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Effect of powder to liquid ratio on tensile strength and glass transition temperature of alumina filled poly methyl methacrylate (PMMA) denture base material

Mohamed SH, Arifin A, Mohd Ishak ZA, Nizam A, Samsudin AR

Med J Malaysia, 2004 May;59 Suppl B:147-8.
PMID: 15468861

The aim of this study was to evaluate the mechanical properties and glass transition temperature (Tg) of a denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3). The glass transition temperature was studied by using differential scanning calorimetry (DSC). The effect of powder-to-liquid ratio was investigated. The result showed that the tensile properties and the Tg were slightly effected by the powder-to-liquid ratio. The ratio of 2.2:1 by weight of powder to liquid was found to be the best ratio for mixing the material to give the best result in this formulation.
Tensile strength and water absorption of alumina filled poly (methyl methacrylate) denture base material

Nizam A, Mohamed SH, Arifin A, Mohd Ishak ZA, Samsudin AR

Med J Malaysia, 2004 May;59 Suppl B:145-6.
PMID: 15468860

The aim of this study was to evaluate the tensile properties and water absorption of denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3) as particulate filler. Specimens for mechanical testing were prepared by adding composite powder to the monomer followed by hand mixing as in dental laboratory procedure. The tensile strength of the prepared denture base material was slightly higher than commercial denture base material, while the water absorption was almost the same for all formulation of denture base materials.
Mechanical and thermal properties of hydroxyaptite filled poly (methyl methacrylate) heat processed denture base material

Mohamed SH, Arifin A, Mohd Ishak ZA, Nizam A, Samsudin AR

Med J Malaysia, 2004 May;59 Suppl B:25-6.
PMID: 15468801

The aim of this study was to evaluate the effect of powder-to-liquid ratio on the glass transition temperature (Tg) and the tensile properties of denture base material prepared from poly (methyl methacrylate) (PMMA) and hydroxyapatite (HA) previously treated with 3-trimethoxysilylpropyl methacrylate (gamma-MPS). Specimens for mechanical testing were prepared by adding composites powder (PMMA, BPO and HA) to the monomer (MMA and EGDMA) followed by hand mixing as in dental laboratory description usage. The glass transition temperature was studied by using differential scanning calorimetry (DSC). It was observed that the tensile properties and the Tg were affected by the powder-to-liquid ratio. The mechanical characterization of the materials were performed by using single edge notch-tension (SEN-T) specimens; the fracture toughness was slightly higher in formulation which contained HA filler compared to commercial denture base material.
Fulltext Recycling Waste Cotton Cloths for the Isolation of Cellulose Nanocrystals: A Sustainable Approach

Mohamed SH, Hossain MS, Mohamad Kassim MH, Ahmad MI, Omar FM, Balakrishnan V, et al.

Polymers (Basel), 2021 Feb 19;13(4).
PMID: 33669623 DOI: 10.3390/polym13040626

There is an interest in the sustainable utilization of waste cotton cloths because of their enormous volume of generation and high cellulose content. Waste cotton cloths generated are disposed of in a landfill, which causes environmental pollution and leads to the waste of useful resources. In the present study, cellulose nanocrystals (CNCs) were isolated from waste cotton cloths collected from a landfill. The waste cotton cloths collected from the landfill were sterilized and cleaned using supercritical CO2 (scCO2) technology. The cellulose was extracted from scCO2-treated waste cotton cloths using alkaline pulping and bleaching processes. Subsequently, the CNCs were isolated using the H2SO4 hydrolysis of cellulose. The isolated CNCs were analyzed to determine the morphological, chemical, thermal, and physical properties with various analytical methods, including attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR), field-emission scanning electron microscopy (FE-SEM), energy-filtered transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the isolated CNCs had a needle-like structure with a length and diameter of 10-30 and 2-6 nm, respectively, and an aspect ratio of 5-15, respectively. Additionally, the isolated CNCs had a high crystallinity index with a good thermal stability. The findings of the present study revealed the potential of recycling waste cotton cloths to produce a value-added product.
Fulltext Combined and isolated effects of workstation ergonomics and physiotherapy in improving cervicogenic headache and work ability in office workers: a single-blinded, randomized controlled study

Nambi G, Alghadier M, Pakkir Mohamed SH, Vellaiyan A, Ebrahim EE, Sobeh DE, et al.

Front Public Health, 2024;12:1438591.
PMID: 39697289 DOI: 10.3389/fpubh.2024.1438591

OBJECTIVE: The objective of the study is to compare and investigate the combined and individual effects of workstation ergonomics, physiotherapy and patient education in improving CgH headaches and work ability in office workers.
METHODS: 96 eligible CgH participants were divided into the ergonomics modifications group (EMG; n = 24), physiotherapy group (PTG; n = 24), and ergonomics modifications combined with physiotherapy group (EPG; n = 24) and education control group (CNG; n = 24), the participants received the respective treatment for 4 weeks. Primary (CgH frequency) and secondary (CgH pain intensity, CgH disability, flexion rotation test (right and left), neck disability index and work ability) scores were measured. The effects of treatment at various intervals were analyzed with a 4 × 4 linear mixed model analysis (LMM) between treatment groups and time intervals.
RESULTS: Four weeks following training EPG group showed more significant changes in primary outcome CgH frequency; 4.6 CI 95% 3.63 to 5.56 when compare to control group. The same gradual improvement was noticed at 8 weeks 8.2 CI 95% 7.53 to 8.86 and at 6 months follow up 11.9 CI 95% 11.25 to 12.54 when compare to other groups (p = 0.001) which is statistically 52.97% improvement. Similar improvements can be seen in the secondary outcome measures such as CgH pain intensity, CgH disability, flexion rotation test (right and left), neck disability index and work ability in EPG group than the EMG, PTG, and CNG groups (p = 0.001) at 4 weeks, 8 weeks and at 6 months' follow-up.
CONCLUSION: This study observed that the workstation ergonomics and physiotherapy group experienced significantly more improvements in cervicogenic headache patients.
CLINICAL TRIAL REGISTRATION: Identifier NCT05827185.