MyMedR

A packed bed membrane reactor for production of biodiesel using activated carbon supported catalyst

Baroutian S, Aroua MK, Raman AA, Sulaiman NM

Bioresour Technol, 2011 Jan;102(2):1095-102.

PMID: 20888219 DOI: 10.1016/j.biortech.2010.08.076

In this study, a novel continuous reactor has been developed to produce high quality methyl esters (biodiesel) from palm oil. A microporous TiO2/Al2O3 membrane was packed with potassium hydroxide catalyst supported on palm shell activated carbon. The central composite design (CCD) of response surface methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst amount and cross flow circulation velocity on the production of biodiesel in the packed bed membrane reactor. The highest conversion of palm oil to biodiesel in the reactor was obtained at 70 °C employing 157.04 g catalyst per unit volume of the reactor and 0.21 cm/s cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. High quality palm oil biodiesel was produced by combination of heterogeneous alkali transesterification and separation processes in the packed bed membrane reactor.

Fulltext A review of roll-to-roll nanoimprint lithography

Kooy N, Mohamed K, Pin LT, Guan OS

Nanoscale Res Lett, 2014;9(1):320.

PMID: 25024682 DOI: 10.1186/1556-276X-9-320

Since its introduction in 1995, nanoimprint lithography has been demonstrated in many researches as a simple, low-cost, and high-throughput process for replicating micro- and nanoscale patterns. Due to its advantages, the nanoimprint lithography method has been rapidly developed over the years as a promising alternative to conventional nanolithography processes to fulfill the demands generated from the recent developments in the semiconductor and flexible electronics industries, which results in variations of the process. Roll-to-roll (R2R) nanoimprint lithography (NIL) is the most demanded technique due to its high-throughput fulfilling industrial-scale application. In the present work, a general literature review on the various types of nanoimprint lithography processes especially R2R NIL and the methods commonly adapted to fabricate imprint molds are presented to provide a clear view and understanding on the nanoimprint lithography technique as well as its recent developments.

Fulltext Angioimmunoblastic lymphadenopathy--a fulminant case

Mohamed KN

Singapore Med J, 1991 Aug;32(4):276-8.

PMID: 1776012

A 60 year old male presented with pruritus, excoriations and enlargement of several groups of lymph nodes associated with constitutional symptoms following the intake of an aspirin preparation. Lymph node biopsy established the diagnosis of angioimmunoblastic lymphadenopathy. The need to be aware of this condition is highlighted when patients present with clinical features suspicious of lymphoma.

Antimutagenic effects of aqueous fraction of Myristica fragrans (Houtt.) leaves on Salmonella typhimurium and Mus musculus

Akinboro A, Bin Mohamed K, Asmawi MZ, Yekeen TA

Acta Biochim. Pol., 2014;61(4):779-85.

PMID: 25520963

Natural plant extracts offer a promising hope in the prevention/treatment of cancer arising from genetic mutations. This study evaluated in vitro and in vivo mutagenic and antimutagenic effects of aqueous fraction of Myristica fragrans (AFMF) leaves on TA100 strain of Salmonella typhimurium and Mus musculus (Male Swiss albino mice), respectively. The antioxidant activity of AFMF against 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic and flavonoid contents were determined, followed by its phytochemical elucidation using the Ultra Performance Liquid Chromatography technique (UPLC). The mutagenicity of AFMF at 4, 20, 50, 100, 200, 500, and 1000 µg/well was <2.0 in S. typhimurium and the induced micronucleated polychromatic and normochromatic erythrocytes at 500, 1000, 2000, and 4000 mg/kg were not significantly different from the negative control (p≥0.05). The mutagenic activity of benzo[a]pyrene and cyclophosphamide was significantly suppressed above 50.0% throughout the tested concentrations. Fifty percent of the free radicals from DPPH were scavenged by AFMF at 0.11 mg/ml. Total phenolic and flavonoid contents of AFMF were 51.0 mg GAE/g and 27 mg QE/g, respectively. Rutin was elucidated by the UPLC technique, and thereby suspected to be the phytochemical responsible for the observed antimutagenic activity. Thus far, AFMF seems to contain a promising chemotherapeutic agent for the prevention of genetic damage that is crucial for cancer development.

