78 research outputs found

    Estimation of aboveground biomass of a production forest reserve in Malaysian Borneo using K-nearest neighbor method

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    This study examined the use of the k-nearest neighbour (k-NN) method to estimate aboveground biomass of a logged-over tropical forest in Sabah, Malaysia. To estimate aboveground biomass, field data as well as digital number and normalised difference vegetation index (NDVI) values from Landsat TM-5 data were used to determine the optimum horizontal reference area and the number of reference sample plots (k). An accuracy assessment showed that enhancing the digital number value was superior to enhancing the NDVI value. Root mean square errors of no filtering and 3 × 3 filtering were minimum when k = 4 and k = 5 respectively, when a horizontal reference area of 17 km was applied. The bias was underestimated by 2.01 and 1.62 tonnes ha-1 for k = 4 and k = 5 respectively. Total aboveground biomass of the forest management unit estimated by enhancing the digital number value was 6,873,299 tonnes and average biomass density was 248.8 tonnes ha-1. The results suggest that the k-NN method is an alternative way to estimate and map aboveground biomass of a forest management unit

    Physicochemical properties of tarap (Artocarpus adoratisimus) starch

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    The objective of the research was to investigate the physicochemical characteristics of Tarap fruit starch. In this study, young Tarap fruit starch was extracted and the percentage of total starch, resistant starch, amylose and amylopectin were determined. Scanning electron microscope was used to evaluate the morphological features of the starch granule. Swelling, pasting, gelatinization, retrogradation and in vitro digestibility were also investigated. A total of 17.85% starch was successfully extracted from unripe Tarap fruit, whereas the amount of total starch and resistant starch were 89.14% and 47.82%, respectively. The amounts of rapid digestible starch and slowly digestible starch were 6.58% and 23.25%, respectively. Results found that the amylopectin content was higher than amylose (77.15% and 11.97%). The starch granules were round and polygon in shapes with smooth surfaces. The average of starch granules size was range from 6.50 to 8.30 μm with 7.4 μm of mean granule diameter. Pasting properties showed that peak viscosity was observed at about 6.5 min at 73.5oC. Tarap starch gelatinization temperatures (onset, 71.63°C; peak, 74.56°C; conclusion, 78.24°C) and enthalpy of gelatinization (ΔHgel) (3.74 J/g) were higher while the retrograded starches show lower retrogradation temperature and enthalpy than native starches. Unripe Tarap starch showed good potential to be utilized as adhesives and thickener for industrial applications

    Effects of fractionation technique on triacylglycerols, melting and crystallisation and the polymorphic behavior of bambangan kernel fat as cocoa butter improver

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    Cocoa butter improver (CBI) is typically composed of high melting symmetrical triacylglycerols (TAGs) that aid in the hardness of chocolate products in tropical/subtropical regions. High-melting symmetrical TAG (1,3-di-stearoyl-2-oleoyl-glycerol, SOS) rich fats were produced by two-stage acetone fractionation. Different chromatographic and thermal techniques were used to determine TAGs, thermal properties, and polymorphic behavior of each bambangan kernel fat (BKF) fraction. The first (S-1) and second (S-2) stearins composed of 55.83% and 64.70% symmetrical SOS were the valuable CBIs produced from the fractionated BKF. The stearin fractions also melted and crystallised rapidly at high temperatures with one maximum peak starting at 20.30–21.74 °C and ending at 38.72–42.45 °C (melting), and another starting at 17.05–18.46 °C and ended at 5.63–8.20 °C (crystallisation). In comparison with pure BKF and commercial cocoa butter (CB), the stearins showed sharper melting curves and higher melting properties. The stearins also exhibited β-polymorphic form which was similar to that of CB. Results suggested that the stearins were suitable to be applied as CBI to improve the melting properties and the availability of confectionery products in tropical/subtropical countries

    Valuable components of bambangan fruit (Mangifera pajang) and its coproducts: a review

