Papers by Keyword: ESEM

Abstract: This paper presents physical characteristic of Rhodococcus zopfii through the use of Environment Scanning Electron Microscopy. This bacterium is very significant in enhancing degradation of polycyclic aromatic hydrocarbons (PAHs) in the presence of natural biofilm in waste water treatment system. Rhodococcus Zopfii was isolated from municipal sludge at Universiti Teknologi MARA. The average size of Rhodococcus Zopfii was measured in the range of 1.1–2.85 μm lengths and 0.55-0.80 μm diameters. The colour of this bacterium was slightly pink on agar plate and it had rod shaped. Experimental results obtained from confocal laser scanning microscopy showed that this bacterium can easily attach on the surface of biofilm. The experimental results provide a scientific knowledge of physical characteristic of Rhodococcus Zopfii isolated from municipal sludge to grow on natural biofilm in wastewater treatment system.

Abstract: The purpose of these researches was to determine the effect of silicon carbide particles (SiCp) proportion and the effect of some process parameters (temperatures and times of aging) on characteristics of Al-Cu/SiCp composites obtained by P/M route. The age-hardened composites and un-reinforced alloys solution treated at 515 ± 5°C, maintaining time 360 minutes, quenched in water and artificial aging at 150-190^o C during respectively 240-720 minutes/ furnace cooled, were tested from hardness and microstructural point of view. The effect of SiCp proportion in matrix during cold compaction was observed on densification curves of all experimental powders mixtures Al-4Cu/ (5, 10, 15 and 20) wt.%SiC. The composites were analyzed using optical and electron microscopy (including ESEM-Enviromental Scanning Electron Microscopy), in terms of shape and size of grains, pores, ceramic particles, second phases and precipitates.

Abstract: As the potential of using natural log is explored in the temporary structure, especially in template as the shores, it is important to gain further understanding of the microstructure and properties of cells such as undersize tree of Northeast larch that under macro buckling load. The research described in this paper focuses, for the first time, after the initial preparation by microtoming, on investigating the microstructure of log by analyzing of the ESEM images, and a model for deformation and failure mechanism of the cell had been proposed, then, the properties of cells were calculated through image software. Results show that the cells including early wood and late wood under without extra load are regularly arrayed, the deformation of the wall was induced by asymmetric out of plane twisting and splitting due to buckling of the logs, failure of the early wood cell is easily than late wood that following the large deformation occurs at plasticity, and two properties including late wood percentage and cell wall percentage has a direct proportion with the strength of log. The presented results indicate that it is improve to understand and analyze the failure process of cell when the log under concrete compression loading, and the reason that log as sustainable material is due to the unbroken cell clusters recover themselves as quickly as possible during at a certain enough time.

Abstract: Environmental scanning electron microscopy (ESEM) and complementary methods were employed to study the time dependent film formation of a non-ionic latex dispersion in water @ pH 12.8 and cement pore solution. A commercial liquid ethylene-vinyl acetate latex dispersion stabilized with PVOH possessing a minimum film forming temperature (MFFT) of 3 °C and a Tg of 19 °C was employed in the study. Prior to ESEM imaging the latex dispersion was stored at room temperature and then transferred into the ESEM instrument for imaging. Subsequently, micrographs monitoring its film forming behaviour are obtained. The analysis revealed that upon removal of water, film formation occurs as a result of particle packing, particle deformation and finally particle coalescence. In synthetic cement pore solution film formation occurs faster than in water and is complete within one day. This acceleration can be ascribed to the presence of PVOH on the surface of the latex particles. In water at neutral pH, PVOH forms a shell around the latex particle and hinders the interdiffusion of the macromolecules while in cement pore solution, PVOH precipitates due to high pH and high concentration of cations. This way the latex particles can coalesce faster into a polymer film.

Abstract: Microbe technology is introduced for improving silt The metabolic outcomes and precipitation of microbes can glue the soil granule,plug mineral lattice crystal,simultaneously strengthen their shear resistance.Characteristics of silt before and after modification are compared by CU triaxial compression test. By Scanning Electron Microscope(ESEM) and Energy Dispersive X-ray(EDX),the modification mechanism of silt has been investigated.The results show that the values φ of silt is increased larger modified by carbonate mineralization microbes, while the value of cohesion increases larger by polysaccharides viscose microbes.