Fulltext Application of medical information system to identify dengue outbreak factors: Insights from a hyperendemic city in Malaysia

Keat-Chuan Ng C, Linus-Lojikip S, Mohamed K, Hss AS

Int J Med Inform, 2023 Sep;177:105162.

PMID: 37549500 DOI: 10.1016/j.ijmedinf.2023.105162

BACKGROUND: Dengue is widespread globally, but it is more severe in hyperendemic regions where the virus, its vectors, and its human hosts naturally occur. The problem is particularly acute in cities, where outbreaks affect a large human population living in a wide array of socio-environmental conditions. Controlling outbreaks will rely largely on systematic data collection and analysis approaches to uncover nuances on a city-by-city basis due to the diversity of factors.

OBJECTIVE: The main objective of this study is to consolidate and analyse the dengue case dataset amassed by the e-Dengue web-based information system, developed by the Ministry of Health Malaysia, to improve our epidemiological understanding.

METHODS: We retrieved data from the e-Dengue system and integrated a total of 18,812 cases from 2012 to 2019 (8 years) with meteorological data, geoinformatics techniques, and socio-environmental observations to identify plausible factors that could have caused dengue outbreaks in Ipoh, a hyperendemic city in Malaysia.

RESULTS: The rainfall trend characterised by a linearity of R2 > 0.99, termed the "wet-dry steps", may be the unifying factor for triggering dengue outbreaks, though it is still a hypothesis that needs further validation. Successful mapping of the dengue "reservoir" contact zones and spill-over diffusion revealed socio-environmental factors that may be controlled through preventive measures. Age is another factor to consider, as the platelet and white blood cell counts in the "below 5" age group are much greater than in other age groups.

CONCLUSIONS: Our work demonstrates the novelty of the e-Dengue system, which can identify outbreak factors at high resolution when integrated with non-medical fields. Besides dengue, the techniques and insights laid out in this paper are valuable, at large, for advancing control strategies for other mosquito-borne diseases such as malaria, chikungunya, and zika in other hyperendemic cities elsewhere globally.

Fulltext Borderless collaboration is needed for COVID-19-A disease that knows no borders

Mohamed K, Rodríguez-Román E, Rahmani F, Zhang H, Ivanovska M, Makka SA, et al.

Infect Control Hosp Epidemiol, 2020 Oct;41(10):1245-1246.

PMID: 32319878 DOI: 10.1017/ice.2020.162

COVID-19 vaccinations: The unknowns, challenges, and hopes

Mohamed K, Rzymski P, Islam MS, Makuku R, Mushtaq A, Khan A, et al.

J Med Virol, 2022 Apr;94(4):1336-1349.

PMID: 34845731 DOI: 10.1002/jmv.27487

The entire world has been suffering from the coronavirus disease 2019 (COVID-19) pandemic since March 11, 2020. More than a year later, the COVID-19 vaccination brought hope to control this viral pandemic. Here, we review the unknowns of the COVID-19 vaccination, such as its longevity, asymptomatic spread, long-term side effects, and its efficacy on immunocompromised patients. In addition, we discuss challenges associated with the COVID-19 vaccination, such as the global access and distribution of vaccine doses, adherence to hygiene guidelines after vaccination, the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, and vaccine resistance. Despite all these challenges and the fact that the end of the COVID-19 pandemic is still unclear, vaccines have brought great hope for the world, with several reports indicating a significant decline in the risk of COVID19-related infection and hospitalizations.

Fulltext Characterization of Ternary Blends of Vegetable Oils with Optimal ω-6/ω-3 Fatty Acid Ratios

Nehdi IA, Hadj-Kali MK, Sbihi HM, Tan CP, Al-Resayes SI

J Oleo Sci, 2019;68(11):1041-1049.

