MyMedR

Displaying publications 1 - 20 of 137 in total

Abstract:

Sort:

Pencirian keseragaman campuran dan sifat reologi serbuk alumina-zirkonia untuk pengacuan suntikan seramik

Sarizal Md Ani, Andanastuti Muchtar, Norhamidi Muhamad, Jaharah A. Ghani

Sains Malaysiana, 2013;42:1311-1317.

Pencirian keseragaman campuran dan sifat reologi bahan suapan merupakan elemen penting dalam melaksanakan proses pengacuan suntikan seramik. Kesesuaian bahan suapan yang dibangunkan dapat mengurangkan masalah yang timbul ketika proses pengacuan suntikan, penyahikatan dan pensinteran. Justeru itu, kajian ini dijalankan untuk mengenal pasti pembebanan serbuk yang optimum berdasarkan kepada keseragaman campuran dan sifat reologi bahan. Pencirian keseragaman campuran ditentukan berdasarkan kepada nilai tork yang rendah dan berkeadaan mantap. Kajian reologi pula dilakukan dengan menggunakan mesin reometer rerambut. Ujian dijalankan pada julat suhu 150 dan 170oC dengan beban kenaan antara 20 dan 90 kgf. Bahan suapan yang digunakan terdiri daripada kombinasi serbuk seramik alumina-zirkonia bersama bahan pengikat polietilena berketumpatan tinggi, lilin parafin dan asid stearik. Hasil kajian menunjukkan bahan suapan bersifat pseudoplastik dengan pencampuran bahan yang seragam dalam tempoh kurang daripada 30 min. Hasil keputusan juga mendapati pada pembebanan serbuk 57% isi padu adalah yang paling optimum untuk proses pengacuan suntikan seramik berdasarkan kepada nilai kelikatan, indeks hukum kuasa dan tenaga pengaktifan aliran yang rendah.

Matched MeSH terms: Aluminum Oxide
An investigation on the relationship between physicochemical characteristics of alumina-supported cobalt catalyst and its performance in dry reforming of methane

Khairudin NF, Mohammadi M, Mohamed AR

Environ Sci Pollut Res Int, 2021 Jun;28(23):29157-29176.
PMID: 33550559 DOI: 10.1007/s11356-021-12794-0

This study deals with the development of alumina-supported cobalt (Co/Al2O3) catalysts with remarkable performance in dry reforming of methane (DRM) and least carbon deposition. The influence of Co content, calcination, and reduction temperatures on the physicochemical attributes and catalyst activity of the developed catalysts was extensively studied. For this purpose, several characterization techniques including ICP-MS, H2 pulse chemisorption, HRTEM, H2-TPR, N2 adsorption desorption, and TGA were implemented, and the properties of the developed catalysts were carefully analyzed. The impact of reaction temperature, feed gas ratio, and gas hourly space velocity (GHSV) on the reactants conversion and products yield was investigated. Use of 10%Co/Al2O3 catalyst, calcined at 500°C and reduced under H2 at 900°C in DRM reaction at 850°C, CH4/CO2 ratio of 1:1, and GHSV of 6 L.g-1.h-1 resulted in a remarkable catalytic activity and sustainable performance in long-term operation where great CO2 (96%) and CH4 (98%) conversions and high H2 (83%) and CO (91%) yields with a negligible carbon deposition (3 wt%) were attained in 100-h on-stream reaction. The good performance of the developed catalyst in DRM reaction was attributed to the small Co particle size with well-dispersion on the alumina support which increased the catalytic activity and also the strong metal-support interaction which inhibited any serious metal sintering and enhanced the catalyst stability.

Matched MeSH terms: Aluminum Oxide*
Effects of Bauxite and Alumina Exposure on Incidence of Cancer - Meta-analysis

Thevi T, Abas AL

Kathmandu Univ Med J (KUMJ), 2021 6 25;18(72):414-419.
PMID: 34165102

Bauxite is an ore from which Aluminium is produced. Malaysia, once the leading producer of bauxite has reduced production as mining activity has caused community outrage. Due to concerns about health concerns, rising pollution and environmental hazards, the government has revoked the licenses of bauxite miners. We therefore did a meta-analysis to assess the relationship between exposure to Bauxite and Alumina with incidence of various types of cancers. Bauxite mines and alumina refineries. Individuals of all ages exposed to Bauxite and Alumina. Exposure to bauxite and alumina. Incidence due to overall cancers and specific types of cancers. Exposure to bauxite and alumina did not cause variations in incidence of overall cancer and specific types of cancer such as cancer of lip, cancer of the oral cavity and pharynx, cancer of digestive organs and others. We conclude that there is no evidence that bauxite or alumina exposure cause increase incidence of cancer but due to the small number of studies included in this review, we recommend more cohort studies to be done in future.

