13474 research outputs found
Sort by
Study of delayed cracking behaviors of hydrogen-charged SUS304L deep drawn cylindrical cups under elevated blank holding forces / Mohd Shahir Hadzir
No full textIn this paper the effect of hydrogen charged SUS304L deep drawn cylindrical cups under elevated blank holding forces are investigated. A round SUS 304L blanks was deep drawn at 8, 9, 10 and 11 kN blank holding force, BHF using a die, after the specimens were hydrogen charged for 6, 12, and 24 hours in 1N of H2SO4 and As2O3 solution. It was found that the hydrogen charging of deep drawn cups has resulted in an accelerated appearance of the delayed cracks on the SUS 304L blanks. The 6 hours charged specimen was also deep drawn again using TiN coated die at 7, 10 and 12 kN of BHF, and it was found that delayed cracks still occur, but did not develop as fast as using uncoated die. Understanding the effect blank holding force with hydrogen towards the SUS304L will allow better understanding of the steel characteristic for future application
Investigation of flow patterns and measurement of actual bubble velocity using void fraction profile in a vertical industrial scale two-phase flow channel / Nur Adania Nor Azman
No full textMeasurement of void fraction for two-phase flows involving gas and liquid in a vertical channel have been extensively researched to improve cooling system designs for energy-related industries and process refineries. Void fraction is the representation of gas and liquid ratio in a flow channel at certain working conditions. Using the Constant Electric Current Method (CECM), void fractions were obtained using sensor electrodes connected to data acquisition (DAQ) hardware which outputs the results to LabVIEW® software. Three sets of experiment were run at three fixed liquid superficial velocities
Phytoremediation of domestic wastewater by azolla in a constructed wetland / Redzaniell Afiq Mohd Rosdi
No full textOne of the major environmental problems in the present scenario is water pollution. Increased population and industrialization fasten the water pollution rate. Increase in population leads to high domestic water consumption and domestic wastewater production which plays an important role in polluting water resources. In this study an attempt is made to evaluate effectiveness of phytoremediation technique using Azolla fern (Azolla pinnata) for domestic wastewater by constructed wetland units. Parameters like pH, Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), Ammoniacal nitrogen (NH3-N), Phosphate (PO43-), were analyzed for sample after 7 days of phytoremediation within 49 days of detention period. Constructed wetlands using Azolla fern observed with a high removal efficiency in all tested parameters except pH. Concentration of BOD, COD, NH3-N and PO43- reduced from 27.4 mg/L, 132 mg/L, 3.28 mg/L, 3.42 mg/L to 13.8 mg/L, 9 mg/L, 0.08 mg/L, 0.09 mg/L respectively whereas the pH increase from 6.60 to 7.9. The removal efficiency % BOD (49.64%), COD (93.18%), NH3-N (97.56%) and PO43- (97.37%). The study conducted by Neethu & Chinamma (2017), indicated that after 28 days of treatment the removal efficiency % BOD (89.61%), COD (92.41%), NH3-N (91.12%) and PO43- (94.93%). For future study, it would be recommended to apply appropriate constructed wetland design, implement odour reduction strategies, select suitable plant and determine amount of dissolved oxygen
Detection of histamine 1 (H1) and histamine 2 (H2) receptors on murine spermatozoa by cellular and molecular studies / Nor Azimah Ahmad@Aziz
No full textHistamine is an important biogenic amine in various biological and physiological reactions which mediated by specific histamine receptors. The histaminergic studies in male reproductive system have been revived after the breakthrough of histamine synthesizing enzyme, histidine decarboxylase (HDC) was only found on male germ cell, spermatid acrosome, and spermatozoa, which has led to the ability of histamine synthesised in spermatozoa through in vitro acrosome reaction. There were significant studies reported on the negative effects upon histamine 1 (H1R) and histamine 2 (H2R) receptors antagonist administration on sperm parameters such as sperm count, motility, and sperm viability, herein speculates that H1R and H2R may be present on sperm. Therefore, this study aimed to detect H1R and H2R on murine sperm by cellular and molecular studies. The H1R and H2R localization on murine sperm was detected by immunocytochemistry technique. The sperm was smeared onto poly-lysine coated slide and allowed to dry prior to fixation and permeabilisation processes. The primary antibody encoded for receptors was