The quality and quantity of particulate organic carbon (POC) were investigated in a fringing coral reef of Tioman Island, Malaysia to better understand the food sources for reef meso-zooplankton. Phytoplankton biomass in the water column was on average 0.22 (± 0.07) mg Chl-a m-3, of which picophytoplankton was the most important (size <3 μm, 50-70% of the total Chl-a). The proportion of C biomass by phytoplankton and other plankton to particulate organic carbon (POC) was low (6% and 5%, respectively) and the major portion of POC was occupied by detritus (89%), suggesting that the diet of particle-feeding or suspension feeding meso-zooplankton would chiefly consist of detritus.
The heat transfer behaviour of a viscous fluid over a stretching/shrinking sheet driven by a uniform shear in the far field with a convective surface boundary condition is studied. The boundary layer equations governing the flow are reduced to ordinary differential equations using a similarity transformation. Using a numerical technique, these equations are then solved to obtain the temperature distributions and the heat transfer rate at the surface for various values of Prandtl number, stretching/shrinking parameter and convective parameter. Dual solutions are found to exist for the shrinking case, whereas for the stretching case, the solution is unique.
MeSH terms: Clothing; Hot Temperature; Temperature; Physical Phenomena
The classical problems of forced convection boundary layer flow and heat transfer near the stagnation point on a permeable stretching/shrinking surface in a nanofluid is studied theoretically. The similarity equations were solved numerically for two types of nanoparticles, namely copper and silver in the base fluid of water with the Prandtl number Pr = 6.7850 to investigate the effect of the solid volume fraction or nanoparticle volume fraction parameter φ of the nanofluid. Also the case of conventional or regular fluid (φ = 0) with Pr = 0.7 is considered for comparison with previously known results from the open literature. The comparison showed excellent agreement. The skin friction coefficient, the Nusselt number and the velocity and temperature profiles were presented and discussed in detail. It was found that the nanoparticle volume fraction substantially affects the fluid flow and heat transfer characteristics.
Eleven different brands of mineral water available in Malaysia were assessed in comparison with two criteria for ingested radiation dose. It is concluded that mineral water can only contribute a very small fraction of the typical daily intake of potassium, and that the radiation dose acquired from any of the brands can never exceed a small fraction of the recommended limits.
MeSH terms: Androsterone; Eating; Malaysia; Mineral Waters; Potassium; Radiation Dosage
Metal nanoparticles having interesting shapes can be prepared in aqueous solutions through simple reductions of metal ions with the presence of some additive reagents, such as cetyltrimethylammonium bromide and hexamethylenetetramine. In this review, some successful results for shape-controlled synthesis of metal nanoparticles in our group are summarized, which includes the synthesis of palladium nanocubes, palladium nanobricks, gold nanotripods. In addition, combining with indium tin oxide electrode surfaces, shape-controlled growth is shown to be possible to form gold nanoplates and copper oxide nanowires. Even in relatively mild synthetic conditions, interesting shape-controlled synthesis of metal nanoparticles is possible.
MeSH terms: Cetrimonium Compounds; Copper; Electrodes; Gold; Indicators and Reagents; Ions; Methenamine; Oxides; Palladium; Tin Compounds; Metal Nanoparticles; Nanowires
This paper elaborates on the inseparable link between sustainability of natural resources and food security. A strategic framework that envisages conservation, improvement and sustainable uses of natural resources is proposed which meets the essential requirements for food security. Sustainability has traditionally been accepted as encompassing three dimensions, namely environment, economics and society but it is necessary to widen this approach for a more complete understanding of this term. Environmental degradation curtails ecosystem services, leading to impoverishment of vulnerable communities and insecurity. Food, whether derived from land or sea, is a product of complex environmental linkages, and biodiversity has a pivotal role to play in producing it. Technology, production methods and management requirements are different for food derived from land and sea, but essentially all foodstuffs utilize environmental resources whose sustainability is crucial for food security. This analysis necessitates consideration of the basic concepts of sustainable development and food security, the strength of the link between these and differences in the patterns of sustainable management of agriculture, fisheries and aquaculture. The growing role of genetically engineered organisms has been included because of the immense possibilities these offer for maximizing food production despite the environmental and ethical concerns raised.
