Stretchable conductive ink (SCI) had been extensively studied for fabricating stretchable electronic devices. In this study, silver conductive ink and thermoplastic polyurethane (TPU) were used as substrate. The ink was printed on the substrate using screen printing with different shaped patterns varied by the widths of 1 mm, 2 mm and 3 mm: (a) straight, (b) zig-zag, (c) square and (d) sinusoidal. The measurement of resistance was performed using four-point measurement during unloaded and loaded conditions of the shape pattern. This study revealed that width had influenced the resistivity in all shape patterns, where the narrow the width, the higher the resistance is. Comparative studies of electromechanical analysis of the shaped patterns had showed that a 3 mm width of zig-zag pattern had a better electromechanical performance by having stretchability to maximum of 7.78%. Straight and square shape patterns, however, exhibited the poor tolerate deformation as both failed to conduct electricity upon straining at the minimum elongation of 1.11%.

Public awareness of the environment and legislation has promoted intensive studies on the reduction of greenhouse gases (GHGs) emission. One of the promising breakthroughs discovered was the polymer blend membrane that demonstrated significant carbon dioxide (CO 2 )/nitrogen (N 2 ) separation performance. Instead of other polymers, cellulose acetate butyrate (CAB) polymer was chosen due to its high CO 2 sorption ability. This membrane was prepared by optimising the ratios of the CAB molecular weights (Mn) of 12000, 70000 and 30000 to enhance the CO 2 /N 2 separation. The single gas permeation test results showed that the CO 2 /N 2 separation performance had increased from 0.7396 0.0396 (M3) to 1.8986 0.0195 (M6) due to the presence of the hydroxyl (OH) group in the membrane. In this study, the newly fabricated polymer blend membrane demonstrated an improvement in the CO 2 /N 2 separation performance. Therefore, this membrane qualifies to be applied in the industry.

Among the carbon dioxide (CO 2 ) separation methods, the membrane separation technology has been mostly applied to reduce the CO 2 emission. Since most CO 2 are emitted from power generation plants, the CO 2 /nitrogen (N 2 ) separation was selected. In this project, the blend cellulose acetate (CA) membranes were prepared by mixing CA with 39% acetyl concentration (CA-39) and 56% acetyl content (CA-56) through the wet-phase inversion method. The CO 2 /N 2 separation performance was determined by evaluating the permeation of gases and the CO 2 /N 2 selectivity by modifying the polymer concentration. The characterisation of the membrane was carried out by using the scanning electron spectrometry (SEM) and attenuated total reflectance Fourier transform infrared spectrometry analysis (ATR-FTIR). The optimal membrane obtained was M3 with polymer concentration of 4:6 (CA-39:CA-56) that had defect-free membrane surface with smooth dense skin layer. The functional groups present enhanced the gas permeance rate. With regards to the gas permeation test, M3 presented the best CO 2 /N 2 separation performance with CO 2 permeance of 99.26 3.08 GPU, N 2 permeance of 87.12 0.81 GPU and CO 2 /N 2 selectivity of 1.139 0.037. It is expected that the results obtained from this work can be applied to industries, such as the gas separation field or power generation plant, in order to reduce CO 2 emission.

First-principles electronic structure calculations were employed for the electronic, magnetic and structural properties of rutile CrO 2 . This material is a ferromagnetic half-metal with a semiconducting gap of 1.85 eV. The sharing of a single electron by Cr-3d yz and d xz orbitals is responsible for the metallic behaviour of CrO 2 for the majority spin channel. For the application of on-site Coulomb interaction U up to 4 eV, the electrons in the valence band polarise towards the Fermi level (E F ), while the electrons in the conduction band polarise away from E F . The enhanced shifting of conduction bands of the spin minority channel is responsible for the augmentation of the semiconducting spin gap. This system undergoes a metal-insulator transition (MIT) upon the application of U = 5 eV. Due to the presence of electron correlation, the electron in the d xy orbital shifts well below E F , while bonding components of d yz and d xz orbitals are occupied by the remaining single electron. Nevertheless, anti-bonding components of these two states remain unoccupied. Consequently, a band gap of E g ~ 0.2 eV is opened near E F . The double exchange interactions between the partially occupied Cr-t 2g states and p-d hybridisations are responsible for the ferromagnetic behaviour of CrO 2 in both halfmetallic and insulating phases.

