionic conductivity increased one magnitude order to 2.20 × 10-3 S cm-1.
Influence of Applied Potential on Electrodeposited ZnSe/ZnO Nanostructured Films for Photoelectrochemical Cell
Authors: Fudzi Laimy Mohd , Zainal Zulkarnain , Lim Hong Ngee , Shafie Suhaidi , Chang Sook Keng
Published: May 2021

Zinc oxide (ZnO) nanorods is widely investigated due to its high photoelectrochemical conversion performance. Further enhancement may be afforded by introducing a metal chalcogenide sensitization layer such as zinc selenide (ZnSe). In this study, ZnO nanorods were electrodeposited with ZnSe at potential range from -0.5 V to -0.9 V vs Ag/AgCl reference electrode. Structural, morphological and optical properties of ZnSe electrodeposited were investigated as a function applied potential by using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). ZnSe electrodeposited for 15 minutes at -0.7 V showed crystallite size of 20.13 nm with the lowest band gap energy of 2.97 eV. The existence of ZnSe particles with the size of 41.8 nm were proven by FESEM images, after ZnSe particles were electrodeposited onto ZnO nanorods that have an average diameter of 62.6 nm and length of 1.6 µm. The photocurrent density generated by samples were measured in a three-electrodes cell incorporated with halogen lamp. The photocurrent generated increased between -0.5 V to -0.7 V before dropped at higher applied potential due to hydrogen evolution process which affected the thin film quality, ultimately affecting photoconversion performance. The highest photocurrent density of 0.2621 mAcm-2 was recorded for samples prepared at -0.7 V vs Ag/AgCl.
The Effect of pH and Monomer Concentration on Polyaniline Thin Films Grown Using Electrodeposition
Authors: Shaari Nur Atikah , Abdul-Manaf Nor Azlian
Published: May 2021

Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H2SO4) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, Eg of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.
Effect of Mechanical Agitation on Cr-Al2O3 Nanocomposite Coatings Fabricated from Trivalent Chromium Electrodeposition
Authors: Tey Eydar , Zainal Zulkarnain , Pah Lim Kean , Ismail Ismayadi
Published: May 2021

In the present work, Cr-Al2O3 nanocomposite coatings were electrodeposited onto a copper substrate using a modified trivalent chromium electroplating bath with the addition of 80nm Al2O3 powder. The effects of mechanical agitation of electrodeposition bath on Al2O3 particles dispersion and particles embedment were studied. The Cr-Al2O3 nanocomposite samples were subjected to different tests to characterize their surface morphology, crystalline structure, and mechanical properties. The crystalline structure, composition and surface morphology of the deposits were studied by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). The corrosion resistance test was carried out by electrochemical polarization method. The microhardness was studied via Vickers Microhardness Test. The variation in the microhardness as a main property to achieve enhancement of Al2O3 incorporations with Cr matrix. From the EDX analysis, Cr-Al2O3 nanocomposite deposited at 200 rpm stirring speed showed the highest weight percentage (wt%) of alumina. The hardness results showed the Cr-Al2O3 composite coating has the best performance at 200 rpm stirring speed which the hardness increased 32.3 % compared to that of Cr coating. The corrosion current density (icorr) of Cr-Al2O3 coating achieved highest value at 200 rpm. This result revealed that the corrosion resistance of Cr-Al2O3 coating decreases with increasing Al2O3 particles content.
Effect of Vanadium Doping on Thermoelectric Properties of CaMnO3 Using First Principle Calculations
Authors: Chik Abdullah , Zaki Ruhiyuddin Mohd , Adewale Akeem Adekunle , Pa Faizul Che , Yeoh Cheow Keat
Published: May 2021

