Occurrence of Volatile Organic Compounds and Extrafloral Nectaries in Tropical Rainforest Species in Danum Valley Conservation Area, Sabah, Malaysia

Plants synthesize numerous classes of secondary metabolites that are crucial in plant defense. Two of the common but non-ubiquitous defenses are the emission of volatile organic compounds (VOCs) and production of extrafloral nectaries (EFN). This study investigates the occurrence of emission of VOC and production of EFN in forest species in Danum Valley Conservation Area, Sabah, Malaysia. From the 165 species screened, 131 species were found to emit VOC while 41 species were EFN-bearing plants. There are 34 species that are both emitting VOC and producing EFN, while 97 species were found to be emitting VOC with no EFN observed. On the other hand, there are 7 species that were EFN bearing but non-VOC emitter, while 27 species were neither emitting VOC nor producing EFN. All 12 dipterocarp species were observed to emit VOC, of these 3 are non-EFN bearing. VOC emissions were further classified into isoprene (C5) and monoterpene (C10) compounds. There are 46 species that were detected to emit both isoprene and monoterpenes, while there are more exclusive monoterpene emitters (62 species) than isoprene-only emitters (23 species). This study showcased the ability of plants to produce a wide array of secondary metabolites as plant defense making them successfully adapt to the complexities of tropical rainforest ecosystem

Occurrence of volatile organic compounds and extrafloral nectaries in tropical rainforest species in Danum Valley Conservation Area, Sabah, Malaysia

Plants synthesize numerous classes of secondary metabolites that are crucial in plant defense. Two of the common but non-ubiquitous defenses are the emission of volatile organic compounds (VOCs) and production of extrafloral nectaries (EFN). This study investigates the occurrence of emission of VOC and production of EFN in forest species in Danum Valley Conservation Area, Sabah, Malaysia. From the 165 species screened, 131 species were found to emit VOC while 41 species were EFN-bearing plants. There are 34 species that are both emitting VOC and producing EFN, while 97 species were found to be emitting VOC with no EFN observed. On the other hand, there are 7 species that were EFN bearing but non-VOC emitter, while 27 species were neither emitting VOC nor producing EFN. All 12 dipterocarp species were observed to emit VOC, of these 3 are non-EFN bearing. VOC emissions were further classified into isoprene (C5) and monoterpene (C10) compounds. There are 46 species that were detected to emit both isoprene and monoterpenes, while there are more exclusive monoterpene emitters (62 species) than isoprene-only emitters (23 species). This study showcased the ability of plants to produce a wide array of secondary metabolites as plant defense making them successfully adapt to the complexities of tropical rainforest ecosystem

The sintering temperature effect on the shrinkage behavior of cobalt chromium alloy

Problem Statement: Co-Cr based alloys which is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance is an important metallic bio�material. However, till date there are only two type of Co-Cr alloy which are the castable and wrought cobalt alloy. Powder Metallurgy route for cobalt is expected to give better result of Co-Cr alloy. The purpose of this research was mainly to study the sintering temperature effect to the shrinkage behavior of Cobalt Chromium (Co-Cr) alloy of the powder metallurgy route. Approach: Co-Cr was produced following P/M route under sintering temperature of 1000, 1100, 1200, 1300 and 1400oC. The sintering time was fixed at 60 min. Several tests has been conducted to determine this effect such as the rate of shrinkage measurement, the bulk density and porosity percentage measurement, compression and hardness tests and micro structural study. Result: From the study, it was found that the sintering temperature has caused the shrinkage of Co-Cr. The increasing of the sintering temperature has caused to the increasing of shrinkage of Co-Cr. This has resulted to the reduction of the pore volume and hence increased it density. In conjunction to that, the strength and the hardness of Co-Cr was increased. Conclusion: Therefore, it is hope that it will bring new view of powder metallurgy Co-Cr alloy as bio-material

The sintering temperature effect on the shrinkage behavior of cobalt chromium alloy

