19672 research outputs found
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The effect of particle size on the dispersion and wear protection ability of MoS2 particles in polyalphaolefin and trimethylolpropane ester
No full textThe effect of particle size and surfactant on dispersion stability and wear protection ability was experimentally evaluated for polyalphaolefin (PAO 10) and bio-based base oil (palm trimethylolpropane ester) added with molybdenum disulfide (MoS2) particles. Nanolubricants were developed by adding 1 wt% of MoS2 particles that varied in size. In addition to the variation in particle size, an anionic surfactant was also used to analyze its interaction with both types of nanoparticles for stable suspensions and for the related effects on the antiwear characteristics. The wear protection characteristics of the formulations were evaluated by four-ball extreme pressure tests and piston ring on cylinder sliding wear tests. The wear surfaces were analyzed by scanning electron microscopy along with an energy-dispersive X-ray and an atomic force microscopy. The MoS2 nanoparticles with a nominal size of 20 nm exhibited a better load-carrying capacity, while better sliding wear protection was provided by nanoparticles with a nominal size of 50 nm
A new method for intermediate power point tracking for PV generator under partially shaded conditions in hybrid system
No full textThe tracking of the Intermediate Power Point is more important than the Maximum Power Point when the photovoltaic system becomes a part of a hybrid power generation system. It means that the photovoltaic system can either work on the Maximum Power Point or on the Intermediate Power Point. An optimized control technique for hybrid power generation system is developed in this study to work in both cases with high accuracy and good efficiency, under normal or partially shaded conditions. This technique is based on the combination of two algorithms, the particle swarm optimization algorithm for tracking the global maximum power point, while a newly developed algorithm is used for attaining any other supervisory control set point. Furthermore, the new proposed algorithm has the advantage of choosing the point of highest voltage and lower current among the other points that provide the same power, which would increase the efficiency of the system by reducing the power losses. A simulation work is carried out to assess the effectiveness of the proposed technique. Different scenarios under normal and partially shaded conditions are verified. Finally, the combined control algorithm was implemented using a DSpace 1104 environment and extensively tested under various partially shaded patterns. The experimental results of the prototype have proven that the newly developed algorithm improves the capability of photovoltaic system to response quickly and precisely to the supervisor of the hybrid power system under different partially shaded conditions
Amino acid analysis of lipases from oil pollutant isolates: Cunninghamella verticillata and geotrichum candidum
No full textLipase is an enzyme commonly used in food, dairy, and other industries. Fungal lipases are more commonly used due to their secretion and easier production. Analyses of the amino acid composition of microbial lipases will hasten their potential usage in industrial applications. In this study, the major amino acid compositions of lipases secreted by oil pollutant isolates (Cunninghamella verticillata and Geotrichum candidum) enriched with fatty substances were analyzed by high performance liquid chromatography. Among eight major amino acids found in these lipases, histidine and ornithine were predominant. Lysine was absent from lipase generated by C. verticillata, while glutamine was absent from that produced by G. candidum. Conversely, glutamic acid, asparagine, histidine and arginine were present in slightly higher amounts in G. candidum. However, a slight decrease in aspartic acid and ornithine was observed in G. candidum. Analyses of the amino acids composition of lipase can potentially facilitate to predict the nature of this enzyme
An audiological evaluation of syndromic and non-syndromic craniosynostosis in pre-school going children
