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Oilfield-produced water treatment using conventional and membrane-based technologies for beneficial reuse: A critical review

Samuel O, Othman MHD, Kamaludin R, Sinsamphanh O, Abdullah H, Puteh MH, et al.

J Environ Manage, 2022 Feb 03;308:114556.
PMID: 35124308 DOI: 10.1016/j.jenvman.2022.114556

Oilfield produced water (OPW) is one of the most important by-products, resulting from oil and gas exploration. The water contains a complex mixture of organic and inorganic compounds such as grease, dissolved salt, heavy metals as well as dissolved and dispersed oils, which can be toxic to the environment and public health. This article critically reviews the complex properties of OPW and various technologies for its treatment. They include the physico-chemical treatment process, biological treatment process, and physical treatment process. Their technological strengths and bottlenecks as well as strategies to mitigate their bottlenecks are elaborated. A particular focus is placed on membrane technologies. Finally, further research direction, challenges, and perspectives of treatment technologies for OPW are discussed. It is conclusively evident from 262 published studies (1965-2021) that no single treatment method is highly effective for OPW treatment as a stand-alone process however, conventional membrane-based technologies are frequently used for the treatment of OPW with the ultrafiltration (UF) process being the most used for oil rejection form OPW and oily waste water. After membrane treatment, treated effluents of the OPW could be reused for irrigation, habitant and wildlife watering, microalgae production, and livestock watering. Overall, this implies that target pollutants in the OPW samples could be removed efficiently for subsequent use, despite its complex properties. In general, it is however important to note that feed quality, desired quality of effluent, cost-effectiveness, simplicity of process are key determinants in choosing the most suitable treatment process for OPW treatment.
Pattern and predictors of soil-transmitted helminth reinfection among aboriginal schoolchildren in rural Peninsular Malaysia

Hesham Al-Mekhlafi M, Surin J, Atiya AS, Ariffin WA, Mohammed Mahdy AK, Che Abdullah H

Acta Trop, 2008 Aug;107(2):200-4.
PMID: 18582430 DOI: 10.1016/j.actatropica.2008.05.022

Data on soil-transmitted helminth (STH) infections and reinfection among Orang Asli (aborigine) schoolchildren and their nutritional and socioeconomic status were analyzed to investigate the pattern and the possible predictors of STH reinfection. In this longitudinal study, 120 (60 males and 60 females) Orang Asli primary schoolchildren aged 7-12 years and living in remote areas in Pos Betau, Kuala Lipis, Pahang were screened for the presence of STH using modified cellophane thick smear and Harada Mori techniques. The overall prevalence of ascariasis, trichuriasis and hookworm infections were 65.8, 97.5 and 10.8%, respectively. After complete deworming with a 3-day course of 400mg/daily of albendazole tablets, children were re-examined at 3 and 6 months from baseline. The reinfection rate, by one or more of STH species, at 3 months after deworming was high (49.5%) while 79.6% of the children were reinfected at 6 months after deworming. Logistic regression analyses showed that females, stunted children and those living in houses without toilets had significantly higher reinfection rates than others at 3 months (P<0.05). At 6 months, maternal employment status emerged as another predictor where children of working mothers had significantly higher reinfection rates (P=0.026). In conclusion, reinfection rate of STH is high and thus necessitates frequent and periodic deworming among children. Public health personnel need to re-look at the current control measures and identify innovative and integrated ways in order to reduce STH significantly in the rural communities.
Clinical pairing revisited: a study at the University of Malaya, Malaysia

Ahmad NA, Naimie Z, Lui JL, Aziz AA, Abdullah M, Abu Kasim NH, et al.

