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Cr2O3 nanoparticles anchored on ZnO nanorods as active heterostructure catalysts for phenol degradation

Lam SM, Sin JC, Abdul Rahman Mohamed

Sains Malaysiana, 2018;47:253-259.

With the rapid civilization and industrialization, water pollution is becoming more and more intricate. Heterogeneous photocatalysis using metal oxide loaded ZnO nanorods is a well-known environmental technology to degrade toxic organic pollutants. In this study, Cr2O3 particles anchored on the ZnO nanorods (Cr2O3/ZnO) were successfully synthesized by a hydrothermal-deposition technique. Microscopic and crystallographic analyses indicated that the synthesized samples consisted of two-phase heterostructure of Cr2O3 and ZnO. The photocatalytic results showed that the phenol degradation by Cr2O3 /ZnO heterostructures was higher than those of pure ZnO and commercial TiO2. The synergetic effect between Cr2O3 and ZnO was the pivotal reason for the improvement of photoactivity as proven by the photoluminescence and terephthalic acid–photoluminescence analyses.
Size and stability of curcumin niosomes from combinations of tween 80 and span 80

Masrina Mohd Nadzir, Tan Wei Fen, Abdul Rahman Mohamed, Siti Farhana Hisham

Sains Malaysiana, 2017;46:2455-2460.

The ratios of Tween 80 to Span 80 are important in controlling the physicochemical characteristics of curcumin niosomes. Thus, in this study the correlations of combination of Tween 80 and Span 80 at different ratios with the size and stability of curcumin niosomes were investigated. Initially curcumin was dissolved in chloroform and methanol (v/v= 3:1), followed by the preparation of niosomes by thin-film hydration method with the mole ratio of mixture of Tween 80 and Span 80 to cholesterol of 2:1. The ratios of Tween 80 to Span 80 in the mixture were set at 1:1, 1:9, 9:1, 2:3 and 3:2 with Hydrophilic-Lipophilic Balance (HLB) values of 9.65, 5.37, 13.93, 8.58 and 10.72, respectively. As expected, niosome barely formed at HLB value 13.93. This might be due to the molecule being hydrophilic and well hydrated which inhibits the formation of a stable bilayer in solution. It was found that the formulation which has higher Span 80 and lower HLB value leads to larger niosome before sonication. The largest niosome size achieved from Tween 80 to Span 80 ratio of 1:9 and 2:3 was 77.36 and 59.85 μm, respectively. On the other hand, for the ratio of 3:2, the largest niosome formed before sonication was less than 50.00 μm. After sonication, the niosome size reduced to less than 35.00 μm for all formulations. It was showed that formulation with Tween 80 to Span 80 ratio of 1:9 has superior curcumin entrapment efficiency and best stability during storage. The results demonstrated that appropriate ratio of Tween 80 to Span 80 was necessary for forming small and stable curcumin niosomes.
Electrophoretic deposition of carbon nanotubes on heat spreader for fabrication of thermal interface materials (TIM)

Raihana Bahru, Abdul Rahman Mohamed, Yeoh WM, Khatijah Aisha Yaacob

Sains Malaysiana, 2017;46:1075-1082.

Thermal interface materials (TIMs) are applied in packaging of electronic devices for heat dissipation purposes. Carbon nanotubes (CNTs) are promising material due to their high thermal conductivity properties which will give optimum performance as TIMs. In this research study, electrophoretic deposition (EPD) is used which enables the deposition process conduct at room temperature with simple equipment setup which beneficial for CNTs deposition. As-produced CNTs was purified and directly deposited on heat spreader using direct current (DC) electricity. Dimethylformamide (DMF) was used as suspension medium for CNTs and the effect of suspension concentration was studied. From the screening of suspension concentration, 0.50 mg/mL yielded good deposition with thickness of 4.78 μm of CNTs deposited on heat spreader at applied voltage of 150V and 10 min deposition time. Further studied in different applied voltage and voltage of 250 V shows the maximum thickness of 15.01 μm with 2.0 mg weight of deposited CNTs which is suitable for fabrication of TIM.
Effect of nickel catalyst layer thickness and grain size prepared by electroplating method to the growth of carbon nanostructures by chemical vapour deposition

Roszaini Md Salleh, Abdul Rahman Mohamed, Raihana Bahru, Wei-Ming Yeoh

Sains Malaysiana, 2018;47:393-402.

A simple method of growing carbon nanostructures (CNS), a mixture of carbon nanotube (CNT) and carbon nanofiber (CNF),
directly on a nickel catalyst layer electroplated on the copper substrate at low reaction temperature and atmospheric
pressure via chemical vapor deposition (CVD) was investigated in this study. The nickel catalyst was prepared using
electroplating methods and the current density was varied to give the nickel catalyst layer with different thicknesses
and grain sizes prior to the growth of CNS which was carried out at 600°C and under a mixture of 25 sccm: 100 sccm of
acetylene to nitrogen for 40 min. A nickel catalyst layer electroplated at 1 mA/cm2, which possess a smaller grain size and
thinner layer of nickel catalyst, enables the synthesis of high quality and dense CNS as well as high ratio of CNT over CNF.
Fulltext Mechanical versus manual cardiopulmonary resuscitation (CPR): an umbrella review of contemporary systematic reviews and more

El-Menyar A, Naduvilekandy M, Rizoli S, Di Somma S, Cander B, Galwankar S, et al.

Crit Care, 2024 Jul 30;28(1):259.
PMID: 39080740 DOI: 10.1186/s13054-024-05037-4

BACKGROUND: High-quality cardiopulmonary resuscitation (CPR) can restore spontaneous circulation (ROSC) and neurological function and save lives. We conducted an umbrella review, including previously published systematic reviews (SRs), that compared mechanical and manual CPR; after that, we performed a new SR of the original studies that were not included after the last published SR to provide a panoramic view of the existing evidence on the effectiveness of CPR methods.
METHODS: PubMed, EMBASE, and Medline were searched, including English in-hospital (IHCA) and out-of-hospital cardiac arrest (OHCA) SRs, and comparing mechanical versus manual CPR. A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) and GRADE were used to assess the quality of included SRs/studies. We included both IHCA and OHCA, which compared mechanical and manual CPR. We analyzed at least one of the outcomes of interest, including ROSC, survival to hospital admission, survival to hospital discharge, 30-day survival, and survival to hospital discharge with good neurological function. Furthermore, subgroup analyses were performed for age, gender, initial rhythm, arrest location, and type of CPR devices.
RESULTS: We identified 249 potentially relevant records, of which 238 were excluded. Eleven SRs were analyzed in the Umbrella review (January 2014-March 2022). Furthermore, for a new, additional SR, we identified eight eligible studies (not included in any prior SR) for an in-depth analysis between April 1, 2021, and February 15, 2024. The higher chances of using mechanical CPR for male patients were significantly observed in three studies. Two studies showed that younger patients received more mechanical treatment than older patients. However, studies did not comment on the outcomes based on the patient's gender or age. Most SRs and studies were of low to moderate quality. The pooled findings did not show the superiority of mechanical compared to manual CPR except in a few selected subgroups.
CONCLUSIONS: Given the significant heterogeneity and methodological limitations of the included studies and SRs, our findings do not provide definitive evidence to support the superiority of mechanical CPR over manual CPR. However, mechanical CPR can serve better where high-quality manual CPR cannot be performed in selected situations.