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Fulltext Near infrared spectral linearisation in quantifying soluble solids content of intact carambola

Omar AF, MatJafri MZ

Sensors (Basel), 2013;13(4):4876-83.
PMID: 23584118 DOI: 10.3390/s130404876

This study presents a novel application of near infrared (NIR) spectral linearisation for measuring the soluble solids content (SSC) of carambola fruits. NIR spectra were measured using reflectance and interactance methods. In this study, only the interactance measurement technique successfully generated a reliable measurement result with a coefficient of determination of (R2) = 0.724 and a root mean square error of prediction for (RMSEP) = 0.461° Brix. The results from this technique produced a highly accurate and stable prediction model compared with multiple linear regression techniques.
Fulltext NIR spectroscopic properties of aqueous acids solutions

Omar AF, Atan H, Matjafri MZ

Molecules, 2012 Jun 15;17(6):7440-50.
PMID: 22706373 DOI: 10.3390/molecules17067440

Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R² above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918-925 nm and 990-996 nm, while at 975 nm for water.
Fulltext Turbidimeter design and analysis: a review on optical fiber sensors for the measurement of water turbidity

Omar AF, Matjafri MZ

Sensors (Basel), 2009;9(10):8311-35.
PMID: 22408507 DOI: 10.3390/s91008311

Turbidimeters operate based on the optical phenomena that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within it. This review paper elaborates on the standards and factors that may influence the measurement of turbidity. The discussion also focuses on the optical fiber sensor technologies that have been applied within the lab and field environment and have been implemented in the measurement of water turbidity and concentration of particles. This paper also discusses and compares results from three different turbidimeter designs that use various optical components. Mohd Zubir and Bashah and Daraigan have introduced a design which has simple configurations. Omar and MatJafri, on the other hand, have established a new turbidimeter design that makes use of optical fiber cable as the light transferring medium. The application of fiber optic cable to the turbidimeter will present a flexible measurement technique, allowing measurements to be made online. Scattered light measurement through optical fiber cable requires a highly sensitive detector to interpret the scattered light signal. This has made the optical fiber system have higher sensitivity in measuring turbidity compared to the other two simple turbidimeters presented in this paper. Fiber optic sensors provide the potential for increased sensitivity over large concentration ranges. However, many challenges must be examined to develop sensors that can collect reliable turbidity measurements in situ.
A comparison of radiometric correction techniques in the evaluation of the relationship between LST and NDVI in Landsat imagery

Tan KC, Lim HS, Matjafri MZ, Abdullah K

Environ Monit Assess, 2012 Jun;184(6):3813-29.
PMID: 21755424 DOI: 10.1007/s10661-011-2226-0

Atmospheric corrections for multi-temporal optical satellite images are necessary, especially in change detection analyses, such as normalized difference vegetation index (NDVI) rationing. Abrupt change detection analysis using remote-sensing techniques requires radiometric congruity and atmospheric correction to monitor terrestrial surfaces over time. Two atmospheric correction methods were used for this study: relative radiometric normalization and the simplified method for atmospheric correction (SMAC) in the solar spectrum. A multi-temporal data set consisting of two sets of Landsat images from the period between 1991 and 2002 of Penang Island, Malaysia, was used to compare NDVI maps, which were generated using the proposed atmospheric correction methods. Land surface temperature (LST) was retrieved using ATCOR3_T in PCI Geomatica 10.1 image processing software. Linear regression analysis was utilized to analyze the relationship between NDVI and LST. This study reveals that both of the proposed atmospheric correction methods yielded high accuracy through examination of the linear correlation coefficients. To check for the accuracy of the equation obtained through linear regression analysis for every single satellite image, 20 points were randomly chosen. The results showed that the SMAC method yielded a constant value (in terms of error) to predict the NDVI value from linear regression analysis-derived equation. The errors (average) from both proposed atmospheric correction methods were less than 10%.
Fulltext A blood-mimicking fluid with cholesterol as scatter particles for wall-less carotid artery phantom applications

Dakok KK, Matjafri MZ, Suardi N, Oglat AA, Nabasu SE

J Ultrason, 2021 Aug 16;21(86):e219-e224.
PMID: 34540276 DOI: 10.15557/JoU.2021.0035

