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This review (with 99 refs.) summarizes the progress that has been made in colorimetric (i.e. spectrophotometric) determination of organophosphate pesticides (OPPs) using gold and silver nanoparticles (NPs). Following an introduction into the field, a first large section covers the types and functions of organophosphate pesticides. Methods for colorimetric (spectrophotometric) measurements including RGB techniques are discussed next. A further section covers the characteristic features of gold and silver-based NPs. Syntheses and modifications of metal NPs are covered in section 5. This is followed by overviews on enzyme inhibition-based assays, aptamer-based assays and chemical (non-enzymatic) assays, and a discussion of specific features of colorimetric assays. Several Tables are presented that give an overview on the wealth of methods and materials. A concluding section addresses current challenges and discusses potential future trends and opportunities. Graphical abstract Schematic representation of organophosphate pesticide determinations based on aggregation of nanoparticles (particular silver or gold nanoparticles). This leads to a color change which can be determined visually and monitored by a red shift in the absorption spectrum.

Non-covalent functionalisation of the carbon nanotube (CNT) sidewall through polymer wrapping is the key strategy for improving well-dispersed CNTs without persistent alteration of their electronic properties. In this work, the effect of reaction time on regioregular poly (3-hexylthiophene-2,5-diyl) (P3HT)-wrapped hydroxylated multi-walled CNT (MWCNT-OH) nanocomposites was investigated. Five different reaction times (24, 48, 72, 96, and 120 h) were conducted at room temperature in order to clearly determine the factors that influenced the quality of wrapped MWCNT-OH. Morphological analysis using Field Emission Scanning Electron Microscopic (FESEM) and High-Resolution Transmission Electron Microscope (HRTEM) analysis showed that P3HT successfully wrapped the MWCNT-OH sidewall, evidenced by the changes in the mean diameter size of the nanocomposites. Results obtained from Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) as well as Thermogravimetric Analysis (TGA) showed a significant effect of the wrapped polymer on the CNT sidewall as the reaction time increased. Overall, the method used during the preparation of P3HT-wrapped MWCNT-OH and the presented results significantly provided a bottom-up approach to determine the effect of different reaction times on polymer wrapping to further expand this material for novel applications, especially chemical sensors.

A novel coronavirus (2019-nCoV) became the seventh member in the family of Coronavirus that infect human. 2019-nCoV became the most severe virus compare to another family of coronavirus. Human airway ephitelial cells have been used to identify and isolate the virus before proceed to reverse trancriptase Polymerase Chain Reaction (RT-PCR). Detailed biological knowledge is crucial for the development of effective countermeasures, diagnostic tests, vaccines and antiviral drugs against the 2019-nCoV. Conserved coding sequences within the spike glycoprotein region of open reading frame in the coronavirus genome was used as the basis to design oligonucleotide probe to detect the virus. Analyses on different strain of coronavirus sequences were done to check the percentage of similarity and consensus region that cause different strain of viruses. The biomarker needed an acceptable length between 22 and 31 mers. The choice of S gene region was identified and can be used as a biomarker probe for biosensor development. It has implications for coronavirus detection techniques in clinical and biosensor diagnostic system.

Agriculture is known as one of the main factor for a growth of a country. Paddy plantation is the most widely planted crop in Malaysia. The rice produced is the main food source to Malaysian’s people and source of income to this country as well. However, a disease known as Brown Spot (BS) attacks the paddy plants and threats their quality. This disease caused by bipolar fungus, which represent by the development of an oval, dark brown to purplish-brown spot on leaf. This disease observed as among the hazardous disease that may result in degradation of paddy production. Brown Spot disease could spread through airborne spores from plant to plant on the field. In this research, a system that could help people, especially farmers, to detect the disease at early stage is developed. The real image capture at paddy field is processed in the MATLAB software with image enhancement, background removal as well as binary and RGB image masking process. To determine the Brown Spot area, pixel intensity between the infected and non-infected areas is calculated. The severity level table developed by Horsfall and Heuberger is then used as reference to classify the severity level of Brown Spot disease. A GUI is created to detect the Brown Spot disease automatically. From the study conducted, the accuracy of Brown Spot detection is approximately 89% accurate compared to manual evaluation by plant pathology.

A steady stagnation point flow of an incompressible Williamson nanofluid towards a horizontal linearly stretching/shrinking sheet with active and passive controls on the wall mass flux is numerically studied. The governing partial differential equations are reduced into a system of ordinary differential equations using a similarity transformation and are solved using the bvp 4 c package in MATLAB. The velocity, temperature and nanoparticle volume fraction profiles together with the reduced skin friction coefficient, reduced Nusselt number and reduced Sherwood number are graphically presented to visualize the effects of parameters involved in the study. Results show that temperature and nanoparticle volume fraction are decreasing functions of the stagnation parameter, r . It is also found that the diffusivity ratio N bt and Lewis number Le have almost negligible effects on heat transfer rate in passive control. Increasing value of Williamson parameter λ will increase the skin friction in both stretching and shrinking surfaces.

