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Fulltext Relationship between Attachment Styles and Risk Behavior (Smoking and Bullying) among Secondary School Students: An Experience from Hulu Langat, Malaysia

Mohammadzadeh M, Awang H, Jun CY, Hashim NF, Premkumar A

Iran J Public Health, 2020 Oct;49(10):2006-2008.
PMID: 33346208 DOI: 10.18502/ijph.v49i10.4708
Fulltext Physiology of microalgal biofilm: a review on prediction of adhesion on substrates

Cheah YT, Chan DJC

Bioengineered, 2021 12;12(1):7577-7599.
PMID: 34605338 DOI: 10.1080/21655979.2021.1980671

In view of high energy cost and water consumption in microalgae cultivation, microalgal-biofilm-based cultivation system has been advocated as a solution toward a more sustainable and resource friendlier system for microalgal biomass production. Algal-derived extracellular polymeric substances (EPS) form cohesive network to interconnect the cells and substrates; however, their interactions within the biofilm are poorly understood. This scenario impedes the biofilm process development toward resource recovery. Herein, this review elucidates on various biofilm cultivation modes and contribution of EPS toward biofilm adhesion. Immobilized microalgae can be envisioned by the colloid interactions in terms of a balance of both dispersive and polar interactions among three interfaces (cells, mediums and substrates). Last portion of this review is dedicated to the future perspectives and challenges on the EPS; with regard to the biopolymers extraction, biopolymers' functional description and cross-referencing between model biofilms and full-scale biofilm systems are evaluated. This review will serve as an informative reference for readers having interest in microalgal biofilm phenomenon by incorporating the three main players in attached cultivation systems: microalgae, EPS and supporting materials. The ability to mass produce these miniature cellular biochemical factories via immobilized biofilm technology will lay the groundwork for a more sustainable and feasible production.
A methodological review on the characterization of microalgal biofilm and its extracellular polymeric substances

Cheah YT, Chan DJC

J Appl Microbiol, 2022 Jan 21.
PMID: 35061929 DOI: 10.1111/jam.15455

Biofilm secreted by microalgae are extracellular polymeric substances (EPSs) composed mainly of polysaccharides, proteins, nucleic acids and lipids. These EPSs immobilize the cells and stabilize biofilm, mediating adhesion towards solid surfaces. The EPSs valorization through industrial exploitations and scientific works is becoming more popular, but the bottleneck of such studies is the lack of consensus among researchers on the selection of detection techniques to be used, especially for novice researchers. It is a daunting task for any inexperienced researcher when they fail to identify the right tools needed for microalgal biofilm studies. In this review, a well-refined analysis protocol about microalgal biofilm and EPSs were prepared including its extraction and characterization. Pros and cons of various detection techniques were addressed and cutting-edge methods to study biofilm EPSs were highlighted. Future perspectives were also presented at the end of this review to bridge research gaps in studying biofilm adhesion via EPSs production. Ultimately, this review aims to assist novice researchers in making the right choices in their research studies on microalgal biofilms in accordance to the available technologies and needs.
Effect of high temperature toward microalgal organic matter and its impact toward membrane distillation application

Cheah YT, Lakbir Singh HKK, Chan DJC

Water Environ Res, 2021 Jan 23.
PMID: 33484623 DOI: 10.1002/wer.1515

Membrane distillation (MD) frequently deals with membrane biofouling caused by deposition of algal organic matter (AOM) from algal blooms, hampering the treatment efficiency. In this study, AOMs, which are soluble extracellular polymeric substance (sEPS), bounded EPS (bEPS), and internal organic matter (IOM) from three benthic species (Amphora coffeaeformis, Cylindrotheca fusiformis, and Navicula incerta) were exposed to a temperature range to resemble the MD process. Results showed that EPS had higher polysaccharide fraction than protein with 85.71%, 68.26%, and 71.91% for A. coffeaeformis, N. incerta, and C. fusiformis, respectively. Both the EPS polysaccharide and protein concentration linearly increase with temperature, but the opposite was true for IOM and high-molecular-weight (HMW) polysaccharide. At 80°C, 5812.94 μg/g out of 6304.28 μg/g polysaccharide in A. coffeaeformis was of low molecular weight (LMW); hence, these findings suggested that they were the major foulants to clog the narrow pores within virgin hydrophobic membrane, forming a conditioning layer followed by deposition of HMW and hydrophilic polysaccharides onto the macropores to cause irreversible fouling. Cell lysis occurring at higher temperature increases the total protein content about 25% within the EPS matrix, inducing membrane plugging via hydrophobic-hydrophobic interactions. Overall, the AOM composition at different temperatures will likely dictate the fouling severity in MD. PRACTITIONER POINTS: EPS production of three benthic diatoms was the highest at 80°C. EPS from diatoms consists of at least 75.29% of polysaccharides. Small molecular weight carbohydrates (<12 kDa) were potential foulants. Proteins of internal organic matter (>56%) give irreversible attachment towards membranes. A. coffeaeformis was considered as the most fouling diatoms with highest EPS amount of 6304.28 μg/g.
A novel cultivation platform of duckweed (Lemna minor) via application of beeswax superhydrophobic coatings