No full textObjective: To study the audiological outcome and early screening of pre-school going children with craniosynostosis under follow-up at the University of Malaya Medical Center(UMMC), Kuala Lumpur, Malaysia over a 10 year period. Methods: A retrospective descriptive cohort study on the audiological findings detected during the first hearing assessment done on a child with craniosynostosis using otoacoustic emissions, pure tone audiometry or auditory brainstem response examination. The main aim of this study was to evaluate the type and severity of hearing loss when compared between syndromic and non-sydromic craniosynostosis, and other associated contributory factors. Results: A total of 31 patients with 62 ears consisting of 14 male patients and 17 female patients were evaluated. Twenty two patients (71%) were syndromic and 9 (29%) were non-syndromic craniosynostosis. Amongst the syndromic craniosynostosis, 9 (41%) had Apert syndrome, 7 (32%) had Crouzon syndrome, 5 (23%) had Pfieffer syndrome and 1 (4%) had Shaethre Chotzen syndrome. Patients with syndromic craniosynostosis were more likely to present with all types and severity of hearing loss, including severe to profound sensorineural hearing loss while children with non-syndromic craniosynostosis were likely to present with normal hearing (p < 0.05). In addition, when the first hearing test was done at a later age, a hearing loss including sensorineural hearing loss is more likely to be present in a child with syndromic craniosynostosis (p < 0.05). Conclusion: Our study suggested that children who are born with syndromic craniosynostosis were more likely to suffer from a hearing loss, including that of a severe to profound degree compared to children with non-syndromic craniosynostosis. In addition to that, hearing loss is more likely to be detected when the first hearing test is done at a later age, and this can be an irreversible sensorineural hearing loss. We would like to advocate the need for early audiological screening and follow up in children with syndromic craniosynostosis
Impact of religious values and habit on an extended green purchase behaviour model
No full textGreen purchase behaviour is an increasingly important topic, gaining much attention. A review of current literature reveals that the relationship between green attitudes and green purchase behaviour is contentious because consumers’ attitudes do not necessarily translate into green purchase behaviour. This paper examines the relationships between religious values, green habit, and green purchase behaviours via a holistic approach based on the Theory of Reasoned Action and Homer and Kahle's (1988) cognitive hierarchy model. Data were collected from 504 Muslim consumers in two Southeast Asian countries, namely, Indonesia and Malaysia. Partial least squares (PLS), a variance-based structural equation–modelling technique, was selected to test the research model and hypotheses. The term “religious values” is conceptualised in this paper as a multidimensional construct with reflective first-order and formative second-order items. Previous studies have ignored the quest orientation, which refers to constant questioning and doubting as a way of being religious. The results demonstrate that religious values have a positive impact on natural environmental orientation, environmental concerns, green purchase attitudes, and green purchase intentions. Green habit and green purchase intentions were also found to positively affect green purchase behaviours. This study also highlights the important role of habit, namely, a stronger impact on green behaviour than intentions. Green habit was also found to moderate the relationship between green attitudes and green intentions. The study has practical implications for green marketers, green policy makers, and green consumers, as well as directions for future research
Tongue necrosis secondary to mucormycosis in a diabetic patient: A first case report in Malaysia
No full textMucormycosis is a rare fungal infection and high mortality that commonly affects patients with the weakened immune system. We present an unusual case of tongue necrosis probably due to the healthcare-associated mucormycosis (HCM) in a diabetic patient. Although cannot be proved with certainty, we surmise that intubation as a risk factor in our case. The diagnosis was confirmed by histopathological examination (HPE) of the necrotic tissue specimen. The patient was responded well to lipid complex amphotericin B (250 mg) regime after surgery. Subsequent follow up revealed that no signs of recurrence. Early, recognition, diagnosis, prompt treatment and awareness among clinician are representing the most effective way of managing the disease
Docking studies reveal zerumbone targets β-catenin of the Wnt-β-catenin pathway in breast cancer
No full textBreast cancer is the second most common cancer among women worldwide.The Wnt-ß-catenin pathway appears to be deregulated in most cancer cells including breast cancer.The role of zerumbone, the active sesquiterpene from Zingiber zerumbet Roscoe, on the Wnt-ß-catenin pathway is relatively unknown, especially detailed molecular studies have yet to be published. Using the Chemistry at HARvard Macromolecular Mechanics (CHARMm) force field-based docking protocol, CDOCKER, the molecular interactions between zerumbone and key proteins of the Wnt-ß-catenin pathway were evaluated in this study.The results suggest that zerumbone has a strong affinity for free ß-catenin in the cytoplasm, as well as the ß-catenin-transcription factor 4 complex in the nucleus.The overall hydrophobic nature of zerumbone allowed its interaction with other hydrophobic residues, such as Trp383, while its active a,ß-unsaturated carbonyl facilitated its interaction with positively charged residues, such as Lys345, Arg386 and Asn415 in the ß-catenin binding pocket. However, the Wnt protein and its frizzled receptor showed no attraction to zerumbone