exposed to fluorescently tagged antibody; fluorescein isothiocyanate (FITC) conjugate followed by nuclear staining with 4’, 6-diamino-2-phenylindole dihydrochloride (DAPI). The testis, stomach, and skin of mice were used as the positive control tissues, underwent the same procedures as sperm to verify the immunocytochemical evidence. In molecular study, sperm RNA was extracted by TRIzol method and reverse transcribed for complementary DNA (cDNA) synthesis prior to Polymerase Chain Reaction (PCR) for amplification of H1R and H2R genes which subsequently to detect the presence of the receptors molecularly. The purified DNA underwent DNA sequencing as a final verification step of study. Result showed that H1R and H2R were present on the midpiece and acrosome of epididymal sperm in cellular study and the presence of both receptors was supported by molecular evidence. The presence and immunolocalisation of H1R and H2R on the midpiece and acrosome coincide with the mapping of corresponding G-proteins on similar locations on mature sperm. The H1R-Gαq/11 and H2R-Gαs coupling initiate the signalling cascades through phospholipase C and adenylyl cyclase, respectively. Therefore, present study proposes that these receptors would be involved in calcium regulatory mechanism and protein phosphorylation which are responsible for fertilisation-related processes
Pulse laser generation using Mxene / max phase as saturable absorber / Hissah Saedoon M Albaqawi
No full textOptical fiber lasers have drawn a lot of researchers’ interest and attention in recent years particularly as sources for laser signals. This could be attributed to its number of significant advantages, such as more compact and robust form factors as well as being significantly less costly to build and operate as compared to their conventional bulk laser counterparts. Moreover, the utilisation of fiber laser provides much more flexibility in terms of design and usage of the laser. While optical fiber lasers are highly suited for applications that require relatively low laser powers, they are generally not used for applications requiring higher powers. This is because in most cases, optical fiber lasers operate in a continuous wave (CW) mode at low powers. In order to overcome this limitation, significant efforts have been made to increase the output power of optical fiber lasers by pulsing, allowing them to accumulate power before discharging the energy as a lasing signal. Pulsing in an optical fiber can be realised through multiple techniques, with Q-switching and mode-locking being the most common and both techniques can be further classified as either active or passive systems. In the present study, passively Qswitched and mode-locked pulse lasers has been achieved through the use of saturable absorbers (SA) namely Ti3AlC2 MAX phase and Ti3C2Tx MXene. Both materials were chosen as the SA materials because they possess good optoelectronic and optical properties such as high damage thresholds and modulation depth. Besides that, they also exhibit nonlinear saturable absorption and increased transmittance at higher light fluences, which is useful especially for mode-locking in fiber-based femtosecond lasers. Initially, Ti3C2Tx MXene was synthesized from Ti3AlC2 MAX phase by etching with a mixture of lithium fluoride (LiF) and hydrochloric acid (HCl) to remove the aluminium (Al) layers from the Ti3AlC2 MAX phase. Two different structures of SA, namely polyvinyl alcohol (PVA) thin film and side-polished fiber (SPF), were examined for their potential in the generation of pulse laser. The erbium-doped fiber (EDF) and thuliumholmium co-doped fiber (THDF) serve as the gain medium in which EDF is capable of amply light efficiently within the region of 1550 nm wavelength, whereas the trivalent thulium-holmium ions (Tm3+ - Ho3+) have emerged as a promising rare-earth ion that has a radiative transition within the 2.0 μm wavelength region. Based on the experiment conducted in this study, it has been proven that the proposed systems were able to generate Q-switching and mode-locking operation at the 1.5 μm and 2.0 μm wavelength regions. The generated outputs indicated that the Ti3AlC2 MAX phase and Ti3C2Tx MXene based SA can induce high quality and stable Q-switched and mode-locked pulses in the EDF and THDF laser cavity, thus have significant contributions and uses in several fields of photonics applications
Identification and characterization of a novel Epstein-barr virus-encoded circular RNA from LMP-2 Gene / Tan Ke En
