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Comparative evaluation of antioxidant activities and chemical composition of selected Schizophyllum commune Fr. natural, gamma-irradiated and hybrid strains / Alyaa Abbas Fadhil Alkhafaji
No full textDue to the uncontrolled production of reactive oxygen species, excessive level of free radicals leads to oxidative stress which is linked to many diseases such as cancers, diabetes, neurological disorder and hypertension. The major countermeasure to balance the excessive presence of free radicals in the body is to obtain substantial amounts of dietary antioxidants. Mushrooms contain many bioactive compounds with health-promoting effects including antioxidants. Therefore, this study was designed to investigate the antioxidants activities and chemical compositions of different strains of Schizophyllum commune Fr. The crude extracts of the natural (isolated from Malaysia and Thailand), gamma-irradiated (strains obtained when natural strains subjected to different doses of gamma radiation) and hybrid (strains obtained from hybridisation between the natural strains) strains of S. commune were prepared using 80% (v/v) aqueous ethanol. The antioxidant activities of the extracts were then measured using 2,2 diphynel-1-picrylhydrazyl radical scavenging activity (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and cupric ion-reducing antioxidant capacity (CUPRAC) assays, and correlated to their chemical compositions. S. commune strains showed moderate total phenolic content (11.7-22.8 mg GAE/g extract) and high protein content (293.5-486.8 mg protein/g extract). The crude extracts of S. commune strains showed comparable scavenging activities in both DPPH radicals scavenging activities ranged from 2.30 to 2.48 (mmol TE/g extract) and ABTS radicals scavenging activities ranged from 0.07 to 0.15 (mmol TE/g extract). In FRAP (0.22 to 0.30 mmol Fe2+/g extract) and CUPRAC (0.10 to 0.13 mmol TE/g extract) assays, the crude extracts showed comparable reducing activities. The antioxidant activities of the crude extracts showed moderate correlation with the total phenolic (r = 0.625) and flavonoid (r = 0.535) content. Further investigation was on the liquid-liquid fractionation of the crude extracts of the strains W, W2000 and W4000 to yield the hexane, ethyl acetate and water fractions. For all selected strains, the water fractions contained the highest sugar, protein and phenolic content while the hexane fractions gave the highest flavonoid content. The ethyl acetate fractions of all selected strains also showed stronger antioxidant activities approximately one time higher than water fractions and two times higher than hexane fractions in all antioxidant assays. These findings suggest that the antioxidant compounds in the crude aqueous ethanol extracts of S.commune were successfully concentrated in the ethyl acetate fractions and the strongradical scavenging and reducing activities of the fractions might be attributed to the abundance both phenolics and flavonoids based on the correlation studies. Our findings have shown that S. commune strains and ethyl acetate fractions of the selected strains (W, W2000 and W4000) are a good source of natural antioxidants and hence, they will be potentially useful for medicinal and food applications
Evaluation of turbulent forced convection heat transfer and pressure drop of nanofluids flow in different closed conduit configurations / Ali Hassan Abdelrazek Elsayed
No full textNanofluids are a relatively new class of fluids consisting of a base fluid with suspended nano-sized particles (1–100 nm). Nanofluids are suggested as a favorable convective medium because the thermal conductivity of the suspensions is typically an order-of-magnitude higher than those of normal fluids such as water. In convection heat transfer applications, some researchers reported that enhancing the convection heat transfer coefficient is directly proportional to nanofluids' thermal conductivity increment. In contrast, others said that the nanofluid thermal conductivity is not the critical parameter for enhancing convection heat transfer. Therefore, experimental and numerical work was conducted in the current study to evaluate the thermal performance of different nanofluids in different pipe geometries with the same hydraulic diameter. Three different aqua-based nanofluids of weight concentrations 0.05%, 0.075%, and 0.1% were prepared using the two-step method. One nanofluid was prepared from composite nanoparticles, composed of 60 % Al2O3 and 40% f-MWCNTs by weight. The second one was prepared from the Al2O3, and the third nanofluid was prepared from SiO2 nanoparticles. All the nanofluids showed an excellent dispersion in the stability test over one month, and their thermophysical properties were evaluated experimentally except the specific heat, which was calculated theoretically. The experimental work was conducted using a test rig containing circular and square test sections of 10 mm hydraulic diameter exposed to a uniform heat flux on their outer surfaces. The inlet flow temperature was kept constant at 30 °C in all the runs. All experimental work was done under steady-state fully developed turbulent flow conditions with the Reynolds number range of 6000-11000. The results obtained experimentally showed that the Prandtl number has the most significant effect compared to the thermal conductivity on the Nusselt number and the convection heat transfer coefficient. The numerical work was conducted to evaluate the heat transfer and pressure drop through the same geometries in the experimental work in addition to an annular heat exchanger of the same hydraulic diameter and an eccentricity range from 0.0 to 0.6. The continuity, momentum, and energy equations were solved using the finite volume approach available in the ANSYS-Fluent commercial software with the same flow and boundary conditions as the experimental work. The results obtained numerically were in good agreement with those obtained experimentally for the circular and square pipes. The annular pipe’s model was validated with some empirical correlations, shown an average error of less than 10%. All the results obtained numerically confirmed the experimental findings. Finally, the thermal performance evaluation showed that the distilled water (DW) has the highest thermal performance, and the lower nanofluid concentration has also shown the higher thermal performance.
