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A LabVIEW module to promote undergraduate research in control of AC servo motors of robotics manipulator
No full textThis paper presents a project-based learning pedagogy for undergraduate mechanical engineering students which integrates traditional hardware-based laboratory with LabVIEW to control the angular position, velocity, and acceleration of AC servo motors of a six-degree of freedom manipulator. The proposed experimental modules have been proved to be very effective in assisting teams of undergraduate students within the Department of Mechanical, Materials and Manufacturing Engineering at the University of Nottingham, Malaysia Campus, who have used the modules in designing a new mechanical structure of a robot during their capstone design project. The proposed pedagogy inspired undergraduate students to publish their first paper based on the outcomes of their project. The focus on this paper is to present how the students' learning experience has been significantly enforced and their role in developing the modules introduced in this paper. Three modules are presented; the first configures a timer to generate a signal that drives the servo motors. The second drives the servo motor to a specific angular position with a constant angular velocity. Finally, the third is used to control the servo motor to follow any desired angular position, velocity, and acceleration. © 2019 Wiley Periodicals, Inc
Toxicity comparison among four strains of Margalefidinium polykrikoides from China, Malaysia, and USA (belonging to two ribotypes) and possible implications
No full textThe unarmored dinoflagellate Margalefidinium polykrikoides is a well-known cosmopolitan harmful alga that forms intensive blooms causing massive fish kills and mortality of other marine animals. Globally distributed populations of M. polykrikoides have been categorized into four ribotypes: East Asian, American/Malaysian, Philippines, and Mediterranean, according to their characteristic sequences in LSU rRNA gene and primary geographic distributions, while no discernible morphological feature has been observed to distinguish. Here we examined the toxicity of four strains of M. polykrikoides including MPJZB-C3 and MPJZB-D6 (East Asian ribotype, from China), CP1 (American/Malaysian ribotype, from USA), and MPCoKK23 (American/Malaysian ribotype, from Malaysia), to three aquatic animals including the marine medaka (Oryzias melastigma), rotifer (Brachionus plicatilis, L-type), and brine shrimp (Artemia salina). With equivalent initial cell densities ranged from 1000 to 7000 cells mL−1, CP1 and MPCoKK23 displayed acute toxicity in a dose-response manner to the three target animals (100% mortality at higher cell densities) within 24 h, MPJZB-C3 also displayed acute toxicity to the fish and rotifer in 24 h (up to 50% mortality) when the cell densities were above 3000 cells mL−1. The strain MPJZB-D6 did not exhibit significant toxicity to all three animals in 24 h, but, in 120 h, caused 50–100% mortalities in fish when the cell density was >3000 cells mL−1 and 17% mortality in brine shrimp when the cell density was >5000 cells mL−1. Statistical analysis of the data indicated that the strains CP1 and MPCoKK23 exhibited significantly higher toxicity (50–100% mortalities) to all three animals than the strains MPJZB-C3 and MPJZB-D6 (0–100% mortality) did within 24 h exposure, while, however, the difference in toxicity between the American and Malaysian strains and that between the two Chinese strains were both not significant in terms of the mortality of test animals. While the cell-free culture media (by filtration) and sonicated cultures were less toxic to test animals than the live cultures for all M. polykrikoides strains, sonicated cultures were even less toxic than the cell-free culture media. Among the three target animals, the marine medaka exhibited most sensitive to the toxicity, followed by rotifer and then brine shrimp. Collectively, while our results demonstrated that all strains, or both ribotypes, of M. polykrikoides are toxic, the results may also suggest the differences in toxicity to three test animals among the four cultures of M. polykrikoides reflect the inherent difference in toxicity between East Asian and American/Malaysian ribotypes, which stimulated us to propose a further investigation on whether or not the four different ribotypes also differ inherently in their toxicity in the future, via comparing more strains of all four ribotypes and relevant genetic characterizations. © 2019 Elsevier B.V
Lindernia Micrantha D. Don (Linderniaceae): A red listed plant species new discoveryto Tamil Nadu, India
No full textLindernia micrantha D. Don is a red listed (Least Concern) species, recorded first time from Sathuragiri hills, Madurai District, Southern Western Ghats of Tamil Nadu, India. This communication brings with detailed description, distribution, phenology and photographs of the species for easy identification. © 2020 Plant Archives. All rights reserved
Hygro-Thermo-Mechanical Responses of Balsa Wood Core Sandwich Composite Beam Exposed to Fire
