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Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application

Reshak AH, Shahimin MM, Shaari S, Johan N

Prog Biophys Mol Biol, 2013 Nov;113(2):327-32.
PMID: 24139943 DOI: 10.1016/j.pbiomolbio.2013.10.002

The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
Comparative study on human and bovine AT-SC isolation methods

Reshak AH, Shahimin MM, Buang F

Prog Biophys Mol Biol, 2013 Nov;113(2):295-8.
PMID: 24080186 DOI: 10.1016/j.pbiomolbio.2013.09.001

Mammalian adipose tissue derived stem cells (AT-SC) have a tremendous potential in regenerative medicine for tissue engineering and somatic nuclear transfer (SNT). The isolation methods of human and bovine adipose tissue derived stem cells are compared in this paper to determine the feasibility and optimum method of isolation. The optimum isolation method will reduce the processing time, efforts and money as isolation is the first crucial and important step in stem cells research. Human abdominal subcutaneous adipose tissue and bovine abdominal subcutaneous adipose tissue are digested in three collagenase type 1 concentration 0.075%, 0.3% and 0.6% agitated at 1 h and 2 h under 37 °C in 5% CO2 incubator. The cultures are then morphologically characterised. Human adipose tissue stem cells are found to be best isolated using abdominal subcutaneous depot, using 0.075% collagenase type 1 agitated at 1 h under 37 °C in CO2 incubator. While bovine adipose tissue derived stem cells are best isolated using abdominal subcutaneous depot, using 0.6% collagenase type 1 agitated at 2 h under 37 °C in CO2 incubator.
Electrical behaviour of MEH-PPV based diode and transistor

Reshak AH, Shahimin MM, Juhari N, Suppiah S

Prog Biophys Mol Biol, 2013 Nov;113(2):289-94.
PMID: 24080185 DOI: 10.1016/j.pbiomolbio.2013.09.002

The potential of organic semiconductor based devices for light generation is demonstrated by the commercialisation of display technologies using organic light emitting diode (OLED). In OLED, organic materials plays an important role of emitting light once the current is passed through. However OLED have drawbacks whereby it suffers from photon loss and exciton quenching. Organic light emitting transistor (OLET) emerged as a new technology to compensate the efficiency and brightness loss encountered in OLED. The structure has combinational capability to switch the electronic signal such as the field effect transistor (FET) as well as to generate light. Different colours of light could be generated by using different types of organic material. The light emission could also be tuned and scanned in OLET. The studies carried out in this paper focuses on investigation of fabricated MEH-PPV based OLED and also OLET via current voltage characteristics. These studies will continue with a view to develop an optimised MEH-PPV based OLET.
A Brief Review on Breast Carcinoma and Deliberation on Current Non Invasive Imaging Techniques for Detection

Vairavan R, Abdullah O, Retnasamy PB, Sauli Z, Shahimin MM, Retnasamy V

Curr Med Imaging Rev, 2019;15(2):85-121.
PMID: 31975658 DOI: 10.2174/1573405613666170912115617

BACKGROUND: Breast carcinoma is a life threatening disease that accounts for 25.1% of all carcinoma among women worldwide. Early detection of the disease enhances the chance for survival.
DISCUSSION: This paper presents comprehensive report on breast carcinoma disease and its modalities available for detection and diagnosis, as it delves into the screening and detection modalities with special focus placed on the non-invasive techniques and its recent advancement work done, as well as a proposal on a novel method for the application of early breast carcinoma detection.
CONCLUSION: This paper aims to serve as a foundation guidance for the reader to attain bird's eye understanding on breast carcinoma disease and its current non-invasive modalities.
Fulltext Peripheral Eye Length Evaluation in Myopic Children Undergoing Orthokeratology Treatment for 12 Months Using MRI

