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Analysis of 1,2(2,3)- and 1,3-positional isomers of diacylglycerols from vegetable oils by reversed-phase high-performance liquid chromatography

Lo SK, Baharin BS, Tan CP, Lai OM

J Chromatogr Sci, 2004 Mar;42(3):145-54.
PMID: 15023251

Separation of 1,2(2,3)- and 1,3-positional isomers of diacylglycerols (DAG) from vegetable oils by reversed-phase high-performance liquid chromatography (RP-HPLC) is investigated. The method is based on isocratic elution using 100% acetonitrile and UV detection at 205 nm. The following elution order of DAG molecular species is identified: 1,3-dilinolein < 1,2-dilinolein < 1,3-dimyristin < 1-oleoyl-3-linoleoyl-glycerol < 1,2-dimyristoyl-rac-glycerol < 1(2)-oleoyl-2(3)-linoleoyl-glycerol < 1-linolenoyl-3-stearoyl-glycerol < 1(2)-linolenoyl-2(3)-stearoyl-glycerol < 1,3-diolein < 1-palmitoyl-3-oleoyl-glycerol < 1,2-dioleoyl-sn-glycerol < 1(2)-palmitoyl-2(3)-oleoyl-glycerol < 1-linoleoyl-3-stearoyl-glycerol < 1,3-dipalmitin < 1(2)-linoleoyl-2(3)-stearoyl-glycerol < 1-oleoyl-3-stearoyl-glycerol < 1,2-dipalmitoyl-rac-glycerol < 1-palmitoyl-3-stearoyl-sn-glycerol < 1,3-distearin < 1,2-distearoyl-rac-glycerol. Linearity is observed over three orders of magnitude. Limits of detection and quantitation range 0.2-0.7 microg/mL for 1,3-dilinolein to 0.6-1.9 microg/mL for 1,2-dioleoyl-sn-glycerol, respectively. Precision and accuracy of the method are also demonstrated. The method is developed to separate mixtures of DAG molecular species produced from edible oils.
Fulltext An Interoperable Component-Based Architecture for Data-Driven IoT System

Lo SK, Liew CS, Tey KS, Mekhilef S

Sensors (Basel), 2019 Oct 09;19(20).
PMID: 31600904 DOI: 10.3390/s19204354

The advancement of the Internet of Things (IoT) as a solution in diverse application domains has nurtured the expansion in the number of devices and data volume. Multiple platforms and protocols have been introduced and resulted in high device ubiquity and heterogeneity. However, currently available IoT architectures face challenges to accommodate the diversity in IoT devices or services operating under different operating systems and protocols. In this paper, we propose a new IoT architecture that utilizes the component-based design approach to create and define the loosely-coupled, standalone but interoperable service components for IoT systems. Furthermore, a data-driven feedback function is included as a key feature of the proposed architecture to enable a greater degree of system automation and to reduce the dependency on mankind for data analysis and decision-making. The proposed architecture aims to tackle device interoperability, system reusability and the lack of data-driven functionality issues. Using a real-world use case on a proof-of-concept prototype, we examined the viability and usability of the proposed architecture.
Diacylglycerol and triacylglycerol as responses in a dual response surface-optimized process for diacylglycerol production by lipase-catalyzed esterification in a pilot packed-bed enzyme reactor

Lo SK, Cheong LZ, Arifin N, Tan CP, Long K, Yusoff MS, et al.

J Agric Food Chem, 2007 Jul 11;55(14):5595-603.
PMID: 17571899

Diacylglycerol (DAG) and triacylglycerol (TAG) as responses on optimization of DAG production using a dual response approach of response surface methodology were investigated. This approach takes the molecular equilibrium of DAG into account and allows for the optimization of reaction conditions to achieve maximum DAG and minimum TAG yields. The esterification reaction was optimized with four factors using a central composite rotatable design. The following optimized conditions yielded 48 wt % DAG and 14 wt % TAG: reaction temperature of 66.29 degrees C, enzyme dosage of 4 wt %, fatty acid/glycerol molar ratio of 2.14, and reaction time of 4.14 h. Similar results were achieved when the process was scaled up to a 10 kg production in a pilot packed-bed enzyme reactor. Lipozyme RM IM did not show any significant activity losses or changes in fatty acid selectivity on DAG synthesis during the 10 pilot productions. However, lipozyme RM IM displayed higher selectivity toward the production of oleic acid-enriched DAG. The purity of DAG oil after purification was 92 wt %.
Fulltext A Mobile Web App to Improve Health Screening Uptake in Men (ScreenMen): Utility and Usability Evaluation Study