J Dent Educ, 2012 Oct;76(10):1377-83.
PMID: 23066138

This study is part of ongoing educational research conducted by the Department of Conservative Dentistry, University of Malaya, Malaysia, to evaluate the perception of clinical pairing. A thirteen-question survey was distributed to 148 dental students after they had experienced four-handed dentistry. The objectives were to identify the advantages, disadvantages, and the acceptance of the implementation of clinical pairing from the students' point of view. The responses from the open-ended questions were categorized into six main themes (areas of interest): quality-related (Q), patient-related (PT), partner-related (P), lecturer-related (T), infection control (IC), and learning environment (L). Data analysis was done using SPSS version 18. Results indicated that the students perceived they possessed enough knowledge regarding clinical pairing. However, it was found that they still preferred to work independently as compared to working in pairs. The benefits of clinical pairing may not be viewed in the same vein by both dental students and teachers. The quality-related theme was perceived by students as the main advantage of clinical pairing, whilst the partner-related theme was perceived otherwise. The study also revealed that students may have some preconceived notions about pairing that may have impaired their acceptance. As a consequence, some reluctance was seen in their responses.
Outcomes of an In Vitro Fertilization Pregnancy With COVID-19 and the Perinatal Outcome in Riyadh, Saudi Arabia

Alhamoud AH, Matary F, Bukhari S, Kelantan M, Bajahzer M

Cureus, 2020 Dec 26;12(12):e12296.
PMID: 33510990 DOI: 10.7759/cureus.12296

Coronavirus disease 2019 (COVID-19) caused by the novel severe respiratory syndrome coronavirus 2 (SARS-CoV-2) is a pandemic and potentially fatal disease. COVID-19 cases are on the rise globally; this also includes risk groups such as pregnant women and neonates. Herein, we report the first COVID-19 cesarean delivery case of an in vitro fertilization (IVF) pregnancy in a Saudi woman. A postdate pregnant healthy woman tested positive with COVID-19 on her 38 weeks + five days. On her 40 weeks + five days, the woman had dilation without contractions; thereby, cesarean delivery was decided. The delivery was successful, with no complications in the mother and neonate. The preferable outcomes of this case could be attributable to some factors: multidisciplinary medical management, the mother's young age, and COVID-19 infection during the late trimester.
Fulltext Cloning, Expression and Functional Characterization of a Novel α-Humulene Synthase, Responsible for the Formation of Sesquiterpene in Agarwood Originating from Aquilaria malaccensis

Sundaraj Y, Abdullah H, Nezhad NG, Rodrigues KF, Sabri S, Baharum SN

Curr Issues Mol Biol, 2023 Nov 10;45(11):8989-9002.
PMID: 37998741 DOI: 10.3390/cimb45110564

This study describes the cloning, expression and functional characterization of α-humulene synthase, responsible for the formation of the key aromatic compound α-humulene in agarwood originating from Aquilaria malaccensis. The partial sesquiterpene synthase gene from the transcriptome data of A. malaccensis was utilized for full-length gene isolation via a 3' RACE PCR. The complete gene, denoted as AmDG2, has an open reading frame (ORF) of 1671 bp and encodes for a polypeptide of 556 amino acids. In silico analysis of the protein highlighted several conserved motifs typically found in terpene synthases such as Asp-rich substrate binding (DDxxD), metal-binding residues (NSE/DTE), and cytoplasmic ER retention (RxR) motifs at their respective sites. The AmDG2 was successfully expressed in the E. coli:pET-28a(+) expression vector whereby an expected band of about 64 kDa in size was detected in the SDS-PAGE gel. In vitro enzyme assay using substrate farnesyl pyrophosphate (FPP) revealed that AmDG2 gave rise to two sesquiterpenes: α-humulene (major) and β-caryophyllene (minor), affirming its identity as α-humulene synthase. On the other hand, protein modeling performed using AlphaFold2 suggested that AmDG2 consists entirely of α-helices with short connecting loops and turns. Meanwhile, molecular docking via AutoDock Vina (Version 1.5.7) predicted that Asp307 and Asp311 act as catalytic residues in the α-humulene synthase. To our knowledge, this is the first comprehensive report on the cloning, expression and functional characterization of α-humulene synthase from agarwood originating from A. malaccensis species. These findings reveal a deeper understanding of the structure and functional properties of the α-humulene synthase and could be utilized for metabolic engineering work in the future.
Fulltext Structural, Morphological, and Electron Transport Studies of Annealing Dependent In2O3 Dye-Sensitized Solar Cell