No full textIn this study, the hygro-thermo-mechanical responses of balsa core sandwich structured composite was investigated by using experimental, analytical and numerical results. These investigations were performed on two types of specimen conditions: dry and moisture saturation sandwich composite specimens that are composed of E-glass/polyester skins bonded to a balsa core. The wet specimens were immersed in distilled water at 40 °C until saturated with water. The both dry and wet sandwich composite specimens were heated by fire. The mass loss kinetic and the mechanical properties were investigated by using a cone calorimeter following the ISO 5660 standard and three-point bending mechanical test device. Experimental data show that the permeability and fire resistance of the sandwich structure are controlled by two composite skins. Obtained results allow us to understand the Hygro-Thermo-Mechanical Responses of the sandwich structured composite under application conditions. © 2019 by the authors
Electronic surface, optical and electrical properties of p – GaN activated via in-situ MOCVD and ex-situ thermal annealing in InGaN/GaN LED
No full textElectronic surface properties, optical and electrical characteristics of p-type Mg-doped Gallium Nitride (p-GaN) activated under different thermal annealing condition were investigated. In this work, p-GaN samples were subjected to in-situ and ex-situ thermal annealing process at 650 °C in Nitrogen (N2) rich condition. In-situ annealing process took place in Metal Oxide Chemical Vapor Deposition (MOCVD) chamber while ex-situ annealing process was carried out in the conventional oven. X-Ray and Ultraviolet Photoemission Spectroscopy (XPS/UPS) were used to observe the energy alignment of the p-GaN surface. From PES spectra, the sample subjected to in-situ thermal annealing shown to exhibit lower surface bend bending of 0.28 eV as compared to ex-situ thermal annealing activation with 0.45 eV band bending. This result is in agreement with specific contact resistance measurement that shows in-situ sample exhibits lower resistance resulted in better carrier injection from metal to p-GaN. Photoluminescence (PL) spectra elucidates that in-situ sample has a good surface quality with less nitrogen related vacancies (VN) formed on the p-GaN surface. All these results are further proved with the higher output power from LED with in-situ annealing. At 20 mA, in-situ sample shown an increment of ~14% light output power compared to ex-situ sample. Results obtained in this work suggest that the thermal activation condition for p-GaN activation process plays an active role on the surface quality as well as the energy alignment of the film surface and shows the potential of in-situ p-GaN activation for tunnel junction structure. © 2019 Elsevier Lt
Ultrasonic assisted oil extraction and biodiesel synthesis of Spent Coffee Ground
No full textSpent Coffee Ground (SCG) was studied as a potential source of oil feedstock for biodiesel production as an alternative waste utilisation instead of being disposed as municipal waste. This study evaluated the ultrasonic assisted oil extraction from SCG, which was followed by biodiesel conversion via transesterification. Hexane was found to be the most effective extractant for SCG oil. Soxhlet extraction could obtain maximum SCG oil yield of 12.5% within 3 h whereas the highest SCG oil yield (14.52%) using ultrasonic extraction was obtained at hexane to SCG ratio of 4 mL g−1 and at 30% ultrasonic amplitude for 30 min. The improved oil yield with shorter extraction time was due to the ultrasonic fragmentation on SCG cells, which enhanced the interactions between oil and solvents. Fourier transform infrared analysis showed that the SCG oil possessed suitable functional groups for biodiesel conversion. Then, the SCG oil was successfully converted to biodiesel via ultrasonic assisted transesterification. The optimal FAME yield (97.11%) was achieved with molar ratio of methanol to SCG oil of 30:1, 4 wt% of catalyst concentration, at 30% ultrasonic amplitude and for 3 h. The produced SCG biodiesel has promising properties which adhere to the biodiesel standards but acid value was beyond the permissible limit which could be overcome by utilising as blend feedstock with other commercially available biodiesel. The high calorific value along with low viscosity, density and corrosion properties suggested SCG biodiesel as an interesting and viable option for biodiesel blending. © 201
Understanding the reading habit and attitudes among the rural community in low literacy rate areas in Malaysia
No full textPurpose: The purpose of this paper is to investigate the reading habit and attitude among rural communities in the low literacy rate areas in Malaysia. Design/methodology/approach: Multi-stage cluster and simple random sampling were employed and 400 respondents who live nearby the rural library were selected. Findings: Moderate levels of reading attitude were obtained from the result of the study, in which several variables produced a significant relationship in the reading attitude (education level, household income and time spent in reading). Practical implications: Better understanding on the reading habit and attitude among rural communities could produce better information on the service provision towards the establishment of rural libraries in low literacy rate areas in Malaysia. This would also increase the utilisation of reading sources and services provided. Originality/value: The paper provides better understanding on the reading habit and attitude among the rural communities in the low literacy rate areas in using the facilities provided by the rural libraries. The findings may be useful to the rural literacy and library development community in the developing countries. © 2019, Emerald Publishing Limited
