19672 research outputs found
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Investigating the effective factors influencing surface runoff generation in urban catchments – A review
No full textThe natural water cycle in an urban catchment normally results from climate, physical characteristics and natural surface coverage. The hydrological process in urban catchments can drastically change due to urbanization, human activities, modified physiography and climate change. Urbanization typically results in a larger runoff volume, higher peak discharge, faster time of concentration as well as lower infiltration. It also has a significant impact on the precipitation intensity and patterns. Antecedent soil moisture, steep slopes and roughness will lead to uncertain rainfall-runoff behavior as well. Climate change will usually alter temperature, precipitation intensity and duration along with the runoff timing and magnitude. Various number of studies have proved that urbanization and climate change would have stronger effect on urban rainfall-runoff behavior than other factors. We have reviewed and investigated various and the most effective factors influencing urban runoff generation in this paper. Particularly, the anthropogenic, geomorphologic and meteorological impacts on urban surface runoff have been the focus of this review paper. The study gaps and suggestions for further research have also been discussed at the end. Finally, the best measures to be taken into consideration to mitigate urban excess runoff have been suggested in the final section. © 2019 Desalination Publications. All rights reserved
Synthesis, characterization, stability and thermal conductivity of multi-walled carbon nanotubes (MWCNTs) and eco-friendly jatropha seed oil based nanofluid: An experimental investigation and modeling approach
No full textDespite the remarkable nanofluids potential in energy storage applications, the long-term dispersion stability of the nanoparticles in a base fluid along with improved thermal conductivity is a significant challenge towards their commercialization. Therefore, a novel surfactant MWCNTs and eco-friendly Jatropha seed oil based nanofluid are synthesized via one-step synthesis method and subjected to characterization via visual analysis, FTIR, Zeta potential, pore size distribution, thermogravimetric analysis (TGA), and UV analysis to investigate MWCNTs dispersion stability along with thermal conductivity measurement. The results showed the excellent MWCNTs dispersion stability in Jatropha seed oil and thermal conductivity improvement from 2.29% to 6.76% over the temperature within the range of 25–65 °C and nanoparticle weight fraction in the range of 0.2–0.8 wt%. Furthermore, two new correlations are proposed based on multiple non-linear regression analysis and dimensionless group analysis in the replacement of classical models which are failed to accurate prediction of thermal conductivity. The developed models showed remarkable thermal conductivity prediction accuracy with the value of R2 > 0.991. © 201
Purification and identification of novel cytotoxic oligopeptides from soft coral Sarcophyton glaucum
No full textGlobally, peptide-based anticancer therapies have drawn much attention. Marine organisms are a reservoir of anticancer peptides that await discovery. In this study, we aimed to identify cytotoxic oligopeptides from Sarcophyton glaucum. Peptides were purified from among the S. glaucum hydrolysates produced by alcalase, chymotrypsin, papain, and trypsin, guided by a methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay on the human cervical cancer (HeLa) cell line for cytotoxicity evaluation. Purification techniques adopted were membrane ultrafiltration, gel filtration chromatography, solid phase extraction (SPE), and reversed-phase high-performance liquid chromatography (RP-HPLC). Purified peptides were identified by de novo peptide sequencing. From papain hydrolysate, three peptide sequences were identified: AGAPGG, AERQ, and RDTQ (428.45, 502.53, and 518.53 Da, respectively). Peptides synthesized from these sequences exhibited cytotoxicity on HeLa cells with median effect concentration (EC 50 ) values of 8.6, 4.9, and 5.6 mmol/L, respectively, up to 5.8-fold stronger than the anticancer drug 5-fluorouracil. When tested at their respective EC 50 , AGAPGG, AERQ, and RDTQ showed only 16%, 25%, and 11% cytotoxicity to non-cancerous Hek293 cells, respectively. In conclusion, AERQ, AGAPGG, and RDTQ are promising candidates for future development as peptide-based anticancer drugs. © 2019, Zhejiang University and Springer-Verlag GmbH Germany, part of Springer Nature
Investigation of Future 5G-IoT Millimeter-Wave Network Performance at 38 GHz for Urban Microcell Outdoor Environment