Mahalingam S, Abdullah H, Shaari S, Muchtar A, Asshari I

ScientificWorldJournal, 2015;2015:403848.
PMID: 26146652 DOI: 10.1155/2015/403848

Indium oxide (In2O3) thin films annealed at various annealing temperatures were prepared by using spin-coating method for dye-sensitized solar cells (DSSCs). The objective of this research is to enhance the photovoltaic conversion efficiency in In2O3 thin films by finding the optimum annealing temperature and also to study the reason for high and low performance in the annealed In2O3 thin films. The structural and morphological characteristics of In2O3 thin films were studied via XRD patterns, atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), EDX sampling, and transmission electron microscopy (TEM). The annealing treatment modified the nanostructures of the In2O3 thin films viewed through FESEM images. The In2O3-450 °C-based DSSC exhibited better photovoltaic performance than the other annealed thin films of 1.54%. The electron properties were studied by electrochemical impedance spectroscopy (EIS) unit. The In2O3-450 °C thin films provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSC.
Techno-economic optimization and Nox emission reduction through steam injection in gas turbine combustion chamber for waste heat recovery and water production

Hai T, El-Shafay AS, Goyal V, Alshahri AH, Almujibah HR

Chemosphere, 2023 Sep 01.
PMID: 37660791 DOI: 10.1016/j.chemosphere.2023.139782

Considering the persistent human need for electricity and fresh water, cogeneration systems based on the production of these two products have attracted the attention of researchers. This study investigates a cogeneration system of electricity and fresh water based on gas turbine (GT) as the prime mover. The wasted energy of the GT exhaust gases is absorbed by a heat recovery steam generator (HRSG) and supplies the superheat steam required by the steam turbine (ST). In order to produce fresh water, a multi-effect desalination (MED) system is applied. The motive steam required is provided by extracting steam from the ST. In order to reduce the environmental pollution of this cogeneration system, the steam injection method is proposed in the GT's combustion chamber (CC). This system is optimized by a multi-objective optimization tool based on the Genetic Algorithm (GA). The design variables include pressure ratio of compressor (CPR), inlet temperature of gas turbine (TIT), steam injection mass flow rate in the CC, HRSG operating pressure, HRSG evaporator pinch point temperature difference (PPTD), steam pressure of the MED ejector, ejector motive steam flow rate, number of MED effects, and return effect. The goals are to minimize the total cost rate (TCR), which includes the cost of initial investment and maintenance of the system, the cost of consumed fuel, and the cost of disposing of CO and NO pollutants, as well as maximizing the exergy efficiency. In the end, it is observed that the steam injection in the CC leads to the reduction of the mentioned pollutant index, and it is proposed as a suitable solution to reduce the pollution of the proposed cogeneration system.
Fulltext Hybrid fuzzy inference rules of descent method and wavelet function for volatility forecasting

