Assessment of drought impacts on vegetation health: a case study in Kedah

Prolonged drought in the early of 2014 has caused Malaysia to experience water supply shortage which directly affects both health and growth of vegetation. Thus this study aims to assess the risk vegetation areas that were impacted during 2014's drought by integrating the Standardized Precipitation Index (SPI) and Normalized Differentiation Vegetation Index (NDVI) methods. These two methods were able to assess the risk areas for the vegetation by measuring its health and classifying them according to its severity while considering the rainfall reduction at the specific time and location. The results obtained from this study shows that the central and north west of Kedah was vulnerable to the occurrence of drought. Kedah was more impacted by the dry event during the northeast monsoon. This study is significant as a fundamental input for further research and as an alternative approach by the application of space technology

Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

In this work, the role of reduced graphene oxide (rGO) with hyperbranched surfactant and its hybridisation with multiwalled carbon nanotubes (MWCNTs) and platinum (Pt) nanoparticles (NPs) as counter electrode (CE) were investigated to determine the photovoltaic performance of dye-sensitised solar cells (DSSCs). Sodium 1,4-is(neopentyloxy)-3-(neopentyloxycarbonyl)- 1,4-dioxobutane-2-sulphonate (TC14) surfactant was utilised as dispersing and stabilising agent in electrochemical exfoliation to synthesise graphene oxide (GO) as initial solution for rGO production prior to its further hybridisation and fabrication as thin film. A chemical reduction process utilising hydrazine hydrate was conducted to produce rGO due to the low temperature process and water-based GO solution. Subsequently, hybrid solution was prepared by mixing 1 wt% MWCNTs into the produced rGO solution. TC14-rGO and TC14-rGO_MWCNTs hybrid solution were transferred into fluorine-doped tin oxide substrate to fabricate thin film by spraying deposition method. Finally, the CE films were prepared by coating with thin Pt NPs. Photoanode film was prepared by a two-step process: hydrothermal growth method to synthesise titanium dioxide nanowires (TiO2 NWs) and subsequent squeegee method to apply TiO2 NPs. According to solar simulator measurement, the highest energy conversion efficiency (η) was achieved by using CE-based TC14-rGO_MWCNTs/Pt (1.553%), with the highest short current density of 4.424 mA/cm2. The highest η was due to the high conductivity of CE hybrid film and the morphology of fabricated TiO2 NWs/TiO2 NPs. Consequently, the dye adsorption was high, and the photovoltaic performance of DSSCs was increased. This result also showed that rGO and rGO_MWCNTs hybrid can be used as considerable potential candidate materials to replace Pt gradually

Os isotopes in SNC meteorites and their implications to the early evolution of Mars and Earth

A new development on the measurement of the Os isotopic composition by mass spectrometry using negative ions opened a new field of applications. The Re-Os systematic provides time information on the differentiation of the nobel metals. The nobel metals are strongly partitioned into metal and sulphide phases, but also the generation of silicate melts might fractionate the Re-Os system. Compared to the other isotopic systems which are mainly dating the fractionation of the alkalis and alkali-earth elements, the Re-Os system is expected to disclose entirely new information about the geochemistry. Especially the differentiation and early evolution of the planets such as the formation of the core will be elucidated with this method

Efficient removal of partially hydrolysed polyacrylamide in polymer-flooding produced water using photocatalytic graphitic carbon nitride nanofibres

In this work, graphitic carbon nitride (GCN) photocatalyst-incorporated polyacrylonitrile (PAN) nanofibres (GCN/PAN nanofibres) were successfully prepared using electrospinning technique. The physicochemical properties of the fabricated GCN/PAN nanofibres were analysed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analyser, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV–vis–NIR spectroscopy. The photocatalytic degradation by GCN/PAN nanofibres exhibited 90.2% photodegradation of partially hydrolysed polyacrylonitrile (HPAM) after 180 min under UV light irradiation in a suspension photocatalytic reactor. The results suggest that the photodegradation of HPAM contaminant by GCN/PAN nanofibres was due to the synergetic effects of HPAM adsorption by the PAN nanofibres and HPAM photodegradation by the GCN. This study provides an insight into the removal of HPAM from polymer-flooding produced water (PFPW) through photocatalytic degradation of liquid-permeable self-supporting nanofibre mats as a potentially promising material to be used in industrial applications

Mechanistic insight of the formation of visible-light responsive nanosheet graphitic carbon nitride embedded polyacrylonitrile nanofibres for wastewater treatment

Effective capture and in situ photodegradation of methylene blue (MB) dye is a promising technique to purify wastewater containing MB. With recently elicited ripples of discovery on graphitic carbon nitride (g-C3N4), this study investigates the performance of g-C3N4 on photodegradation of MB. In this study, polyacrylonitrile (PAN) nanofibres embedded with g-C3N4 photocatalyst was successfully prepared using electrospinning technique which produced liquid-permeable self-supporting photocatalytic nanofibre mats that can be handled easily. Different configurations of g-C3N4 were synthesised, bulk g-C3N4 (bg-C3N4) and nanosheets g-C3N4 (nsg-C3N4) from urea using a green facile template-free method. Effective photocatalytic activity of the g-C3N4 nanofibres was confirmed by 97.3% degradation of MB under visible light irradiation. Photodegradation of MB in aqueous solution by g-C3N4 nanofibres predominantly attributed to the synergetic effects of MB adsorption by PAN nanofibres and photocatalytic degradation of MB by g-C3N4 photocatalyst. This present work not only presents the simplest ecofriendly and economical approach to fabricate g-C3N4 nanofibre photocatalyst, but also paves new opportunities for this advanced photocatalyst as great potential in environmental remediation for treatment of industrial MB wastewater