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Potential electricity savings analysis from implementing building integrated photovoltaics at an industrial plant / Jonathan Teo Kok Chiang
No full textMalaysia is striving towards meeting its climate goals as part of the Paris Agreement,
of which Malaysia is one of the signatories. Two of our current main sources of
greenhouse gas emissions in Malaysia is the energy industries and manufacturing
industries. To develop more energy diversity in our country, solar photovoltaic
technology will be key to further reduce our greenhouse gas emissions, given its
suitability for our climate and the advancements in the technology that has lowered its
cost and increased its electricity generation capacity. Therefore, this study was done to
spur the adoption of BIPV technology in the industrial sector by showcasing the
electricity savings potential at industrial sites by using an existing site to simulate the
estimated savings from implementing a BIPV system. This study utilised a method for
estimating the BIPV system by considering the current available Solar PV technologies
that can be implemented, and considering the physical, geographic, technical and
economic potential for a selected site. This study used a widely used simulation software
PVSyst to input the localised meteorological data and utilising its wide database of PV
modules. The chosen site has an effective roof area of 7,000m2 was selected for the study
and PV modules were selected based on their availability in the Malaysian market. The
electricity tariff used was based on the local electric utilities provider’s classification for
medium voltage industries. System losses were also considered in the simulation model
to provide better relations to real world conditions. By applying the proposed methods, a
total of six models were developed, with each utilising different PV technologies to
generate the technical and economic potential, which led to an analysis on the electricity
savings for each type of proposed system. Overall, the estimated annual electrical savings
was from a range of 1,503MWh/year to 1,801MWh/year, with an LCOE range of between 0.182 MYR/kWh to 0.351 MYR/kWh. The thin film cellsimulation model was also found
to have the best payback period among all generated models. While this study has shown
that, different types of technology will provide varying results in terms of potential
electric savings for a company, further studies can be conducted to expand the technical
and economic aspect to provide more accurate simulations in future reports, with focus
provided on any potential funding aids e.g. private or government and more research on
degradation over time of PV modules
Productive engagement of older adults in China: A longitudinal multilevel analysis / Sia Bik Kai
No full textPopulation ageing poses significant challenges, but it also provides opportunities to harness the human capital of a large pool of experienced and skilled workers. In 2019, there were 164.4 million (11.5%) older persons aged 65 years and older in China, and undoubtedly the effective utilisation of this large pool of human resources is crucial for sustainable development. The present study aimed to investigate the effects of health, personal, behavioural, social, economic, physical environment, and demographic factors on the productive engagement of older adults, considering the provincial differences in economic conditions. This study used data from the 2002, 2005, 2008, and 2011 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The respondents comprised 3,208 older adults aged 65 and over at wave 2002. The older adults were categorised as actively engaged in paid jobs, actively engaged in unpaid work, and less active. As they aged over nine years, the percentage engaged in a paid job declined from 45.5% to 25.1%, while those engaged in unpaid activities rose from 48.3% to 59.2%. The findings from employing a random intercept multilevel multinomial logit model developed from the mixed-effects models indicated a strong association between physical, cognitive, and functional health with paid and unpaid productive engagement. Also, older adults more likely to be involved in unpaid productive activities have the following characteristics: better self-rated health, greater cognitive health, better functionally independence, drinking and exercising habits, active participation in social activities, living alone, and female. Additionally, those who exercised regularly were more likely to participate more actively in paid and unpaid productive work. Participation in social activities was also positively associated with paid and unpaid productive engagement. Rural older adults not subject to the mandatory retirement age and those financially inadequate were more likely to continue working. However, having chronic diseases, advanced age, and low education did not deter older adults from participating in unpaid productive engagement. The likelihood of being productively engaged among the older adults was higher in the provinces with lower gross domestic product (GDP) per capita. The person-mean centring models provided more insight than the grand-mean centring models, highlighting the importance of between- and within-person differences in explaining the variation in productive engagement. Health and exercising behaviour participation were particularly significant in explaining changes over time. The recommendations to promote active and productive ageing included enhancing the existing work system for older workers, raising the statutory retirement age, establishing social enterprises and entrepreneurship, accelerating the healthcare reform, promoting prevention-based healthy ageing, promoting regular exercise, and promoting social participation