Matched MeSH terms: Aluminum Oxide/adverse effects; Aluminum Oxide/analysis
Synthesis and characterization of mesoporous molybdenum catalysts for hydrocracking of atmospheric residual oil

Looi PY, Mohamed AR, Tye CT

J Nanosci Nanotechnol, 2013 Oct;13(10):6988-95.
PMID: 24245175

In this study, performances of mesoporous Mo/Al2O3 catalysts prepared by sol-gel and post-hydrolysis methods in hydrocracking of atmospheric residual oil were compared. In addition, different methods: (i) the single step and (ii) conventional impregnation method to incorporate active metal over the mesoporous support were also investigated. For single step method, Mo/Al2O3 catalysts were synthesized directly by sol-gel and post-hydrolysis method. On the other hand, the impregnation method was a two step procedure which involved the production of alumina via sol-gel or post-hydrolysis method and followed by respective Mo impregnation. In general, mesoporous Mo/Al2O3 catalysts prepared by sol-gel method resulted in relatively higher surface area (> 400 m2/g) and large pore volume (- 0.8 cm3/g). Mo/Al2O3 catalysts prepared by sol-gel method exhibited higher hydrocracking activity as well. The Mo crystal size was found to relate directly with the hydrocracking result.

Matched MeSH terms: Aluminum Oxide
Spatial distribution of heavy metal assessment in beach sediment due to bauxite mining in Kuantan, Pahang, Peninsular Malaysia

Anees MT, Abu Bakar AFB, Khan MMA, Akhtar N, Khan MR, Khan MS

Environ Geochem Health, 2025 Jan 06;47(2):42.
PMID: 39760768 DOI: 10.1007/s10653-024-02347-y

The effect of open-pit bauxite mining on beach sediment contamination in the urban coastal environment of Kuantan City, Malaysia, was investigated. The contents of 11 heavy metals (Pb, Cd, Al, Mn, Cu, Zn, Fe, As, Ni, Cr, and Ag) in 30 samples from Kuantan beach sediment zones (supratidal, intertidal, and subtidal) were determined using inductively coupled plasma optical emission spectrometry followed by contamination indexes, Pearson's correlation analysis, and principal component analysis (PCA). The results indicated that Cd, As, Ni, and Ag values in beach sediment zones were significantly higher compared to background values. Contamination indexes suggest that Cd, As, Ni, and Ag were highly contaminated, and moderate to extremely enriched near the Kuantan Port. However, these heavy metal concentrations are lower compared to previous studies in the region. Sediment quality guidelines highlighted the occasional presence of Cd and Ag. Based on Pearson's correlation analysis, PCA, and cluster analysis, sources of these heavy metals in beach sediments were likely from agricultural runoff, uncontrolled industrial and residential discharge, and unprotected mine waste near the Kuantan Port. Furthermore, effective management of mining practices and ongoing monitoring are essential to reduce contamination risks.

Matched MeSH terms: Aluminum Oxide/analysis
Metal Oxide Nanoparticles Exhibit Anti-Acanthamoeba castellanii Properties by Inducing Necrotic Cell Death

Ahmed U, Gew LT, Siddiqui R, Khan NA, Alharbi AM, Alhazmi A, et al.

Acta Parasitol, 2024 Sep;69(3):1717-1723.
PMID: 39153011 DOI: 10.1007/s11686-024-00891-2