The seeds of C. cleomifolia (locally known as kacang hantu) collected along Simpang Pulai - Berinchang Road, Cameron Highlands, was defatted with hexane and the resulting oil was analysed for their physico-chemical properties. The percentage yield of the oil was calculated as 5.3%. The acid value (1.2%), iodine value (85), peroxide value (0.6), saponification value (192.0) and unsaponifiable matter (2.3%) were determined to assess the quality of the oil. The physico-chemical characterisation showed that C. cleomifolia seeds oil is unsaturated semi-drying oil, with high saponifi cation and acidic values. The fatty acid composition of C. cleomifolia seed oil was determined by Gas Chromatography and Gas Chromatography-Mass Spectrometry (ToF). The seed oil of C. cleomifolia contained linoleic acid (57.59%) and palmitic acid (5.07%), the most abundant unsaturated and saturated fatty acids, respectively. The polyunsaturated triacylglycerol (TAG) in C. cleomifolia seed oil determined by reverse phase High performance Liquid Chromatography; contained as PLL (18.04%) followed by POL + SLL (11.92%), OOL (7.04%) and PLLn (6.31%). The melting and cooling point of the oil were 16.22°C and -33.54°C, respectively
The corrosion inhibitor of carbon steel in 1% NaCl solution by curcuminoids has been studied at 27oC using weight loss and electrochemical method. The determination of corrosion inhibition efficiency (%eff) utilising weight loss method at the concentration of 80 ppm showed the best result of 78.70% for third isolated fraction. Further determination utilising Tafel method showed the following results: raw pure extract of curcuminoid gave 89.88% at 50 ppm; the first isolated fraction gave 46.50% at 80 ppm; the second isolated fraction gave 44.83% at 30 ppm; and the third isolated fraction gave 92.44% at 70 ppm. Based on the analysis of Tafel extrapolation curve, the raw pure extract and the third fraction of curcuminoid acted as anodic inhibitor, whereas the first and the second fraction performed as cathodic inhibitors. The evaluations of synergism parameter (Sθ) indicate that the enhancement in inhibition efficiency towards raw pure extract was caused by the presence of second and third fractions as cathodic and anodic inhibitors. The contribution of steric hindrance of methoxy groups in curcuminoid structure causes the decrease in curcuminoid activity to be adsorbed on the electrode (carbon steel) surface.
A functional cookie formulation containing oligofructose, dietary fibre and lower calorie, fat and sugar contents than conventional cookies was optimized using Response Surface Methodology (RSM). Instant N-Oil II was used as a fat replacer, while Raftilose ®P95 was used as a sugar substitute with the addition of fructose to enhance sweetness. Selection of the optimal formulation was based on caloric content. An optimized formulation, V1, was obtained from the model Y = 4927.70 – 152.34X1 – 155.42X3 + 104.20X32 + 151.71X33 – 95.08X34, where Instant N-Oil II replaced 30% of butter and 24.4%, w/w (30.5g) fructose replaced 40.0%, w/w (50.0g) sucrose. Two additional optimized formulations, S1 and S2, were proposed which contained the same ingredients as V1, but both contained 19.0%, w/w (23.8g) Raftilose ®P95. Also, S2 had a higher fat replacement level (42%). A reference cookie prepared from a conventional recipe received significantly higher scores (P < 0.05) than the functional cookies V1, S1 and S2 in the sensory evaluation. However, when health benefits of the functional cookies were explained to the panel after the sensory evaluation had concluded, majority of the panelists stated that they would prefer S1, had they known of its health benefits. S1 contained 19.04% fat, 8.62% fructose and 0.74% sucrose, namely, significantly lower fat and sucrose levels and higher fructose content than the conventional cookie.