Development of functional electrical stimulation system using mechanomyography as muscle state feedback for paraplegics / Jannatul Naeem
No full textFunctional electrical stimulation (FES) supported exercises aid purposeful muscle contractions to restore the lost motor functions with associated health benefits in individuals with spinal cord injury (SCI). The use of this device globally is majorly still restricted to the laboratory, especially in developing countries such as countries in Asia. This challenge is principally due to the high cost of the device for home care use and even for clinical deployment and the complexity of the commercially available options. One limitation of the available options is the inefficient muscle stimulation outcome due to the early onset of muscle fatigue. The reversal of motor unit recruitment in FES-evoked muscle contractions is one of the reasons for quicker muscle fatigue than the natural muscle contractions that occur from the central nervous system in a healthy person. The FES systems with sensor feedback are used to lessen this limitation with improved
functional outcomes. The use of muscle contraction signals such as electromyography marred with stimulation artefacts, and the removal of these artefacts often presents another challenge. The studies reported in this thesis proposed and developed an FES system to monitor muscle condition using mechanomyography (MMG) without the limitation of stimulation artefacts. Before the implementation, a unique Mel-frequency cepstral coefficient (MFCC) feature of the MMG signal was introduced to classify the fresh muscle and muscle fatigue contractions in cycling exercise. Using this MFCC feature of MMG, 90.7% average classification accuracy was achieved, while the root mean square (RMS) feature of MMG had an accuracy of 74.5%. However, the computational cost needed for this research is supported using the RMS amplitude feature of MMG. This is also based on the literature that the MMG-RMS has a positive and primarily linear relationship with torque generated from FES-evoked muscle actions. The developed FES system created sufficient stimulation power to support standing exercise and monitor muscle condition using MMG signal related to knee-buckling, which indicates muscle fatigue. Furthermore, the developed FES system was applied to detect muscle fatigue in realtime using the MMG-RMS feature during isometric knee extension. The torque generated when tested on the isometric dynamometer was related to 70% drop in MMG-RMS threshold as actual muscle fatigue. Finally, an investigation of different modes of user control strategies of FES standing was simulated as the increase of amplitude by button pressing to sustain standing and detect muscle fatigue using the MMG-RMS feature. The outcome of this investigation showed that the single press 10 s mode provides optimal standing duration compared to other modes. Overall, this research shows the development of real-time muscle monitoring and prevention FES system with MMG sensor
Building information modelling readiness level for government project in Malaysia / Chong Chee Ying
No full textThe Malaysian construction industry has often been associated with low productivity, quality and standards, despite being one of the major sectors contributing to the Gross Domestic Product (GDP) of the country. The Construction Industry Development Board Malaysia (CIDB) highly encourages the adoption of Building Information Modelling (BIM) among the construction stakeholders to improve the overall standards of the Malaysian construction industry. Nevertheless, BIM adoption rate remains low albeit it was introduced about a decade ago. There have been many studies in the literature investigating the benefits of BIM adoption, factors leading to the low BIM adoption rate and perceptions of stakeholders towards the adoption of BIM in the construction industry. However, there is a lack of case studies that report on the adoption level of BIM during project life cycle (i.e., in which phase BIM was adopted, who are the stakeholders commonly use BIM, etc.) in the Malaysian construction. Therefore, this study attempts to fill in the gap by studying the stakeholder that utilise BIM during project life cycle in the Malaysian government project. Additionally, the pros and cons associated with the use of BIM will also be gathered in this study. Lastly, the readiness of BIM adoption will be investigated as well. Data and information will be acquired through qualitative approach towards targeted projects in Klang Valley, Malaysia. It is hopeful that the findings from this real case scenario study could provide a better insight to the government and/or stakeholder the rooms for improvement in the support from the government in introducing BIM in this industry in order to achieve the goal that has been set by Public Works Department (JKR) Strategic Plan 2021-2025 to achieve 50% BIM adoption rate by next year and 80% by year 2025. This in return, is hopeful to promote greater BIM adoption in the construction industry, which will improve the overall standard and quality of the Malaysian construction industry