PURPOSE: The treatment of amoebic infections is often problematic, largely due to delayed diagnosis, amoebae transformation into resistant cyst form, and lack of availability of effective chemotherapeutic agents. Herein, we determined anti-Acanthamoeba castellanii properties of three metal oxide nanoparticles (TiO2, ZrO2, and Al2O3).
METHODS: Amoebicidal assays were performed to determine whether metal oxide nanoparticles inhibit amoebae viability. Encystation assays were performed to test whether metal oxide nanoparticles inhibit cyst formation. By measuring lactate dehydrogenase release, cytotoxicity assays were performed to determine human cell damage. Hoechst 33342/PI staining was performed to determine programmed cell death (apoptosis) and necrosis in A. castellanii.
RESULTS: TiO2-NPs significantly inhibited amoebae viability as observed through amoebicidal assays, as well as inhibited their phenotypic transformation as evident using encystation assays, and showed limited human cell damage as observed by measuring lactate dehydrogenase assays. Furthermore, TiO2-NPs altered parasite membranes and resulted in necrotic cell death as determined using double staining cell death assays with Hoechst33342/Propidium iodide (PI) observed through chromatin condensation. These findings suggest that TiO2-NPs offers a potential viable avenue in the rationale development of therapeutic interventions against Acanthamoeba infections.

Matched MeSH terms: Aluminum Oxide/pharmacology; Aluminum Oxide/chemistry
Fulltext Mechanical and morphological properties of polypropylene/nano α-Al2O3 composites

Mirjalili F, Chuah L, Salahi E

ScientificWorldJournal, 2014;2014:718765.
PMID: 24688421 DOI: 10.1155/2014/718765

A nanocomposite containing polypropylene (PP) and nano α-Al2O3 particles was prepared using a Haake internal mixer. Mechanical tests, such as tensile and flexural tests, showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant agent to the polymer. Tensile strength was approximately ∼ 16% higher than pure PP by increasing the nano α-Al2O3 loading from 1 to 4 wt% into the PP matrix. The results of flexural analysis indicated that the maximum values of flexural strength and flexural modulus for nanocomposite without dispersant were 50.5 and 1954 MPa and for nanocomposite with dispersant were 55.88 MPa and 2818 MPa, respectively. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties that could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became rougher by increasing the content of filler loading from 1 to 4% wt.

Matched MeSH terms: Aluminum Oxide/chemistry*
Optically stimulated Al2O3:C luminescence dosimeters for teletherapy: Hp(10) performance evaluation

Hashim S, Musa Y, Ghoshal SK, Ahmad NE, Hashim IH, Yusop M, et al.

Appl Radiat Isot, 2018 May;135:7-11.
PMID: 29353759 DOI: 10.1016/j.apradiso.2018.01.010

The performance of optically stimulated luminescence dosimeters (OSLDs, Al2O3:C) was evaluated in terms of the operational quantity of HP(10) in Co-60 external beam teletherapy unit. The reproducibility, signal depletion, and dose linearity of each dosimeter was investigated. For ten repeated readouts, each dosimeter exposed to 50mSv was found to be reproducible below 1.9 ± 3% from the mean value, indicating good reader stability. Meanwhile, an average signal reduction of 0.5% per readout was found. The dose response revealed a good linearity within the dose range of 5-50mSv having nearly perfect regression line with R2 equals 0.9992. The accuracy of the measured doses were evaluated in terms of operational quantity HP(10), wherein the trumpet curve method was used respecting the 1990 International Commission on Radiological Protection (ICRP) standard. The accuracy of the overall measurements from all dosimeters was discerned to be within the trumpet curve and devoid of outlier. It is established that the achieved OSL Al2O3:C dosimeters are greatly reliable for equivalent dose assessment.

Matched MeSH terms: Aluminum Oxide/chemistry*
Fulltext Development of Magnesium Aluminate (MgAl2O4) Nanoparticles for refractory crucible application

Khan SA, Mohd Zain Z, Siddiqui Z, Khan W, Aabid A, Baig M, et al.

