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Novel electronic nanomaterial, the carbon nanotube (CNT) has emerged in many sensor applications as such its state dispersion has considerable importance to ensure the sustainability of its electronic properties. In this paper, we reported a state of art conductivity mapping on nanostructure surface of single walled carbon nanotubes (SWCNT) and poly(3-hexylthiophene-2,5-diyl), (P3HT) as potential sensing film. This composite is proposed to give selective analyte anchoring across the film as well as improved carrier mobility. The easy solution processing method was chosen to produce non-covalently wrapped conducting polymer onto the surface of SWCNT. We successfully observed high resolution images of the SWCNT walls that indicated increase of the thickness due to polymer wrapping. The image obtained from conductivity atomic force microscopy (CAFM) show the film’s electrical distribution that correlated with the observed nanostructure of film. Supporting optical characteristics of the nanocomposite obtained from UV-Vis spectroscopy and Raman spectroscopy discussed the morphology of the polymer wrapping and the state of dispersion of the polymer and the nanotubes. It is hypothesized the filament structures made by P3HT/SWCNT can give better sensing performance due to modification of π-π electronic band of SWCNT.

In this paper, trap levels around the glass transition temperature (Tg) of polymers have been characterized using Thermally Stimulated Current (TSC) technique. Deconvolution on α-peaks of the Tg for PE (-104 °C), plasticized PVC (-35 °C), PMMA (90 °C) and PET (96 °C) were carried out based on the first-order kinetic theory for non-Debye relaxation. Using temperature, T from TSC experimental data, we have successfully separated the α-peaks of the thermoplastic polymers. It is found that the complex curve of α-peaks can composed of four (4) to eight (8) sub peaks. Dominant sub peaks were identified at Tmax = -105 °C, -34 °C, 89 °C and 92 °C for PE, pPVC, PMMA and PET, respectively. These peaks show activation energy, Ea of shallow and deep trap centers ranged from 0.3 eV to 4.6 Ev where they represent the depolarization of localized dipoles and space charges relaxations in the polymers.

Graphene is a single-atom-thick sheet of sp2 hybridized carbon atoms that are packed in a hexagonal honeycomb crystalline structure. This promising structure has endowed graphene with advantages in electrical, thermal, and mechanical properties such as room-temperature quantum Hall effect, long-range ballistic transport with around 10 times higher electron mobility than in Si and thermal conductivity in the order of 5,000 W/mK, and high electron mobility at room temperature (250,000 cm2/V s). Another promising characteristic of graphene is large surface area (2,630 m2/g) which has emerged so far with its utilization as novel electronic devices especially for ultrasensitive chemical sensor and reinforcement for the structural component applications. The application of graphene is challenged by concerns of synthesis techniques, and the modifications involved to improve the usability of graphene have attracted extensive attention. Therefore, in this review, the research progress conducted in the previous decades with graphene and its derivatives for chemical detection and the novelty in performance enhancement of the chemical sensor towards the specific gases and their mechanism have been reviewed. The challenges faced by the current graphene-based sensors along with some of the probable solutions and their future improvements are also being included.

PurposeThis paper aims to discuss the use of the sensor material in coating to detect defects which can cause corrosion on metal substrate. This coating consists of sodium polyacrylate (SP) to detect the presence of water and fluorescence substance 2-[4-(piperidin-1-yl)-5H-chromeno-[2,3-d]pyrimidin-2-yl]phenol [benzopyranopyrimidine (BPP)] to detect crack formation.Design/methodology/approachThe coating resin is a mixture of poly(methyl methacrylate) (PMMA) and poly (methyl vinyl ether-alt-maleic anhydride). The additives are used to provide a visual indicator to the observer for when the coating exhibits any defects, so that quick action can be taken before corrosion develops further. SP has absorbent properties and expand when in contact with water, while BPP exhibits high luminous intensity in its solid form that is easily perceivable when exposed to UV. PVM/MA was used as the binder with ethanol as the solvent. The resistance of this coating towards water penetration was investigated using electrochemical impedance spectroscopy (EIS). The coating’s performance was observed in terms of visible optical appearance.FindingsThe sensor coating developed in this project serves as visual aid to the observer through the expansion of SP and high fluorescence of BPP material after the top coat is physically damaged. These findings are in provision of preventive measures that can be taken in case of top coat failure.Research limitations/implicationsThe resistance of the coating that contained SP could not be investigated with EIS due to its ability to expand immediately when in contact with liquids.Practical implicationsThe coating developed in this study may be to detect corrosion.Originality/valueThe sensor material used has not been previously studied in applications to detect the presence of water or used to detect crack formation.

