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Performance of high strength lightweight concrete using palm wastes
No full textThe performance of high strength structural lightweight concrete (LWC) using palm wastes, oil palm shell (OPS) as well as palm oil clinker (POC) is of foremost concern. Existing literature used either OPS or POC individually for production of LWC. In this study, both OPS and POC have been put together as coarse aggregate on the way to see the improvement of mechanical properties of waste-based LWC. Regular coarse aggregate has been fully replaced by OPS and POC in the concrete. This structural-grade, lightweight concrete is called palm shell and clinker concrete (PSCC). A series of OPS and POC mixtures have been investigated aimed at identifying better performance. The quantity of OPS and POC mix has been varied as 30, 40, 50, 60 and 70%. Evaluated mechanical properties of PSCC include density, workability, compressive strength at different ages, flexural strength, splitting tensile strength as well as modulus of elasticity. It is revealed that the proposed PSCC has extensive potential in terms of high compressive strength and good material behavior to perform as a better LWC. The study could offer structural lightweight concrete of compressive strength up to 46.47 MPa that is 30.5% higher than the control mix (P100). The usage of 50% OPS to 50% POC coarse aggregate by vol. in the concrete mix is found to be the optimum mix. Furthermore, simple correlation equations have been developed that can be used to predict the compressive strength, splitting tensile strength, flexural strength, modulus of elasticity and ultrasonic pulse velocity of the lightweight concrete using POC. © 2018, International Islamic University Malaysia-IIUM.
Prestasi struktur konkrit ringan (LWC) berkekuatan tinggi menggunakan sisa sawit, iaitu daripada minyak kulit kelapa sawit (OPS) dan juga mendakan (klinker) minyak kelapa sawit (POC) adalah keprihatinan utama. Kajian sedia ada telah mengguna pakai sama ada OPS atau POC secara berasingan bagi menghasilkan LWC. Dalam kajian ini, kedua-dua OPS dan POC telah digabungkan sebagai agregat kasar bagi mengkaji pembaikan pada ciri-ciri mekanikal sisa LWC. Agregat kasar tetap telah digantikan sepenuhnya dengan menggunakan OPS dan POC dalam konkrit. Struktur gred konkrit ringan ini telah dinamakan sebagai kulit kelapa sawit dan konkrit mendakan klinker (PSCC). Satu siri campuran OPS dan POC telah dikaji bagi mengenal pasti prestasi terbaik. Kuantiti campuran OPS dan POC telah diubah kepada 30, 40, 50, 60 dan 70%. Ciri-ciri mekanikal yang dikaji pada PSCC ini adalah ketumpatan, kebolehkerjaan, kekuatan mampatan pada umur berlainan, kekuatan lenturan, kekuatan tegangan pecahan, serta keanjalan modulus. Hasil menunjukkan PSCC ini mempunyai potensi luas dari segi kekuatan mampatan yang tinggi dan struktur material yang baik sebagai LWC terbaik. Kajian ini menawarkan struktur konkrit ringan berkekuatan mampatan sehingga 46 MPa iaitu sebanyak 31% lebih baik daripada campuran kawalan. Penggunaan 50% OPS kepada 50% POC agregat kasar secara vol. dalam campuran konkrit adalah campuran optimum. Tambahan pula, korelasi mudah telah dibangunkan bagi menjangkakan dengan mudah kekuatan mampatan, kekuatan tegangan pecahan, kekuatan lenturan, keanjalan modulus dan halaju signal ultrasonik konkrit ringan
Low-dissolved-oxygen nitrification in tropical sewage: an investigation on potential, performance and functional microbial community
No full textIntensive aeration for nitrification is a major energy consumer in sewage treatment plants (STPs). Low-dissolved-oxygen (low-DO) nitrification has the potential to lower the aeration demand. However, the applicability of low-DO nitrification in the tropical climate is not well-understood. In this study, the potential of low-DO nitrification in tropical setting was first examined using batch kinetic experiments. Subsequently, the performance of low-DO nitrification was investigated in a laboratoryscale sequential batch reactor (SBR) for 42 days using real tropical sewage. The batch kinetic experiments showed that the seed sludge has a relatively high oxygen affinity. Thus, the rate of nitrification was not significantly reduced at low DO concentrations (0.5 mg/L). During the operation of the low-DO nitrification SBR, 90% of NH4-N was removed. The active low-DO nitrification was mainly attributed to the limited biodegradable organics in the sewage. Fluorescence in-situ hybridisation and 16S rRNA amplicon sequencing revealed the nitrifiers were related to Nitrospira genus and Nitrosomonadaceae family. Phylogenetic analysis suggests 47% of the operational taxonomic units in Nitrospira genus are closely related to a comammox bacteria. This study has demonstrated active low-DO nitrification in tropical setting, which is a more sustainable process that could significantly reduce the energy footprint of STPs