Alenezy AH, Ismail MT, Jaber JJ, Wadi SA, Alkhawaldeh RS

PLoS One, 2022;17(12):e0278835.
PMID: 36490280 DOI: 10.1371/journal.pone.0278835

This research employs the gradient descent learning (FIR.DM) approach as a learning process in a nonlinear spectral model of maximum overlapping discrete wavelet transform (MODWT) to improve volatility prediction of daily stock market prices using Saudi Arabia's stock exchange (Tadawul) data. The MODWT comprises five mathematical functions and fuzzy inference rules. The inputs are the oil price (Loil) and repo rate (Repo) according to multiple regression correlation, and the Engle and Granger Causality test Engle RF, (1987). The logarithm of the stock market price (LSCS) in Tadawul reflects the output variable. The correlation matrix reveals that there is no collinearity between the input variables, and the causality test demonstrates that the input variables significantly influence the outcome variable. According to the multiple regression, there is a substantial negative influence between Loil and LSCS but a significant positive effect between Repo and output. For the 80% dataset under ME (0.000005), MAE (0.003214), and MAPE (0.064497), the MODWT-LA8 (ARIMA(1,1,0) with drift) for the LSCS variable performs better than other WT functions. In the novel hybrid model MODWT-FIR.DM, each function's approximation coefficient (LSCS) is applied with input variables (Loil and Repo). We evaluate the performance of the proposed model (MODWT-LA8-FIR.DM) using different statistical measures (ME, RMSE, MAE, MPE) and compare it to two established models: the original FIR.DM and other MODWT-FIR.DM functions for forecasting 20% of datasets. The outcomes show that the MODWT-LA8-FIR.DM performs better than the traditional models based on lower ME (3.167586), RMSE (3.167638), MAE (3.167586), and MPE (80.860849). The proposed hybrid model may be a potential stock market forecasting model.
Molecular detection of Candidatus Anaplasma camelii in camels (Camelus dromedarius) from Asir Province, Saudi Arabia

Alshahrani MY, Alanazi AD, Alouffi AS, Abdullah HHAM, Allam AM, Mahmoud MS, et al.

Trop Biomed, 2020 Sep 01;37(3):587-598.
PMID: 33612774 DOI: 10.47665/tb.37.3.587

Knowledge of molecular identification of tick-borne pathogens in camels in Saudi Arabia is very limited; few molecular epidemiological studies have been under taken. This study was to detect Anaplasma spp. and Piroplasma spp. in camels from Asir Province, Saudi Arabia. A total of 150 blood samples were collected from camels in Asir Province and investigated by polymerase chain reaction (PCR) that targeted 18S rRNA and 23S rRNA to detect the DNA of Piroplasma spp. and Anaplasma spp., respectively. The positive samples for 23S rRNA were assayed again by PCR targeting the 16S rRNA. All the blood samples were free from Piroplasma spp. infection. Three camels (2%) were found to be positive for Anaplasma infection through use of PCR that targeted the 23S rRNA gene. There were no significant differences between ages or sexes in the camels that tested positive for Anaplasma. All positive Anaplasma infections were recorded in camels that were infested by ticks. Two Anaplasma sequences for the16S rRNA gene were deposited in GenBank with accession numbers MN882724 and MN882725. They recorded 99.16% and 99.34% similarities (respectively) with KF843825.1 (Candidatus Anaplasma camelii reported in Unizah, Saudi Arabia). Phylogenetic analyses revealed that the two sequences recorded in this study were close to each other; both were located in one cluster with Candidatus Anaplasma camelii isolates that were recorded before in the adjacent areas of Unizah in Saudi Arabia and Iran. In conclusion: two new Anaplasma genotypes close to Candidatus Anaplasma camelii were found in camels in Asir Province, Saudi Arabia for the first time. The camels in this province were found to be free of Piroplasma infection.
Fulltext Effect of thermocycling on the compressive strength of selected luting cements

Al-Khadim Aws H., Abdullah H., Al-Ani Sarah T.

International Medical Journal Malaysia, 2018;17(3):75-80.
MyJurnal

Introduction: The purpose of this in vitro study was to evaluate the effect of thermocycling on the compressive strength of selected luting cements. Material and methods: 5 types of luting cements were tested. A total of thirty cylindrical specimens measuring 6mm in height and 4mm in diameter were prepared for each type of cement which were then divided into two groups ie Group 1: Exposure, and Group 2: Control. Both groups were stored in distilled water at 37°C for 24 hours. Group 1 was subjected to 500 cycles in a thermocycling baths of 5ºC and 55ºC with 20 seconds in each bath. Group 2 was not exposed to thermocycling procedure. The compressive strength for each cement type was determined by using a universal testing machine. Results: Resin adhesive cement had the highest compressive strength; followed by conventional glass ionomer cement (GIC) whilst resin modified GIC was the least. Thermocycling had no significant effect on the compressive strength of RelyXTM ARC and Fuji I (p>0.05), but a significant effect on Fuji I CAPSULE, Fuji CEM, Fuji Plus CAPSLUE (p
Fulltext Breast Surgery International--breast cancer in developing countries