PMID: 31695014 DOI: 10.5650/jos.ess19111

An optimal ratio of omega-6 to omega-3 (ω-6/ω-3) polyunsaturated fatty acids (PUFA) in the diet prevents the pathogenesis of many inflammatory diseases. This study aimed to synthesize and characterize ternary oil blends with optimal ω-6/ω-3 ratios using olive (OL), sunflower (SU), and cress (CR) oils. The oxidative stability, thermal profile, fatty acid (FA) and tocopherol compositions, and the physicochemical properties of the blends were used to determine their quality. Oil mixtures were prepared with 2, 3, 4, and 5 ω-6/ω-3 ratios. FA composition and tocopherol content were the most important factors affecting the oxidation and thermal stabilities of the oils. All oil mixtures showed good quality indices. Thus, synthetized oil blends with high oxidative stability, high antioxidant content, optimal ω-6/ω-3 ratios, and recommended FA compositions can influence human health. The composition of healthy oil blends with optimal ω-6/ω-3 ratios was expressed mathematically and depicted graphically in a ternary diagram.

Fulltext Comparative validity of a Food Frequency Questionnaire (MyUM Adolescent FFQ) to estimate the habitual dietary intake of adolescents in Malaysia

Mohamed K, Tin TS, Jalaludin MY, Al-Sadat N, Majid HA

Asia Pac J Clin Nutr, 2018 7 27;27(4):898-907.

PMID: 30045437 DOI: 10.6133/apjcn.022018.03

BACKGROUND AND OBJECTIVES: The food frequency questionnaire (FFQ) is a dietary tool used to assess the habitual intake of the population. The goal of this study is to examine the reproducibility and validity of the FFQ that was developed for a multi-ethnic population in Malaysia.

METHODS AND STUDY DESIGN: Collective food data from MyHeARTs 2012 database were used to construct the MyUM Adolescent FFQ. Seventy-eight participants between 13 and 15 years old in 2014 were selected through convenient sampling for test-retest study. They completed the MyUM Adolescent FFQ twice, with an interval period of one week. One hundred and fifty-six MyHeARTs study participants who were 15 years old in 2014 were randomly selected for this comparative valid-ity study. They completed a 7-day diet history (7DDH) and subsequently completed the self-administered MyUM Adolescent FFQ.

RESULTS: Pearson's correlations between the FFQ and 7DDH for all macronutrients were statistically significant. Energy-adjusted correlations for protein, carbohydrate, and fat were 0.54, 0.63 and 0.49 respectively. Most of the micronutrients and minerals, were statistically correlated ranging from 0.31 to 0.49 after energy adjustment. Cross-classification analyses revealed that more than 70 percent of adolescents were classified into either the same or adjacent quartile of nutrient intake when comparing data of 7DDH and FFQ. No serious systematic bias was evident in the Bland-Altman plots.

CONCLUSION: The 200-item FFQ developed for Malaysian adolescents has moderate to good comparative validity for assessment of macronutrient and micronutrient intake.

Fulltext Evaluation of cytogenotoxic and antimutagenic potency of water extract of Centella asiatica Linn. using the Allium cepa assay

Akinboro, A., Baharudeen, I., Mohamed, K.

International Food Research Journal, 2016;23(6):2449-2452.

MyJurnal

In this study, toxicological safety (mutagenicity) and therapeutic potential (antimutagenicity)
of water extract of Centella asiatica Linn., were evaluated using the Allium cepa assay. The
mitotic index (MI) at 6.25% concentration of the extract decreased significantly from 3.13% to
2.05% after 24 h and 48 h, respectively, however, the MI increased significantly by 60% and
400% at 12.5% and 50.0% concentrations, respectively. There was total arrest of cell division
at 100% concentration after 24 h and 48 h of onion’s roots exposure to the water extract.
The chromosomal aberrations (CA) induced by the extract were not significantly different
from the negative control (p ≥ 0.05) at the tested concentrations. The mutagenic activity of
cyclophosphamide was significantly suppressed above 50% at the tested concentrations. These
results suggest non-genotoxic effect, and antimutagenic potency of water extract of C. asiatica
in A. cepa cells, being desirable characteristics of anticancer therapeutics.