The search for clean energy conversion technologies promotes the study of thermoelectric materials. In this paper, the electronic structure and thermoelectric properties of CaMnO3 doped with 17% V using first principles calculations and semi-classic Boltzmann theory on Ca site as well as Mn sites. The G-type AFM magnetic ordering is most stable among four types of magnetic ordering for CaMnO3 and V doped CaMnO3 a Mn site while FM ordering was found for V doped CaMnO3 at Ca site. The calculated partial density of states plot shows half metallic and metallic behavior for V doped at A site and B site respectively. Thermoelectric property calculations show that the magnitude of Seebeck coefficient decreased with V doping at both sites with V doping at Mn sites has the lowest magnitude of Seebeck coefficient. All samples show the negative Seebeck coefficient indicating n type behavior. The magnitude of conductivity increases with V doping with the highest magnitude belong to V doped at Mn site. The magnitude of thermal conductivity also increased with V doping at Mn site, but shows a reduction for V doping at Ca site. The figure of merit (ZT) for V doping at Ca site shows a significant improvement over intrinsic CaMnO3 at 0.14 at 1000 K. However, V doping at Mn site sample shows a reduction of ZT at 0.0028 for CaMnO3 at 1000 K which is much lower than CaMnO3 at 0.08.
Structural and Electronic Properties of Ag-Doped in Ba-Site of YBa2-xAgxCu3Oδ Using Density Functional Theory via First Principle Study
Authors: Saipuddin Siti Fatimah , Mahmood Muhammad Syafie , Hashim Azhan , Suhaimi Nurbaisyatul Ermiza , Taib Mohamad Fariz Mohamad
Published: May 2021

This study reports on the First Principle Study via Density Functional Theory (DFT) used to determine the structural and electronic properties of Ag-dopant in Ba-site of YBa2-xAgxCu3Oδ superconductor. The computational method adopting CASTEP computational code was used to calculate the structural and electronic properties for Ag-dopant in range of x=0.150 to x=0.250 in Ba-site of YBa2-xAgxCu3Oδ to enhance the performance finding of experimental work shown at dopant x=0.20 ceramic superconductor. The structural changes in terms of lattice parameters were compared as the percentage of dopant increases to seek both CuO chain and CuO2 plane bond length and the spontaneous strain variance on the structure orthorhombicity. The crystal structure constructed and calculated using Visual Crystal Approximation (VCA) applying the local density approximation (LDA) and ultrasoft pseuodopotential. Geometry optimization shown energy converged at 400 eV with k-point sampling of 4x4x1. The structural properties of YBa2-xAgxCu3Oδ are observed to be approximately close to the experimental data obtained by other researches. The electronic properties were determined via energy band gap, density of states and electron energy differences visualisation a to further enhance the experimental findings.
Studying the Dynamics and Complexity of a 3D Laser Plasma System
Authors: Rahim Muhammad Firdaus Abdul , Natiq Hayder , Fataf Nur Aisyah Abdul
Published: May 2021

In this paper, a 3D laser plasma interaction system is presented, analysed, and implemented. The system has two unstable equilibria, and two types of coexisting attractors in which the coexistence of two periodic orbits and the coexistence of two chaotic attractors can be clearly observed. The multistability behaviours are determined by the bifurcation diagrams, largest Lyapunov exponents, and phase spaces. Moreover, the complexity performance of the laser plasma interaction system is investigated by the contour plot of the Sample Entropy.
Structural and Electrical Properties of La0.7Ca0.3MnO3 /α-Fe2O3 Composites
Authors: Lau Lik Nguong , Lim Kean Pah , Ishak Amirah Natasha , Kechik Mohd Mustafa Awang , Chen Soo Kien , Ibrahim Noor Baayah , Shaari Abdul Halim , Lim Eijin
Published: May 2021

Colossal magnetoresistive (CMR) materials have huge potential in modern application and it has been widely used in magnetic sensing industry. From the literature, an incorporation of secondary insulating phase into mixed-valence manganites could improve its extrinsic effect especially low-field magnetoresistance (LFMR). However, nanoparticle addition could lead to substitution and diffusion with its parent compound. In this work, the structural and electrical properties of La0.7Ca0.3MnO3 (LCMO) were investigated by adding the α-Fe2O3 nanoparticle with ratio of 0.00, 0.05, 0.10, 0.15 and 0.20 as the artificial grain boundaries. The LCMO compound has been synthesised using sol-gel route. The samples were chosen to sinter at 800°C to obtain the pure LCMO phase by referring to the thermogravimetric analysis (TGA). The structural properties were investigated by an X-ray diffractometer (XRD) while electrical properties were measured by a four-point probe (4PP) system. XRD patterns showed the coexistence of two phases (LCMO & α-Fe2O3). LCMO crystallised in orthorhombic structure with space group Pnma while α-Fe2O3 exhibited in hexagonal form with space group R-3c. As the content of α-Fe2O3 increases, the resistivity of the samples increases drastically. Nevertheless, the addition of iron oxide has no significant effect on the metal-insulator transition temperature (T­MI). From the XRD and 4PP analysis, it can be deduced that the α-Fe2O3 nanoparticles do not react with LCMO compound and successfully formed the La0.7Ca0.3MnO3 /α-Fe2O3 composites. The resistivity increases when the nano-sized α-Fe2O3 is added into LCMO nanocomposites due to the insulator nature of α-Fe2O3.
Linear Shrinkage, Strength and Porosity of Alumina-Based Ceramic Foam with Corn Starch as Pore Former
Authors: Rahman Nurul Farhana Abdul , Rahman Hamimah Abdul , Azhan Wan Muhammad Syahmi Wan , Yatim Nor Hamidah
Published: May 2021