Low YC, Mohd-Ali B, Shahimin MM, Mohidin N, Abdul-Hamid H, Mokri SS

Clin Optom (Auckl), 2024;16:35-44.
PMID: 38351972 DOI: 10.2147/OPTO.S448815

PURPOSE: To investigate changes in peripheral eye length (PEL) in myopic children undergoing orthokeratology (Ortho-K) treatment for 12 months using MRI. The results were compared to single vision spectacle wearers (SVS).
PATIENTS AND METHODS: A total of 70 children with myopia (aged 8-9 years old) were recruited. A total of 45 children were fitted with Ortho-K, and 25 were fitted with SVS. The PEL and axial length (AL) were measured by using MRI 3-Tesla, whereas central and peripheral refraction (PR) measurements were conducted at ±30 degrees horizontally with nasal (N) and temporal (T) intervals of 10°, 20°, and 30° and with an open field autorefractometer (WAM-5500 Grand Seiko). All the measurements were conducted at the baseline and 12 months.
RESULTS: The MRI analysis indicates that at 12 months, the SVS group showed more elongation of the PEL and AL at all eccentricities than the Ortho-K group did (p < 0.05). The Ortho-K group only showed significant PEL elongation beyond 20 degrees at N20, N30, T20, and T30 (p < 0.05); however, a significant reduction in the AL was detected in the center AL, N10, and T10 (p < 0.05). All eccentricities in the relative PR of the Ortho-K group were significantly more myopic than at the baseline (p < 0.05), whereas in the SVS group, all eccentricities in the relative PR were shown to be significantly more hyperopic than at the baseline (p < 0.05). The PEL and PR showed negative correlations at 12 months in the Ortho-K group.
CONCLUSION: MRI analysis can be utilized to describe changes in PEL in myopic children. It appears that as myopia progressed in Ortho-K lens wearers, the PEL increased by a greater amount than the AL did; thus, the retina was reshaped to become increasingly oblate and to display peripheral myopic defocus.
Electrical detection of dengue virus (DENV) DNA oligomer using silicon nanowire biosensor with novel molecular gate control

Nuzaihan M N M, Hashim U, Md Arshad MK, Kasjoo SR, Rahman SF, Ruslinda AR, et al.

Biosens Bioelectron, 2016 Sep 15;83:106-14.
PMID: 27107147 DOI: 10.1016/j.bios.2016.04.033

In this paper, a silicon nanowire biosensor with novel molecular gate control has been demonstrated for Deoxyribonucleic acid (DNA) detection related to dengue virus (DENV). The silicon nanowire was fabricated using the top-down nanolithography approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved by combination of the electron-beam lithography (EBL), plasma dry etching and size reduction processes. The surface of the fabricated silicon nanowire was functionalized by means of a three-step procedure involving surface modification, DNA immobilization and hybridization. This procedure acts as a molecular gate control to establish the electrical detection for 27-mers base targets DENV DNA oligomer. The electrical detection is based on the changes in current, resistance and conductance of the sensor due to accumulation of negative charges added by the immobilized probe DNA and hybridized target DNA. The sensitivity of the silicon nanowire biosensors attained was 45.0µAM(-1), which shows a wide-range detection capability of the sensor with respect to DNA. The limit of detection (LOD) achieved was approximately 2.0fM. The demonstrated results show that the silicon nanowire has excellent properties for detection of DENV with outstanding repeatability and reproducibility performances.
Ocular dimensions by three-dimensional magnetic resonance imaging in emmetropic versus myopic school children

Mohd-Ali B, Chen LY, Shahimin MM, Arif N, Abdul Hamid H, Wan Abdul Halim WH, et al.

Med Hypothesis Discov Innov Ophthalmol, 2022;11(2):64-70.
PMID: 37641786 DOI: 10.51329/mehdiophthal1447

BACKGROUND: Magnetic resonance imaging (MRI) has been used to investigate eye shapes; however, reports involving children are scarce. This study aimed to determine ocular dimensions, and their correlations with refractive error, using three-dimensional MRI in emmetropic versus myopic children.
METHODS: Healthy school children aged < 10 years were invited to take part in this cross-sectional study. Refraction and best-corrected distance visual acuity (BCDVA) were determined using cycloplegic refraction and a logarithm of the minimum angle of resolution (logMAR) chart, respectively. All children underwent MRI using a 3-Tesla whole-body scanner. Quantitative eyeball measurements included the longitudinal axial length (LAL), horizontal width (HW), and vertical height (VH) along the cardinal axes. Correlation analysis was used to determine the association between the level of refractive error and the eyeball dimensions.
RESULTS: A total of 70 eyes from 70 children (35 male, 35 female) with a mean (standard deviation [SD]) age of 8.38 (0.49) years were included and analyzed. Mean (SD) refraction (spherical equivalent, SEQ) and BCDVA were -2.55 (1.45) D and -0.01 (0.06) logMAR, respectively. Ocular dimensions were greater in myopes than in emmetropes (all P < 0.05), with no significant differences according to sex. Mean (SD) ocular dimensions were LAL 24.07 (0.91) mm, HW 23.41 (0.82) mm, and VH 23.70 (0.88) mm for myopes, and LAL 22.69 (0.55) mm, HW 22.65 (0.63) mm, and VH 22.94 (0.69) mm for emmetropes. Significant correlations were noted between SEQ and ocular dimensions, with a greater change in LAL (0.46 mm/D, P < 0.001) than in VH (0.27 mm/D, P < 0.001) and HW (0.22 mm/D, P = 0.001).
CONCLUSIONS: Myopic eyeballs are larger than those with emmetropia. The eyeball elongates as myopia increases, with the greatest change in LAL, the least in HW, and an intermediate change in VH. These changes manifest in both sexes at a young age and low level of myopia. These data may serve as a reference for monitoring the development of refractive error in young Malaysian children of Chinese origin.