No full textThe advent of fifth-generation (5G) systems and their mechanics have introduced an unconventional frequency spectrum of high bandwidth with most falling under the millimeter wave (mmWave) spectrum. The benefit of adopting these bands of the frequency spectrum is two-fold. First, most of these bands appear to be unutilized and they are free, thus suggesting the absence of interference from other technologies. Second, the availability of a larger bandwidth offers higher data rates for all users, as there are higher numbers of users who are connected in a small geographical area, which is also stated as the Internet of Things (IoT). Nevertheless, high-frequency band poses several challenges in terms of coverage area limitations, signal attenuation, path and penetration losses, as well as scattering. Additionally, mmWave signal bands are susceptible to blockage from buildings and other structures, particularly in higher-density urban areas. Identifying the channel performance at a given frequency is indeed necessary to optimize communication effciency between the transmitter and receiver. Therefore, this paper investigated the potential ability of mmWave path loss models, such as floating intercept (FI) and close-in (CI), based on real measurements gathered from urban microcell outdoor environments at 38 GHz conducted at the Universiti Teknologi Malaysia (UTM), Kuala Lumpur campus. The measurement data were obtained by using a narrow band mmWave channel sounder equipped with a steerable direction horn antenna. It investigated the potential of the network for outdoor scenarios of line-of-sight (LOS) and non-line-of-sight (NLOS) with both schemes of co- (vertical-vertical) and cross (vertical-horizontal) polarization. The parameters were selected to reflect the performance and the variances with other schemes, such as average users cell throughput, throughput of users that are at cell-edges, fairness index, and spectral effciency. The outcomes were examined for various antenna configurations as well as at different channel bandwidths to prove the enhancement of overall network performance. This work showed that the CI path loss model predicted greater network performance for the LOS condition, and also estimated significant outcomes for the NLOS environment. The outputs proved that the FI path loss model, particularly for V-V antenna polarization, gave system simulation results that were unsuitable for the NLOS scenario. © 2019 by the authors. Licensee MDPI, Basel, Switzerland
Optimization of CTAB-based RNA Extraction for in planta Fusarium oxysporum f. sp. cubense Gene Expression Study
No full textA crucial prerequisite for an insightful gene expression study is the quality of the nucleic acid extracted. High-quality nucleic acids allow comparative downstream analyses for both organisms during a phytopathogen infection. However, RNA extraction of pathogen-infected host materials usually involves extraction methods that are optimised individually for either the pathogen or the host. Different sets of buffers or specialised commercial kits are often required. In this study, a streamlined CTAB-based extraction protocol was optimised for both the pure culture of Fusarium oxysporum f. sp. cubense (Foc) and infected banana roots. Foc cultures were grown on PDA overlaid by a nylon membrane and total nucleic acids were successfully extracted from mycelia with a ratio of 100 mg mycelia powder mass to 2 mL of CTAB buffer. Using the optimised protocol, LiCl-precipitated RNAs showed higher values of A260/280 (2.064 ± 0.021) and A260/230 (1.937 ± 0.076) compared to ethanol precipitated RNAs. Similar observation was observed for inoculated banana roots where LiCl-precipitated RNAs showed higher values of A260/230 and A260/280 compared to ethanol precipitated RNAs. qRT-PCR analysis using a pair of Foc specific primers, FoTEF1a, confirmed that the LiCl-precipitated RNA was more suitable for downstream gene expression studies. This extraction protocol is applicable for Foc in planta gene expression study with a high potential to be extended to other filamentous fungal pathogens. © 2019 Penerbit Universiti Kebangsaan Malaysia. All rights reserved
Dickeya undicola sp. nov., a novel species for pectinolytic isolates from surface waters in Europe and Asia
No full textStrains 2B12T, FVG1-MFV-O17 and FVG10-MFV-A16 were isolated from fresh water samples collected in Asia and Europe. The nucleotide sequences of the gapA barcodes revealed that all three strains belonged to the same cluster within the genus Dickeya. Using 13 housekeeping genes (fusA, rpoD, rpoS, glyA, purA, groEL, gapA, rplB, leuS, recA, gyrB, infB and secY), multilocus sequence analysis confirmed the existence of a new clade. When the genome sequences of these three isolates and other Dickeya species were compared, the in silico DNA–DNA hybridization and average nucleotide identity values were found to be no more than 45.50 and 91.22 %, respectively. The closest relative species was Dickeya fangzhongdai. Genome comparisons also highlighted genetic traits differentiating the new strains from D. fangzhongdai strains DSM 101947T (=CFBP 8607T) and B16. Phenotypical tests were performed to distinguish the three strains from D. fangzhongdai and other Dickeya species. The name Dickeya undicola sp. nov. is proposed with strain 2B12T (=CFBP 8650T =LMG 30903T) as the type strain. © 2019 IUMS
Micro- and macroscopic observations of the nucleation process and crystal growth of nanosized Cs-pollucite in an organotemplate-free hydrosol
