iharyati Mohd Zain

Status of a grid-connected MBIPV project in Malaysia

This paper discussed the current status of a grid-connected photovoltaic (PV) system installed in Malaysia. There are 97 locations with capacity of array power, which is 857.92 kWp grid-connected PV systems are monitored by the Photovoltaic System Monitoring Centre (PVSMC), UiTM. Since monitoring the performances for grid-connected system, there are several sites had been detected facing problems involve technical problem like an inverter fault, sensor fault and environmental problem such as shading effect and lower energy. All the problem will be affected the PV system performances in terms of final yield and performance ratio thus it will be inclined the data availability problem. Furthermore, it could waste the energy produced by PV array and energy payback period. An established practical knowledge in designing a PV system need to be taken seriously in order to avoid improper design before installation to maximize the energy production. It is very important to structure proper design and sizing procedures, identify the factors which affect the performances and component sizing for PV system to optimize and utilize the energy production before any actual implementation of solar power energy system installed.

A signal-amplified electrochemical DNA biosensor incorporated with a colorimetric internal control for Vibrio cholerae detection using shelf-ready reagents

A novel enzyme/nanoparticle-based DNA biosensing platform with dual colorimetric/electrochemical approach has been developed for the sequence-specific detection of the bacterium Vibrio cholerae, the causative agent of acute diarrheal disease in cholera. This assay platform exploits the use of shelf-stable and ready-to-use (shelf-ready) reagents to greatly simplify the bioanalysis procedures, allowing the assay platform to be more amenable to point-of-care applications. To assure maximum diagnosis reliability, an internal control (IC) capable of providing instant validation of results was incorporated into the assay. The microbial target, single-stranded DNA amplified with asymmetric PCR, was quantitatively detected via electrochemical stripping analysis of gold nanoparticle-loaded latex microspheres as a signal-amplified hybridization tag, while the incorporated IC was analyzed using a simplified horseradish peroxidase enzyme-based colorimetric scheme by simple visual observation of enzymatic color development. The platform showed excellent diagnostic sensitivity and specificity (100%) when challenged with 145 clinical isolate-spiked fecal specimens. The limits of detection were 0.5ng/ml of genomic DNA and 10 colony-forming units (CFU)/ml of bacterial cells with dynamic ranges of 0-100ng/ml (R2=0.992) and log10 (1-104 CFU/ml) (R2=0.9918), respectively. An accelerated stability test revealed that the assay reagents were stable at temperatures of 4-37°C, with an estimated ambient shelf life of 200 days. The versatility of the biosensing platform makes it easily adaptable for quantitative detection of other microbial pathogens.

Noninvasive glucose level determination using diffuse reflectance near infrared spectroscopy and chemometrics analysis based on in vitro sample and human skin

Fourier Transform Near Infrared Spectroscopy (FT-NIRS) is a bright method to estimate glucose concentration level by detecting glucose molecular properties in tissue and blood. NIRS technique consists of many method measurements including diffuse reflection method. It capable to predict blood glucose level in human blood noninvasively without pain. However the main weakness of FT-NIRS is the low absorption spectrum of glucose and not a straight forward signal for quantification analysis. Therefore, preprocessing data and chemometrics analysis is required to enhance the spectrum performance and identified certain chemical information present in the sample. The main objective in this paper is to evaluate the potential of low level detection using FT-NIRS towards glucose spectrum in water and intralipid. This study also observed the relationship between human skin spectrums with its blood glucose level value. Utilizing a few preprocessing method and PLS regression technique, Root Mean Square Error Cross Validation (RMSECV) and Coefficient of determination Cross validation (R2CV) were observed to validate the model. RMSECV obtained for glucose in water and intralipid were 47.05 mg/dl (2.6 mmol) and 31.17 mg/dl (1.7 mmol) respectively. Meanwhile R2CV achieved for glucose in water and intralipid were at 0.94 and 0.97 respectively. The Clarke Error Grid shows 97% of the measurement fell within zone A and B. This study has shown that, glucose detection was possible to be monitored in human blood by using FT-NIRS and PLS regression analysis.

Two-year performance monitoring of amorphous-Silicon Grid-Connected Photovoltaic system

This paper presents the thin-film performance with a total nominal array of 0.9 kWp Grid-Connected Photovoltaic system using single-junction amorphous-Silicon for two years of operation in Malaysia. Since the operation, the system has injected into the Tenaga Nasional Berhads grid with the total energy production of about 2,232.8 kWh. Additionally, the daily average for the final PV system yield, the efficiencies of system and inverter were recorded at 3.39 kWh/kWp.d, 5.08% and 89.6%, respectively. The daily operation showed that it has been operating in better condition under Malaysian climate with the performance ratio measured at 80.6% during the monitored period.

An impedimetric micro-immunosensing assay to detect Alzheimer's disease biomarker: Aβ40

A miniaturized biosensing platform, based on monoclonal amyloid-beta antibodies (mAβab) that were immobilized on a disc-shaped platinum/iridium (Pt/Ir) microelectrode surface coupled with an impedimetric signal transducer, was developed for the label-free and sensitive detection of amyloid-beta peptide fragment 1-40 (Aβ40); a reliable biomarker for early diagnosis of Alzheimers disease (AD). A Pt/Ir microelectrode was electropolymerized with poly (ortho-phenylenediamine), a conducting free amine-containing aromatic polymer; followed by crosslinking with glutaraldehyde for subsequent coupling of mAβab on the microelectrode surface. This modification strategy efficiently improved the impedimetric detection performance of Aβ40 in terms of charge transfer resistance (∼400-fold difference) and normalized impedance magnitude percentage change (∼40% increase) compared with a passive adsorption-based immobilization method. The sensitivity of the micro-immunosensing assay was found to be 1056 kΩ/(pg/mL)/cm2 and the limit of detection was found to be 4.81 pg/mL with a dynamic range of 1-104 pg/mL (R2 = 0.9932). The overall precision of the assay, as measured by relative standard deviation, ranged from 0.84 to 5.15%, demonstrating its reliability and accuracy; while in respect to assay durability and stability, the immobilized mAβab were able to maintain 80% of their binding activity to Aβ40 after incubation for 48 h at ambient temperature (25 °C). To validate the practical applicability, the assay was tested using brain tissue lysates prepared from AD-induced rats. Results indicate that the proposed impedimetric micro-immunosensing platform is highly versatile and adaptable for the quantitative detection of other disease-related biomarkers.

The electroanalytical detection of triglyceride concentrations in olive oil using modified screen printed electrodes with ionic liquid [1-(2-ethoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide]-lipase

Triglycerides (TG) can be generated by esterification process of three hydroxyl (-OH) groups of glycerol with three molecules of fatty acids. Triglyceride acts not only in human metabolisms but also as energy sources and dietary fat transporter. The determinations of triglyceride levels in urine, blood and food is important for clinical or medical analysis to determine the clinical disorders due to abnormal levels of triglyceride. Standard methods for triglyceride determination in serum based on fluorometric, chromatographic, and high performance liquid chromatographic (HPLC) methods are not extensively available and unsuitable for point-of-care applications due to expensive instrumentation and complicated sample pre-processing. Therefore, biosensors offer advantages for triglyceride determination due to relatively low cost, ease of use and good selectivity. The most recent reports of triglyceride biosensors found in literature1–3 are based on interactions of three enzymes, lipase, glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO). Pundir et al.4 reported an electrochemical sensor for triglyceride by measuring the oxygen consumption or the amount of hydrogen peroxide produced by the enzymatic reactions.