Entrepreneurship development among RISDA farmers in Malaysia / Muhammad Firos Mustaffa
No full textRubber farmers in Malaysia have been saddled with poverty, and mostly hard core. To overcome poverty, the government has supported farmers to engage in small businesses by providing training and grants, but only a small number of participants have succeeded. The study intends are to identify factors that influence the success or failure of small businesses in the context of RISDA farmers. A primary motivation for undertaking the study arises from the desire to understand why this programme had a high failure rather than a success rate, despite the fact that many resources were being given to these farmers to objectively raise their income and improve their well-being. This study fills the gaps in knowing the farmer's ability to engage in entrepreneurship by considering other dimensions such as internal and external factors. A quantitative approach using a questionnaire survey of 398 RISDA farmers who were enlisted as active for two years in small businesses was employed in this study. The study finds a significant relationship between support services, opportunities, self-efficacy, attitudes, as well as demographic factors and success or failure in small businesses. Among the main causes for their failure are a lack of knowledge and skills in small business, short of family support and inadequate training. Those who succeed in small businesses are found to have higher educational attainment, are middle-aged, and have the support of their family members. The study also ranked the important factors that influence small business success. The findings of the study may be used to enhance policy and programme design in order to increase the success rate of farmers in small businesses. The participants should be assessed on their business readiness before accepting them into the entrepreneurship development programme. Small business programmes should only target those with at least secondary schooling, while the authorities need to improve their monitoring, support services, and appropriate training of the recipients to ensure better success of the programmes. The study concludes that getting farmers out of poverty using entrepreneurial approach programs needs not only focus on financial support, but also other factors mentioned above
Microzooplankton dynamics in relation to the microbial loop in Matang estuarine waters / Yong Yu Lin
No full textMicrozooplankton (20-200 μm), along with phytoplankton, bacteria and heterotrophic nanoplankton in a tropical estuary (Matang Mangrove Forest Reserve, MMFR) were investigated to evaluate their abundance in relation to the various environmental and biotic parameters, along with their interactions in the microbial food web to elucidate the role of microzooplankton in the estuarine water. This study looked into the microzooplankton composition, taxonomically and abundance (Chapter 4) and their feeding interaction with the other microbial component in the estuary (Chapter 5). With this information gathered we can thus fill the knowledge gap of the carbon flow in the estuary. A total of 39 microzooplankton taxa comprising of four major groups, i.e. loricate ciliates (37.72 %), aloricate ciliates (29.46 %), dinoflagellates (24.33 %) and meroplanktonic nauplius (8.49 %) were identified. The loricate ciliates were the most diverse group with 31 taxa recorded. Four major species of loricate ciliates were identified, i.e. Tintinnopsis beroidea, Tintinnopsis rotundata, Stenosemella avellana and Tintinnidium primitivum, while Strombidiidae and Strobilidiidae dominated the aloricate ciliates. Although small loricate ciliates were ubiquitous, redundancy analysis shows marked shifts in microzooplankton community structure, from one that was dominated by loricate ciliates during the drier South West (SW) monsoon, to aloricate ciliates at the onset of the wet North east (NE) monsoon, and then to dinoflagellates towards the end of the drier NE monsoon period. These shifts were associated with rainfall, dissolved inorganic nutrients, salinity, temperature and microbial food abundance. There was no clear lunar effect on abundance of microzooplankton except for Favella ehrenbergii and copepod nauplii that were more abundant during neap than spring tide. Rain-driven monsoonal effects showed significant impacts on microzooplankton herbivory and primary production; both significantly higher during the drierSouth West monsoon. The MMFR was characterised by high primary production (148 to 4021 μgC l-1d-1; 1190 ± 249.6 μgC l-1d-1 ) and low bacterial production (1 to 6.1 μgC l-1d-1 ; 3.7 ± 1.5 μgC l-1d-1). There is no coupling observed among bacterial production and primary production. Microzooplankton grazing on primary production was profound (887.02 μgC l-1d-1), followed by heterotrophic nanoplankton (1.33μgC l-1d-1) and bacterial production (1.28μgC l-1d-1). More than 70% of the primary production was transferred to the microzooplankton via grazing, compared to only about 30% of both bacterial production and HNP production. The present study highlighted the role of microzooplankton as an important consumer of phytoplankton production in the highly turbid but productive mangrove estuary