The present investigation deals with the effect of substrate orientation effect on the growth of thermally oxidized Ge. The thermal oxidation was performed at temperature between 375 and 550°C in dry oxygen ambient under atmospheric pressure. The thickness of thermally oxidized Ge films was measured by spectroscopic ellipsometry and the chemical bonding structures were characterized by using x-ray photoelectron spectroscopy (XPS). No orientation dependence was observed for the oxidation at temperature of 375°C while for oxidation at 490 and 550°C, Ge oxidation and GeO desorption rate of (100) orientation yield higher rate than (111). The larger atomic space of (100) orientation explains the higher oxidation and desorption rate at Ge surface.

The effects of annealing treatment on the polarization of copolymer P(VDF-TrFE) free-standing films were thoroughly studied by the thermally stimulated current (TSC) method using decomposition analysis and first-order kinetic theory. The TSC measurement mainly revealed three depolarization peaks, which are known as the β, α and Curie mode (ρ) peaks in P(VDF-TrFE). The origin of the TSC peaks and their relaxation behaviour were correlated with structural, morphological and electrical properties such as ferroelectricity, dielectricity and pyroelectricity. Spin-coated copolymer thin films with thicknesses of 300 nm were also prepared from 5 wt.% solutions. Both free-standing and thin films were initially annealed in the range of their Curie temperature up to the melting point [80–140°C] to increase their crystallinity. A remnant polarization current of 76.7 mC m−2, which gives a pyroelectric coefficient of 31 μC m−2K−1 and a figure of merit FD of 86 μC m−2K−1 (1 kHz), was obtained from the sample annealed at 100°C, where the percentage of crystallinity was maximum and the phase was about to transition from ferroelectric to paraelectric.

Packaging material such as plastic bags is one of the main factors that contribute to the environmental pollution due to slow degradation. The usage of metal oxide as pro-oxidant has been proven to accelerate the degradation of these materials, but the excessive usage of this pro-oxidant will be harmful to the human body. Therefore, in this research, spear grass is investigated to be used as natural based pro-oxidant that can increase the degradation rate of the polymers. In terms of that, spear grass is extracted by using pressurized hot water extraction (PHWE) to obtain the metal element such as zinc (Zn) and ferum (Fe). PHWE is using water as a solvent which is highly favourable due to non-toxicity and non-flammable characteristics that make it easy to handle. Box-Behnken design is used to optimize the temperature, extraction time, and sample-to-solvent ratio to get the maximum amount of Zn and Fe concentration from the extracted spear grass. As a conclusion, the leaf of spear grass contributed the highest amount of Zn and Fe concentration. The highest amount of Zn and Fe concentration is achieved at 150 °C, 20 minutes, and 3 g of sample to 45 ml of water.

Since before the British rule, the issues and problems of urban transformation growth have continued until today, especially in rural areas and small towns. Rural communities also have undergone significant transformations in recent decades. There are positive and negative impacts on adaptation the growth of regional development that impact significantly on the rural community, which needs to be addressed to overcome the adverse effects on those that involved. This also included the changes in a case study of rural areas that have been chosen, which is located in sub-district that categorize under rural areas at Johor Bahru due to Iskandar Malaysia region expansions. Furthermore, the developmental transformation has mainly affected the changes in the socio-economic well-being of rural communities. Therefore, the purpose of this paper is to provide an overview of studies on a factor of socio-economic well-being development in rural areas for creating a framework to measure the impact of regional development on the socio-economic well-being of the rural.

The Covid-19 pandemic has impacted the socio-economic well-being of people either in urban or rural areas. The Covid-19 cases and fatalities that concentrated in major urban areas in Malaysia. However, as the pandemic progressed, the rural community faced health vulnerability due to the Covid-19 pandemic threat. Among the significant impacts of the Covid-19 pandemic are income generation, economic activity work, and health vulnerability, especially the rural community involved in rural economic activities such as agriculture and fishery. Therefore, this paper aims to investigate the impact of the Covid-19 pandemic on the socio-economic well-being of rural communities in Malaysia. The case study selection is in Mersing, Pontian and Batu Pahat involving three villages using GIS mapping. The methodology used is quantitative research through a household survey conducted using 182 heads of households based on the economic and social dimensions. The finding reveals that most of the target group experienced a decline in income generation, economic activity restriction, and education issues. Furthermore, there are also decreasing in the economically active population (age 15-60) in the village. As a result, this study is essential in formulating a post-Covid-19 recovery plan regarding socio-economic well-being impacts and the revival of rural community well-being in Malaysia through Geographic Information Systems (GIS) mapping.