Influence of injection timing and split injection strategies on performance, emissions, and combustion characteristics of diesel engine fueled with biodiesel blended fuels
No full textBiodiesel can be used as alternative to replace fossil diesel. However, usage of biodiesel in an unmodified diesel engine can cause higher in nitrogen oxides (NOx) emission. In order to reduce the harmful emission, certain injection strategies can be carried out. In this paper, the effects of biodiesel blends, fuel injection timing and split injection schemes on the engine performance, emissions and combustion characteristics of a medium-duty diesel engine are investigated. Parametric studies relating with start of injection timing variation and multiple injection schemes using B20 and B50 biodiesel blends were performed and benchmarked with petroleum diesel fuel as baseline. A remarkably lower NOx level below 100 ppm can be obtained by retard start of injection (SOI) timing for both of the B20 and B50 fuel operations and with triple injection scheme. It was found that with the use of B50, simultaneous NOx and smoke suppression from the levels of petroleum diesel fuel is attainable in parallel with the implementation of late SOI timing and triple injection scheme in a diesel engine. In conclusion, multiple split injections is a practical strategies to simultaneously decrease NOx and smoke emissions when the SOI timing is fine-tuned and is an ideal alternative to operate with biodiesel fuel
CFRP strips for enhancing flexural performance of RC beams by SNSM strengthening technique
No full textSide Near Surface Mounted (SNSM) strengthening technique is among the latest technique introduced recently. In this paper, SNSM carbon fiber reinforced polymer (CFRP) strips strengthening technique is proposed for enhancing the flexural performance of reinforced concrete (RC) beams. A total of seven RC beam specimens were tested: one un-strengthened control specimen, and six specimens strengthened by SNSM-CFRP strips. All beam specimens were tested under four-point bending. Analytical prediction methods were used to verify the experimental results. The load, mid-span, deflection, and strains data were recorded until failure of the specimens. The ductility, stiffness, and energy absorption capacity of the strengthened specimens by CFRP strips were enhanced due to SNSM technique. The results also showed that the SNSM-CFRP strips strengthening technique significantly enhanced the first cracking, yield, and ultimate load capacities up to 153%, 108%, and 147% respectively, compared with that of the control beam. Further, the comparison between the experimental and predicted values shows good agreement
Symptom prevalence, bother, and treatment satisfaction in men with lower urinary tract symptoms in Southeast Asia: a multinational, cross-sectional survey
No full textPurpose: The overall objective of the survey was to systematically examine patients’ perspectives on lower urinary tract symptoms (LUTS) and their treatment in Southeast Asia. Methods: A multinational cross-sectional survey involving adult men seeking consultation at urology outpatient clinics because of LUTS in Southeast Asia was conducted using convenience sampling. Self-reported prevalence, bother, treatment and treatment satisfaction of selected LUTS including urgency, nocturia, slow stream, and post-micturition dribble were evaluated. Results: In total, 1535 eligible patients were enrolled in the survey. A majority of respondents were aged 56–75 years, not employed, and had not undergone prostate operation before. Overall, the self-reported prevalence of nocturia was 88% (95% CI 86–90%), slow stream 61% (95% CI 59–63%), post micturition dribble 55% (95% CI 52–58%), and urgency 52% (95% CI 49–55%). There were marked differences in the country specific prevalence of LUTS complaints. Frequently, symptoms coexisted and were combined with nocturia. More than half of patients felt at least some degree of bother from their symptoms: 61% for urgency, 57% for nocturia, 58% for slow stream, and 60% for post-micturition dribble. Before seeing the present urologists, nearly half of patients have received some form of prescribed treatment and more than 80% of patients indicated they would like to receive treatment. Conclusion: Men who sought urologist care for LUTS often presented with multiple symptoms. Nocturia emerged as the most common symptom amongst the four core symptoms studied