Fossil fuels (petroleum, natural gas and coal) are the main resources for generating electricity. However, they have been major contributors to environmental problems. One potential alternative to explore is the use of microbial fuel cells (MFCs), which generate electricity using microorganisms. MFCs uses catalytic reactions activated by microorganisms to convert energy preserved in the chemical bonds between organic molecules into electrical energy. MFC has the ability to generate electricity during the wastewater treatment process while simultaneously treating the pollutants. This study investigated the potential of using different types of mixed cultures (raw sewage, mixed liquor from the aeration tank & return waste activated sludge) from an activated sludge treatment plant in MFCs for electricity generation and pollutant removals (COD & total kjeldahl nitrogen, TKN). The MFC in this study was designed as a dual-chambered system, in which the chambers were separated by a NafionTM membrane using a mixed culture of wastewater as a biocatalyst. The maximum power density generated using activated sludge was 9.053 mW/cm2, with 26.8% COD removal and 40% TKN removal. It is demonstrated that MFC offers great potential to optimize power generation using mixed cultures of wastewater.
MeSH terms: Bioelectric Energy Sources; Coal; Electricity; Nitrogen; Petroleum; Sewage; Biological Oxygen Demand Analysis; Natural Gas; Waste Water
The solid phase synthesis is a method by which organic compound synthesis are performed on a support. With this method, the purification can be carried out easily by simple filtration and washing procedures. Long-chain alcohol (C-100 alcohol) can be used as a support because of its insolubility in organic solvents and its simple structure which enables it to be stable in various reaction conditions. In this study, a 4-aminopyridine derivative has been synthesized from C-100 β-keto ester and a cyano enamine using tin(VI)chloride as catalyst. C-100 β-keto ester was obtained by transesterification of long chain alcohol (the support) with ethyl acetoacetate using boric acid protocol. The cyano enamine was successfully synthesized by Thorpe-Ziegler cyclization initiated by sodium hydride. The 4-aminopyridine derivative was successfully cleaved from the support using sodium isopropoxide in refluxing isopropanol. From the 1H-NMR spectrum at ~ 120oC, it was found that the cleaved support has the same spectrum with the long-chain alcohol used in the beginning of reaction, thus, this long chain alcohol can be reused for other reactions.
Corrosion is one of the major problems in petroleum mining and processing industry. The pipelines used to transport crude oil from reservoir to the processing installation were made from carbon steel that is susceptible towards corrosion. One of the best methods to prevent corrosion that occurred at the inner parts of carbon steel pipelines is to use organic corrosion inhibitor. One of the potent organic corrosion inhibitors is amino acids derivatives. In this study, dipeptide compound namely benzoylalanylglycine methyl ester and benzoylalanylglycine have been synthesized. The structure elucidation of the products was performed by IR, MS and NMR spectroscopy. The determination of corrosion inhibition activity utilized the Tafel method. The corrosion inhibition efficiency of glycine methyl ester, benzoylalanine, dipeptide benzoylalanylglycine methyl ester and dipeptide benzoylalanylglycine were 63.34%, 35.86%, 68.40% and 27.72%, respectively. These results showed that the formation of dipeptide benzoylalanylglycine methyl ester, derived from carboxylic protected glycine and amine protected alanine, increased the corrosion inhibition activity due to the loss of acidity center in the structure of glicine and L-alanine that would induce the corrosive environment towards carbon steel.
In spite of their excellent catalytic properties, enzymes should be improved before their implementation both in industrial and laboratorium scales. Immobilization of enzyme is one of the ways to improve their properties. Candida antarctica lipase B (Cal-B) has been reported in numerous publications to be a particularly useful enzyme catalizing in many type of reaction including regio- and enantio- synthesis. For this case, cross-linking of immobilized Cal-B with 1,2,7,8 diepoxy octane is one of methods that proved significantly more stable from denaturation by heat, organic solvents, and proteolysis than lyophilized powder or soluble enzymes. More over, the aim of this procedure is to improve the activity and reusability of lipase. Enzyme kinetics test was carried out by transesterification reaction between 4-nitrophenyl acetate (pNPA) and methanol by varying substrate concentrations, and the result is immobilized enzymes follows the Michaelis-Menten models and their activity is match with previous experiment. Based on the Vmax values, the immobilized enzymes showed higher activity than the free enzyme. Cross-linking of immobilized lipase indicate that cross-linking by lower concentration of cross-linker, FIC (immobilized lipase that was incubated for 24 h) gave the highest activity and cross-linking by higher concentration of cross-linker, PIC (immobilized lipase that was incubated for 2 h) gives the highest activity. However, pore size and saturation level influenced their activity.
