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Fulltext In vitro antimicrobial activity of Cymbopogon citratus (lemongrass) extracts against selected foodborne pathogen

Zulfa, Z., Chia, C. T., Rukayadi, Y.

International Food Research Journal, 2016;23(3):1262-1267.
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Microbial contamination in food system poses risk towards public health. The usage of synthetic
and chemical preservatives to prevent the contamination has become a growing concern due
to the presence of deleterious and harmful substances that can cause environment and health
problems in prolonged exposure. Thus, there are needs to overcome this problem by using
natural products as food preservatives. In this study, the antimicrobial activities of methanolic
Cymbopogon citratus (lemongrass) extracts were tested against five foodborne pathogens,
namely Bacillus cereus, Escherichia coli O157:H7, Klebsiella pneumoniae, Staphylococcus
aureus and Candida albicans. The susceptibility test, minimum inhibitory concentrations
(MIC) and minimum bactericidal concentration (MBC) or minimum fungicidal concentration
(MFC) were conducted using the broth microdilution techniques as described by Clinical and
Laboratory Standard Institute (CLSI). C. citratus extract showed antimicrobial activity against
all tested foodborne pathogens; B. cereus, E. coli O157:H7, K. pneumoniae, S. aureus and C.
albicans with the inhibition zone of 12 mm, 7.5 mm, 11 mm, 10 mm and 9 mm, respectively.
The MIC of C. citratus extract against B. cereus, E. coli O157:H7, K. pneumoniae, S. aureus
and C. albicans was 0.08 mg/ml, 0.63 mg/ml, 0.04 mg/ml, 0.31 mg/ml, and 0.16 mg/ml,
respectively, while the MBC or MFC was 1.25 mg/ml, 2.50 mg/ml, 2.50 mg/ml, 1.25 mg/
ml and 1.25 mg/ml, respectively. Time–kill curves were determined to assess the correlation
between MIC and bactericidal activity of C. citratus extract at concentrations ranging from 0×
MIC to 4× MIC. The bactericidal endpoint for B. cereus, E. coli O157:H7, S. aureus and C.
albicans was at 4× MIC after 2 h, 4× MIC after 2 h, 4× MIC after 30 min and 4× MIC after 4
h, respectively whereas K. pneumoniae was not completely killed after 4 hours of incubation at
4× MIC. The potent antimicrobial activity of C. citratus extract may support its usage as natural
antimicrobial agent
Fulltext Low birth weight babies (letter 1)

Chia CP

Med J Malaysia, 1995 Mar;50(1):120.
PMID: 7752969

Comment on: Yadav H. Low birth weight incidence in Lundu, Sarawak. Med J Malaysia. 1994 Jun;49(2):164-8
Transfer of knowledge, skills and confidence from a faculty development programme for health professions educators into practice

Chia CF, Nadarajah VD, Lim V, Kutzsche S

Med Teach, 2021 Jul;43(sup1):S46-S52.
PMID: 32552199 DOI: 10.1080/0142159X.2020.1776239

BACKGROUND: Faculty development programmes should incorporate the transfer of knowledge, skills, and confidence from the training to educational practice. However, there is a risk that transfer may fail due to inadequate integration of knowledge, skills, and confidence. The study evaluated transfer levels, guided by learned principles from a faculty development programme.
METHOD: The submitted self-reports on a pedagogical intervention of 92 out of 190 health professions educators who participated in a mandatory teaching and learning training programme, were analysed by a mixed-method approach guided by a structured conceptual framework.
RESULTS: Overall 93.4% reported the successful transfer of learning. Participants incorporated sustainable changed practice (level A, 57.6%), showed reflection on the impact of changed practice (level B, 21.7%), and performed effect analysis (level C, 14.1%). The rest planned application of learning (level D, 4.4%) and identified gaps in current practice or developed an idea for educational intervention but did not implement (level E, 2.2%).
CONCLUSION: The majority of participants transferred their learning. Faculty development programmes must ensure successful transfer of knowledge, skills, and confidence from the training to educational practice to ensure sustainable development of teaching and learning practices.
Thermodynamic aspects of sorption of Fe2+ onto unbleached Kraft fibres

