1,112 research outputs found

    Chiral microstructures (spirals) fabrication by holographic lithography

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    We present an optical interference model to create chiral microstructures (spirals) and its realization in photoresist using holographic lithography. The model is based on the interference of six equally-spaced circumpolar linear polarized side beams and a circular polarized central beam. The pitch and separation of the spirals can be varied by changing the angle between the side beams and the central beam. The realization of the model is carried out using the 325 nm line of a He-Cd laser and spirals of sub-micron size are fabricated in photoresist.Comment: 6 page

    Ocean container transport in global supply chains: Overview and research opportunities

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    This paper surveys the extant research in the field of ocean container transport. A wide range of issues is discussed including strategic planning, tactical planning and operations management issues, which are categorized into six research areas. The relationships be- tween these research areas are discussed and the relevant literature is reviewed. Representative models are selected or modified to provide a flavour of their functions and application context, and used to explain current shipping practices. Future research opportunities bearing in mind the emerging phenomena in the field are discussed. The main purpose is to raise awareness and encourage more research into and application of operations management techniques and tools in container transport chains

    Bacterial diversity and community structure of banana rhizosphere in Orang Asli fields and commercial plantations

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    Bacteria play an important roles in the soil ecosystem and in the rhizosphere, they are intricately linked to nutrient content and its accessibility to plants, plant protection and sometimes pathogenicity. Banana grows well in the tropics and it is popularly grown in Orang Asli (OA) (indigenous people) settlements. Banana is also grown in commercial plantations. In traditional planting practices, the OA do not add pesticide nor fertilizer to their crops which are planted for selfsustenance mainly. On the other hand, fertilizer and pesticide are added to commercial banana plantations to maximise yield. Rhizosphere bacteria from the banana plant, Pisang Nipah, grown in OA fields and commercial plantations were identified by clone library construction of the 16S rRNA gene. This was to determine whether farming practices influenced the bacterial community in the banana plant rhizosphere. Acidobacteria, Proteobacteria and Actinobacteria were found in all the soil. Other common phyla found in some soil (but not all) were Nitrospirae, Firmicutes, Bacteroidetes, Chloroflexi, Verrumicrobia, Gemmatimonadetes and Cyanobacteria. The bacterial diversity was a little more diverse in the OA fields than the commercial plantations. The latter had higher contents of nitrogen, phosphorus and potassium. These could have exerted selective pressure to reduce the bacterial diversity in the commercial plantations

    Sponges from North Borneo and their bioactivity against human colorectal cancer cells

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    Sponges are major source of numerous cytotoxic compounds that are used for defence as well as adaptation to the environment. Numerous studies have discovered compounds from sponge extracts that were effective against a wide range of cancer cells. In this study, a total of 23 sponges comprising of 19 species were collected from Northeast Borneo. Sponges were treated and extracted using modified Folch extraction method, followed by cytotoxicity assay to determine their effectiveness against different colorectal cancer cells. Our results demonstrate that Monanchora clathrata, Dysidea sp., and Jaspis sp. possess different degrees of cytotoxicity against a wide range of human colorectal cancer cells. Monanchora clathrata (KDT07), Dysidea sp. (KDT09), and Jaspis sp. (KDT18) are among the demosponges which possess significant cytotoxicity against colorectal cancer cell lines, including HCT116, LoVo, SW480, and SW620. KDT08 and KDT21 which fall under the same genus Dysidea, possess insignificant cytotoxicity against colorectal cancer cells suggested environmental factors (symbiotic organisms) play a role in biosynthesizing bioactive compounds. Presented results suggested the importance of intensifying research on isolating and purifying natural products from marine sponges for useful applications

    Physicochemical and sensory analyses of high fibre bread incorporated with corncob powder

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    The primary objectives of the present work were to produce corncob powder (CCP) from corncobs and incorporate the CCP into bread formulation in order to develop high fibre bread, and to investigate the physicochemical and sensory properties of the produced high fibre bread (HFB). The corncobs were collected and washed before they underwent the grinding and drying processes. The obtained CCP was incorporated into the bread formulation in three different proportions (5, 10 and 20%) to partially substitute bread flour in the formulation. All three bread samples and the control (0% CCP in the formulation) were analysed to obtain their physicochemical and sensory properties. The incorporation of CCP significantly affected the texture, colour and volume attributes of the produced breads. Increasing the content of CCP in the formulation was found to be responsible for firmer, smaller and darker bread loaves as compared to the composite bread samples. The bread formulation incorporated with 10% CCP had the highest mean scores (7.00) of overall acceptability among all the other formulations, and it was comparable to the commercial breads in the current market

    Changes in Water and Sediment Quality of a River Being Impounded and Differences Among Functional Zones of the New Large Tropical Hydroelectric Reservoir

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    Though more large tropical reservoirs are being constructed to meet the increasing energy demand, knowledge on the impact of damming a tropical river and the differences along the river after its impoundment is scarce. Thus, the present study aimed to increase our understanding of such differences both longitudinally and vertically. Water and sediment samples were collected at three different functional zones in the Murum River basin 10 months after impoundment began. Results show that the impoundment has an impact on both the water and sediment. Longitudinal variations of water and sediment characteristics were observed at different functional zones. The upstream riverine zone subjected to anthropogenic activities serves as the main input of suspended solids and nutrients to the reservoir. The nitrogen changed from a high nitrate and low ammonia condition prior to impoundment to a low nitrate and high ammonia condition due to the accumulation of organic matter and slow nitrification rate after impoundment. In the transitional and lacustrine zones, vertical stratifications of dissolved oxygen and temperature were observed. The thickness of a well-oxygenated column for sensitive aquatic organisms was only 2 m at some stations. Water quality in all zones showed impairment during the filling phase as compared to the good water quality index before impoundment. The reduction of suspended solids in the surface water column in the transitional and lacustrine zones is a positive change for aquatic organisms. Sediment characteristics were found to be distinct in the transitional zone, where it was lower in sand and higher in silt, clay, organic carbon and nutrients in contrast to the riverin

    Baseline trace metals in water and sediment of the Baleh River—a tropical river in Sarawak, Malaysia

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    Quantitative indices are classically employed to evaluate the contamination status of metals with reference to the baseline concentrations. The baselines vary considerably across different geographical zones. It is imperative to determine the local geochemical baseline to evaluate the contamination status. No study has been done to establish the background concentrations in tropical rivers of this region. This paper reports the background concentrations of metals in water and sediment of the Baleh River, Sarawak, derived based on the statistical methods where the areas possibly disturbed are distinguished from the undisturbed area. The baseline levels of six elements in water determined were Al (0.34 mg/L), Fe (0.51 mg/L), Mn (0.12 mg/L), Cu (0.01 mg/L), Pb (0.03 mg/L), and Zn (0.05 mg/L). Arsenic and selenium were below the detection limit. For sediment, the background values were established according to statistical methods including (mean + 2σ), iterative 2σ, cumulative distribution frequency, interquartile, and calculation distribution function. The background values derived using the iterative 2σ algorithm and calculated distribution function were relatively lower. The baseline levels calculated were within the range reported in the literatures mainly from tropical and subtropical regions. The upper limits proposed for nine elements in sediment were Al (100,879 mg/kg), Cr (75.45 mg/kg), Cu (34.59 mg/kg), Fe (37,823 mg/kg), Mn (793 mg/kg), Ni (22.88 mg/kg), Pb (27.26 mg/kg), Zn (70.64 mg/kg), and Hg (0.33 mg/kg). Quantitative indices calculated suggest low risk of contamination at the Baleh River
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