The external sector vulnerability monitoring index (Λ): The case of Chinese and Asean-5 economies
No full textThis paper introduces an alternative indicator to evaluate the external sector behavior of a country or region. The objective of this indicator, titled “The External Sector Vulnerability Monitoring Index” (henceforth ESVM) (λ), is to offer policy-makers and researchers a new analytical tool to study the external sector trends and stages of any country from a global perspective. The ESVM-index (λ) is not intended to be a forecasting model. It is focused on showing the past and present economic situation in any country’s external sector performance. It can provide a general idea of the situation and evolution of the foreign sector performance of any country. Therefore, the application of the ESVM-index (λ) is based on the characteristics, conditions and historical moments that any country presents in its external sector development. ESVM-index (λ) acts as a simulator that allows the application of a series of different scenarios and phases of external sector performance of any country. In our case, we apply the external sector vulnerability monitoring index (λ) on the Chinese and ASEAN-5 economies
International Contributions to the System of Scholarly Communication in Iran
No full textWith an increasing number of Iranian journals indexed in global citation databases such as the Web of Science (WoS), it is important to identify to what extent these journals are “internationalized” and if the international composition of these journals influences their quality. To ascertain this, a total of 38 Iranian journals covered in the Journal Citation Reports (JCR) 2013 was sampled. The internationalization of Iranian journals is considered in terms of: (a) direct contributions in terms of foreign authors’ articles published in Iran, (b) indirect contribution in terms of citations from foreign authors’ documents to articles published in Iranian journals, and (c) editorial board composition in the field drawn internationally from foreign institutions. Findings revealed that (a) foreign researchers contributed 34.8% of papers in Iranian WoS-indexed journals, (b) a total of 30.6% of citations to Iranian WoS-indexed journals were received from foreign papers or Iranian internationally collaborative papers, and (c) foreign researchers occupied 33.6% of the editorial board membership in Iranian journals. The study found that only two Iranian journals in environmental sciences and chemistry have Impact Factors (IFs) above the median of the journals in the disciplinary category areas in which they are classified in JCR (general medicine, applied mathematics, civil engineering, environmental sciences, chemistry, polymer science, agriculture, and agronomy). Additionally, eight Iranian journals have been placed in the first and second quartile (top 50%) of journals of the same field in the JCR. Results also show that some Iranian journals suffer from low international recognition depicted from foreign contributions
Temporal and spatial variation of fish community and their nursery in a tropical seagrass meadow
No full textFish species composition and spatio-temporal variability of the community were studied in a tropical seagrass meadow located in a lagoon in the eastern part of North Sulawesi. The diversity of fish community in the seagrass meadows was relatively high, with the Shannon-Wiener index ranging from 1.57 to 3.69. The family Apogonidae was the most dominant in abundance (8.27 ind./(100 m2)) and biomass (28.49 g/(100 m2)). At the species level, Apogon lateralis and Sphaeramia orbicularis were the most dominant species in abundance and biomass, respectively. For spatial distribution on species, the end, middle and mouth of the lagoon clustered together as a whole, which may be due to the substrate types found in those zones. The fish species, fish abundance and fish biomass were greater in the dry and wet seasons than in the transition season, which is explained by the strong monsoon, which provides a more suitable environment and food for the fish. The maximum length of 93.10% of the captured species was less than their length at maturity, indicating that seagrass meadows are nursery habitats for many fishes. Therefore, protection of the seagrass meadows is essential for fisheries and sustainable resource utilization