In this study, ceramic foams were produced using starch consolidation casting method. This research focused on the preparation of alumina-based ceramic foam by using corn starch as a pore-forming agent. Preparation of alumina based ceramic foam is studied to observe the effect of the addition of corn starch on its physical, mechanical and morphological properties. The composition of the suspension used included 64–58 wt.% alumina, 55 wt.% deionised water and other materials, such as silica and polyethylene glycol (PEG), were used as additive and dispersing agent respectively. Corn starch was added at 4, 6, 8 and 10 wt.%. The samples were preheated for gelation and coagulation processes, then dried and sintered at 1250 °C for 2 h. The ceramic foam gave a linear shrinkage from 1.07% to 3.39%. The obtained flexural strength was between 0.594 and 1.996 MPa. The average total porosity ranged from 54.05% to 70.70%. This study found that the suitable amount of corn starch in alumina foam is 4 wt.% because the resulting porosity values and flexural strength are appropriate for ceramic foams.
Harmonic Elimination in Multilevel Inverter Using TLBO Algorithm for Marine Propulsion System
Authors: Muralidharan Srinivasan , Gnanavadivel Jothimani , Muhaidheen Mohammed Yousuf Shifli , Menaka Srinivasan
Published: May 2021

Abstract Stringent environmental regulations and increasing oil prices showcase the need for renewable energy sources like solar in marine transportation. The application of solar energy in electric propulsion systems is growing tremendously. Power electronics-based inverters
help in harvesting direct current (DC) power into alternating current (AC) power. A multilevel inverter (MLI) is a popular power electronic converter producing the desired output voltage from several DC input voltage sources like batteries, supercapacitors, and solar panels. An MLI consists
of several switches whose action results in severe harmonic issues. Specific harmonic elimination in MLI is a challenging job and is resolved conventionally by the Newton-Raphson method. However, nowadays, soft computing techniques are used to solve nonlinear equations optimally. In this manuscript,
minimization of total harmonic distortion in MLI has been taken as an optimization problem and is solved using teaching-learning‐based optimization (TLBO). The TLBO algorithm is applied to compute the optimum switching angles for MLI to produce the required fundamental output voltage
with less harmonic distortion. As it does not require any algorithm-specific parameters, TLBO is an effective method to obtain optimum MLI solutions. A 21-level symmetric MLI is simulated and is used to evaluate the performance of the TLBO algorithm. The simulation results are validated using
an experimental model of proposed MLI with a Xilinx Spartan-SA field programmable gate array‐based controller. This research outcome bears testimony to TLBO optimization's efficiency in improving the quality of the power generated in ships using renewable sources.
Timing of Stress Fractures in Soldiers During the First 6 Career Months: A Retrospective Cohort Study
Authors: Kardouni Joseph R. , McKinnon Craig J. , Taylor Kathryn M. , Hughes Julie M.
Published: May 2021

Context

Stress fractures (SFs) are injuries that can result from beginning new or higher-volume physical training regimens. The pattern of clinical presentation of SFs over time after individuals start a new or more demanding physical training regimen is not well defined in the medical literature.

Objective

To report trends in the clinical presentation of SFs over the first 6 months of soldiers' time in the service.

Design

Retrospective cohort study.

Setting

This study was conducted using medical encounter and personnel data from US Army soldiers during the first 6 months of their career.

Patients or Other Participants

United States Army soldiers beginning their careers from 2005 to 2014 (N = 701 027).