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    Fruits are important food commodities that can be consumed either raw or processed and are valued for their taste, nutrients, and healthy compounds. Mangifera pajang Kosterm (bambangan) is an underutilized fruit found in Malaysia (Sabah and Sarawak), Brunei, and Indonesia (Kalimantan). It is highly fibrous and juicy with an aromatic flavour and strong smell. In recent years, bambangan fruit has been gaining more attention due to its high fibre, carotenoid content, antioxidant properties, phytochemicals, and medicinal usages. Therefore, the production, trade, and consumption of bambangan fruit could be increased significantly, both domestically and internationally, because of its nutritional value. The identification and quantification of bioactive compounds in bambangan fruit has led to considerable interest among scientists. Bambangan fruit and its waste, especially its seeds and peels, are considered cheap sources of valuable food and are considered nutraceutical ingredients that could be used to prevent various diseases. The use of bambangan fruit waste co-products for the production of bioactive components is an important step towards sustainable development. This is an updated report on the nutritional composition and health-promoting phytochemicals of bambangan fruit and its co-products that explores their potential utilization. This review reveals that bambangan fruit and its co-products could be used as ingredients of dietary fibre powder or could be incorporated into food products (biscuits and macaroni) to enhance their nutraceutical properties

    Development of gluten-free steamed cake using green saba banana flour

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    Along with the increase of diagnosed Celiac patient, gluten-free (GF) foods have shown a significant increase in worldwide consumption. The removal of gluten and replacement with other ingredients to improve the palatability have caused unsatisfactory nutritional profile in GF foods. Green banana flour is known to content high resistant starch (RS) that is beneficial for human health. Saba banana is a locally grown banana, though widely available, but it has limited industrial applications. To add-value to Saba banana and addressing the issue of low nutritional quality of GF food, a steamed cake was developed using green Saba banana flour (GSBF), soy protein isolate (SPI) (0%, 10% and 15%) and a commercial cake stabilizer, Ovelette (0%, 3.5% and 7%). Characterisation of the flour (colour, oil holding capacity, water holding capacity, proximate content and resistant starch content) and cake batters (viscosity and specific gravity) were carried out. The specific volume, weight loss, colour, texture and sensory acceptance of the cake were investigated. GSBF was found to contain high RS and dietary fibre but darker in colour. Depending on the concentration, SPI and stabilizer increased the batter viscosity and affected the specific volume and colour of the cakes. The texture properties were generally improved with the additives used. The most acceptable formulation was identified from sensory evaluation; it contained higher protein, dietary fibre and RS than its gluten-containing counterpart. Results obtained show that appropriate amount of SPI and Ovelette could effectively improve the physical, textural and nutritional properties of the cake

    Investigation of the electrical conductivity of propylene glycol-based ZnO nanofluids

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    Electrical conductivity is an important property for technological applications of nanofluids that has not been widely studied. Conventional descriptions such as the Maxwell model do not account for surface charge effects that play an important role in electrical conductivity, particularly at higher nanoparticle volume fractions. Here, we perform electrical characterizations of propylene glycol-based ZnO nanofluids with volume fractions as high as 7%, measuring up to a 100-fold increase in electrical conductivity over the base fluid. We observe a large increase in electrical conductivity with increasing volume fraction and decreasing particle size as well as a leveling off of the increase at high volume fractions. These experimental trends are shown to be consistent with an electrical conductivity model previously developed for colloidal suspensions in salt-free media. In particular, the leveling off of electrical conductivity at high volume fractions, which we attribute to counter-ion condensation, represents a significant departure from the "linear fit" models previously used to describe the electrical conductivity of nanofluids

    Optical Magnetometry

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    Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic

    Neuronal Function and Dysfunction of Drosophila dTDP

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    Background: TDP-43 is an RNA- and DNA-binding protein well conserved in animals including the mammals, Drosophila, and C. elegans. In mammals, the multi-function TDP-43 encoded by the TARDBP gene is a signature protein of the ubiquitinpositive inclusions (UBIs) in the diseased neuronal/glial cells of a range of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-U). Methodology/Principal Findings: We have studied the function and dysfunction of the Drosophila ortholog of the mammalian TARDBP gene, dTDP, by genetic, behavioral, molecular, and cytological analyses. It was found that depletion of dTDP expression caused locomotion defect accompanied with an increase of the number of boutons at the neuromuscular junctions (NMJ). These phenotypes could be rescued by overexpression of Drosophila dTDP in the motor neurons. In contrast, overexpression of dTDP in the motor neurons also resulted in reduced larval and adult locomotor activities, but this was accompanied by a decrease of the number of boutons and axon branches at NMJ. Significantly, constitutive overexpression of dTDP in the mushroom bodies caused smaller axonal lobes as well as severe learning deficiency. On the other hand, constitutive mushroom body-specific knockdown of dTDP expression did not affect the structure of the mushroom bodies, but it impaired the learning ability of the flies, albeit moderately. Overexpression of dTDP also led to the formation of cytosolic dTDP (+) aggregates
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