No full textThe nucleation and crystal growth of a nanoscale cesium pollucite aluminosilicate zeolite (ANA topology) from an organotemplate-free precursor suspension are reported. By using a new and reactive synthesis recipe (5.5SiO2 : 1Al2O3 : 6Cs2O : 140H2O), zeolite nanocrystals with higher Al content (Si/Al ratio = 2.12) are obtained within 120 min under mild conditions (180 °C), which is much faster and safer as compared to those previously reported. The solid initially experiences amorphous phase re-organization before nucleation, crystallization and crystal growth take place. The resulting Cs-pollucite nanocrystals (average size 55 nm) display a trapezohedron morphology. The nanocrystals are colloidally stabilized in water and they are very active in the base-catalyzed cyanoethylation of dipropylamine reaction, giving 89.6% conversion at 180 °C within 50 min. In addition, a high solid yield of nanocrystals (ca. 70%) is also achieved, thus offering a green pathway for synthesizing zeolite nanocrystals with high basicity on a large scale. © 2019 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique
Construction of 3D lung image morphology using 3D distance regularized level set
No full textThe World Health Organization (WHO) has stated in its report that lung disease is a wide spread in Malaysia which caused 2.77% of total death in Malaysia making it the 6th main cause of death in Malaysia. One of the lung diseases included in the list is interstitial lung disease (ILD). ILD includes an extensive group of disorders which leads breathing complications as a result of the alteration and fibrosis to anatomical structures in the alveolar structures. Therefore, diagnosis and analysis of ILD can be performed by segmenting the lung morphology on CT scans images. This study aims to construct a 3D lung image morphology using 3D distance regularized level set evolution (DRLSE). The 3D performance evaluations for normal lungs on average yielded better results than that of ILD lungs with a Dice's similarity coefficient of 93.19%. The constructed lungs from 3D DRSLE has good representation of the segmented normal lungs while suggesting deformities in segmented ILD lungs. © 2006-2019 Asian Research Publishing Network (ARPN)
Effect of nanofluids on heat transfer and cooling system of the photovoltaic/thermal performance
No full textPurpose: Effective cooling is one of the challenges for photovoltaic thermal (PVT) systems to maintain the PV operating temperature. One of the best ways to enhance rate of heat transfer of the PVT system is using advanced working fluids such as nanofluids. The purpose of this research is to develop a numerical model for designing different form of thermal collector systems with different materials. It is concluded that PVT system operated by nanofluid is more effective than water-based PVT system. Design/methodology/approach: In this research, a three-dimensional numerical model of PVT with new baffle-based thermal collector system has been developed and solved using finite element method-based COMSOL Multyphysics software. Water-based different nanofluids (Ag, Cu, Al, etc.), various solid volume fractions up to 3 per cent and variation of inlet temperature (20-40°C) have been applied to obtain high thermal efficiency of this system. Findings: The numerical results show that increasing solid volume fraction increases the thermal performance of PVT system operated by nanofluids, and optimum solid concentration is 2 per cent. The thermal efficiency is enhanced approximately by 7.49, 7.08 and 4.97 per cent for PVT system operated by water/Ag, water/Cu and water/Al nanofluids, respectively, compared to water. The extracted thermal energy from the PVT system decreases by 53.13, 52.69, 42.37 and 38.99 W for water, water/Al, water/Cu and water/Ag nanofluids, respectively, due to each 1°C increase in inlet temperature. The heat transfer rate from heat exchanger to cooling fluid enhances by about 18.43, 27.45 and 31.37 per cent for the PVT system operated by water/Al, water/Cu, water/Ag, respectively, compared to water. Originality/value: This study is original and is not being considered for publication elsewhere. This is also not currently under review with any other journal. © 2019, Emerald Publishing Limited
Isoprene hotspots at the Western Coast of Antarctic Peninsula during MASEC′16
No full textIsoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) which contributed to the climate change. This study aims to determine hourly distribution of tropospheric isoprene over the Western Coast of Antarctic Peninsula (WCAP) during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC′16). In-situ measurements of isoprene were taken using a custom-built gas chromatography with photoionization detector, known as iDirac. Biological parameters such as chlorophyll a (chl-a) and particulate organic carbon (POC) were compared to the in-situ isoprene measurements. Significant positive correlation was observed between isoprene and POC concentrations (r2 = 0.67, p < 0.001), but not between isoprene and chl-a. The hotspots of isoprene over maritime Antarctic were then were investigated using NAME dispersion model reanalysis. Measurements showed that isoprene mixing ratio were the highest over region of King George Island, Deception Island and Booth Island with values of ∼5.0, ∼0.9 and ∼5.2 ppb, respectively. Backward trajectory analysis showed that air masses may have lifted the isoprene emitted by marine algae. We believe our findings provide valuable data set of isoprene estimation over the under sampled WCAP. © 2018 Elsevier B.V. and NIP