Experimental study of Co2 injection into carbonate depleted field: A case study from central Luconia field, Sarawak, East Malaysia / Nur Zafirah Mat Razali
No full textThis study aimed to address the challenges and strategies to determine the critical rate of CO2 injection into carbonate depleted gas fields. In this research, the critical rate is the maximum allowable injection rate before formation damage initiation. The cause of formation damage could be due to in-situ mobilization or trapping of migratory fines resulting in plugging of the flow path. This study performed a thorough investigation of a different rock-fluid system to evaluate the safe injection limit, as the critical rate is different for each rock-fluid system. The geochemical effect of CO2 injection toward carbonate formation was also investigated in this research. Other than that, the porosity and permeability changes due to CO2-brine-rock multiphase flow characteristics were considered to understand the feasibility of CO2 sequestration into carbonate formation. This research discussed experimental design to mimic the injection scenario of CO2 into carbonate depleted gas field. Therefore, several sets of core flooding experiments were conducted under reservoir conditions using representative native cores, CO2, and synthetic formation brine. Abrupt changes in differential pressure (ΔP), analysis of effluent collected after CO2 multi-rate flow, and pH reading are the key indicators to consider that the condition has reached a critical rate. The experimental result demonstrated the existence of fines migration, scale formation, and salt precipitation after the core was subjected to supercritical CO2 multi-rate flow. Considering these issues and challenges associated with injectivity, this study recommended a maximum injection rate prior to field scale injection
Production of alpha humulene and zerumbone in adventitious root cultures of Zingiber zerumbet (L.) smith through synergistic effect of elicitors and plant growth regulators / Nurul Huda Alwakil
No full textPlant secondary metabolites are gaining huge interest from their phytomedical potential viz. antimicrobial, anticancer, anti-inflammatory, drug and pesticides. There are many active researches being carried out to isolate and commercialize these valuable bio-products. Plant cell culture is a feasible alternative route to produce the bioactive compounds as its offers good quality materials less affected by uncertainties in environmental, ecological or climatic conditions. Zingiber zerumbet Smith widely known as shampoo ginger or common to Malay as ‘Lempoyang’ is a small perennial medicinal herb plant belonging to the Zingiberaceae family. Zerumbone presents dominantly in the rhizome of Zingiber zerumbet with α-humulene as its intermediate, and exhibits important phytomedicinal properties such as anticancer, antimicrobial, anti-inflammatory, antinociceptive, chemopreventive and antioxidant. Efficient production of zerumbone through the establishment of adventitious root culture has been investigated previously. However, the production of α-humulene and the synergistic effects of elicitors on the production of α-humulene and zerumbone in vitro are yet to be investigated. The combination of auxin-auxin and auxin-cytokinin causes a significant decrease in adventitious root growth at high IBA and BAP concentrations. The highest specific growth rate for root biomass production is obtained on media supplemented with 5 mg L-1 IBA and 1 mg L-1 NAA with maximum fresh weight of 6.90 ± 0.08 g and dry weight of 2.10 ± 0.01 g was not significant with 3 mg L-1 BAP and 1 mg L-1 NAA. Meanwhile, maximum productions of α-humulene (3759 ± 798 μg/g) and zerumbone (3440 ± 168 μg/g) are observed in the media containing 3 mg L-1 BAP and 1 mg L-1 NAA under 16:08 photoperiod along with abundant root biomass (1.90 ± 0.05 g DW). Elicitation studies shows that root growth and compounds production are negatively correlated events, which a significance decline in biomass growth is observed with the increase in elicitor concentration. The yields of zerumbone and α-humulene at 43 mg/g DW and 15.8 mg/g DW, respectively are obtained at low concentration range of elicitors i.e. 400μM to 600μM methyl jasmonate and salicyclic acid and represent better production compared to control. In conclusion, synergistic effects from application of elicitor combination to induce excess secondary metabolites in plant culture could be a practical route for larger scale production