Sandelin K, Apffelstaedt JP, Abdullah H, Murray EM, Ajuluchuku EU

Scand J Surg, 2002;91(3):222-6.
PMID: 12449462

Breast Surgery International (BSI) was formed in 1999 as an integrated society within the International Surgical Society ISS/SIC. One goal is to promote breast surgery world wide and focus on the situation in the developing countries. An edited summary of a symposium on locally advanced breast cancer (LABC) and the current situation in two African countries and in Malaysia is reported. Diagnosis, management and treatment options differ from recommendations that prevail due to lack of resources, lack of access to facilities and cultural and socioeconomic barriers. Younger age at onset, more men are affected and locally advanced breast cancer dominates the clinical panorama. A rational treatment plan for LABC should have chemotherapy, surgery, radiotherapy and hormonal therapy as armaments. A unique opportunity exists for international interchange within a professional organization such as BSI, for providing training opportunities, for clinical and experimental studies of the world' s most common female malignancy.
Fulltext Smartphone addiction and phubbing behavior among university students: A moderated mediation model by fear of missing out, social comparison, and loneliness

Safdar Bajwa R, Abdullah H, Zaremohzzabieh Z, Wan Jaafar WM, Abu Samah A

Front Psychol, 2022;13:1072551.
PMID: 36687837 DOI: 10.3389/fpsyg.2022.1072551

INTRODUCTION: This article examines mediators and moderators that may explain the link between smartphone addiction and phubbing behavior using a sample of 794 university students.
METHODS: A mediation model was tested to test the hypothesis that social comparison orientation and fear of missing out would mediate the link between smartphone addiction and phubbing behavior. Additionally, a moderated mediation model was leveraged to examine loneliness as a moderator within the hypothesized model. The data collected were analyzed using SPSS.
RESULTS AND DISCUSSION: The findings show a significant positive relationship between smartphone addiction and phubbing behavior. The findings confirm the hypothesized associations and reveal that smartphone addiction is positively linked to phubbing behavior. The link, on the other hand, is partially and sequentially mediated by the fear of missing out and social comparison orientation. As a result, both mediators might be regarded as proximal variables of phubbing behavior. Moreover, the associations between both smart addiction and phubbing behaviors as well as social comparison orientation and phubbing behaviors are moderated by loneliness. These two effects were stronger for university students with high loneliness than for those with low loneliness. This study addresses a major gap in the clinical psychology literature through the attempt to explore the relationship between smartphone addiction and increased phubbing behavior among university students.
Low-melting-point polymeric nanoshells for thermal-triggered drug release under hyperthermia condition

Dabbagh A, Mahmoodian R, Abdullah BJ, Abdullah H, Hamdi M, Abu Kasim NH

Int J Hyperthermia, 2015;31(8):920-9.
PMID: 26670340 DOI: 10.3109/02656736.2015.1094147

The aim of this paper was to synthesise core-shell nanostructures comprised of mesoporous silica core and a low melting-point polyethylene glycol (PEG) nanoshell with a sharp gel-liquid phase transition for rapid drug release at hyperthermia temperature range.
Stress distributions in maxillary central incisors restored with various types of post materials and designs

Madfa AA, Kadir MR, Kashani J, Saidin S, Sulaiman E, Marhazlinda J, et al.