Purpose The effect of using microcrystalline cellulose (MCC) as an additive in coating paint films for non-stick coatings was studied in this work. This paper aims to discuss the benefits of MCC blended in the coating paint film that consists of poly(methyl methacrylate) (PMMA) and dammar. Design/methodology/approach PMMA and dammar mixed at a specific Wt.% ratio with xylene as its solvent. Two sets of mixtures were prepared, where one mixture contained MCC and another, without. The mixtures were applied to metal substrates as coating paint films. The performance of the non-stick coating paint film was observed through the adhesive test between adhesion layers on the coating paint film and also through the cross-hatch test for the adhesion of the non-stick coating paint film to the metal substrate. The results correlate with the surface roughness and glossiness tests. Findings The results showed that for the coating paint films, Sample B consisted of 80:20 Wt.% ratio of PMMA-dammar with an addition of 5 Wt.% MCC had an excellent performance as non-stick coating paint films. The MCC formed microparticles on the surface of the coating paint film sample and this causes the coating paint film samples with MCC to develop a rougher surface compared to the coating paint film without MCC. Sample B coating paint film had the highest average surface roughness (Ra) of 383 µm. The cross-hatch test showed the coating paint film with the addition of MCC had stronger adhesiveness on the substrate’s surface thus prevents the coating from peeling off from the surface. Practical implications The developed coating paint film in this study would be suitable for outdoor applications to prevent illegal advertisements and stickers. Originality/value MCC added to the coating paint film improves the surface performance as a non-stick coating.

Dehydration within low temperature range (30 °C − 100 °C) of Ca2+−Montmorillonite or Ca2+−Mon had caused water removal, where its endothermic from DSC curve reveals the heat of fusion H is about 336.96 J/g. Comparable endothermic within similar temperature range detected in PE-Mon, DPNR-Mon, ENR50-Mon and pPVC-Mon composite profile also indicates the present of interlayer water from Ca2+−Mon particles in the composites. The reduced H about 13% (DPNR-Mon), 32% (PE-Mon), 61% (ENR-50) and 70% (pPVC-Mon) suggests that water removal had occurred during composite fabrication in colloidal systems. XRD analysis however demonstrates that the clay interlayer structure in PE-Mon and DPNR-Mon remain unaffected with similar d001 = 1.46 nm as in pristine Ca2+−Mon. Structural effect from water removal can be seen in the case of ENR50-Mon and pPVC-Mon composites, where the reduced gallery height gives d001 = 1.29 nm and 1.34 nm respectively. Peak intensity behaviors as shown by hydroxyl ((∂HOH) and (νOH)) and silicate (Si-O) bands in FTIR spectra help to explain the observations, particularly the appearance of Si-O band (1017 cm−1) that proves the occurrence of water removal inside the clay composites.

The search for new compounds other than oxime as potential reactivator that is effective upon organophosphate poisoning treatments is desired. The less efficacy of oxime treatment has been the core factor. Fourteen compounds have been screened via in silico approach for their potential as sarin-inhibited human acetylcholinesterase poisoning antidotes. The selection of the compounds to be synthesized based on this computational screening, reduces the time and cost needed. To perform the docking study of sarin-inhibited acetylcholinesterase and reactivator-sarin inhibited acetylcholinesterase complexations, a bioinformatics tool was used. Estimation of the nucleophilic attack distance and binding energy of fourteen potential compounds with sarin inhibited acetylcholinesterase complexes to determine their antidote capacities was carried out using Autodock. A commercially available antidote, 2-PAM was used for the comparison. The best docked-pose was further examined with molecular dynamics simulation. Apart from being lipophilic, a compound with a carboxylic acid, (R)-Boc-nipecotic acid is shown to exhibit 6.29 kcal/mol binding energy with 8.778 Å distance of nucleophilic attack. The stability and flexibility of the sarin-inhibited acetylcholinesterase, complexed with (R)-Boc-nipecotic acid suggests this compound should be tested experimentally as a new, promising antidote for sarin-inhibited acetylcholinesterase poisoning.

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 abstractSchematic 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.

Thermal analysis on organically modified Ca2+-montmorillonite (OMON) and its source materials—octadecylamine (ODA) and Ca2+-montmorillonite (Ca2+-Mon)—was studied using thermally stimulated current (TSC) technique. The appearance of ρ MON peak with the T max = 75 °C shows the ability of the developed TSC system to demonstrate the relaxation effects of dehydration in Ca2+-Mon. It appeared within the temperature range of DSC endothermic peak (30–100 °C) where the T mMON = 58 °C. Segmental motions of ODA chains and structural disruptions in the modifier agent compound produced TSC α ODA, ρ ODA and ρ 1ODA peaks that are comparable to thermal transition and endothermic peaks in DSC profile (T gODA, T m1ODA and T m2ODA). The effect of localized motion in ODA chains as revealed by the TSC βOMON peak (T max = −23 °C), however, is absent in the DSC profile of OMON. It shows TSC technique has high sensitivity in detecting various relaxation behaviors at molecular level. More evidences are demonstrated by the ρ OMON (T max = 86 °C) and ρ 1OMON (T max = 105 °C) peak originated from the ODA chains structures. These peaks also confirm the intercalation of the modifier cations inside the Ca2+-Mon gallery.