Main Outcome Measure(s)

Weekly SF numbers and incidence were calculated overall, as well as by sex, over the first 6 months of military service.

Results

Stress fracture diagnoses (n = 14 155) increased steeply in weeks 3 and 4, with a peak in the overall incidence during weeks 5 to 8. Although the clinical incidence of SFs generally decreased after 8 weeks, incident lower extremity SFs continued to present for more than 20 weeks. The hazard ratio for SFs among women compared with men was 4.14 (95% CI = 4.01, 4.27).

Conclusions

Across the 6-month study period, women showed a more than 4 times greater hazard for SFs than men. The results also suggest that health care providers should be particularly vigilant for SFs within 3 weeks of beginning of a new or higher-intensity exercise regimen. The incidence of SFs may continue to climb for several weeks. Even as the SF incidence declines, these injuries may continue to appear clinically several months after a change in activity or training.
Vestibular/Ocular Motor Screening Assessment Outcomes After Sport-Related Concussion in High School and Collegiate Athletes
Authors: Tomczyk Christopher P. , Anderson Morgan , Petit Kyle M. , Savage Jennifer L. , Covassin Tracey
Published: May 2021

Context

Vestibular and ocular motor assessment is an emerging clinical assessment for patients with sport-related concussion (SRC). The increased use of these assessments by clinicians calls for the examination of outcomes that may affect clinical practice.

Objective

To compare vestibular and ocular motor impairments in high school and collegiate athletes within 72 hours of SRC and examine the distribution of impairments in these populations based on pre-established clinical cutoff scores.

Design

Cross-sectional study.

Setting

High school and collegiate athletics.

Patients or Other Participants

Data were collected from 110 athletes (high school: n = 47, age = 15.40 ± 1.35 years; college: n = 63, age = 19.46 ± 1.28 years) within 72 hours of sustaining an SRC.

Main Outcome Measure(s)

Total and change scores were calculated for the Vestibular/Ocular Motor Screening (VOMS) tool, along with average near point of convergence (NPC) distance. Separate Mann-Whitney U tests were used to compare group differences, and χ2 analyses were used to examine the proportion of athletes with scores greater than clinical cutoff scores for all VOMS outputs. The α level was set a priori at .05.

Results

No differences were found between high school and collegiate athletes for VOMS total and change scores and NPC distance. A larger proportion of the sample had scores greater than the cutoff for all total scores (P < .001) and change scores in horizontal vestibulo-ocular reflex (59.01%; P < .001), vertical vestibulo-ocular reflex (60.91%; P < .001), and visual motion sensitivity (60.91%; P < .001). However, a larger proportion demonstrated smooth pursuit change scores (85.45%; P < .001) and NPC distances (73.64%; P = .01) that were less than the cutoff scores.

Conclusions

During the acute phase of SRC, high school and collegiate athletes presented with similar vestibular and ocular motor impairments as measured using the VOMS, but vestibular tasks appeared to cause greater symptom provocation. Lastly, VOMS change scores may offer more clinical utility compared with total scores in assessing specific impairments after SRC.
Emerging Role of the Ketogenic Dietary Therapies beyond Epilepsy in Child Neurology
Authors: Kapoor Dipti , Garg Divyani , Sharma Suvasini
Published: May 2021

Ketogenic dietary therapies (KDTs) have been in use for refractory paediatric epilepsy for a century now. Over time, KDTs themselves have undergone various modifications to improve tolerability and clinical feasibility, including the Modified Atkins diet (MAD), medium chain triglyceride (MCT) diet and the low glycaemic index treatment (LGIT). Animal and observational studies indicate numerous benefits of KDTs in paediatric neurological conditions apart from their evident benefits in childhood intractable epilepsy, including neurodevelopmental disorders such as autism spectrum disorder, rarer neurogenetic conditions such as Rett syndrome, Fragile X syndrome and Kabuki syndrome, neurodegenerative conditions such as Pelizaeus-Merzbacher disease, and other conditions such as stroke and migraine. A large proportion of the evidence is derived from individual case reports, case series and some small clinical trials, emphasising the vast scope for research in this avenue. The term 'neuroketotherapeutics' has been coined recently to encompass the rapid strides in this field. In the 100th year of its use for paediatric epilepsy, this review covers the role of the KDTs in non-epilepsy neurological conditions among children.
Laparoscopic posterior rectopexy for complete rectal prolapse
Authors: Ganapathi Senthil Kumar , Subbiah Rajapandian , Rudramurthy Sathiyamoorthy , Kakkilaya Harish , Ramakrishnan Parthasarathi , Chinnusamy Palanivelu
Published: May 2021

Background:

Rectal prolapse is more common in elderly women worldwide, but in India, it predominantly occurs in young- and middle-aged males. While ventral mesh rectopexy is proposed as the preferred procedure in females, the debate on the best procedure in men is still wide open.

