13474 research outputs found
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Formation and characterization of rare earth oxides as high-K gate dielectrics on germanium substrate / Tahsin Ahmed Mozaffor Onik
No full textIn this study, Sm2O3/Ge and Ho2O3/Ge stack based metal oxide semiconductor (MOS) capacitors were prepared from radio frequency (RF) sputtered metallic Sm on Ge sub-strate and metallic Ho on Ge substrate followed by thermal oxidation/nitridation in N2O ambient. The effects of several oxidation/nitridation temperatures, i.e., 300 °C – 600 °C on the sputtered Sm/Ge and influence of various oxidation/nitridation durations, i.e., 5 – 20 min on both sputtered Sm/Ge and Ho/Ge system have been comprehensively investi-gated. The film crystallinity and phase identification, chemical composition, interface chemical bonding states stability and structural morphology were characterized from X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and High-resolution transmission electron microscopy (HRTEM). Formation of stoichi-ometric trigonal-Sm2O3 dielectric interface has been verified for thermally oxidized/ni-trided sputtered Sm/Ge system. In contrary, sub-stoichiometric cubic-Ho2O3 has been identified for thermally oxidized/nitrided sputtered Ho/Ge system. Both the stacking structure produced sandwiched interfacial layer containing asymmetrically distributed Ge−O, and Ge−N contents while oxidized/nitrided Sm/Ge stack produced an additional stable interfacial germanate (Sm−O−Ge). Suppression of GeO (g) volatilization was ev-ident from the XPS analysis due to GeO (g) trapping mechanism instigated by interfacial germanate (Sm−O−Ge) formation for oxidized/nitrided Sm/Ge while IL rich with Ge3N4 contributed to inhibit the volatilization of GeO (g) for oxidized/nitrided Ho/Ge system. The HRTEM analysis also validated double stack amorphous interfaces obtaining physi-cal oxide thickness
A secure pin-entry method resistant to shoulder-surfing and recording attacks / Farid Binbeshr
No full textThe regular PIN-entry method has been considered the most common method of authentication
for systems and networks. However, PINs are easy to be captured through
shoulder-surfing and recording attacks. An adversary may shoulder surf the authentication
session to obtain the PIN. He or she may use a video-recording device to record a user
while performing authentication and later reproduce the PIN. It is also possible that the
adversary might install spyware on the compromised device and capture the user input and
screen content. This problem with the regular PIN-entry method could be attributed to
the involuntary nature of entering the original PIN during authentication. A plethora of
PIN-entry methods have been proposed in the literature to mitigate such attacks. They
are categorised into direct input and indirect input methods according to the way of
entering the original PIN. Unfortunately, these methods either provide no protection against
shoulder-surfing and recording attacks (video-based and spyware-based) or hamper the
PIN-entry method’s usability or compatibility. In this research, an indirect input method
that employs the challenge-response approach is proposed in order to produce a One Time
PIN (OTP) that obscures the original PIN. Three versions of the proposed PIN-entry
method are designed. Two user studies were conducted; preliminary and primary. The
preliminary user study was used to find the best version of the proposed PIN-entry method.
The primary user study was used to evaluate the security and usability of the best version
and compared it with the related work. The results of the user study manifest that the
proposed PIN-entry method provides better security than the existing PIN-entry methods
while maintaining an acceptable level of usability. Moreover, the user feedback fully supports the use of the proposed PIN-entry method in critical-security situations
Carbon dioxide (CO₂) absorption in blends of aqueous solutions of monoethanolamine (MEA) and L-serine / Mishalny Nair Raghavan
No full textExpansion in carbon dioxide discharges in the climate is a widespread matter that needs a conclusive determination in order to direct the creating hazard of environment change. Various examinations have been led over the end to settle this issue. The principal investigation of this study is to investigate the solubility of CO2 in aqueous MEA + L-Ser solution. This is done by exploring the effect of various elements on the absorption process, for example, concentration, temperature and CO2 loading. In this work, CO2 solubility is estimated in the aqueous solution of monoethanolamine (MEA) + Serine (L-Ser) using a high-pressure CO2 absorption reactor. The analysis was done at various pressure (50–200 psi) and under four distinct temperatures (303.15 K–333.15 K). The composition of aqueous solutions was used as 2.0 M MEA, 1.5 M MEA + 0.5 M L-SER and 1.0 M MEA + 1.0 M L-SER. It was seen that at a similar pressure; the CO2 loading decreases with an increase in temperature. For sure, at a consistent temperature, the solution loading increases as the pressure builds, which shows that the response is exothermic response. It is prescribed to investigate more on the solubility of CO2 absorption using original form of amino acids with various solvents like MDEA, DEA, DIPA and so forth
Online learning in undergraduate medical education: Exploring students' preference on online learning tools and modes of learning / Nur Amirah Farhanah Hashim