Study on feed-in-tariff (FiT) for BIPV system, a Malaysia scenario

Feed-In Tariff (FiT) was introduced in Malaysia in 2004 and has been undergone many stages to make its implementation in Malaysia successful. The first Building Integrated Photovoltaic (BIPV) introduced in Malaysia is Suria 1000 under the supervision of Pusat Tenaga Malaysia (PTM). The aim of this paper was to study the FiT and BIPV implementation in Malaysia. It is observed that Malaysian did not invest in BIPV due to its expensive investment. The FiT Calculator was developed to prove the benefits of FiT in BIPV by practically calculating the investment and profit in the long run which was after 21 years of implementation. FiT Calculator was developed using Microsoft Visual Basic 2010 and variable parameter such as the solar irradiation, types of solar panel and inverter were studied to obtain the estimation of power output, the annual income, net income and the payback period of BIPV. Results of all case studies were verified with MBIPV mileage report and the built FiT Calculator has shown up to 96.89% accuracy against the case study done

Toxicity of imidacloprid gel bait against laboratory strain of Periplaneta americana (L.) (Dictyoptera : Blattidae) and Blattella germanica (L.)(Dictyoptera : Blattellidae)

The efficacy of a 2.15% imidacloprid gel bait against laboratory strain Periplaneta americana and Blattella germanica was evaluated under laboratory conditions. The susceptibility trend of both species towards imidacloprid was: adult male < adult female < nymphs. All stages of both species were dead within 10 days in primary poisoning testing. Periplaneta americana adult male (LT50 = 0.47 h; LT95 = 5.24 h) died fastest, while nymphs of B. germanica took the longest time to reach 95% mortality (LT95 = 43.84 h). In indirect exposure via secondary poisoning, only adult males of P. americana (LT50 = 100.63 h) and B. germanica (LT50 = 54.66 h) obtained 50% mortality before the testing ended. No complete mortalities were achieved in any stages of both species within 10 days of secondary poisoning testing. Therefore, imidacloprid gel bait used in this study was able to cause complete mortalities within less than 2 days of 10-day primary poisoning testing but less effective in the 10-day secondary poisoning testing

Study on the performance of two topology multilevel inverter

It has been accepted that conventional inverters have limitation dealing with high voltage and high power applications. Lately, multilevel inverters are popular for high power applications due to its improved harmonic profile and increased power ratings. There are various literatures regarding topology and control techniques of multilevel inverters. This paper presents the performance of two Flying Capacitor Multilevel Inverter (FCMI) topologies particularly a 3-level and 5-level multilevel inverters. Besides that, concept of the topologies and its modulation techniques were described. Sinusoidal pulse width modulation (SPWM) techniques were utilized in this paper as the topologies control strategy. Two control parameters, namely the amplitude modulation index, ma and the frequency modulation index, mfwere varied in order to control the output voltage of the inverters. The model and simulation study were carried out using Matlab/Simulink software. Analyses on the performance of the two topologies were based on the fundamental voltage, output voltage waveform, output harmonic spectrum and total harmonic distortion (THD). It’s found that the five level FCMI have shown better performance in terms of THD compared to the three level FCMI in all conditions of varied ma and mf. Based on the study also, five level FCMI shows a better voltage output waveform; close to a sinusoidal waveform compared to the three level FCMI

Development of modified double-weight code and its implementation in multi-rate transmissions

This paper presents a new code structure and its ability in supporting multiple transmission rates in point to point Spectral Amplitude Coding- Optical Code Division Multiple Access (SAC-OCDMA) links. The Double-Weight (DW) code family that has a basic fixed weight of 2 was proposed. Modified Double Weight (MDW) Code is a DW code family variation that has variable weight of greater than two. The ability of MDW codes to support simultaneous transmissions at different bit rates is shown through simulated results of the bit error rate (BER) and the eye patterns. Four MDW encoded channels were used at the bit rates of 2.5Gbps and 10Gbps. MDW code shown here significantly performs better than Hadamard and Modified Frequency Hopping (MFH) codes

Superparamagnetic iron oxide as photocatalyst and adsorbent in wastewater treatment - a review

Superparamagnetic iron oxide has been applied in different fields for various reasons. Its abundant availability, non-toxic properties, environmentally friendly and good chemical stability in aqueous medium are beneficial for water treatment applications. In addition, its low bad gap (2.3 ~ 2.4 eV) has contributed to highly possible electrons-holes activation under the visible light spectrum. On the realization of iron oxide capabilities as a promising alternative to conventional anatase TiO2 photocatalysts, this review is presented to critically discuss the photocatalytic behaviour of organic water pollutants as a function of iron oxide properties. The concluding remarks in terms of the way forward in the opportunities of iron oxide superparamagnetic properties can benefit towards the photocatalytic activities including recycling, retrieving and controlling in wastewater treatment