PLoS One, 2024;19(1):e0296793.
PMID: 38227597 DOI: 10.1371/journal.pone.0296793

Ceramics are the oxides of metals and nonmetals with excellent compressive strength. Ceramics usually exhibit inert behavior at high temperatures. Magnesium aluminate (MgAl2O4), a member of the ceramic family, possesses a high working temperature up to 2000°C, low thermal conductivity, high strength even at elevated temperatures, and good corrosion resistance. Moreover, Magnesium Aluminate Nanoparticles (MANPs) can be used in the making of refractory crucible applications. This study focuses on the thermal behavior of Magnesium Aluminate Nanoparticles (MANPs) and their application in the making of refractory crucibles. The molten salt method is used to obtain MANPs. The presence of MANPs is seen by XRD peaks ranging from 66° to 67°. The determination of the smallest crystallite size of the sample is achieved by utilizing the Scherrer formula and is found to be 15.3 nm. The SEM micrographs provided further information, indicating an average particle size of 91.2 nm. At 600°C, DSC curves show that only 0.05 W/g heat flows into the material, and the TGA curve shows only 3% weight loss, which is prominent for thermal insulation applications. To investigate the thermal properties, crucibles of pure MANPs and the different compositions of MANPs and pure alumina are prepared. During the sintering, cracks appear on the crucible of pure magnesium aluminate. To explore the reason for crack development, tablets of MgAl2O4 are made and sintered at 1150°C. Ceramography shows the crack-free surfaces of all the tablets. Results confirm the thermal stability of MANPs at high temperatures and their suitability for melting crucible applications.

Matched MeSH terms: Aluminum Oxide*
Fulltext Gate length variation effect on performance of gate-first self-aligned In₀.₅₃Ga₀.₄₇As MOSFET

Mohd Razip Wee MF, Dehzangi A, Bollaert S, Wichmann N, Majlis BY

PLoS One, 2013;8(12):e82731.
PMID: 24367548 DOI: 10.1371/journal.pone.0082731

A multi-gate n-type In₀.₅₃Ga₀.₄₇As MOSFET is fabricated using gate-first self-aligned method and air-bridge technology. The devices with different gate lengths were fabricated with the Al2O3 oxide layer with the thickness of 8 nm. In this letter, impact of gate length variation on device parameter such as threshold voltage, high and low voltage transconductance, subthreshold swing and off current are investigated at room temperature. Scaling the gate length revealed good enhancement in all investigated parameters but the negative shift in threshold voltage was observed for shorter gate lengths. The high drain current of 1.13 A/mm and maximum extrinsic transconductance of 678 mS/mm with the field effect mobility of 364 cm(2)/Vs are achieved for the gate length and width of 0.2 µm and 30 µm, respectively. The source/drain overlap length for the device is approximately extracted about 51 nm with the leakage current in order of 10(-8) A. The results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared.

Matched MeSH terms: Aluminum Oxide
Fulltext Comments on 'Lattice Boltzmann simulation of alumina-water nanofluid in a square cavity' by Yurong He, Cong Qi, Yanwei Hu, Bin Qin, Fengchen Li and Yulong Ding

Sidik NA, Safdari A

Nanoscale Res Lett, 2012;7(1):648.
PMID: 23176814 DOI: 10.1186/1556-276X-7-648

This work presents some comments concerning the paper entitled 'Lattice Boltzmann simulation of alumina-water nanofluid in a square cavity' by Yurong He, Cong Qi, Yanwei Hu, Bin Qin, Fengchen Li and Yulong Ding which was published in Nanoscale Research Letters in 2011. The comments are related to the numerical parameters and the computed results of average Nusselt number.

Matched MeSH terms: Aluminum Oxide
Fulltext Effect of MgO Addition on the Mechanical and Dynamic Properties of Zirconia Toughened Alumina (ZTA) Ceramics

Arab A, Sktani ZDI, Zhou Q, Ahmad ZA, Chen P

Materials (Basel), 2019 Jul 31;12(15).
PMID: 31370216 DOI: 10.3390/ma12152440

Zirconia toughened alumina (ZTA) is a promising advanced ceramic material for a wide range of applications that are subjected to dynamic loading. Therefore, the investigation of dynamic compressive strength, fracture toughness and hardness is essential for ZTA ceramics. However, the relationship between these mechanical properties in ZTA has not yet been established. An example of this relationship is demonstrated using ZTA samples added with MgO prepared through conventional sintering. The microstructure and mechanical properties of ZTA composites were characterized. The hardness of ZTA composites increased for ≤0.7 wt.% MgO due to the pinning effect of MgO and decrease of the porosity in the microstructure. Oppositely, the fracture toughness of ZTA composites continuously decreased due to the size reduction of Al2O3 grains. This is the main reason of deteriorate of dynamic compressive strength more than 0.2 wt.% of MgO addition. Therefore, the SHPB test shows the improvement of the dynamic compressive strength only up to a tiny amount (0.2 wt.% of MgO addition) into ZTA ceramics.