Aim of the study: At present, there are few scatter particles used in preparing blood-mimicking fluids, such as nylon, sephadex, polystyrene microsphere, and poly(4-methystyrene). In this study, we present cholesterol as a new scatter particle for blood-mimicking fluid preparation. Materials and methods: The procedure for the preparation of the proposed blood-mimicking fluid involved the use of propylene glycol, D(+)-Glucose and distilled water to form a ternary mixture fluid, with cholesterol used as scatter particles. Polyethylene glycol was first used as part of the mixture fluid but the acoustic and physical properties were not suitable, leading to its replacement with D(+)-Glucose, which is soluble in water and has a higher density. A common carotid artery wall-less phantom was also produced to assess the flow properties. Results: The prepared blood-mimicking fluid with new scatter particles has a density of 1.067 g/cm3, viscosity of 4.1 mPa.s, speed of sound 1600 m/s, and attenuation of 0.192 dB/cm at 5 MHz frequency. Peak systolic velocity, end diastolic velocity and mean velocity measurements were gotten to be 40.2 ± 2.4 cm/s, 9.9 ± 1.4 cm/s, and 24.0 ± 1.8 cm/s, respectively. Conclusion: Based on the results obtained, the blood-mimicking fluid was found suitable for ultrasound applications in carotid artery wall-less phantoms because of its good acoustic and physical properties.
Fulltext A Review of Medical Doppler Ultrasonography of Blood Flow in General and Especially in Common Carotid Artery

Oglat AA, Matjafri MZ, Suardi N, Oqlat MA, Abdelrahman MA, Oqlat AA

J Med Ultrasound, 2018 03 28;26(1):3-13.
PMID: 30065507 DOI: 10.4103/JMU.JMU_11_17

Medical Doppler ultrasound is usually utilized in the clinical adjusting to evaluate and estimate blood flow in both the major (large) and the minor (tiny) vessels of the body. The normal and abnormal sign waveforms can be shown by spectral Doppler technique. The sign waveform is individual to each vessel. Thus, it is significant for the operator and the clinicians to understand the normal and abnormal diagnostic in a spectral Doppler show. The aim of this review is to explain the physical principles behind the medical Doppler ultrasound, also, to use some of the mathematical formulas utilized in the medical Doppler ultrasound examination. Furthermore, we discussed the color and spectral flow model of Doppler ultrasound. Finally, we explained spectral Doppler sign waveforms to show both the normal and abnormal signs waveforms that are individual to the common carotid artery, because these signs are important for both the radiologist and sonographer to perceive both the normal and abnormal in a spectral Doppler show.
Fulltext A Review of Carotid Artery Phantoms for Doppler Ultrasound Applications

Dakok KK, Matjafri MZ, Suardi N, Oglat AA, Nabasu SE

J Med Ultrasound, 2021 05 14;29(3):157-166.
PMID: 34729323 DOI: 10.4103/JMU.JMU_164_20

Ultrasound imaging systems need tissue-mimicking phantoms with a good range of acoustic properties. Many studies on carotid artery phantoms have been carried out using ultrasound; hence this study presents a review of the different forms of carotid artery phantoms used to examine blood hemodynamics by Doppler ultrasound (DU) methods and explains the ingredients that constitute every phantom with their advantages and disadvantages. Different research databases were consulted to access relevant information on carotid artery phantoms used for DU measurements after which the information were presented systematically spanning from walled phantoms to wall-less phantoms. This review points out the fact that carotid artery phantoms are made up of tissue mimicking materials, vessel mimicking materials, and blood mimicking fluid whose properties matched those of real human tissues and vessels. These materials are a combination of substances such as water, gelatin, glycerol, scatterers, and other powders in their right proportions.
A statistical model to predict and analyze air surface temperature based on remotely sensed observations

Lim HS, Rajab J, Al-Salihi A, Salih Z, MatJafri MZ

Environ Sci Pollut Res Int, 2022 Feb;29(7):9755-9765.
PMID: 34505243 DOI: 10.1007/s11356-021-16321-z

Air surface temperature (AST) is a crucial importance element for many applications such as hydrology, agriculture, and climate change studies. The aim of this study is to develop regression equation for calculating AST and to analyze and investigate the effects of atmospheric parameters (O3, CH4, CO, H2Ovapor, and outgoing longwave radiation (OLR)) on the AST value in Iraq. Dataset retrieved from the Atmospheric Infrared Sounder (AIRS) at EOS Aqua Satellite, spanning the years of 2003 to 2016, and multiple linear regression were used to achieve the objectives of the study. For the study period, the five atmospheric parameters were highly correlated (R, 0.855-0.958) with predicted AST. Statistical analyses in terms of β showed that OLR (0.310 to 1.053) contributes significantly in enhancing AST values. Comparisons among selected five stations (Mosul, Kanaqin, Rutba, Baghdad, and Basra) for the year 2010 showed a close agreement between the predicted and observed AST from AIRS, with values ranging from 0.9 to 1.5 K and for ground stations data, within 0.9 to 2.6 K. To make more complete analysis, also, comparison between predicted and observed AST from AIRS for four selected month in 2016 (January, April, July, and October) has been carried out. The result showed a high correlation coefficient (R, 0.87 and 0.95) with less variability (RMSE ≤ 1.9) for all months studied, indicating model's capability and accuracy. In general, the results indicate the advantage of using the AIRS data and the regression analysis to investigate the impact of the atmospheric parameters on AST over the study area.
Fulltext A Review of Suspension-Scattered Particles Used in Blood-Mimicking Fluid for Doppler Ultrasound Imaging