Abundance and Distribution of the Potentially Toxic Thecate Dinoflagellate Alexandrium tamiyavanichii (Dinophyceae) in the Central Mexican Pacific, Using the Quantitative PCR Method
No full textMost of the toxic algal blooms in coasts of the Mexican Pacific are attributed to planktonic dinoflagellates. Recently, some new records of dinoflagellates producers of emergent toxins have been documented. The genus Alexandrium encompasses several toxic species which produce saxitoxin. In this work, the abundance and distribution of the potentially toxic species Alexandrium tamiyavanichii from coasts of the central Mexican Pacific were studied, following the method of quantitative real-time PCR. During the oceanographic cruise "MareaR IX" (19-30 April, 2017), carried out along coasts of the Mexican Pacific, hydrographic, and environmental variables were measured, and net and bottle samples were collected and preserved in modified saline ethanol buffer for analysis in the laboratory. In order to perform the qPCR method, the molecular target used was the ITS2 of the rDNA of A. tamiyavanichii. From 45 samples analyzed, 14 yielded positive results, showing the presence and abundance of the species in fixed stations of Cabo Corrientes, Manzanillo and Acapulco, with low densities (less than 40 cells/m3), which is an evidence of the sensitiveness of the method. On the other hand, chains of cells of the species were found in net samples, in stations where its presence was detected by qPCR, confirming results by the method. General distribution showed presence of the species in two zones where upwellings were detected, but not at coastal stations, except in Acapulco where a more stratified water column was found. Vertical distribution indicated that highest densities were found at subsurface layers, in association with the chlorophyll a maxima (between 11 and 30 m depth). The results show the importance of assessing the abundance and distribution of a species which may be systematically monitored, and that the method of the qPCR may be very useful
Synthesis and evaluation of nuciferine and roemerine enantiomers as 5-HT2 and α1 receptor antagonists
No full textIn this study, the (S)-enantiomers of the aporphine alkaloids, nuciferine and roemerine, were prepared via a synthetic route involving catalytic asymmetric hydrogenation and both stereoisomers were evaluated in vitro for functional activity at human 5-HT2 and adrenergic α1 receptor subtypes using a transforming growth factor-α shedding assay. Both enantiomers of each of the compounds were found to act as antagonists at 5-HT2 and α1 receptors. (R)-roemerine was the most potent compound at 5-HT2A and 5-HT2C receptors (pKb = 7.8-7.9) with good selectivity compared to (S)-roemerine at these two receptors and compared to its activity at 5-HT2B, α1A, α1B and α1D receptors
Detecting opinion spams through supervised boosting approach
No full textProduct reviews are the individual’s opinions, judgement or belief about a certain product or service provided by certain companies. Such reviews serve as guides for these companies to plan and monitor their business ventures in terms of increasing productivity or enhancing their product/service qualities. Product reviews can also increase business profits by convincing future customers about the products which they have interest in. In the mobile application marketplace such as Google Playstore, reviews and star ratings are used as indicators of the application quality. However, among all these reviews, hereby also known as opinions, spams also exist, to disrupt the online business balance. Previous studies used the time series and neural network approach (which require a lot of computational power) to detect these opinion spams. However, the detection performance can be restricted in terms of accuracy because the approach focusses on basic, discrete and document