Purpose This paper aims to study the colour stability of chlorophyll and the effect of copper (II) nitrate – Cu(NO3)2 – as an additive in natural dye coating films after being exposed to ultraviolet-A (UV-A). Design/methodology/approach The natural dye was extracted from the leaves of Cassia alata L. using absolute ethanol as the solvent. The extract was divided into two parts and, one of it was added with 3 wt.% Cu(NO3)2 as an additive. The polymer blend of poly(methyl methacrylate) (PMMA) and acrylic polyol was used as the coating binder. Both parts of the dye with and without additive were mixed with the blended polymer in a specific ratio. The resulted mixtures were applied as coating films on glass substrates. The colour stability of the coating films on exposure to UV-A with the time of exposure was observed with Commission internationale de l’éclairage (CIE) L*a*b* colour coordinates. The hidden power by the means of reflectivity and glossiness of the coatings was also studied. Statistical standard deviation (STD) was used to analyse the data. Findings The test showed that the coating films containing Cu(NO3)2 had smaller colour differences, (ΔE*) indicating higher colour stability. The analysis on hidden power also showed that the coating film with Cu(NO3)2 was 1.6 times more stable than the film without additive. All the measurements in this study were observed within 35 days of duration. Research limitations/implications This paper implies the potential of using natural dye extracted from Cassia alata L. leaves as a stable dye colourant for coating applications. Practical implications The coating film developed in this study is suitable for glass substrate applications. Originality/value A new method of preparing solvent-based coating film from PMMA–acrylic polyol with chlorophyll colourant is introduced in this study.

Micrifibrillated cellulose (MFC) is generally can be prepared either by acid hydrolysis, chemical treatments, or by a high pressure refiner. In this study, the MFC of Resak’s hardwood waste with high degree of crystallinity has been obtained by an acid hydrolysis using mineral acid H2SO4. The microstructures of the MFC were characterized via X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM).

Banana pseudostems waste is abundantly available as agro-waste and has been used in different applications. In this work, the isolation of CMNF from the pseudostems of banana plant were explored. The dried stems from the species Musa acuminata were first cleaned by soxhlet extraction, alkali treatment and bleaching. Segal method will be employed to analyze data from XRD to determine crystallinity of the CMNF. Morphology of the CMNF will be determined using FESEM. Characterizations of treated and untreated samples were compared. The comparison between those treated and untreated samples giving the information about crystallite size, crystallinity and surface morphology for each treatment.

Cellulose Micro/Nano fibers (CMNF) from various plants which is Resak (Vatica spp.) waste, Merbau (Intsia bijuga) waste, banana (Musa acuminata) pseudo-stem and pineapple (Ananas comosus) leaf fibers have been isolated and characterized. Isolation of microfibril cellulose from raw fibers was achieved using alkaline treatment and bleaching. The treated and untreated samples were characterized using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Characterizations of treated and untreated samples were compared. The comparison between those treated and untreated samples giving different crystallite size, crystallinity, arrangement of CMNF and surface morphology from different plants. Hence, with these information different nanocomposite from CMNF can be constructed and manipulated for various application.

This review encompasses a literature review of chemical warfare agents (CWAs) and the attendant advantages and limitations of existing techniques (i.e. gas chromatography, liquid chromatography and ion mobility spectrometry) used for the detection of CWAs in previous decades. CWAs include the following agent classes i.e. nerve agents, blister agents, blood agents and incapacitating agents. Nerve agents are among the most toxic and have been used by certain military forces and terrorists in many conflicts and consequently have caused both death and disability to humans. Here, we focus on current developments in biosensor approaches used for the detection of organophosphorus CWAs, especially those that are able to overcome the limitations found in earlier detection techniques. The biosensor approach offers rapid, sensitive, selective, portable, simple and low-cost on-site detection capability that would meet the requirements for CWA detection in the event of future events. The future prospects and challenges of biosensor development for CWA detection is also discussed.

The role of phosphotriesterase as an enzyme which is able to hydrolyze organophosphate compounds cannot be disputed. Contamination by organophosphate (OP) compounds in the environment is alarming, and even more worrying is the toxicity of this compound, which affects the nervous system. Thus, it is important to find a safer way to detoxify, detect and recuperate from the toxicity effects of this compound. Phosphotriesterases (PTEs) are mostly isolated from soil bacteria and are classified as metalloenzymes or metal-dependent enzymes that contain bimetals at the active site. There are three separate pockets to accommodate the substrate into the active site of each PTE. This enzyme generally shows a high catalytic activity towards phosphotriesters. These microbial enzymes are robust and easy to manipulate. Currently, PTEs are widely studied for the detection, detoxification, and enzyme therapies for OP compound poisoning incidents. The discovery and understanding of PTEs would pave ways for greener approaches in biotechnological applications and to solve environmental issues relating to OP contamination.