Abstract: A field pilot test was constructed on a two stage Dissolved Air Floatation (DAF) combined with Activated Sludge Process (ASP) and Immobilized microorganism biological filter (I-BF) has been constructed in Liaohe oilfield, China to treat heavy oil wastewater with large amounts of dissolved recalcitrant organic compounds and low nutrient of nitrogen and phosphorus. By operating the system for 185 days, chemical oxygen demand (COD) removal rates were 67.9 % and 88.4 % in DAF and I-BF effluents, respectively. Environment Scanning electron microscope (ESEM) showed that large quantity of filamentous microorganisms was immobilized on carriers without causing foaming or bulking. This integrated system appeared to be a useful option for the treatment of heavy oil wastewater in Liaohe oil field.

Abstract: Fair dispersion of polymer and control of component grain size are key properties to achieve high performances building material (i.e. ultra high strength concrete, self-levelling floor, or exterior insulation composite system). As microstructure analysis in an organic/inorganic hydrated co-matrix material is time consuming, mechanical spectroscopy temperature analysis could characterise both the polymer and the hydrates in the same run. The temperature dependence of the storage modulus G’ and the loss modulus G’’ of some composite building material was therefore measured between 173 and 470 K by mechanical spectroscopy (Dynamic Mechanical Analysis). A model material was then defined to enable DMA latex/cement interaction study. The latex was reinforced by either a microfiller (OMYA limestone) or a microfiller and a nanofiller (hydrated Lafarge cement paste CEM I 52.5 R). The latex evaluated in this study was a 210nm styrene butyl acrylate (SBA). The measurements confirmed that polymer environment was not hindered by micro or nanofiller (i.e. cement). The hydrated cement paste transformation onset was measured at 373K, but occurred at higher temperature as latex content increased. ESEM micrographs performed during heating have proven that within the hydrated cement paste many parallel cracks propagated at once, while within SBA hydrated cement paste no cracks were observed. The hydrated cement microstructure was modified by SBA, and became less sensitive to temperature increase due to SBA latex ability to deform.

Abstract: This study proposes a new mixing process for producing commercially acceptable DSP mortar of high flowability, using commercial materials and water-bath curing at about 20°C. That is “three- speed mixing technics (TSMT)”. The properties of mortars mixed by TSMT and conventional technics (CT) are compared. At a water-to-binder ratio of 0.2, the compressive strength of the TSMT mixed DSP mortars was about 41.2% higher than that of the CT mixed DSP mortars of the same composition, the workability was also increased. The increase reason was investigated by the wedge-splitting section and Environmental SEM (ESEM) images. Additionally, for TSMT, the influence of mix-design parameters such as cement grade, the water/binder (w/b) ratio, the silicon fume/cement (sf/c) ration and the superplasticizer/cement (sp/c) ratio were studied.

Abstract: The potential of using cellulose to reinforce the thermal stability of kenaf derived cellulose (KDC)/polylactic acid (PLA) composite was investigated in this study. The cellulose was derived from kenaf bast fibre which was chemically treated via chlorination and mercerisation processes. The composites with various loadings of cellulose (dry weight basis) ranging from 0% to 60% were produced by melt mixing and compression moulding. Dynamic mechanical properties namely storage modulus (E’), loss modulus (E”) and tan δ of the KDC/PLA composites and the commercial PLA were analysed and compared as a function of temperature. ESEM micrographs demonstrated that the mercerisation of kenaf fibres have successfully removed the lignin and hemicellulose, thus producing cellulose which can be observed by its rougher surface and greater size reduction than the raw fibre. The DMA results demonstrated that the storage modulus of 60% KDC/PLA composite is twice higher than the commercial PLA and the rest of the composites within a high temperature range (above 80°C). The glass transition temperatures (Tg) generated from the loss modulus curves exhibit that the peak of the loss modulus was shifted to higher temperature as the percentage of the cellulose loading was increased. These results show a better thermal stability of the composites when incorporated with the cellulose.

Abstract: Hydration of cement in the presence of SBR dispersion and powder respectively was investigated using the methods of ITC, XRD and ESEM. The results show that both the dispersion and powder of SBR facilitate the formation, enhance the stability of AFt and inhibit the formation of C4AH13 in cement paste; the effect of the powder is more evident than the dispersion. Both the dispersion and powder of SBR delay the formation of C-S-H and Ca(OH)2 in cement paste, and the effect of the dispersion is more evident. Up to 3 days, the structure of the SBR dispersion – or powder – modified cement pastes has no significant difference with that of control paste except due to a thin polymer film on the surface. The two polymers delay the early cement hydration, but have no significant effect after 3 days.