Med Eng Phys, 2014 Jul;36(7):962-7.
PMID: 24834856 DOI: 10.1016/j.medengphy.2014.03.018

Different dental post designs and materials affect the stability of restoration of a tooth. This study aimed to analyse and compare the stability of two shapes of dental posts (parallel-sided and tapered) made of five different materials (titanium, zirconia, carbon fibre and glass fibre) by investigating their stress transfer through the finite element (FE) method. Ten three-dimensional (3D) FE models of a maxillary central incisor restored with two different designs and five different materials were constructed. An oblique loading of 100 N was applied to each 3D model. Analyses along the centre of the post, the crown-cement/core and the post-cement/dentine interfaces were computed, and the means were calculated. One-way ANOVAs followed by post hoc tests were used to evaluate the effectiveness of the post materials and designs (p=0.05). For post designs, the tapered posts introduced significantly higher stress compared with the parallel-sided post (p<0.05), especially along the centre of the post. Of the materials, the highest level of stress was found for stainless steel, followed by zirconia, titanium, glass fibre and carbon fibre posts (p<0.05). The carbon and glass fibre posts reduced the stress distribution at the middle and apical part of the posts compared with the stainless steel, zirconia and titanium posts. The opposite results were observed at the crown-cement/core interface.
Fulltext Fetal MRI of thoraco-omphalopagus conjoined twins

Abdullah H, Abdul Wahab N, Abu Bakar K

BMJ Case Rep, 2017 Jun 13;2017.
PMID: 28611167 DOI: 10.1136/bcr-2017-219793
Fulltext Comparative Study On Microleakage Of Composite Inlays Using Various Resin Luting Cements

Annuar, W.A., Abdullah, H.

Ann Dent, 2003;10(1):-.
MyJurnal

This study is conducted to compare two resin luting cements (Rely XTMARC,3M and Compolute™ESPE) on their microleakage with one composite inlay system (Filtek™ Z250 Universal Restorative Materials, 3M). Thirty conventional inlays, Class II MOIDO cavity with gingival margin I mm above the cementoenamel junction, were prepared in premolar teeth. The composite inlays were fabricated directly on the prepared teeth using layering technique. Fifteen of the inlays were cemented with RelyTMX ARC and fifteen with Compolute™ (ESPE). The specimens were kept at 370 C for 10 days before thermocycling and immersed in methylene blue 2% solution for 24 hours. The teeth were sectioned mesio-distally. The site and degree of leakage of each section was scored using a visual scoring system under a stereomicroscope at a magnification of 1.5X. Results showed that there was no significant difference in'leakage extent (p>O.05), between Rely X™ARC and Compolute™. For both materials, leakage occurred most commonly within the enamel surface and between the cement-tooth interfaces. None of the leakage occurred between inlay - cement interface. There is no significant difference in the extent of leakage between Rely XTMARC compared to Compolute™.
Anaemia and iron deficiency anaemia among aboriginal schoolchildren in rural Peninsular Malaysia: an update on a continuing problem

Al-Mekhlafi MH, Surin J, Atiya AS, Ariffin WA, Mahdy AK, Abdullah HC

Trans R Soc Trop Med Hyg, 2008 Oct;102(10):1046-52.
PMID: 18617209 DOI: 10.1016/j.trstmh.2008.05.012

A cross-sectional study to determine the current prevalence of anaemia and iron deficiency anaemia (IDA) and to investigate the possible risk factors for IDA was carried out on 241 aboriginal schoolchildren (120 boys, 121 girls) aged 7-12 years and living in remote areas in Pos Betau, Pahang, Malaysia. Haemoglobin (Hb) level was measured and serum iron status was assessed by serum ferritin (SF), serum iron (SI) and total iron binding capacity measurements. Socioeconomic data were collected using pre-tested questionnaires. All children were screened for intestinal parasitic infections. Overall, 48.5% (95% CI 42.3-54.8) of children were anaemic (Hb<12 g/dl). The prevalence of IDA was 34% (95% CI 28.3-40.2), which accounted for 70.1% of the anaemia cases. The prevalence of IDA was significantly higher in females than males. Low levels of mothers' education and low household income were identified as risk factors for IDA. Severe trichuriasis also found to be associated with low SF and SI. Logistic regression confirmed low levels of mothers' education and gender as significant risk factors for IDA. Improvement of socioeconomic status and health education together with periodic mass deworming should be included in public health strategies for the control and prevention of anaemia and IDA in this population.
Current prevalence and predictors of protein-energy malnutrition among schoolchildren in rural Peninsular Malaysia

