19672 research outputs found
Sort by
Greenhouse gas emissions associated with electric vehicle charging: The impact of electricity generation mix in a developing country
No full textSince 2012, the government has been promoting the electric vehicles and the development of related infrastructure to encourage local automakers to explore into the alternatively powered vehicles. However, the benefits of grid-dependent EVs can only be harvested under the condition that their use is coupled with a low carbon electricity grid. Thus, it is an additional challenge for Malaysia's that are largely dependent on fossil fuels for electricity generation. The object of this paper is to perform a well-to-wheel life cycle assessment for calculating the greenhouse gas emissions attributable to the usage of ICEVs, HEVs and EVs in Malaysian scenario. These emission calculations will provide the best information for policymakers, researchers, and investors to make appropriate and effective decisions on policies, research and investments in future transport energy. The results show that running EVs with national grid will produce an average of 7% more GHG emissions than HEVs at the same distance. However, they will produce an average of 19% less GHG emissions than the ICEVs. Overall the GHG emissions produced through the usage of EVs are substantial based on the well-to-wheel analysis, as the environmental profile of EVs is linked with the national grid. Therefore, in order to harvest the benefit of EVs towards climate change and global warming mitigation, massive modernization and transformation should be taken for the development of the national grid towards greener sources
Automated impact device with non-synchronous impacts: a practical solution for modal testing during operation
No full textPrevious study has shown that synchronization of phases between impacts and the cyclic load component should be avoided to improve the effectiveness of operational modal testing, i.e. impact-synchronous modal analysis in obtaining a cleaner frequency response function (FRF) estimation with fewer number of averages. However, avoiding the phase synchronization effect is rarely achievable with the current manual impact hammer because of the lack of control of the impact timing. We investigate how to improve FRF estimation in the presence of harmonic disturbances, such as those present in operating rotating machines. An auto impact device is therefore introduced to replace the manual impact hammer. This device ensures that impact intervals can be applied at non-synchronous instances with respect to the harmonic disturbance. We demonstrate that this new device is a viable option for operational modal testing. It allows significant improvement in FRF estimation and shows good correlation of modal extraction data with benchmark experimental modal analysis results
Regional or global shock? A global VAR analysis of Asian economic and financial integration
No full textThis study employs a global vector autoregressive (GVAR) model to empirically investigate the viability of regional monetary arrangements in Asia. In marked contrast to the previous studies, we analyzed whether recent regional economic and financial integration in Asia were driven by global (U.S.) shock or regional (Japanese and Chinese) shock, using the GVAR model that allows global inter-linkages between domestic and foreign variables. By estimating generalized impulse responses of Asian economies’ real outputs and interest rates to global and regional shocks, we found that the Chinese shock exerted more real and financial influences on Asian economies than the U.S. shock. Another regional shock, i.e., the Japanese shock, had a far smaller influence on Asian economies. The relative importance of regional shocks originating from China needs to be considered when establishing regional monetary arrangements in Asia
Laboratory Evaluation of a Rapid IgG4 Antibody Test (BLF Rapid™) for Bancroftian Filariasis
No full textAt the end phase of the Global Programme to Eliminate Lymphatic Filariasis, antibody testing may have a role in decision-making for bancroftian filariasis–endemic areas. This study evaluated the diagnostic performance of BLF Rapid ™ , a prototype immunochromatographic IgG4-based test using BmSXP recombinant protein, for detection of bancroftian filariasis. The test was evaluated using 258 serum samples, comprising 96 samples tested at Universiti Sains Malaysia (in-house) and 162 samples tested independently at three international laboratories in the USA and India, and two laboratories in Malaysia. The independent testing involved 99 samples from Wuchereria bancrofti microfilaria or antigen positive individuals and 63 samples from people who were healthy or had other infections. The in-house evaluation showed 100% diagnostic sensitivity and specificity. The independent evaluations showed a diagnostic sensitivity of 84–100% and 100% specificity (excluding non-lymphatic filarial infections). BLF Rapid has potential as a surveillance diagnostic tool to make “Transmission Assessment Survey”–stopping decisions and conduct post-elimination surveillance
Hits-to-Lead Optimization of the Natural Compound 2,4,6-Trihydroxy-3-geranyl-acetophenone (tHGA) as a Potent LOX Inhibitor: Synthesis, Structure-Activity Relationship (SAR) Study, and Computational Assignment
No full textA new series of 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA) analogues were synthesized and evaluated for their lipoxygenase (LOX) inhibitory activity. Prenylated analogues 4a-g (half maximal inhibitory concentration (IC50) values ranging from 35 μM to 95 μM) did not exhibit better inhibitory activity than tHGA (3a) (IC50 value: 23.6 μM) due to the reduction in hydrophobic interaction when the alkyl chain length was reduced. One geranylated analogue, 3d, with an IC50 value of 15.3 μM, exhibited better LOX inhibitory activity when compared to tHGA (3a), which was in agreement with our previous findings. Kinetics study showed that the most active analogue (3e) and tHGA (3a) acted as competitive inhibitors. The combination of in silico approaches of molecular docking and molecular dynamic simulation revealed that the lipophilic nature of these analogues further enhanced the LOX inhibitory activity. Based on absorption, distribution, metabolism, excretion, and toxicity (ADMET) and toxicity prediction by komputer assisted technology (TOPKAT) analyses, all geranylated analogues (3a-g) showed no hepatotoxicity effect and were biodegradable, which indicated that they could be potentially safe drugs for treating inflammation