level features only thereby, projecting little statistical relationships. Aiming to improve the detection of opinion spams in mobile application marketplace, this study proposes using statistical based features that are modelled through the supervised boosting approach such as the Extreme Gradient Boost (XGBoost) and the Generalized Boosted Regression Model (GBM) to evaluate two multilingual datasets (i.e. English and Malay language). From the evaluation done, it was found that the XGBoost is most suitable for detecting opinion spams in the English dataset while the GBM Gaussian is most suitable for the Malay dataset. The comparative analysis also indicates that the implementation of the proposed statistical based features had achieved a detection accuracy rate of 87.43 per cent on the English dataset and 86.13 per cent on the Malay dataset
Eliciting teachers’ understanding and their reported practices on school-based formative assessment: Methodological challenges
No full textMinistries of Education in many countries have adopted various forms of school-based assessment (SBA) to replace (for example, New Zealand) or complement (for example, England, Australia and Malaysia) more conventional forms of assessment such as tests and examinations. Central to these alternative approaches to SBA is formative assessment. In recent years, a body of research has been built investigating various aspects of SBA in Malaysia, but there has been a dearth of studies exploring what practising teachers believe and do regarding implementing formative assessment in their own classrooms. The present article reports some of the findings of a case study in which ten Malaysian primary school teachers of English were interviewed to identify the extent of their understanding of formative assessment and their reported practices of providing feedback in an SBA environment. Initially, the teachers revealed a general lack of understanding of the difference between formative and summative assessment. In such a situation, it would seem that the teachers are unready to implement SBA at the present stage, despite it having been mandated in Malaysian schools since 2011-12. However, later in the interview, they reported implementing various forms of feedback, some of which might be regarded as formative. There is a need, therefore, to differentiate between teachers' explicit knowledge and their implicit understanding of matters such as formative feedback. The inherent limitations of self-report data emerging from interviews will be discussed and how these might be overcome
Comparative Evaluation of Antioxidant Properties and Isoflavones of Tempeh Fermented in Two Different Wrapping Materials
No full textTempeh is an Indonesian traditional fermented soybean food that is well known for its nutritional value and health benefit. This study aimed to evaluate the effects of two commonly used packaging materials in tempeh production, namely banana leaf and polyethylene bag, on the antioxidant properties. Isoflavones, include daidzein and genistein, of tempeh fermented in banana leaf (TBL) and polyethylene bag (TP) were analysed with high-performance liquid chromatography. Total phenolic content and antioxidant activities were evaluated using Folin-Ciocalteu reagent, DPPH radical scavenging and β-carotene-linoleate bleaching assays, respectively. The changes of antioxidant properties of tempeh after different fermentation periods in both wrapping materials were observed, on day 0 (unfermented), day 1, day 2 and day 4. Total phenolic content, daidzein, genistein and the antioxidant activities were significantly (p < 0.05) increased in both TBL and TP as the fermentation progressed. A higher total phenolic content was found in TBL on day 1 and day 2 but TP exhibited the highest total phenolic content on day 4. Daidzein was the highest in TBL on day 2 but it was reduced on day 4 while genistein was the highest in TP on day 4. Antioxidant activities were positively (r = 0.272–0.969, p < 0.05) correlated to total phenolic content, daidzein and genistein. Although tempeh wrapped in banana leaf is a traditional way for tempeh packaging, it provided better antioxidant properties on day 1 and day 2, which is within the best period of tempeh consumption. Hence, the current findings provided useful information to manufacturer and consumer in selecting the suitable wrapping material for tempeh with optimal phytonutrients