Al-Mekhlafi MS, Surin J, Atiya AS, Ariffin WA, Mahdy AK, Abdullah HC

Southeast Asian J. Trop. Med. Public Health, 2008 Sep;39(5):922-31.
PMID: 19058591

A cross-sectional study was carried out to determine the current prevalence of protein-energy malnutrition (PEM) among Orang Asli schoolchildren and to investigate the potential predictors of malnutrition. A total of 241 (120 males and 121 females) Orang Asli schoolchildren age 7-12 years living in remote areas of Pos Betau, Pahang participated voluntarily in this study. Anthropometric and socioeconomic data were collected and the children were screened for intestinal parasitic infections. The overall prevalences of mild and significant underweight conditions were 52.3% and 37.3%, respectively, and the prevalences of mild stunting and wasting were 43.6% and 43.1%, respectively, while the prevalences of significant stunting and wasting were 43.6% and 5.6%, respectively. There was a significant association between gender (male) and malnutrition (p = 0.029). The results also showed a higher prevalence of stunting among children age < or = 10 years than in older children (p = 0.001). Other independent variables, including socioeconomic status and intestinal parasitic infections, had no significant associations with malnutrition indices. PEM is prevalent among schoolchildren in rural Malaysia and therefore of public health concern since PEM diminishes immune function and impairs cognitive function and educational performance. School-based programs of prevention through health education and interventions should be considered as an essential part of measures to improve the quality of life of schoolchildren in rural Malaysia.
Fulltext Effect of porosity on compressive strength of resin modified glass ionomer luting cements

Al-Kadhim, A.H.A., Abdullah H.

International Medical Journal Malaysia, 2018;17(2):33-40.
MyJurnal

Introduction: The purpose of this study was to decide on the relation between types of mixing and the porosity of diameter (1-100) µm and compressive strength of RMGIC. Methods: Fifteen specimens 6mm height and 4mm in diameter were prepared for each type of luting cement and were stored in distilled water at 37° C for 24 hours. The compressive strength was determined. The fractured surfaces of 10 randomly selected specimens of each cement type were analyzed using SEM at 250 times magnification, and five photomicrographs were taken at five random places. All the photomicrographs were analyzed using image analyzer software to determine the amount and size of porosity present. Results: There was no significant difference in compressive strength between different mixing methods, but it had a significant impact by increasing the percentage of porosity of diameter (1-100) µm in diameter of RMGIC. There was no linear relationship between compressive strength and porosity (1-100) µm in diameter for both types of luting cements (P>0.05). Conclusion: No significant differences in compressive strength were found using different mixing methods. The size and number of porosity in the specimens of encapsulated cements were greater than those of hand-mixed cements. The porosity (1-100) µm in diameter and the compressive strength bore no linear relationship to each other.
Integrated technologies for solid waste bin monitoring system

Arebey M, Hannan MA, Basri H, Begum RA, Abdullah H

Environ Monit Assess, 2011 Jun;177(1-4):399-408.
PMID: 20703798 DOI: 10.1007/s10661-010-1642-x

The integration of communication technologies such as radio frequency identification (RFID), global positioning system (GPS), general packet radio system (GPRS), and geographic information system (GIS) with a camera are constructed for solid waste monitoring system. The aim is to improve the way of responding to customer's inquiry and emergency cases and estimate the solid waste amount without any involvement of the truck driver. The proposed system consists of RFID tag mounted on the bin, RFID reader as in truck, GPRS/GSM as web server, and GIS as map server, database server, and control server. The tracking devices mounted in the trucks collect location information in real time via the GPS. This information is transferred continuously through GPRS to a central database. The users are able to view the current location of each truck in the collection stage via a web-based application and thereby manage the fleet. The trucks positions and trash bin information are displayed on a digital map, which is made available by a map server. Thus, the solid waste of the bin and the truck are being monitored using the developed system.

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