Kajian ini bertujuan untuk menentukan jenis bakteria yang hadir di dalam air sisa kumbahan yang dapat membantu menghasilkan tenaga elektrik dan pada masa yang sama dapat menyingkirkan kandungan karbon dan nitrogen. Kaedah pengesanan kumpulan bakteria yang digunakan adalah teknik penghibridan in situ berpendarfluor (FISH) manakala kaedah tindak balas berantai polimerase (PCR) untuk mengenalpasti bakteria tersebut. Penentuan ciri biokimia menggunakan BIOLOG GEN III MICROPLATE™ turut digunakan. Bakteria yang didapati daripada air sisa dikultur dan ditulenkan di atas agar zat makanan untuk menentukan ciri-ciri morfologi koloni bakteria tersebut. Berdasarkan pencirian koloni dan pewarnaan Gram, sebanyak 21 pencilan telah diperolehi daripada tiga lokasi sampel air sisa kumbahan daripada loji rawatan enap cemar teraktif (enam koloni air sisa mentah; sebelas koloni tangki pengudaraan; empat koloni tangki kitaran enap cemar teraktif). Penentuan awal daripada ketiga-tiga kaedah yang dijalankan tidak dapat memberikan padanan yang tepat dengan hanya mencatatkan kehadiran bakteria pengoksida ammonia (FISH) dan Kurthia Gibsoni (BIOLOG) di dalam sampel tangki pengudaraan; bakteria Bacillus sp (PCR) dan Bacillus Pseudomycoides (BIOLOG) di dalam sampel kitaran enap cemar teraktif. Ketumpatan kuasa maksimum yang diperoleh daripada sampel kitaran enap cemar teraktif adalah 9.053 mW/cm2 dengan tahap penyingkiran COD dan jumlah nitrogen adalah (TKN) masing-masing 26.8% dan 40%.
In principle, adsorption of biological molecules on a functionalized surface of a microfabricated cantilever will cause a surface stress and consequently the cantilever bending. In this work, four different type of polysilicon-based piezoresistive microcantilever sensors were designed to increase the sensitivity of the microcantilevers sensor because the forces involved is very small. The design and optimization was performed by using finite element analysis to maximize the relative resistance changes of the piezoresistors as a function of the cantilever vertical displacements. The resistivity of
the piezoresistivity microcantilevers was analyzed before and after dicing process. The maximum resistance changes were systematically investigated by varying the piezoresistor length. The results show that although the thickness of piezoresistor was the same at 0.5 μm the resistance value was varied.
Silicon nanowires (SiNWs) have been synthesized by plasma enhanced chemical vapor deposition (PECVD) at different power for generation of plasma and different flow rate of silane gas. Silane (10% SiH4 in Ar) gas with flow rate ranging between 6-15 standard cubic centimeter per minute(sccm) were employed as the source and gold colloid as the catalyst. A p-type Si (100) wafer was used as substrate in this experiment and the substrate’s temperature was 370°C.The plasma power range was 12-17 watts. The grown silicon nanowires were analyzed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). FESEM results show that some silicon nanowires are cone like and some of them are cylindrical. The EDX result revealed that the existence of silicon and oxygen elements in the nanowires. The silicon nanowires obtained have different diameters and lengths and the SiNWs consist of silicon core which are surrounded by oxide sheath. It has been found that the plasma power and flow rate of the silane gas influence the size of silicon nananowires growth by PECVD. The diameter of wires decreased from 140 nm to 80 nm averagely when plasma power was increased from 12 to 17 watts. The diameter also increased about 90 nm to 150 nm when the flow rate of silane gas is increased from 6 to 15 sccm.
