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Fulltext Impact of different lifting height and load mass on muscle performance using periodogram

Shair, E. F., Ahmad, S. A., Marhaban, M. H., Abdullah, A. R., Mohd Tamrin, S. B.

Pertanika Journal of Science & Technology, 2017;25(101):1-8.
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Musculoskeletal disorders (MSDs) caused by muscle fatigue have been a major problem for industry
which needs to be resolved to save costs related to human resource development (extra training and
compensation). Detailed fatigue monitoring researches aimed at finding the best fatigue indices is not
new although studies on the causes of fatigue can be explored further. Identification analysis is required
to monitor the factors that influence muscle performance characteristic of surface electromyography
(sEMG) signal. Periodogram monitoring technique applies a frequency domain signal and represents the
distribution of the signal power over the frequency. It is a technique that allows the tracing of small
changes in the behaviour of sEMG signal when external parameters are varied. This technique is used
in this paper to monitor the sEMG signal changes in muscle performance when the lifting height and
load mass are varied. The periodogram amplitude, which represents the power, increases with the rise in
lifting height and load mass. From the frequency representation of the periodogram, the root mean square
voltage (Vrms) is calculated where the muscle performance characteristic could be further identified. The
Vrms also shows a similar trend when the lifting height and load mass are varied proving the periodogram
technique is useful to monitor changes in the muscle performance during manual lifting.
Fulltext Alteration in morphological features of Puntius javanicus liver exposed to copper sulfate

Sabullah, M. K., Gansau, A. J., Ahmad, S. A., Shamaan, N. A., Khalid, A., Sulaiman, M. R.

International Food Research Journal, 2017;24(3):1314-1320.
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The environmental toxicants such as copper are known to affect vital organ especially liver.
This study examined the effects of copper sulfate (CuSO4) on the liver morphological structure
of P. javanicus. The untreated control, 0.1 and 0.3 mg/L CuSO4 treated groups displayed normal
polygonal structure of the hepatocyte. However, at the concentrations of 0.5, 1.0 and 5.0 mg/L
CuSO4, the hepatostructure was significantly affected, as shown by the increasing number of
dilation and congestion of sinusoids, vacuolation, macrophage activities and peliosis. The
damage level and HSI value were increased while the number of hepatic nuclei per mm2 was
decreased with the increasing of copper concentration. In conclusion, this study shows that the
degree of liver damage in P.javanicus is dependent to the dose exposure.
Fulltext Cholinesterase-based biosensor for preliminary detection of toxic heavy metals in the environment and agricultural-based products

Sabullah, M. K., Khalidi, S. A. M., Abdullah, R., Sani, S. A., Gansau, J. A., Ahmad, S. A., et al.

International Food Research Journal, 2020;27(4):597-609.
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Heavy metals with high chemical activity from sludge and waste release, agriculture, and
mining activity are a major concern. They should be carefully managed before reaching the
main water bodies. Excessive exposure to heavy metal may cause toxic effect to any types of
organism from the biomolecular to the physiological level, and ultimately cause death. Monitoring is the best technique to ensure the safety of our environment before a rehabilitation is
needed. Nowadays, enzyme-based biosensors are utilised in biomonitoring programmes as
this technique allows for a real-time detection and rapid result. It is also inexpensive and easy
to handle. Enzyme-based biosensors are an alternative for the preliminary screening of
contamination before a secondary screening is performed using high-performance technology.
This review highlights the current knowledge on enzyme-based biosensors, focusing on
cholinesterase for toxic metal detection in the environment.
Voltammetric determination of iodide in iodized table salt using cetyltrimethylammonium bromide as ion-pairing

Jamilan MA, Abdullah J, Alang Ahmad SA, Md Noh MF

J Food Sci Technol, 2019 Aug;56(8):3846-3853.
PMID: 31413410 DOI: 10.1007/s13197-019-03855-x