Oglat AA, Suardi N, Matjafri MZ, Oqlat MA, Abdelrahman MA, Oqlat AA

J Med Ultrasound, 2018;26(2):68-76.
PMID: 30065522 DOI: 10.4103/JMU.JMU_1_17

Doppler ultrasound imaging system description and calibration need blood-mimicking fluids (BMFs) for the test target of medical ultrasound diagnostic tools, with known interior features and acoustic and physical properties of this fluid (BMF). Physical and acoustical properties determined in the International Electrotechnical Commission (IEC) standard are specified as constant values, the materials used in the BMF preparation should have values similar to the IEC standard values. However, BMF is ready-made commercially from a field of medical usage, which may not be appropriate in the layout of ultrasound system or for an estimate of novel imaging mechanism. It is often eligible to have the capability to make sound properties and mimic blood arrangement for specific applications. In this review, sufficient BMF materials, liquids, and measures are described which have been generated by utilizing diverse operation mechanism and materials that have sculptured a range of biological systems.
Fulltext A New Scatter Particle and Mixture Fluid for Preparing Blood Mimicking Fluid for Wall-Less Flow Phantom

Oglat AA, Matjafri MZ, Suardi N, Abdelrahman MA, Oqlat MA, Oqlat AA

J Med Ultrasound, 2018;26(3):134-142.
PMID: 30283199 DOI: 10.4103/JMU.JMU_7_18

BACKGROUND: To examine the blood flow and detection of the issues related to it by medical ultrasound, it is extremely important to have suitable blood mimicking fluid (BMF) to be used in vitro and to have a movable or portable Doppler flow phantom to use it as a standardizing tool. As known, the main drawbacks of the currently commercial BMF used in the research studies are high in cost and the long time needed for preparation, which is at least 5-7 h. Moreover, there are only two common scatter particles using in BMF as suspension materials such as nylon (Orgasol) and polystyrene. Thus, we need to prepare BMF with both a new mixture fluid and new scatter particle to be as a reflecting factor of ultrasonic waves, for evaluating the speed of sound of the blood flow in the same method like in the research study of ultrasound with relatively low-cost and less consuming time of preparation. However, both the acoustical and physical features of the Doppler flow phantom components (BMF and tissue mimicking material) must correspond the features of the human tissues to make the examination significance. In addition, the BMF must also represent the hemodynamic features of real human blood.
METHODS: In this experiment, a new adequate ternary mixture liquid for preparation of BMF applied and suspended with a new scatter particle material, this scatter particle material called poly (4-methylstyrene), it used to be adequate with the mixture density and for saving neutrally buoyant. This BMF was prepared for use in the test objects or Doppler flow phantom. The poly (4-methylstyrene) particles were applied for suspension in a mixture liquid or fluid based on three items, which were distilled water, propylene glycol (PG), and polyethylene glycol (PEG) (200 Mw). The diameter of poly (4-methylstyrene) particles is 3-8 μm, which determined by specific sieve in a unit of μm, and the density is 1.040 g/ml.
RESULTS: Speed of sound, viscosity, density, Backscatter power and attenuation features of mixture fluid or liquid which used for preparing a BMF were measured, discussed, and agreed with draft International Electrotechnical Commission values.
CONCLUSIONS: There are three various types of ternary items of mixture fluid (water, PG, and PEG [200 Mw]), and a new type of scatter particle material poly (4-methylstyrene) was utilized for preparing the BMF. The scatter particles and mixture fluid prepared and measured at a temperature that simulates the body temperature 37°C. Moreover, one of the advantages of this new blood that is being cheaper than the commercially available BMF products because the PG and the polyethylene glycol (200 Mw) are much cheaper and more available than glycerol and the Dextran that used usually. In addition, new BMF needs less time for preparation compared to the commercial one.
Fulltext Chemical Items Used for Preparing Tissue-Mimicking Material of Wall-Less Flow Phantom for Doppler Ultrasound Imaging

Oglat AA, Matjafri MZ, Suardi N, Oqlat MA, Abdelrahman MA, Oqlat AA, et al.

J Med Ultrasound, 2018;26(3):123-127.
PMID: 30283197 DOI: 10.4103/JMU.JMU_13_17

The wall-less flow phantoms with recognized acoustic features (attenuation and speed of sound), interior properties, and dimensions of tissue were prepared, calibrated, and characterized of Doppler ultrasound scanning demands tissue-mimicking materials (TMMs). TMM phantoms are commercially available and ready-made for medical ultrasound applications. Furthermore, the commercial TMM phantoms are proper for ultrasound purpose or estimation of diagnostic imaging techniques according to the chemical materials used for its preparation. However, preparing a desirable TMM for wall-less flow phantom using a specific chemical material according to the specific applications is required for different flow. In this review, TMM and wall-less flow phantoms prepared using different chemical materials and methods were described. The chemical materials used in Doppler ultrasound TMM and wall-less flow phantoms fabricated over the previous decades were of high interest in this review.