Water/MWCNT nanofluid based cooling system of PVT: Experimental and numerical research
No full textIn this research, an indoor experiment has been carried out of a PV module under controlled operating conditions and parameters. A novel design of thermal collector has been introduced, a complete PVT system assembled and water/MWCNT nanofluid used to enhance the thermal performance of PVT. An active cooling for PVT system has been maintained by using a centrifugal pump and a radiator have been used in the cycle to dissipate the heat of nanofluid in the environment to maintain proposed inlet temperature. 3D numerical simulation has been conducted with FEM based software COMSOL Multiphysics and validated by an indoor experimental research at different irradiation level from 200 to 1000 W/m2, weight fraction from 0 to 1% while keeping mass flow rate 0.5 L/min and inlet temperature 32 °C. The numerical results show a positive response to the experimental measurements. In experimental case, percentage of enhanced PV performance is found as 9.2% by using water cooling system. Higher thermal performance is obtained as approximately 4 and 3.67% in numerical and experimental studies, respectively by using nanofluid than water. In the PVT system operated by nanofluid at 1000 W/m2 irradiation, the numerical and experimental overall efficiency are found to be 89.2 and 87.65% respectively
Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models
No full textThe Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O 3 ) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC’16). Hourly O 3 data was measured continuously for 23 days using an EcoTech O 3 analyzer. To understand more about the distribution of surface O 3 over the Antarctic, we present the spatial and temporal of surface O 3 of long-term data (2009–2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O 3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O 3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O 3 mixing ratio during MASEC’16 increased from a minimum of 5 ppb to ~ 10–13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O 3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O 3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O 3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O 3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O 3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC’16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O 3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O 3 and CO hourly mixing ratios reached up to ~ 38 ppb (O 3 ) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O 3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O 3 over the Antarctic region
Utility of Using the Montreal Cognitive Assessment (MoCA) as a Screening Tool for HIV-Associated Neurocognitive Disorders (HAND) In Multi-Ethnic Malaysia
No full textThis study determines the optimal cut-off scores for the Montreal Cognitive Assessment (MoCA) to detect HIV-associated neurocognitive disorders (HAND) in a multi-ethnic Malaysian HIV-positive cohort by developing demographically corrected normative standards among 283 HIV-negative community-based controls with overlapping demographic characteristics. The norms (corrected for age, sex, education, ethnicity) were applied to 342 HIV-positive virally suppressed individuals on cART. Impairment rates were classified using the Global Deficit Score (GDS ≥.5) method. The MoCA was also scored according to the recommended cut-off of ≤ 26, and functional decline was applied to both impairment definitions to classify HAND per the Frascati criteria. The ≤ 26 cut-off considerably overestimated cognitive impairment in both samples (59.4% HIV-negative; 69.3% HIV-positive). In contrast, corrected scores yielded impairment rates consistent with what has been reported internationally in virally suppressed cohorts (23.4% with 83.3% mild impairment, 16.7% moderate impairment). A supplemental file allowing the computation of corrected MoCA scores and impairment status is included
All-fiber ytterbium doped Q-switched fiber laser based on copper nanoparticles saturable absorber
No full textThe Q-switching pulses generation in an Ytterbium-doped fiber laser (YDFL) passively Qswitched by a copper nanoparticles (CuNP) based saturable absorber (SA) was experimentally demonstrated. The high-quality SA with a modulation depth of 36% was fabricated by depositing nano-sized particles of Cu layer onto the surface of polyvinyl alcohol (PVA) film through the thermal evaporation process. By inserting the SA into a YDFL cavity, stable Q-switched operation was achieved with the maximum pulse energy up to 7.48 nJ, the shortest pulse width of 3.89 µs and pulse repetition rates varying from 41 to 104 kHz. These results suggested that CuNP could be developed as an effective SA for pulsed laser operation at 1 µm
Effects of electrolysis on magnetic abrasive finishing of AA6063-T1 tube internal surface using combination machining tool
No full textIn this research, we studied the effects of electrolysis in the magnetic abrasive finishing of an AA6063-T1 tube internal surface. The finishing surface‘s hairline morphology was removed in a short time by physical characteristic transformation of the finishing surface in which the aluminum oxide film was formed during the electrolysis. Next, magnetic abrasive finishing was used to eliminate the oxidation layer and polish the surface to a mirror-finishing standard. The two-step process effectively improved the surface roughness in a shorter time. The morphology changes before and after the finishing process, was studied by surface roughness measurement and scanning electron microscope photographs. Notably, the pit or micro holes formation during the electrolysis on the aluminum oxide film was examined and its effect on the surface roughness was studied. The elements’ residual on the surface was investigated by X-ray photoelectron spectroscopy analyzer before and after the process to confirm the formation and removal of oxidation film on the finishing surface. The lower value for torque measurement in electrolysis combined process compared to the conventional method was due to the porous characteristic of aluminum oxide film