In this work, voltammetric study based on cetyltrimethylammonium bromide (CTAB) as an ion-pairing agent for the determination of iodine level in iodized table salt has been explored. CTAB was used as an intermediate compound between iodide (I-) and the electrode due to its ability to dissociate to produce cetyltrimethylammonium ions ([CTA]+). The [CTA]+ with a long hydrophobic alkyl chain can be directly adsorbed onto the surface of the working electrode, and this in turns coated the electrode with cationic charge and enhance the electrode ability to bind to iodide (I-) and other molecular iodine ions. A mixture of iodide and CTAB ([CTA]+I-) was prepared and potential of 1.0 V for 60.0 s was applied to pre-concentrate the solution on the working electrode causing the [CTA]+I- to oxidize to iodine (I2). The produced I2 immediately react with chloride ion (Cl-) from the electrolyte of hydrochloric acid (HCl) to produce I2Cl- and form ion-pair with CTA+ as [CTA]+I2Cl-. The linear calibration curve of the developed method towards iodide was in the concentration range of 0.5-4.0 mg/L with sensitivity of - 1.383 µA mg/L-1 cm-2 (R2 = 0.9950), limit of detection (LOD) of 0.3 mg/L and limit of quantification (LOQ) of 1.0 mg/L, respectively. The proposed method indicates good agreement with the standard method for iodine determination with recovery range from 95.0 to 104.3%. The developed method provided potential application as a portable on-site iodine detector.
Isolation and characterization of a phenol-degrading Rhodococcus sp. strain AQ5NOL 2 KCTC 11961BP

Arif NM, Ahmad SA, Syed MA, Shukor MY

J Basic Microbiol, 2013 Jan;53(1):9-19.
PMID: 22581645 DOI: 10.1002/jobm.201100120

In this work, we report on the isolation of a phenol-degrading Rhodococcus sp. with a high tolerance towards phenol. The isolate was identified as Rhodococcus sp. strain AQ5NOL 2, based on 16S rDNA analysis. The strain degraded phenol using the meta pathway, a trait shared by many phenol-degraders. In addition to phenol biodegradation, the strain was also capable of degrading diesel. Strain AQ5NOL 2 exhibited a broad optimum temperature for growth on phenol at between 20 °C and 35 °C. The best nitrogen sources were ammonium sulphate, glycine or phenylalanine, followed by proline, nitrate, leucine, and alanine (in decreasing efficiency). Strain AQ5NOL 2 showed a high tolerance and degradation capacity of phenol, for it was able to register growth in the presence of 2000 mg l(-1) phenol. The growth of this strain on phenol as sole carbon and energy source were modeled using Haldane kinetics with a maximal specific growth rate (μ(max)) of 0.1102 hr(-1), a half-saturation constant (K(s) ) of 99.03 mg l(-1) or 1.05 mmol l(-1), and a substrate inhibition constant (K(i)) of 354 mg l(-1) or 3.76 mmol l(-1). Aside from phenol, the strain could utilize diesel, 2,4-dinitrophenol and ρ-cresol as carbon sources for growth. Strain AQ5NOL 2 exhibited inhibition of phenol degradation by Zn(2+), Cu(2+), Cr(6+), Ag(+) and Hg(2+) at 1 mg l(-1).
Fulltext Hexavalent molybdenum reduction to mo-blue by a sodium-dodecyl-sulfate-degrading Klebsiella oxytoca strain DRY14

Halmi MI, Zuhainis SW, Yusof MT, Shaharuddin NA, Helmi W, Shukor Y, et al.

Biomed Res Int, 2013;2013:384541.
PMID: 24383052 DOI: 10.1155/2013/384541

Bacteria with the ability to tolerate, remove, and/or degrade several xenobiotics simultaneously are urgently needed for remediation of polluted sites. A previously isolated bacterium with sodium dodecyl sulfate- (SDS-) degrading capacity was found to be able to reduce molybdenum to the nontoxic molybdenum blue. The optimal pH, carbon source, molybdate concentration, and temperature supporting molybdate reduction were pH 7.0, glucose at 1.5% (w/v), between 25 and 30 mM, and 25°C, respectively. The optimum phosphate concentration for molybdate reduction was 5 mM. The Mo-blue produced exhibits an absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. None of the respiratory inhibitors tested showed any inhibition to the molybdenum-reducing activity suggesting that the electron transport system of this bacterium is not the site of molybdenum reduction. Chromium, cadmium, silver, copper, mercury, and lead caused approximately 77, 65, 77, 89, 80, and 80% inhibition of the molybdenum-reducing activity, respectively. Ferrous and stannous ions markedly increased the activity of molybdenum-reducing activity in this bacterium. The maximum tolerable concentration of SDS as a cocontaminant was 3 g/L. The characteristics of this bacterium make it a suitable candidate for molybdenum bioremediation of sites cocontaminated with detergent pollutant.
Fulltext Molybdate reduction by Pseudomonas sp. strain DRY2