No full textThe declaration of COVID-19 as a pandemic and Movement Control Order (MCO) had transformed the traditional face-to-face learning to online learning. During the pandemic, the online learning activities were conducted in students’ own learning environment. Therefore, this study aimed to explore the preferences of online learning tools and modes of learning among the undergraduate medical students using online learning during their preclinical studies. A qualitative study involving focus group discussions was conducted for this study. Undergraduate medical students of Faculty of Medicine, Universiti Malaya who are currently in Year 2 and Year 3 were recruited for the purpose of this study. Ethical approval was obtained prior to that, and the participants were recruited by approaching the students batch representatives using social media platform (i.e., WhatsApp, email). A total of thirty students participated in four focus group discussions. The discussions were conducted online using Microsoft Teams, and were video recorded. The data were analyzes using thematic analysis with the use of content analysis technique. The trustworthiness of the findings were done via credibility by giving the findings summary to the participants, while transferability was also ensured. Three themes were generated, namely: (i) Online learning tools, (ii) online learning modes, and (iii) concerns and areas of improvement for online learning implemented. Theoretical frameworks using self- regulated learning (SRL) and scaffolding concepts were used in addressing the research gaps found from the previous literatures, in order to answer the research questions of this study. The importance of SRL and scaffolding in online learning remains relevant, and thus modification required to suit with the learner needs in future settings. This study embarks on an improved quality of online learning for medical education to take place. Further investigation such as exploring the relationship between SRL and scaffolding in online learning may further enhance the findings generalizability
Room temperature modified magnetic particles based dispersive solid-phase extraction for the determination of phthalates and mercury(II) ions in water / Abdulhadi Muftah Faraj Benrabha
No full textSample preparation is one of the important procedures in analytical chemistry. Sample preparation techniques have evolved from macro to micro scale to fulfill the requirement of green analytical chemistry. Magnetic dispersive solid-phase extraction (MDSPE) techniques utilizing magnetic solid-based sorbent for the extraction of organic and inorganic compounds from water is one of the emerging sample preparation techniques. On the other hand, the preparation of magnetic solid sorbents for solid-phase extraction often involved time-consuming complex multistep and high-temperature reactions. In this study, the preparation of magnetic solid sorbents was simplified using a single-step coating and the functionalization of magnetic particles at room temperature. The prepared solid adsorbents were a phenyl functionalized magnetic adsorbent (Fe3O4@SiO2-Ph) and poly (4-vinylphenol) coated magnetic adsorbent (Fe3O4@PVP). The Fe3O4@SiO2-Ph was used to determine phthalate esters (butyl phthalate, butyl benzyl phthalate, di-ethylhexyl phthalate, and di-n-octyl phthalate) in water. Under optimized conditions, this developed magnetic dispersive solid-phase extraction method achieved the pre-concentration factor of 100, low method detection limit (0.62–1.02 μgL-1), and limit of quantitation (1.98–3.25 μgL-1), wide linear dynamic range (0.5–100 μgL-1), with a good coefficient of determination (>0.9980) and good repeatability (relative standard deviation <5%) during the extraction of the selected phthalate esters. The developed method was also successfully applied to analyze the selected phthalate esters in drinking water, mineral water, and surface water from the lake with good extraction efficiency (70–102%) and high precision (≤5%). The Fe3O4@PVP was used for the determination of Hg2+ in water. Under optimized conditions, the developed magnetic dispersive solid-phase extraction method reached a low detection limit (0.01 μgL-1), the limit of quantification (0.04 μgL-1), and a good coefficient of determination, R2 of ~1. This method also showed a good recovery (72-90%), high intra-day and inter-day precision at a concentration ranging from 100 to 2000 μgL-1. This method was also used successfully to determine Hg2+ in drinking water, mineral water, and surface water. In conclusion, this study showed that a more sustainable alternative method could be applied in preparing effective magnetic solid sorbent for MDSPE
Micro-bottle resonator for liquid ethanol and sodium hypochlorite sensing / Nurul Atika Baharuddin
No full textOptical micro-bottle resonator (MBR) structure fabricated based on arc fusion approach was widely deployed to implement highly compact, low cost and versatile sensor device. This dissertation presents an investigation on MBR for liquid ethanol and sodium hypochlorite sensing. The resonator was made of an SMF-28 silica fiber using a new method known as “soften-and-compress” to create a bottle structure. At first, the MBR with a midriff diamete
Catalytic reaction of mediated oxidation in ethylbenzenes and benzyl alcohol using gold supported on zinc oxide catalyst / Afiq Anwar