Problem Statement: Co-Cr based alloys which is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance is an important metallic bio�material. However, till date there are only two type of Co-Cr alloy which are the castable and wrought cobalt alloy. Powder Metallurgy route for cobalt is expected to give better result of Co-Cr alloy. The purpose of this research was mainly to study the sintering temperature effect to the shrinkage behavior of Cobalt Chromium (Co-Cr) alloy of the powder metallurgy route. Approach: Co-Cr was produced following P/M route under sintering temperature of 1000, 1100, 1200, 1300 and 1400oC. The sintering time was fixed at 60 min. Several tests has been conducted to determine this effect such as the rate of shrinkage measurement, the bulk density and porosity percentage measurement, compression and hardness tests and micro structural study. Result: From the study, it was found that the sintering temperature has caused the shrinkage of Co-Cr. The increasing of the sintering temperature has caused to the increasing of shrinkage of Co-Cr. This has resulted to the reduction of the pore volume and hence increased it density. In conjunction to that, the strength and the hardness of Co-Cr was increased. Conclusion: Therefore, it is hope that it will bring new view of powder metallurgy Co-Cr alloy as bio-material

Development of high voltage pulse inducement method for biological cell

— Electroporation (EP) system is a process of controlling cell functions by using electromagnetic fields (EMF) to create pores through a cellular membrane that causes cell lysis and apoptosis. In this paper we present an experimental setup for fundamental studies on cell EP. An adjustable high voltage pulse generator (3kV/10μs – 600μs pulse length) system were connected to the EP chamber which subsequently allow real time observation of membrane permeability changes and cellular physiology. In order to initiate higher cell viability rate, high transfection efficiency, lower sample contamination and smaller Joule heating the modification of EP chamber need to be implemented. . Following that, HeLa cell culture has been projected as cell that will be used in this study. Finally, some suggestions are proposed for the future studies

Analytical approach to unidirectional flow of non-Newtonian fluids of differential type

This thesis is regarding the development of mathematical models and analytical techniques for non-Newtonian fluids of differential types on a vertical plate, horizontal channel, vertical channel, capillary tube and horizontal cylinder. For a vertical plate, a mathematical model of the unsteady flow of second-grade fluid generated by an oscillating wall with transpiration, and the problem of magnetohydrodynamic (MHD) flow of third-grade fluid in a porous medium, have been developed. General solutions for the second-grade fluid are derived using Laplace transform, perturbation and variable separation techniques, while for the third-grade fluid are derived using symmetry reduction and new modified homotopy perturbation method (HPM). For a horizontal channel, a new analytical algorithm to solve transient flow of third-grade fluid generated by an oscillating upper wall has been proposed. A new approach of the optimal homotopy asymptotic method (OHAM) have been proposed to solve steady mixed convection flows of fourth-grade fluid in a vertical channel. The accuracy of the approximate solution is achieved through the residual function. For a capillary tube, two flow problems of the second-grade fluid were developed. Firstly, oscillating flow and heat transfer driven by a sinusoidal pressure waveform, and secondly, free convection flow driven due to the reactive nature of the viscoelastic fluid. The solutions for the first problem were derived using Bessel transform technique while for the second problem by using a new modified homotopy perturbation transform method. For a horizontal cylinder, an unsteady third-grade fluid in a wire coating process inside a cylindrical die is developed. A special case of the problem is obtained for magnetohydrodynamic flow with heat transfer for second-grade fluid. Both of these two problems are solved using a new modified homotopy perturbation transform method. Data, graph and solutions obtained are shown and were found in good agreement with previous studies

Mathematical model development on the deformation behaviour of symmetric hexagonal of various angles and square tubes under lateral loading

The purpose of this research is to develop a mathematical model of the collapse behaviour of symmetric hexagonal tubes. For that, a finite element analysis procedure was conducted using ABAQUS software to determine the lateral collapse behaviour of symmetric hexagonal of angles, θ = 30°, 45° and 60° and square tubes to compare the results with the cylindrical tube. Then, a new predictive mathematical model of the lateral collapse behaviour for the generalized symmetrical geometric tubes is developed based on rigid, perfectly plastic model and the energy balance method. The newly mathematical model was validated with the simulation method results. It was discovered that symmetric hexagonal and square tubes performed different deformation behaviour than the cylindrical tube. Square and symmetric hexagonal with θ = 15° tubes performed Type II deformation behaviour. Symmetric hexagonal tubes with θ = 30°, 45° and 60° performed Type I with the perfectly plastic collapse behaviour whereas cylindrical tube performed Type I with strain hardening deformation behaviour. The mathematical prediction model had managed to model the deformation behaviour of symmetric hexagonal tubes with θ = 30°, 45° and 60° but failed to model the square and symmetric hexagonal with θ = 15° tubes because it was the perfectly plastic model which suitable for Type I with perfectly plastic deformation behaviour