Shukor MY, Ahmad SA, Nadzir MM, Abdullah MP, Shamaan NA, Syed MA

J Appl Microbiol, 2010 Jun;108(6):2050-8.
PMID: 19968732 DOI: 10.1111/j.1365-2672.2009.04604.x

To isolate and characterize a potent molybdenum-reducing bacterium.
EMG Processing Based Measures of Fatigue Assessment during Manual Lifting

Shair EF, Ahmad SA, Marhaban MH, Mohd Tamrin SB, Abdullah AR

Biomed Res Int, 2017;2017:3937254.
PMID: 28303251 DOI: 10.1155/2017/3937254

Manual lifting is one of the common practices used in the industries to transport or move objects to a desired place. Nowadays, even though mechanized equipment is widely available, manual lifting is still considered as an essential way to perform material handling task. Improper lifting strategies may contribute to musculoskeletal disorders (MSDs), where overexertion contributes as the highest factor. To overcome this problem, electromyography (EMG) signal is used to monitor the workers' muscle condition and to find maximum lifting load, lifting height and number of repetitions that the workers are able to handle before experiencing fatigue to avoid overexertion. Past researchers have introduced several EMG processing techniques and different EMG features that represent fatigue indices in time, frequency, and time-frequency domain. The impact of EMG processing based measures in fatigue assessment during manual lifting are reviewed in this paper. It is believed that this paper will greatly benefit researchers who need a bird's eye view of the biosignal processing which are currently available, thus determining the best possible techniques for lifting applications.
Quantitative assessment of wound healing using high-frequency ultrasound image analysis

Mohafez H, Ahmad SA, Hadizadeh M, Moghimi S, Roohi SA, Marhaban MH, et al.

Skin Res Technol, 2018 Feb;24(1):45-53.
PMID: 28557064 DOI: 10.1111/srt.12388

PURPOSE: We aimed to develop a method for quantitative assessment of wound healing in ulcerated diabetic feet.
METHODS: High-frequency ultrasound (HFU) images of 30 wounds were acquired in a controlled environment on post-debridement days 7, 14, 21, and 28. Meaningful features portraying changes in structure and intensity of echoes during healing were extracted from the images, their relevance and discriminatory power being verified by analysis of variance. Relative analysis of tissue healing was conducted by developing a features-based healing function, optimised using the pattern-search method. Its performance was investigated through leave-one-out cross-validation technique and reconfirmed using principal component analysis.
RESULTS: The constructed healing function could depict tissue changes during healing with 87.8% accuracy. The first principal component derived from the extracted features demonstrated similar pattern to the constructed healing function, accounting for 86.3% of the data variance.
CONCLUSION: The developed wound analysis technique could be a viable tool in quantitative assessment of diabetic foot ulcers during healing.
Fulltext Molybdate reduction to molybdenum blue by an Antarctic bacterium

Ahmad SA, Shukor MY, Shamaan NA, Mac Cormack WP, Syed MA

Biomed Res Int, 2013;2013:871941.
PMID: 24381945 DOI: 10.1155/2013/871941

A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo⁶⁺ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.
Fulltext Kinetics of molybdenum reduction to molybdenum blue by Bacillus sp. strain A.rzi

Othman AR, Bakar NA, Halmi MI, Johari WL, Ahmad SA, Jirangon H, et al.

Biomed Res Int, 2013;2013:371058.
PMID: 24369531 DOI: 10.1155/2013/371058

Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 °C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants p max, K(s), S(m), and n was 5.88 μmole Mo-blue hr(-1), 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.