Optical constants derived from optical transmission (T) and reflectance (R) spectra in the wavelength range of 220 to 2200 nm are presented in this paper for hydrogenated silicon (Si:H) thin films deposited by plasma enhanced chemical vapor deposition (PECVD) using the layer-by-layer (LBL) deposition technique. The films were deposited on quartz substrate by decomposition of SiH4 and H2 gases at flow-rate of 5 sccm and 20 sccm, respectively. The substrate temperature, deposition pressure and deposition rate are 100°C, 0.8 mbar and 2.8 nm/s, respectively. The as-prepared films were annealed in nitrogen for one hour at annealing temperatures of 400°C, 600°C, 800°C and 1000°C. The as-prepared film thickness of 301 nm decreased to 260 nm when samples were annealed at 1000°C. The refractive indices (~ 3.0 to 3.4) of annealed films were determined from the interference fringes of transmission spectrum following Manifacier and Davies methods. The electronic transition from valence band to conduction band in these films are characterized from the optical energy gap; EG (~1.64 to 2.41 eV), the dispersion energy; Ed (~26.4 to 34.0 eV) and the oscillator strength; Eo (~2.8 to 3.2 eV). It is interesting to note that EG is lowest for the films annealed at temperature of 600°C which has the lowest hydrogen content, CH in the film. Evidence of the presence of nanocrystallites formed in amorphous matrix is also observed for the films annealed at temperatures above 600°C.
We determined theoretically the confined electron states in a colloidal core-shell CdTe-CdS quantum dot system with CdTe as the core material with electron effective mass 0.095 me, CdS as barrier material of electron effective mass 0.25 me and having conduction band offset of 0.265 eV. Based on the one band effective mass approximation, the Schrödinger equation of this system with BenDaniel-Duke Hamiltonian is numerically solved using the finite difference method to obtain the energy level and wave function of the electron confined states. These electronic parameters are obtained by diagonalising the resultant N×N Hamiltonian matrix for principal quantum number n=l – 3, orbital quantum number l=0 – 3 and dot size r=10 – 100 Å. For comparison, we also analytically solve the Schrödinger equation with classical Hamiltonian and similar input parameters to determine the electronic properties. There is good agreement in the results of these two computational methods, where specifically their energy levels differ by less than 15%.
Polymer gel electrolytes (PGEs) based on 49% methyl-grafted natural rubber (MG49) were first prepared by dissolving ammonium triflate (NH4CF3SO3) in propylene carbonate (PC) by various molar concentrations of NH4CF3SO3 to obtain liquid electrolytes and were characterized by AC electrical impedance spectroscopy (EIS) measurements to study their conducting behaviour. The liquid electrolyte with optimum conductivity (0.7M) was then gelled with MG49 and their conductivity was also studied. The highest conductivity of liquid electrolyte was 3.6×10-3 Scm-1 and 2.9×10-2 Scm-1 for PGEs. The molecular interactions between components of NH4CF3SO3, PC, and MG49 have been observed by ATR-FTIR spectroscopy study. The downshifting of C=O stretching frequency of PC from 1785 cm-1 to 1780 cm-1 and NH4+ band from 1634 cm-1 to 1626 cm-1 that has been obtained by spectroscopic data in addition of NH4CF3SO3 confirmed the complexation occurrence. Interaction between NH4CF3SO3 and MG49 has also been investigated. This study is focused on the interactions between components in the PGE system and relates them with their conducting behavior.
In this research we investigated the effect of composition on the fabrication and morphological characteristics of a hybrid polymeric solar cell which consists of an electron donating conjugated polymer, namely is poly(3-hexylthiophene) (P3HT) combined with an electron-accepting component, which is a type of inorganic compound of TiO2 nanocrystals. The composition of TiO2 in the blends is varied and the optimum performance of the devices are studied. The optical and morphological characterizations are carried out via UV-Visible absorption spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrical characteristics of the devices are measured by using Keithley 2400 SMU and solar simulator with light intensity of 100 mW/cm2.