Good stratigraphy mapping of a site is essential in archaeological explorations but Guar Kepah, Penang, Malaysia had no detailed subsurface mapping done previously up till now. As many archaeological remnants in the vicinity have an affiliation with shell middens, better understanding on Guar Kepah's strata will increase the efficiency of uncovering the shell middens while also saving a huge amount of energy in excavating. This research aims to distinguish Guar Kepah's buried shell midden from the surrounding strata using electrical resistivity method. The study area is composed of three shallow strata of unconsolidated soil with low resistivity values. The sandy-clay layer has the lowest resistivity (< 40 m), followed by densely packed shell layer (40-70 m) and sandy layer (> 70 m). The presence of shells indicates that the uppermost strata is of marine origin, which automatically makes Gula Formation the youngest formation in Guar Kepah due to the absence of terrestrial deposits (Beruas Formation) on top of the layer. The shell layer from the resistivity profiles suggests that the layer has relatively uniform thickness throughout the site. The layer also becomes undulating and shallow towards the south (dipping), making the top sandy-clay soil become thinner or absent in the south. The dipping feature of the shell layer acts as an indicator that Guar Kepah used to be a beach ridge during sea transgression, and further proves that the area was once a marine environment. However, the shell layer at the southern zone poses an anomaly where it suddenly dips toward the centre. As a result, two zones were marked as potential shell middens at the south-western zone (only exhibits one side of the midden that is dipping towards centre) and south-eastern zone (shell midden elongated to the east). Subsequent excavation based on this study had successfully exposed the south-eastern midden and proved that resistivity method could be used not only in stratigraphy identification, but also in characterising shell layer and detecting shell midden.

SnO 2 nanostructures are usually modified with some metal dopants in order to improve its gas sensing properties. In this work, pure tin oxide (SnO 2 ), nickel (Ni) doped SnO 2 (Ni:SnO 2 ) and palladium (Pd) doped SnO 2 (Pd:SnO 2 ) nanorods were successfully synthesised via hydrothermal method at low temperature (180C) without templates or further calcination. All the samples were systematically analysed using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The sensor response (R = R 0 /R g ) towards 1000 ppm ethanol gas was investigated using nitrogen gas as a carrier gas. XRD results confirmed that all samples consisted of rutile tetragonal-shaped SnO 2 . It was found that the average diameter of nanorods formed in Ni:SnO 2 and Pd:SnO 2 were decreased to ~6 nm and ~10 nm, compared with nanorods formed in pure SnO 2 (~25 nm). The gas sensing results indicated that the sensor properties of SnO 2 were enhanced after the doping process. At 450C, the Pd:SnO 2 nanorod sensor recorded the highest response value towards 1000 ppm ethanol gas which is 15 times higher than pure SnO 2 nanorods. Interestingly, all samples showed similar response time, ~ 40 s. However, pure SnO 2 and Ni:SnO 2 nanorods sensors exhibited longer recovery time compared to Pd:SnO 2 nanorods. Pd:SnO 2 nanorods recorded only 12 min of almost 100% recovery. It is proposed that Pd:SnO 2 sensor could be a promising candidate for the detection of ethanol gas.

In Samarang oil platform of Repsol (Talisman) Malaysia Limited, there is a need to increase its current oil production that would result in an increase of the associated/excess gas from 21 mmscfd to 31 mmscfd. The current low-pressure gas system on the platform is designed to accommodate up to 21 mmscfd of gas. The excess produced gas of 10 mmscfd, if not re-injected back into the reservoir, shall need to be flared on a daily basis in order to maximise the oil production rate. This gas flaring expends large amounts of energy and causes environmental degradation and potential health risk. There are four practical cases being considered in this unprecedented effort to control the flared gas and its resulting emissions from the industrially practical standpoint. Three cases use the existing compressor and varying compressor suction pressure between 5 barg and 6 barg with total compressors power is limited up to 2280 kW. The flared gas emission for these cases ranges from 7 mmscfd to 1 mmscfd, which is lower than the expected flowrate of 10 mmscfd. In the case where a new compressor is installed, a zero flared rate is achieved.

In this study, the graphene nanoplatelets (GNP)/carbon fabric (CF)/epoxy (EP) hybrid laminated composites were fabricated via electrophoretic deposition (EPD) followed by hand lay-up assisted vacuum bagging technique. GNP were dispersed in two different colloidal suspensions, i.e., distilled water (DW) and N-dimethyformamide (DMF), and the effect of EPD GNP onto CF surface were investigated. The finding indicated that the electrophoretic mobility (EM) of GNP is slightly slower in DMF due to the higher viscosity of DMF (0.92 mPa.s) compared to DW (0.89 mPa.s). Zeta () potential of GNP were slightly higher in DMF, revealing the non-polar behaviour of GNP being easily dispersed in DMF due to its low polar and hydrogen-bonding strength. However, the higher current intensity was observed for the GNP-DW suspension, implying higher dielectric constant of DW adequate for effective deposition of GNP onto CF surface as confirmed via field-emission scanning electron microscopy (FESEM). The GNP-DMF/ CF/EP composites exhibit the highest flexural properties compared to GNP-DW/CF/EP composites. These findings proved the colloidal dispersibility of GNP in DW and DMF suspensions, respectively used in EPD govern the flexural properties of GNP/CF/EP hybrid laminated composites.

International audience