Chua MX, Cheah YT, Tan WH, Chan DJC

Environ Res, 2023 May 01;224:115544.
PMID: 36822535 DOI: 10.1016/j.envres.2023.115544

Conventional establishment of laboratory cultures of duckweed Lemna minor are prepared in beakers, Erlenmeyer flasks or Schott bottles. These conventional cultivation methods limit the available surface area for growth which then causes layering of fronds that reduces the efficiency of plants in sunlight capturing. Here, acrylic sheets were spray-coated with a superhydrophobic (SHP) beeswax suspension and these coated acrylic sheets were used as a novel cultivation platform for L. minor. L. minor was grown for 7 days in conventional glass jar which acted as the control and were compared to SHP coated acrylic (SHPA) and SHP coated acrylic with aluminium mesh centrally placed (SHPAM) at similar duration and cultivation conditions. Addition of mesh was to entrap the plantlets and fixed the plantlets' position on the growing platform. The effects of cultivation platforms on growth rate and biochemical compositions of L. minor were monitored. The highest biomass growth was obtained from SHPA cultivation where the relative growth rate (RGR) was 0.0909 ± 0.014 day-1 and the RGR was 2.17 times higher than the control. Moreover, L. minor harvested from SHPA displayed the highest values in total protein content, total carbohydrates content and crude lipid percentage. The values were 156.04 ± 12.13 mg/g, 94.75 ± 9.02 mg/g and 7.09 ± 1.14% respectively. However, the control showed the highest total chlorophyll content which was 0.7733 ± 0.042 mg/g FW. Although SHPA obtained a slightly lower chlorophyll content than the control, this growing platform is still promising as it displayed the highest growth rate as well as other biochemical composition. Hence, this study proved that the proposed method that applied superhydrophobic properties in cultivation of L. minor provided a larger surface area for L. minor to grow, which then resulted in a greater biomass production while simultaneously maintaining the quality of the biochemical compositions of duckweeds.
Enhancing biomass production and biochemical compositions of Spirodela polyrhiza through superhydrophobic cultivation platforms at low light intensity

Chua MX, Saravanan G, Cheah YT, Chan DJC

Plant Physiol Biochem, 2024 Mar;208:108485.
PMID: 38461755 DOI: 10.1016/j.plaphy.2024.108485

Duckweed, a floating macrophyte, has attracted interest in various fields such as animal feedstocks and bioenergy productions. Its enriched nutritional content and rapid growth rate make it particularly promising. However, common laboratory cultures of duckweed often experience fronds layering, diminishing the efficiency of sunlight capturing due to limited surface area on conventional cultivation platforms. In this work, we aimed to address the issue of fronds layering by introducing a novel cultivation platform - a superhydrophobic coated acrylic sheet. The sheet was prepared by spray-coating a suspension of beeswax and ethanol, and its effectiveness was evaluated by comparing the growth performance of giant duckweed, Spirodela polyrhiza, on this platform with that on a modified version. The superhydrophobic coated acrylic sheet (SHPA) and its variant with a metal mesh added (SHPAM) were employed as growing platforms, with a glass jar serving as the control. The plantlets were grown for 7 days with similar growth conditions under low light stress (25 μmol/m2/s). SHPAM demonstrated superior growth performance, achieving a mass gain of 102.12 ± 17.18 %, surpassing both SHPA (89.67 ± 14.97 %) and the control (39.26 ± 8.94 %). For biochemical compositions, SHPAM outperformed in chlorophyll content, protein content and lipid content. The values obtained were 1.021 ± 0.076 mg/g FW, 14.59 ± 0.58 % DW and 6.21 ± 0.75 % DW respectively. Therefore, this work proved that incorporation of superhydrophobic coatings on a novel cultivation platform significantly enhanced the biomass production of S. polyrhiza. Simultaneously, the biochemical compositions of the duckweeds were well-maintained, showcasing the potential of this approach for optimized duckweed cultivation.
Biomass and eicosapentaenoic acid production from Amphora sp. under different environmental and nutritional conditions