Matched MeSH terms: Aluminum Oxide
Fulltext Bauxite mining activities: concerns of residents of Bukit Goh to radiation exposure

Norshuhadah Hayat, Inayatullah Shah Sayed

International Journal of Allied Health Sciences, 2018;2(1):265-272.
MyJurnal

Bauxite mining in Kuantan district of Pahang has raised health concerns of communities residing near the mining areas. Bauxite mining and transportation activities have contributed a lot to the pollution of environment. There is a fear among the residents of the areas that whether the soil is free from naturally occurring radioactive substances or not. Therefore, the objective of this study was to detect the presence of natural radioactive elements in the soil of bauxite mining field at Bukit Goh, Kuantan.

Matched MeSH terms: Aluminum Oxide
Fulltext New Experimental Zirconia-Reinforced Rice Husk Nanohybrid Composite and the Outcome of Its Surface Roughness and Microhardness in Comparison with Commercialized Nanofilled and Microhybrid Composite Resins

Lin GSS, Ghani NRNA, Ismail NH, Singbal K, Noorani TY, Mamat N

Contemp Clin Dent, 2021 03 20;12(1):21-27.
PMID: 33967533 DOI: 10.4103/ccd.ccd_298_20

Background: An ideal composite resin should demonstrate smooth surface after polishing and high hardness value to provide long-term success. Thus, this study aimed to compare the surface roughness and microhardness of new experimental zirconia-reinforced rice husk nanohybrid composite (Zr-Hybrid) with commercialized nanofilled (Filtek-Z350-XT) and microhybrid composite (Zmack-Comp) resins before and after artificial ageing.
Methods: One hundred and eighty standardized disc samples were prepared, of which ninety samples each were used for surface roughness and microhardness test, respectively. They were divided equally into: Group 1 (Filtek-Z350-XT), Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). For surface roughness test, all samples were polished with aluminium oxide discs and further subdivided into aged and unaged subgroups, in which composite samples in aged subgroups were subjected to 2500 thermal cycles. Next, all the samples were subjected to surface roughness test using a contact stylus profilometer. As for microhardness test, all the aged and unaged samples were tested using a Vickers hardness machine with a load of 300 kgf for 10 s and viewed under a digital microscope to obtain microhardness value. Data were analyzed using two-way ANOVA followed by post hoc Tukey's honestly significant difference and paired sample t-test with significance level set at P = 0.05.
Results: In both the aged and unaged groups, Zr-Hybrid showed statistically significantly lower surface roughness (P < 0.05) than Filtek-Z350-XT and Zmack-Comp, but no statistically significant difference was noted between Filtek-Z350-XT and Zmack-Comp (P > 0.05). A similar pattern was noted in microhardness test, whereby Zr-Hybrid showed the highest value (P < 0.05) followed by Filtek-Z350-XT and lastly Zmack-Comp. Besides, significant differences in surface roughness and microhardness were noted between the aged and unaged groups.
Conclusion: Zr-Hybrid seems to demonstrate better surface roughness and microhardness value before and after artificial ageing.

Matched MeSH terms: Aluminum Oxide
Fulltext The effects of CR2O3 addition on microstructure and fracture toughness of ZTA ceramic composite

Ahmad Zahirani Ahmad Azhar, Hasmaliza Mohamed, Mani Maran Ratnam, Zainal Arifin Ahmad

Journal of Nuclear and Related Technologies, 2013;2013(2):9-15.
MyJurnal

The microstructure and mechanical properties of ceramic composites produced from alumina, yttria stabilized zirconia and chromia oxide system was investigated. The Cr2O3 weight percent was varied from 0 wt% to 1.0 wt%. Each batch of composition was mixed, uniaxially pressed to 13mm diameter and sintered at 1600 ◦C for 4 h in pressureless conditions. Studies on the effects of the sample microstructures on their mechanical and physical properties such as fracture toughness and bulk density were carried out. Results show that an addition of 0.6 wt% of Cr2O3 produces the best mechanical properties. Furthermore, microstructural observations show that the Al2O3 grain size is significantly dependent on the amount of Cr2O3 additives used. Maximum value obtained with 0.6 wt % Cr2O3 for the fracture toughness is 5.36 MPa.m1/2.

Matched MeSH terms: Aluminum Oxide
Efficient Semipolar (11-22) 550 nm Yellow/Green InGaN Light-Emitting Diodes on Low Defect Density (11-22) GaN/Sapphire Templates

Li H, Khoury M, Bonef B, Alhassan AI, Mughal AJ, Azimah E, et al.