No full textGold nanoparticles of 3 nm supported on zinc oxide was synthesized by urea deposition precipitation then utilized as a catalyst in ethylbenzene and benzylalcohol oxidation using tert-butyl hydroperoxide as the oxidant in acetonitrile solvent. The catalyst gave more than 50% conversion and high selectivity towards acetophenone (50%) as the major product but moderate selectivity towards other products such as 1-phenylethanol, benzaldehyde, benzoic acid, and other compounds in 5 mL acetonitrile solvent at 100 °C for 24 hours reaction. The catalyst showed high selective for benzylalcohol oxidation with 60.3 % conversion and 100 % selectivity towards benzaldehyde. The fresh and spent catalysts were comprehensively characterized by XRD, HRTEM, XRF, BET and ATR-IR to correlate the catalyst activity. Factors affecting the catalytic activity in ethylbenzene oxidation such as gold loading, calcination treatment at 300 °C, type of solvent, reaction time, reaction temperature, oxidant to ethylbenzene molar ratio, catalyst weight and solvent volume were studied. The gold nanoparticle introduces a very selective reaction pathway and is an environmentally friendly catalyst as the oxidant used is less harmful
Assessment of river water quality and treats to safe water supply in Malaysia / Adam Harith Zafrul Fazry
No full textThe spatial water quality trends of sixteen monitoring stations distributed along the
Langat River basin are investigated in this study, which spans the years 2016 to 2020.
The health and status of the stream were examined and appraised from numerous angles.
First, agglomerative HCA was used, in which sixteen monitoring sites were grouped into
four groups based on similar land use practices and contaminants. Then, using PCA, it
was determined which contaminants were the most significant contributors to water
contamination. BOD, COD, and NH3 were determined to be the main proponents based
on PCA. The findings were further validated by the M-K test, which revealed a growing trend in COD and BOD. The findings of this study may enable decision-makers in developing a more comprehensive policy, including, without a doubt, upgrading treatment facilities into an upgraded water treatment plant that will aid in accomplishing smooth water supply operations. We can infer from this evaluation that statistical analysis can find substantial data on the geographical fluctuation of a vast and complex river water
quality dataset
Risk assessment on clinical waste activity for a selected dialysis activity / Farid Hakem Nozlan
No full textClinical waste management is the main activities during the dialysis activities. The
activity has been considered as risky activity it because involving the human health. The
purpose of research is to create a safer of workplace for dialysis workers during clinical
waste activity at dialysis center. The main objective of the research is to identify potential
hazard that occur during the dialysis activity, to determine the hazard and access the
control measure to reduce the risk and hazard at dialysis center. The methodology that
been applied in the research which is site observations at selected dialysis center at
Selangor to identify the potential hazard. Questionnaire been constructed thru the survey
and 60 respondents were involve identifying the hazard among dialysis center workers.
The HIRARC form is used to identify the risk assessment and risk control after the
process identification hazard during the survey. The research finds there were potential
hazard occur in clinical waste during dialysis activity which is physical. Biological
,chemical and ergonomic hazard. The analysis from the survey shows that the workers at
dialysis center are aware of the exposed to the hazard. Majority of the respondent were
strongly agreed that by improve the risk control could reduce the hazard exposure. In the
summary of HIRARC assessment found that there were 3 high risk hazard form 19 hazard
that need immediate action and control measure to reduce the risk that will give impact
to the workers. In this research, risk control was suggested to reduce the risk and to
improve the lack of implementation of the control measure. It can be concluded that there
was hazard occur in clinical waste activity during dialysis activity and most of them were
low and medium risk. Without comprehensive action taken by employer, the hazard can
give impact to human and environment
Optimization of biochar yield using hydrothermal carbonization using response surface methodology for the adsorption of methylene blue / Aswwinyy Marimuthu
No full textThe objective of this research study is to produce and optimise the biochar yield using
DOE. In order to achieve the objective of this study, the treated separator sludge that had
undergone submerged fermentation was added into a hydrothermal autoclave reactor to
produce biochar with varying temperatures (150-220oC) and holding times (0.5-2.0
hours) and the yield was calculated and tabulated. The biochar was then used to study the
reduction efficiency of methylene blue solution with the concentration of 50mg/L. Based
on the study, it was found that the optimised condition for this research work was at
temperature 150oC and holding time of 0.5 hours, where the yield produced was 74%. At
these optimised conditions, adsorption studies with different concentration of methylene
blue solution were conducted, where the reduction was above 90% and remained constant
at 150mg/L, thereafter. As for the statistical analysis, the reaction temperature and the
holding time shows significant reliability to the biochar yield produced as the p-values
obtained was less than 0.05