Methods:

A retrospective review of all adult male patients operated for external rectal prolapse (ERP) between January 2005 and December 2019 was performed. Patients either underwent modified laparoscopic posterior mesh rectopexy (LPMR) or laparoscopic resection rectopexy (LRR). The outcome was analysed in terms of recurrence, post-operative constipation, sexual dysfunction and other complications.

Results:

A total of 118 male patients were included (LPMR: 106, LRR: 12). The mean age was 46.2 years (standard deviation [SD] 11.8, range: 21–88). The mean operating time was 108 min (SD: 24). The mean length of hospital stay was 4.8 days (SD: 1.4, range: 3–11 days). There was no anastomotic leak in the LRR group. Other complications included wound infection (n = 2), mesh infection with sigmoid colon perforation (n = 1), constipation (n = 4), sexual dysfunction (n = 2), urinary urgency (n = 3) and retention of urine (n = 4). There was no mortality in both the groups. During a mean follow-up of 5.2 years, recurrent ERP was noted in one patient and partial mucosal prolapse was seen in three patients.

Conclusion:

LPMR/LRR is a safe and effective treatment for ERP in men with very low recurrence rates. Randomised trials comparing modified LPMR with LVMR are needed to establish the better procedure in males.
Human Rights and Corruption
Authors:   Northwestern Pritzker School of Law, US, Sorensen Juliet S.
Published: May 2021

This research review on corruption and human rights examines anti-corruption law and policy through a legal lens. Intended for a global audience of scholars, practitioners and policymakers, the text recommends over twenty key works on the subject of corruption and human rights, together illustrating corruption’s insidious effect on a range of human rights, but also the limitations of a rights-based approach.
PENGARUH MODEL PEMBELAJARAN QUESTION STUDENT HAVE (QSH) BERBANTUAN PERMAINAN BINGO TERHADAP PEMAHAMAN KONSEP MATEMATIKA SISWA KELAS V DI SD TEGALJAYA
Authors: Winaya I Made Astra , Eka Kurniati Putu
Published: May 2021

ABSTRAK

 

Penelitian ini dilatar belakangi oleh keinginan penulis untuk mengetahui perbedaan pemahaman konsep matematika siswa kelas V antara siswa yang mengikuti model pembelajaran Question Student Have (QSH) berbantuan permainan bingo dengan siswa yang mengikuti model pembelajaran konvensional. Penelitian ini dilaksanakan di SD Tegaljaya dengan populasi penelitian ini adalah seluruh siswa kelas V di SD Tegaljaya sejumlah 109 orang. Sampel dalam penelitian ini sebanyak 2 kelas, yaitu kelas eksperimen dan kelas kontrol yang terdiri atas 45 orang. Pengumpulan data dilakukan dengan menggunakan metode tes pemahaman konsep, observasi dan wawancara. Data yang diperoleh dianalisis menggunakan statistik deskriptif dan statistik inferensial, dengan uji-t. Berdasarkan analisis data dengan uji-t, diperoleh nilai thitung sebesar -2,704 dengan signifikansi (sig) sama dengan 0,011, sehingga nilai sig. (0,011) lebih kecil daripada taraf signifikansi 0,05. Hasil penelitian menunjukkan bahwa, terdapat perbedaan yang signifikan pemahaman konsep matematika siswa kelas V antara siswa yang mengikuti model pembelajaran Question Student Have (QSH) berbantuan permainan bingo dengan siswa yang mengikuti model pembelajaran konvensional.  Hal ini menunjukkan model pembelajaran Question Student Have (QSH) berbantuan permainan bingo berpengaruh secara signifikan terhadap pemahaman konsep matematika siswa kelas V di SD Tegaljaya.

 

Kata-kata kunci: question student have, bingo, pemahaman konsep matematika