Fixed drug eruption associated with co-trimoxazole

Mohamed KB

J Pediatr, 1999 Sep;135(3):396.

PMID: 10484812

Hypersensitivity reaction to dapsone: report from Malaysia

Mohamed KN

Lepr Rev, 1984 Dec;55(4):385-9.

PMID: 6527602

Imported yaws in Johor, Malaysia

Mohamed KN

Ann Trop Paediatr, 1988 Dec;8(4):222-4.

PMID: 2467607

Yaws was detected in a six-member family in the southern Malaysia state of Johor. This stresses the need to be vigilant against a long-forgotten disease of childhood which was of great public health concern in the past.

Fulltext Infrared study of Er(3+)/Yb(3+) Co-Doped GeO(2)-PbO-Bi(2)O(3) glass

Bahari HR, Sidek HA, Adikan FR, Yunus WM, Halimah MK

Int J Mol Sci, 2012;13(7):8609-14.

PMID: 22942723 DOI: 10.3390/ijms13078609

Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO(2)-PbO-Bi(2)O(3) glass host doped with Er(3+)/Yb(3+) ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi(2)O(3) participate with PbO(4) tetragonal pyramids and strongly distort BiO(6) octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix.

Investigation of a nanofabrication process to achieve high aspect-ratio nanostructures on a quartz substrate

Mohamed K, Alkaisi MM

Nanotechnology, 2013 Jan 11;24(1):015302.

PMID: 23221357 DOI: 10.1088/0957-4484/24/1/015302

This work investigates the development of a nanofabrication process to achieve high aspect-ratio nanostructures on quartz substrates using electron beam lithography (EBL) patterning and fluorinated plasma etching processes. An imaging layer of a poly(methyl methacrylate) bi-layer resist was spun coated on quartz substrate and exposed by an e-beam with the designed patterns of sub-100 nm feature sizes using a Raith-150 EBL patterning tool. Additive pattern transfer was employed by depositing a 40 nm thick Nichrome layer on the resist pattern using a metal evaporator which was later lifted off by soaking in acetone. Nichrome was employed as an etch mask and an Oxford Plasmalab 80Plus reactive ion etcher was used for the etching process. The etching process was carried out in a gas mixture of CHF(3)/Ar with a flow rate ratio of 50/30 sccm, pressure of 20 mTorr, radiofrequency power of 200 W and at room temperature. These etching process parameters were found to achieve a 10 nm min(-1) etch rate and tall vertical side walls profile. An aspect-ratio of 10:1 was achieved on 60 nm feature size structures.

Late yaws and optic atrophy

Mohamed KN

Ann Trop Med Parasitol, 1990 Dec;84(6):637-9.

PMID: 2076042

Fulltext Molecular Dynamics Study of Poly(dimethylsiloxane) Nanostructure Distortion in a Soft Lithography Demolding Process

Abdul Manap AH, Md Izah SS, Mohamed K

ACS Omega, 2019 Dec 03;4(23):20257-20264.

PMID: 31815228 DOI: 10.1021/acsomega.9b02547

This study aims at investigating the distortion of poly(dimethylsiloxane) (PDMS) nanostructures in a soft lithography demolding process using molecular dynamics simulation. Experimental results show that after peeling, PDMS nanopillars became 10-60% longer in height than the mold size. Molecular dynamics simulations have been employed to plot the stress-strain curve of the nanopillars when subjected to uniaxial stress. Three force fields (COMPASS, CVFF, and PCFF) were used for modeling. The demolding process in soft lithography and nanoimprint lithography causes significant deformation in replication. The experimental results show clear signs of elongation after demolding. Molecular dynamics simulations are employed to study the stress-strain relationship of the PDMS nanopillars. The results from the simulation show that a PDMS nanopillar at temperature T = 300 K under tensile stress shows characteristics of flexible plastic under tensile stress and has a lower Young's modulus, ultimate tensile stress, and Poisson's ratio.