ACS Appl Mater Interfaces, 2017 Oct 18;9(41):36417-36422.
PMID: 28960058 DOI: 10.1021/acsami.7b11718

We demonstrate efficient semipolar (11-22) 550 nm yellow/green InGaN light-emitting diodes (LEDs) with In0.03Ga0.97N barriers on low defect density (11-22) GaN/patterned sapphire templates. The In0.03Ga0.97N barriers were clearly identified, and no InGaN clusters were observed by atom probe tomography measurements. The semipolar (11-22) 550 nm InGaN LEDs (0.1 mm2 size) show an output power of 2.4 mW at 100 mA and a peak external quantum efficiency of 1.3% with a low efficiency drop. In addition, the LEDs exhibit a small blue-shift of only 11 nm as injection current increases from 5 to 100 mA. These results suggest the potential to produce high efficiency semipolar InGaN LEDs with long emission wavelength on large-area sapphire substrates with economical feasibility.

Matched MeSH terms: Aluminum Oxide
Fulltext D-Shaped Polarization Maintaining Fiber Sensor for Strain and Temperature Monitoring

Qazi HH, Mohammad AB, Ahmad H, Zulkifli MZ

Sensors (Basel), 2016 Sep 15;16(9).
PMID: 27649195 DOI: 10.3390/s16091505

A D-shaped polarization-maintaining fiber (PMF) as fiber optic sensor for the simultaneous monitoring of strain and the surrounding temperature is presented. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of the PMF in order to fabricate a D-shaped cross-section. Experimental results show that the proposed sensor has high sensitivity of 46 pm/µε and 130 pm/°C for strain and temperature, respectively, which is significantly higher than other recently reported work (mainly from 2013) related to fiber optic sensors. The easy fabrication method, high sensitivity, and good linearity make this sensing device applicable in various applications such as health monitoring and spatial analysis of engineering structures.

Matched MeSH terms: Aluminum Oxide
Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

Al-Makramani BM, Razak AA, Abu-Hassan MI

J Appl Oral Sci, 2010 Dec;18(6):607-12.
PMID: 21308292

Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures.
OBJECTIVES: The aim of this study was to compare the biaxial flexural strength of three core ceramic materials.
MATERIAL AND METHODS: Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872.
RESULTS: The mean biaxial flexural strength values were: Turkom-Cera: 506.8 ± 87.01 MPa, In-Ceram: 347.4 ± 28.83 MPa and Vitadur-N: 128.7 ± 12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N.
CONCLUSIONS: Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.

Matched MeSH terms: Aluminum Oxide/chemistry*
Fulltext Phase transformations of α-alumina made from waste aluminum via a precipitation technique

Matori KA, Wah LC, Hashim M, Ismail I, Zaid MH

Int J Mol Sci, 2012;13(12):16812-21.
PMID: 23222685 DOI: 10.3390/ijms131216812

We report on a recycling project in which α-Al(2)O(3) was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H(2)SO(4) solution to form an Al(2)(SO(4))(3) solution. The Al(2)(SO(4))(3) salt was contained in a white semi-liquid solution with excess H(2)SO(4); some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al(2)(SO(4))(3)·18H(2)O. The Al(2)(SO(4))(3)·18H(2)O was calcined in an electrical furnace for 3 h at temperatures of 400-1400 °C. The heating and cooling rates were 10 °C /min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al(2)(SO(4))(3)·18H(2)O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al(2)O(3) at high temperatures. The X-ray diffraction results indicated that the α-Al(2)O(3) phase was realized when the calcination temperature was at 1200 °C or higher.

Matched MeSH terms: Aluminum Oxide/chemistry*
Tensile strength and water absorption of alumina filled poly (methyl methacrylate) denture base material

Nizam A, Mohamed SH, Arifin A, Mohd Ishak ZA, Samsudin AR

Med J Malaysia, 2004 May;59 Suppl B:145-6.
PMID: 15468860

The aim of this study was to evaluate the tensile properties and water absorption of denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3) as particulate filler. Specimens for mechanical testing were prepared by adding composite powder to the monomer followed by hand mixing as in dental laboratory procedure. The tensile strength of the prepared denture base material was slightly higher than commercial denture base material, while the water absorption was almost the same for all formulation of denture base materials.

Matched MeSH terms: Aluminum Oxide*

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links