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Effect of strontium substitution on structural, sinterability, physicomechanical and biological properties of akermanite ceramic

Mohammadi H, Baba Ismail YM, Shariff KA, Mohd Noor AF

J Mech Behav Biomed Mater, 2021 04;116:104379.
PMID: 33561674 DOI: 10.1016/j.jmbbm.2021.104379

Despite the excellent in vitro and in vivo performance of akermanite ceramic, its poor toughness and strength limit the biomedical application, particularly under load. Herein, the incorporation of strontium enhanced the physicomechanical properties of akermanite and this is ascribed to the decrease in grain size and better sinterability. To investigate the biological performance, the bone-cell interaction with sintered pellets was assessed by in vitro biocompatibility with human fetal osteoblast cell (hFOB). The cell viability using MTT assay revealed that the Ca1.9Sr0.1MgSi2O7 pellets with finer grain size provided better interaction between the cells compared to the unsubstituted counterpart with larger grain size. Our findings highlighted that the synergistic effect of controlled degradation rate and release of Sr2+ into the medium enhanced the in vitro biological properties of akermanite-based materials.
Tailoring mechanical and in vitro biological properties of calcium‒silicate based bioceramic through iron doping in developing future material

Myat-Htun M, Mohd Noor AF, Kawashita M, Baba Ismail YM

J Mech Behav Biomed Mater, 2022 Feb 07;128:105122.
PMID: 35168129 DOI: 10.1016/j.jmbbm.2022.105122

Dense iron-doped akermanite ceramics with 0.3, 0.6 and 0.9 mol% of Fe3+ were synthesized via high-speed planetary ball milling and subsequently subjected to sintering at 1200 and 1250 °C. The aim of the current work was to investigate the effect of trivalent iron (Fe3+) in tuning the physicomechanical and in vitro biological properties of akermanite. The incorporation of Fe3+ into akermanite host and sintering at a high temperature of 1200 °C resulted in a synergistic effect in enhancing the sinterability and densification of akermanite ceramics. Although varying the Fe3+ content, it was found that similar densification and mechanical properties (i.e., diametral tensile strength, Vickers microhardness and fracture toughness) were observed for the doped ceramics at 1250 °C, indicating that this newly developed formulation is temperature-dependent. Fe3+-doped akermanite ceramics revealed greater in vitro bioactivity as compared to undoped akermanite, demonstrated by better coverage of needle-like apatite precipitates after 21 days of immersion in simulated body fluid. Additionally, Rat-1 cells cultured in direct contact with Fe3+-doped akermanite ceramics showed almost double levels of cell proliferation than their undoped counterpart on both 3 and 7 days of culture. Our finding suggests that 0.9Fe-AK ceramic is a suitable formulation to be considered for future bone substitute material as it provides sufficient mechanical strength as well as good bioactivity and the ability to encourage cell proliferation.
Fulltext Dystrophin gene expression and intracellular calcium changes in the giant freshwater prawn, Macrobrachium rosenbergii, in response to white spot symptom disease infection

Noor AF, Soo TCC, Ghani FM, Goh ZH, Khoo LT, Bhassu S

Heliyon, 2017 Dec;3(12):e00446.
PMID: 29322096 DOI: 10.1016/j.heliyon.2017.e00446

Background: Dystrophin, an essential protein functional in the maintenance of muscle structural integrity is known to be responsible for muscle deterioration during white spot syndrome virus (WSSV) infection among prawn species. Previous studies have shown the upregulation of dystrophin protein in Macrobrachium rosenbergii (the giant freshwater prawn) upon white spot syndrome virus (WSSV) infection. The literature has also suggested the important role of calcium ion alterations in causing such muscle diseases. Thus, the interest of this study lies within the linkage between dystrophin functioning, intracellular calcium and white spot syndrome virus (WSSV) infection condition.
Methods: In this study, the dystrophin gene from M. rosenbergii (MrDys) was first characterised followed by the characterization of dystrophin gene from a closely related shrimp species, Penaeus monodon (PmDys). Dystrophin sequences from different phyla were then used for evolutionary comparison through BLAST analysis, conserved domain analysis and phylogenetic analysis. The changes in mRNA expression levels of dystrophin and the alteration of intracellular calcium concentrations in WSSV infected muscle cells were then studied.
Results: A 1246 base pair long dystrophin sequence was identified in the giant freshwater prawn, Macrobrachium rosenbergii (MrDys) followed by 1082 base pair long dystrophin sequence in P. monodon (PmDys). Four conserved domains were identified from the thirteen dystrophin sequences compared which were classified into 5 different phyla. From the phylogenetic analysis, aside from PmDys, the characterised MrDys was shown to be most similar to the invertebrate phylum of Nematoda. In addition, an initial down-regulation of dystrophin gene expression followed by eventual up-regulation, together with an increase in intracellular calcium concentration [Ca2+]
i
were shown upon WSSV experimental infection.
Discussion: Both the functionality of the dystrophin protein and the intracellular calcium concentration were affected by WSSV infection which resulted in progressive muscle degeneration. An increased understanding of the role of dystrophin-calcium in MrDys and the interactions between these two components is necessary to prevent or reduce occurrences of muscle degeneration caused by WSSV infection, thereby reducing economic losses in the prawn farming industry from such disease.
CdSe nanostructured thin film by electrophoretic deposition for quantum dots sensitized solar cell