No full textEpstein-Barr virus (EBV) is a common human herpesvirus that establishes lifelong infection in its hosts and accounts for various malignancies. EBV was recently found to encode novel circular RNAs (circRNAs) through backsplicing. However, the cataloguing, characterization and functional study of EBV circRNAs are still lacking. Utilizing computational algorithms, psirc and find_circ, a list of putative EBV circRNAs in GM12878, an EBV-transformed lymphoblastoid cell line, was identified with a significant majority encoded from the EBV latent genes. A novel EBV circRNA derived from the exon 5 of LMP-2 gene (termed as circLMP-2_e5) with the highest read count was further validated by RNase R assay and Sanger sequencing. Characterization of circLMP-2_e5 demonstrated that it was readily detected in a panel of EBV-positive cell lines modelling different latency programs, ranging from lower expression in NPC cells to higher expression in B cells and was localized to both cytoplasm and nucleus. Subsequent experiments showed that circLMP-2_e5 was expressed concomitantly with the linear LMP-2 upon EBV lytic reactivation and may be produced as a result of exon skipping with its circularization possibly occur without the presence of cis elements in the short flanking introns. Furthermore, functional characterization showed that circLMP-2_e5 was unlikely to act as a microRNA sponge, and did not affect cell proliferation, host innate immune response, LMP-2 linear transcripts and EBV lytic reactivation. Taken together, this study does not only provide informative addition to the current repertoire of putative EBV circRNAs, but also deepen our understanding of EBV circRNA biology. The results have also laid essential foundation for further investigations on the functional significance of circLMP-2_e5 in EBV life cycle and the development of EBV-associated diseases
Characterization and the effect of waste plastic oil in a diesel engine / Muhammad Ahmad Salman Hisham
No full textThe world currently relies heavily on conventional fuels such as diesel and petrol for
its main source of energy supply. This has affected the environmental balance as has
caused climate change and environmental pollution. Pollution such as plastic waste is also
very common, leading to ocean bio habitat and ecosystems damage. Currently the
solution to such plastic pollution is by burial in large landfills or by incineration. An
innovative idea has come up in recent years in utilising the waste plastics into usable fuel,
solving two of the largest issues faced by the global community with a solution. The
purpose of this study is to investigate the suitability of Waste Plastic Oil (WPO) and
various proportions of blends between WPO and Waste Cooking Biodiesel (WCB) as fuel
in diesel engines. Sample of Malaysian pump diesel of B10, 100% Waste Plastic Oil
(WPO) as well as samples of blend WPO 90 (90% waste plastic oil, 10% waste cooking
biodiesel), WPO 80 (80% waste plastic oil, 20% waste cooking biodiesel) and WPO 70
(70% waste plastic oil, 30% waste cooking biodiesel) were tested for lubricity. The
samples tested were then further analysed and undergone engine testing to determine the
engine performance running on the respective fuels. Among the tested samples, all well
capable of achieving the lubricity and performance similar to or better than of the B10
diesel. The fuels calorific values showed a decreasing trend with increasing WCB content.
Content on pollutants such as eicosane tend to be higher with blends with lower WCB
content. The physical property of the WPO 90 and the added advantage in terms of its
fuel consumption placed it the most suitable fuel to replace the currently available B10
diesel in the market
Study on health risk assessment due to emissions from diesel power plant using AERMOD modeling / Ibrahim Afrah
No full textDiesel engines are the most efficient and reliable power plant among all internal
combustion engines. While the diesel engine offers an efficient and reliable power source
which brings a lot of benefits to the power industry it also contributes harmful emissions
to air pollution. In this research, the studied diesel power plant for electricity generation
is located in the capital city of Maldives which is among the highest densely populated
city to land ratio. Due to the lack of land available in Male’ City the power plant cannot
be relocated away from the residential area hence the emissions from the diesel power
plant are exposed to the population and the environment. This study aims to identify the
pollutants contained in the diesel stack emissions and its concentrations levels. Also, to
analyze the predicted short-term and long-term ground concentrations levels. Finally, to
conduct a health risk assessment (HRA) and identify short-term and long-term health risk
effects.