Enhanced photocatalytic activity of Cuprous Oxide nanoparticles for malachite green degradation under the visible light radiation
No full textPhotocatalysis provides excellent potentials for the complete removal of organic pollutants in environmentally friendly ways and sustainable means of technology. It has been noted that under UV-visible light irradiation, nanostructured semiconductor metal oxides photocatalysts can degrade different organic pollutants. Taking into consideration of the photocatalytic activity, the present study deals with the synthesis of cuprous oxide (Cu2O) nanoparticles (NPs) by the sonochemical method and characterized for their physicochemical, optical, and photocatalytic properties. The powdered X-ray diffraction (XRD) analysis confirmed for the cubic phase crystalline structure while the Field emission scanning electron microscopy (SEM) supported for the icosahedron morphology. The bandgap of the synthesized Cu2O NPs was found to be 2.26 eV, which is the suitable bandgap energy so as to achieve the enhanced photocatalytic degradation efficiency. On testing for the degradation of Malachite green (MG) as a model pollutant, the synthesized Cu2O NPs demonstrated a high degradation efficiency under visible light irradiation. The observed results suggest that the synthesized Cu2O NPs are attractive photocatalysts for the degradation of toxic organic wastes in the water under visible light. Further investigation confirmed for the photocatalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) under aqueous conditions with visible light. © 2020 The Author(s). Published by IOP Publishing Ltd
Identification of Novel Sesamol Dimers with Unusual Methylenedioxy Ring-Opening Skeleton and Evaluation of Their Antioxidant and Cytotoxic Activities
No full textBackground: Sesamol is a widely used antioxidant for the food and pharmaceutical industries. The oxidation products of this compound may be accumulated in foods or ingested. Little is known about its effect on human health. Objective: It is of great interest to identify the oxidation products of sesamol that may be beneficial to humans. This study was undertaken to identify the oxidation products of sesamol and investigate their antioxidant and cytotoxic activities. Materials and Methods: Using the ferricyanide oxidation approach, four oxidation products of sesamol (2, 3, 20 & 21) have been identified. Structural elucidation of these compounds was established on the basis of their detailed NMR spectroscopic analysis, mass spectrometry and x-ray crystallography. Additionally, a formation mechanism of compound 20 was proposed based on high-resolution mass spectrometry-fragmentation method. The antioxidant activities of these compounds were determined by the DPPH, FRAP, and ABTS assays. The in vitro antiproliferative activity of these compounds was evaluated against a panel of human cancer cell lines as well as non-cancerous cells. Results: Two oxidation products of sesamol were found to contain an unusual methylenedioxy ring-opening skeleton, as evidenced by spectroscopic and x-ray crystallographic data. Among all compounds, 20 displayed impressive antiproliferative activities against a panel of human cancer cell lines yet remained non-toxic to non-cancerous cells. The antioxidant activities of compound 20 are significantly weaker than sesamol as determined by the DPPH, FRAP, and ABTS assays. Conclusion: The oxidation products of sesamol could be a valuable source of bioactive molecules. Compound 20 may be used as a potential lead molecule for cancer studies. © 2019 Bentham Science Publishers
Impact of non-surgical periodontal therapy on serum Resistin and periodontal pathogen in periodontitis patients with obesity
Full text linkBackground Non-surgical periodontal therapy (NSPT) known as gold standard treatment in managing periodontitis. The aim of this study was to investigate the response of NSPT in periodontitis subjects who were obese. Clinical parameters of periodontitis, changes in serum resistin and periodontal pathogens in subgingival plaque were compared before and after NSPT in periodontitis subjects who were obese and with normal weight. Methods A total of 48 periodontitis subjects (obese, n = 18; normal weight, n = 30) were recruited (hereafter will be referred as participants) to participate into a prospective, before and after clinical trial. Obesity status is defined by body mass index (BMI) criteria (obese: >= 30 kg/ m(2); normal weight < 25 kg/m(2)). Visible Plaque Index (VPI), Gingival Bleeding Index (GBI), Probing Pocket Depth (PPD) and Clinical Attachment Loss (CAL) were recorded; and serum and plaque were collected at baseline and following 12 weeks post-NSPT. Serum resistin level was analyzed using enzyme-linked immune-sorbant assay (ELISA), while detection of periodontal pathogens in dental plaque were carried out using real time PCR (qPCR). Results Following NSPT, means VPI and GBI showed significant improvement between obese and normal weight groups (p < 0.05), but no difference in means PPD and CAL was observed between groups. Obesity remained as a predictor for VPI and GBI after adjusting for smoking habit. No significant difference was observed in serum resistin level and mean counts for P. gingivalis, T. forsythia, and P. intermedia between obese and normal weight groups following NSPT. Conclusions Regardless of obesity status, NSPT has a significant impact on VPI and GBI in periodontitis subjects. However, the impact of NSPT towards serum resistin and periodontal pathogens was non-significant in those with periodontitis