Teo CH, Ng CJ, Lo SK, Lim CD, White A

JMIR Mhealth Uhealth, 2019 04 15;7(4):e10216.
PMID: 30985280 DOI: 10.2196/10216

BACKGROUND: Globally, the uptake of health screening is suboptimal, especially in men and those of younger age. In view of the increasing internet access and mobile phone ownership, ScreenMen, a mobile Web app, was developed to improve health screening uptake in men.
OBJECTIVE: This study aimed to evaluate the utility and usability of ScreenMen.
METHODS: This study used both qualitative and quantitative methods. Healthy men working in a banking institution were recruited to participate in this study. They were purposively sampled according to job position, age, education level, and screening status. Men were asked to use ScreenMen independently while the screen activities were being recorded. Once completed, retrospective think aloud with playback was conducted with men to obtain their feedback. They were asked to answer the System Usability Scale (SUS). Intention to undergo screening pre- and postintervention was also measured. Qualitative data were analyzed using a framework approach followed by thematic analysis. For quantitative data, the mean SUS score was calculated and change in intention to screening was analyzed using McNemar test.
RESULTS: In total, 24 men participated in this study. On the basis of the qualitative data, men found ScreenMen useful as they could learn more about their health risks and screening. They found ScreenMen convenient to use, which might trigger men to undergo screening. In terms of usability, men thought that ScreenMen was user-friendly and easy to understand. The key revision done on utility was the addition of a reminder function, whereas for usability, the revisions done were in terms of attracting and gaining users' trust, improving learnability, and making ScreenMen usable to all types of users. To attract men to use it, ScreenMen was introduced to users in terms of improving health instead of going for screening. Another important revision made was emphasizing the screening tests the users do not need, instead of just informing them about the screening tests they need. A Quick Assessment Mode was also added for users with limited attention span. The quantitative data showed that 8 out of 23 men (35%) planned to attend screening earlier than intended after using the ScreenMen. Furthermore, 4 out of 12 (33%) men who were in the precontemplation stage changed to either contemplation or preparation stage after using ScreenMen with P=.13. In terms of usability, the mean SUS score of 76.4 (SD 7.72) indicated that ScreenMen had good usability.
CONCLUSIONS: This study showed that ScreenMen was acceptable to men in terms of its utility and usability. The preliminary data suggested that ScreenMen might increase men's intention to undergo screening. This paper also presented key lessons learned from the beta testing, which is useful for public health experts and researchers when developing a user-centered mobile Web app.
Antibiotic resistance, plasmid profile and RAPD-PCR analysis of enteropathogenic Escherichia coli (EPEC) clinical isolates

Wan KF, Radu S, Cheah YK, Benjamin PG, Ling CM, Hon SF, et al.

Southeast Asian J Trop Med Public Health, 2003 Sep;34(3):620-6.
PMID: 15115139

Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea among infants in developing countries. A total of 38 EPEC isolates, obtained from diarrhea patients of Hospital Miri, Sarawak, were investigated through plasmid profile, antibiotic resistance and randomly amplified polymorphic DNA (RAPD) analysis. From the 8 types of antibiotics used, all isolates were 100% resistant to furoxime, cephalothin and sulphamethoxazole and showed high multiple antibiotic resistant (MAR) indexes, ranging from 0.5 to 1.0. In plasmid profiling, 22 isolates (58%) showed the presence of one or more plasmids in the range 1.0 to 30.9 mDa. The dendrogram obtained from the results of the RAPD-PCR discriminated the isolates into 30 single isolates and 3 clusters at the level of 40% similarity. The EPEC isolates were highly diverse, as shown by their differing plasmid profiles, antibiotic resistance patterns and RAPD profiles.