Kyaw HMA, Ishak MN, Mohd Noor AF, Kawamura G, Matsuda A, Yaacob KA

Nanotechnology, 2024 Mar 18;35(23).
PMID: 38387094 DOI: 10.1088/1361-6528/ad2c5a

Cadmium selenide (CdSe) quantum dots (QDs) with different size, 2.5 and 3.2 nm, were successfully deposited on mesoporous titanium dioxide (TiO2) (Degussa-P25) nanostructures by electrophoretic deposition method (EPD) at the applied voltage 100 V for 120 s deposition time. In this study, the morphology of CdSe films deposited by EPD and the performance of the film when assembled into a solar cell were investigated. From the field emission scanning electron microscopy cross-section, the thickness of the CdSe nanoparticles with size 2.5 nm films were 3.4 and 3.0μm for CdSe 3.2 nm nanoparticles film. The structure of 2.5 nm is denser than compare of 3.2 nm CdSe nanoparticles. From UV visible spectroscopy, the band gap calculated for 2.5 nm CdSe nanoparticles is 2.28 eV and for 3.2 nm is 2.12 eV. Photovoltaic characterization was performed under an illumination of 100 mW cm-2. A photovoltaic conversion efficiency of 1.81% was obtained for 2.5 nm CdSe and 2.1% was obtained for 3.2 nm CdSe nanoparticles. This result shows that the photovoltaic efficiency is dependent on CdSe nanoparticle size.
Fulltext Prevalence and associated factors of suspected occupational skin diseases among restaurant workers in peninsular Malaysia: secondary data analysis of Registry for Occupational Disease Screening (RODS)

Ahmad Fuad MH, Samsudin EZ, Yasin SM, Ismail N, Mohamad M, Muzaini K, et al.

BMJ Open, 2024 Aug 13;14(8):e079877.
PMID: 39142678 DOI: 10.1136/bmjopen-2023-079877

OBJECTIVES: Occupational skin diseases (OSDs) pose significant risks to the health and well-being of restaurant workers. However, there is presently limited evidence on the burden and determinants of OSDs among this occupational group. This research aims to estimate the prevalence and associated factors of suspected OSDs among restaurant workers in Peninsular Malaysia.
DESIGN: A secondary data analysis of the 2023 Registry of Occupational Disease Screening (RODS) was performed. The RODS survey tool, which included the Nordic Occupational Skin Questionnaire, a symptoms checklist and items on work-relatedness, was used to screen for OSDs. Logistic regression analyses were performed to identify associated factors.
SETTING AND PARTICIPANTS: Restaurant workers (n=300) registered in RODS from February 2023 to April 2023, aged 18 years and above and working in restaurants across Selangor, Melaka and Pahang for more than 1 year, were included in the study, whereas workers who had pre-existing skin diseases were excluded.
RESULTS: The prevalence of suspected OSDs among study participants was 12.3%. Higher odds of suspected OSDs among study participants were observed among those exposed to wet work (adjusted OR (AOR) 22.74, 95% CI 9.63 to 53.68) and moderate to high job stress levels (AOR 4.33, 95% CI 1.80 to 10.43).
CONCLUSIONS: These findings suggest that OSDs are a significant occupational health problem among restaurant workers. Interventions targeting job content and wet work may be vital in reducing OSDs among this group of workers.