Chia CH, Duong TD, Nguyen KL, Zakaria S

J Colloid Interface Sci, 2007 Mar 1;307(1):29-33.
PMID: 17174968

The sorption of Fe(2+) onto unbleached kraft fibre was investigated at different conditions such as pH, temperature, and concentrations. The sorption, which increased with concentration and temperature, followed the Langmuir isotherm. Thermodynamically, the process was spontaneous and endothermic. It was found that the precipitation of Fe(2+) was highly dependent on pH and reached 100% when pH exceeded approximately 8.
Fulltext Fabrication and characterization of graphene hydrogel via hydrothermal approach as a scaffold for preliminary study of cell growth

Lim HN, Huang NM, Lim SS, Harrison I, Chia CH

Int J Nanomedicine, 2011;6:1817-23.
PMID: 21931479 DOI: 10.2147/IJN.S23392

BACKGROUND: Three-dimensional assembly of graphene hydrogel is rapidly attracting the interest of researchers because of its wide range of applications in energy storage, electronics, electrochemistry, and waste water treatment. Information on the use of graphene hydrogel for biological purposes is lacking, so we conducted a preliminary study to determine the suitability of graphene hydrogel as a substrate for cell growth, which could potentially be used as building blocks for biomolecules and tissue engineering applications.
METHODS: A three-dimensional structure of graphene hydrogel was prepared via a simple hydrothermal method using two-dimensional large-area graphene oxide nanosheets as a precursor.
RESULTS: The concentration and lateral size of the graphene oxide nanosheets influenced the structure of the hydrogel. With larger-area graphene oxide nanosheets, the graphene hydrogel could be formed at a lower concentration. X-ray diffraction patterns revealed that the oxide functional groups on the graphene oxide nanosheets were reduced after hydrothermal treatment. The three-dimensional graphene hydrogel matrix was used as a scaffold for proliferation of a MG63 cell line.
CONCLUSION: Guided filopodia protrusions of MG63 on the hydrogel were observed on the third day of cell culture, demonstrating compatibility of the graphene hydrogel structure for bioapplications.
Fulltext Simple room-temperature preparation of high-yield large-area graphene oxide

Huang NM, Lim HN, Chia CH, Yarmo MA, Muhamad MR

Int J Nanomedicine, 2011;6:3443-8.
PMID: 22267928 DOI: 10.2147/IJN.S26812

Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.
An overview on the key advantages and limitations of batch and dynamic modes of biosorption of metal ions

Malbenia John M, Benettayeb A, Belkacem M, Ruvimbo Mitchel C, Hadj Brahim M, Benettayeb I, et al.

Chemosphere, 2024 Jun;357:142051.
PMID: 38648988 DOI: 10.1016/j.chemosphere.2024.142051

Water purification using adsorption is a crucial process for maintaining human life and preserving the environment. Batch and dynamic adsorption modes are two types of water purification processes that are commonly used in various countries due to their simplicity and feasibility on an industrial scale. However, it is important to understand the advantages and limitations of these two adsorption modes in industrial applications. Also, the possibility of using batch mode in industrial scale was scrutinized, along with the necessity of using dynamic mode in such applications. In addition, the reasons for the necessity of performing batch adsorption studies before starting the treatment on an industrial scale were mentioned and discussed. In fact, this review article attempts to throw light on these subjects by comparing the biosorption efficiency of some metals on utilized biosorbents, using both batch and fixed-bed (column) adsorption modes. The comparison is based on the effectiveness of the two processes and the mechanisms involved in the treatment. Parameters such as biosorption capacity, percentage removal, and isotherm models for both batch and column (fixed bed) studies are compared. The article also explains thermodynamic and kinetic models for batch adsorption and discusses breakthrough evaluations in adsorptive column systems. The review highlights the benefits of using convenient batch-wise biosorption in lab-scale studies and the key advantages of column biosorption in industrial applications.