In this study, five pollutants (CO, SO2, NO2, PM10 and PM2.5) were assessed for health
risk assessment. The stack emission concentration levels of the pollutant were measured
using portable flue gas analyzer and particulate matter analyzer. The results obtained were
compared with Malaysian Environmental Quality (Clean Air) Regulations 2014. All the
pollutant concentration levels were found to be below the mentioned limit in the
guideline. Predicted ground concentration levels were calculated within 3 x 3 km domain
of the point source by utilizing AERMOD dispersion model simulation for short-term and
long-term dispersion. The results show that for pollutants CO, SO2, NO2, PM10 and PM2.5
the short-term concentrations are 29.91, 59.84, 16.93, 6.05, 4.76 (μg/m3
) and for long-term 19.99, 2.11, 0.60, 0.65, 0.51 (μg/m3
) respectively. All the values were compared
with Malaysian Ambient Air Quality guidelines and was found be below the critical values. In addition, risk characterization was conducted by utilizing Hazard Quotient
(HQ). For all the pollutants, HQ value obtained for short-term and long-term dispersions
was less than 1 (HQ<1) hence predicted pollutant concentration levels are below RfC
value and considered safe with no potential to cause adverse health effects. Although the
study calculated pollutant concentration levels are in acceptable range, the accuracy of
the outcome highly depends on the stack emission reading and meteorological data
Greening residential area through cleaner production strategies during planning stage / Logheshwaran M.S.Guna
No full textThe rapid growth of the population will generate greater demand for housing
construction. Throughout the lifespan of a house, the operation phase contributes to an
increase in environmental problems such as global warming. This is due to energy usage
in the operation phase of a home. To date, the electricity sector in Malaysia is excessively
dependent on fossil fuels for electricity generation. The high amount of greenhouse gas
(GHC) emissions is being emitted into the atmosphere due to the usage of fossil fuels for
electricity generation, which contributes to global warming. Besides that, water usage and
waste management also impact the environment during a house's operation phase. With
that, a cleaner production strategy was implemented to green the residential area in the
planning stage of housing construction. A cleaner production strategy is the continuous
application of an integrated preventive environmental strategy to improve the overall
efficiency in reducing emissions and wastes. A case study analysis conducted in Taman
Templer Suasana residential area found that a small group of respondents practice cleaner
production strategies in their homes. From the analysis of the case study, several cleaner
production strategy options can be introduced to construct a new house. Twenty-three
cleaner production strategies were introduced in greening residential areas in the planning
stage of constructing new houses. This strategy compromises energy, water conservation,
house design, housekeeping, and material used for constructing a new house
Design and evaluation of an electronic training system for professional development in Saudi Arabia’s Higher Education / Aizal Yusrina Idris
No full textThe Kingdom of Saudi Arabia (KSA) realized that it should improve the quality of human
resources that universities produce to boost the economy of the country, through
organizing and administering professional development activities. However, in the rapid
growth of information and communication technology, the deliverables of electronic
training system were obstructed by problems that are related to the training needs and
design, which are influenced by culture, religious and technology resistance. This
research is significant in establishing the professional development of higher learning
institutions in KSA, where the design and development of the electronic training system
assist the concern users: institution, experts and trainees to integrate the electronic
training into the professional development plan. This research used qualitative technique,
with the purpose to explore the needs of electronic training environments, designing and
developing a system prototype, known as TaSPoD (electronic Training System for
Professional Development), and evaluate the TaSPoD prototype. Methodologically, it is
based on six phases: analysis, design, validate design, develop system prototype,
evaluate, innovate. Upon two rigorous analysis using Applied Cognitive Task Analysis
in two different phases, the interactive design of TaSPoD allows the educators to virtually
interact with the trainers through the links of forum, activity, modules, online video and
others. Eventually, TaSPoD is a platform to bridge the culture and religious gap, as well
as technological resistance gap, that enable educators regardless of gender, to maximize
their potential through professional development activities