Gauging the current status of natural history collections in Malaysia

This study was carried out to gauge the current status of natural history collection centres in Malaysia, primarily focused on animal collections. Part of the research is reported here and it constituted objective one which is to compare the status of natural history collection between the various centres in Malaysia and also with three selected Southeast Asian tropical region museums in trying to understand need of the Malaysian public for a natural history museum. It maps out the locations, describes the number and kinds of specimens kept at each collection centre. Financial and governance aspects are also described. In total 11 centres were visited all over Malaysia. These collection centres and museums were managed by federal or state government or universities. Duration of visit at each location ranged from one to seven days. During the visit interviews were carried out with collection manager to obtained Questionnaire was also left behind for managers of centre to fill in and sent back to researchers. In addition, three natural history collection centres and museums in South East Asia tropical region were also visited: Bogor Zoological Museum, Indonesia; Lee Kong Chian Natural History Museum, Singapore and Mahachakri Sirindhorn Natural History Museum, Prince of Songkhla University, Thailand. Following the same protocol as with Malaysian centres, the information obtained enable researcher to make comparison between Malaysia and those in the region. This paper found that most of the natural history museums and collection centres were focused in the centre of peninsular Malaysia. However, natural history collections in Malaysia are still limited by state and national borders. Coordination and integration of these centres, currently runned separately by the federal, state governments, research institutions and institution of higher learning, is seen as the way forward to provide for a strong basis of understanding biodiversity among the Malaysian public

Study of effect of microsecond pulsed electric fields on threshold area of HeLa Cells

Microsecond pulse electric field (IlSPEF) application development substantially affected the development of research process including controlling cell functions by using pulses of electrical fields to create pores through a cellular membrane causes cell lysis and apoptosis commonly known as electroporation. Here we demonstrate the influence of the IlSPEF on the threshold area (TA) of human cervical cancer cells (HeLa) membrane. The electric field for IlSPEF is 3kV/cm while the pulse interval is lOOms. The pulse length and the number of pulses were fixed at lOllS and 5, respectively. While the cultured skin cells are placed in 9 mm-gap EP electrode chamber for allowing real time observation of membrane permeability changes and cellular physiology. In order to initiate higher cell viability rate, high transfection efficiency, lower sample contamination and smaller Joule heating effect the modification of EP chamber need to be done which can be controlled by pH scale, temperature and humidity. The experiment using high pulse electrical field with simply repetitive pulses shows the threshold area of cell membrane was decreasing gradually to 44.59Ilm, and is settled within hundreds of second. We found that the threshold area of cells membrane was affected when exposed to high voltage pulse electric field. The dependence of the threshold area on the HeLa cell membrane might be associated with the electrical impedance of the plasma membrane that begins to fluctuate after the application of a certain level of IlSPEF

Electrical and magnetic properties of Ga substituted La2/3 Ca 1/3 MnO3 perovskite

Electrical and magnetic properties of gallium substitution for calcium in ABO3 typed colossal magnetoresistance (CMR) La2/3Ca1/3MnO3 (LCMO) perovskite were studied using DC four point probe and AC susceptometer. La2/3 (Ca1-xGax)1/3MnO3 (LCGMO) samples of concentration of x = 0.6, 0.7 and 0.8 were prepared using the solid state reaction method. Gallium substituted samples show the effect of decreasing Mn4+ concentration and of lattice distortion by incorporation of smaller gallium ionic radius. Electrical transport studies indicate samples with Ga concentration x=0.6 and 0.7 exhibit metal to insulator transition (MIT) at low temperature (50K) and sample x=0.8 only shows insulating behavior with increasing Ga concentration. AC susceptibility studies indicate all samples exhibit ferromagnetic to paramagnetic transition with an antiferromagneric ordering at low temperature showing the effect of decreasing Mn4+ concentration affecting double exchange mechanism and thus magnetic ordering of the samples