Myxozoan infection of the Malaysian mahseer, Tor tambroides, of Tasik Kenyir Reservoir, Malaysia: description of a new species Myxobolus tambroides sp.n

Székely C, Shaharom F, Cech G, Mohamed K, Zin NA, Borkhanuddin MH, et al.

Parasitol Res, 2012 Oct;111(4):1749-56.

PMID: 22782473

Tor tambroides, a common and appreciated cyprinid fish of the Tasik Kenyir water reservoir in Malaysia, is one of the species selected for propagation. This fish was first successfully propagated in Malaysia by the Department of Agriculture, Sarawak, Malaysia, and the breeding program continued throughout the country. The gills were frequently infected by a Myxobolus species to be described as Myxobolus tambroides sp. n. The small, 50 to 70 μm, round plasmodia of this species is located intralamellarly. Plasmodia were filled with pyriform myxospores, 9.9 and 7.4 μm wide. In sutural view, the caudal end of the myxospores had a distinctive valvular groove, parallel with the suture. Plasmodia caused deformations on the affected and the neighbouring gill lamellae. The 18S rDNA sequence of M. tambroides sp.n. did not show a close relationship with any other Myxobolus spp., represented in the GenBank. This might be an emerging parasite likely to impact the propagation of this fish.

Myxozoan pathogens in cultured Malaysian fishes. I. Myxozoan infections of the sutchi catfish Pangasius hypophthalmus in freshwater cage cultures

Molnár K, Székely C, Mohamed K, Shaharom-Harrison F

Dis Aquat Organ, 2006 Mar 2;68(3):209-18.

PMID: 16610586

Cage-cultured sutchi catfish Pangasius hypophthalmus (Sauvage, 1878), a favourite food fish in Southeast Asia, proved to be infected by 6 myxozoan species. Three species belonged to the genus Hennegoides (H. berlandi, H. malayensis, and H. pangasii), 1 to Henneguya (H. shariffi) and 2 to Myxobolus (M. baskai, and M. pangasii). Five myxozoans infected the gills and 1 was found on the spleen. Myxozoans infecting the gills were characterised by a specific site selection. H. shariffi sp. n. and H. berlandi sp. n. formed plasmodia in the multi-layered epithelium of the gill filaments. Of the 2 vascular species H. pangasii sp. n. developed in the gill arteries, while M. baskai sp. n. infected the capillary network of the gill lamellae. Plasmodia of H. malayensis sp. n. were found inside the cartilaginous gill rays of the filaments. Large plasmodia of M. pangasii sp. n. were located in a groove of the spleen but they affected only the serosa layer covering the spleen.

Myxozoan pathogens in cultured Malaysian fishes. II. Myxozoan infections of redtail catfish Hemibagrus nemurus in freshwater cage cultures

Molnár K, Székely C, Mohamed K, Shaharom-Harrison F

Dis Aquat Organ, 2006 Mar 2;68(3):219-26.

PMID: 16610587

Cage-cultured Asian redtail catfish Hemibagrus nemurus (Valenciennes, 1840), a popular food fish in Southeast Asia, proved to be infected by 3 myxozoan species. All the 3 species belonged to the genus Henneguya: 2 were identified as H. mystusia Sarkar, 1985 and H. hemibagri Tchang et Ma, 1993, while the other was described as H. basifilamentalis sp. n. All plasmodia were found in the gills and were characterised by a specific site selection. H. mystusia formed plasmodia in the multi-layered epithelium between the gill lamellae and in the non-lamellar edge of the gill filaments, while H. hemibagri developed in the capillary network of the lamellae. H. basifilamentalis sp. n. had large oval plasmodia located deep among the filaments just above the gill arch.

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