Cheah YT, Ng BW, Tan TL, Chia ZS, Chan DJC

Biotechnol Appl Biochem, 2023 Apr;70(2):568-580.
PMID: 35767864 DOI: 10.1002/bab.2379

Eicosapentaenoic acid (EPA) could be extracted from diatoms such as Amphora sp. present abundantly in the ecosystems. In view of the key environmental and nutritional factors governing the diatoms growth rate, culture conditions were optimized for the biomass yield, total lipid content, EPA yield, and fatty acid composition under two main cultivation regimes: photoautotrophic and heterotrophic. The fastest growth rate about 0.20 ± 0.02 g/L and the highest EPA yield about 9.19 ± 3.56 mg EPA/g biomass were obtained by adding 10 g/L glucose and sucrose, respectively. Under photoautotrophic culture conditions, Amphora sp. rendered higher EPA yield at 100 rpm and 16:8 light/dark cycle. Total fatty acids produced predominantly comprised of an approximate 40-70% of saturated fatty acids, followed by 10-27% of monounsaturated fatty acids and then 8-25% of polyunsaturated fatty acids. These findings were able to pave a way for huge-scale microalgal biomass production in commercial EPA production.
Fulltext Lesbian, gay, bisexual, transgender, queer and intersex (LGBTQI+) healthcare in Singapore: perspectives of non-governmental organisations and clinical year medical students

O'Hara CA, Foon XL, Ng JC, Wong CS, Wang FY, Tan CY, et al.

Med Educ Online, 2023 Dec;28(1):2172744.
PMID: 36744296 DOI: 10.1080/10872981.2023.2172744

PURPOSE: International studies document that lesbian, gay, bisexual, transgender, queer and intersex (LGBTQI+) patients face significant health disparities. Studies exploring the attitudes, knowledge, preparedness and comfort levels of healthcare students towards LGBTQI+ health have been conducted in the United States, United Kingdom and Malaysia. This study aims to investigate stigma in healthcare for LGBTQI+ patients in Singapore, and possible upstream factors within medical education.
METHODS: This mixed-methods study adopts a convergent parallel design. The Health Stigma and Discrimination Framework was referenced to devise in-depth interviews with representatives from 13 LGBTQI-affirming non-governmental organisations, analysed through thematic analysis. 320 clinical medical students were surveyed about attitudes, knowledge, comfort, preparedness, and perceived importance of/towards LGBTQI+ health, analysed via descriptive statistics and multivariate regression.
RESULTS: Prevailing stigma in Singaporean society against LGBTQI+ individuals is exacerbated in healthcare settings. Doctors were cited as unfamiliar or uncomfortable with LGBTQI+ health, possibly from lack of training. Among medical students surveyed, the median composite attitudes, comfort and preparedness index was 3.30 (Interquartile Range (IQR) = 0.50), 3.17 (IQR = 0.83), 2.50 (IQR = 1.00) respectively. Only 12.19% of students answered all 11 true-false questions about LGBTQI+ health correctly.
CONCLUSION: Medical students in Singapore have scored sub-optimally in their knowledge and preparedness towards LGBTQI+ health, while interpersonal and structural stigma in healthcare towards LGBTQI+ people in Singapore negatively affects health and wellbeing. These findings are an impetus to improve medical training in this area. High scores among medical students in attitudes, comfort and perceived importance of LGBTQI+ topics demonstrate that there is space for LGBTQI+ health in the local medical education curriculum. Curricular interventions can prioritise content knowledge, communication skills and sensitivity.
Fulltext Protocol paper: kainic acid excitotoxicity-induced spinal cord injury paraplegia in Sprague-Dawley rats

Anjum A, Cheah YJ, Yazid MD, Daud MF, Idris J, Ng MH, et al.

Biol Res, 2022 Dec 09;55(1):38.
PMID: 36494836 DOI: 10.1186/s40659-022-00407-0

BACKGROUND: Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method.
METHODS: In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher.
RESULTS: This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment.
CONCLUSIONS: Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.