The Prins cyclization of styrene (SE) with paraformaldehyde (PFCHO) was conducted with mesoporous ZnAlMCM-41 catalysts for the synthesis of 4-phenyl-1,3-dioxane (4-PDO) using a liquid phase heterogeneous catalytic method. For a comparison study, the Prins cyclization reaction was also conducted over different nanoporous catalysts, e.g. mesoporous solid acid catalysts, AlMCM-41(21) and ZnMCM-41(21), and microporous catalysts, USY, Hβ, HZSM-5, and H-mordenite. The recyclable mesoporous ZnAlMCM-41 catalysts were reused in this reaction to evaluate their catalytic stabilities. Since ZnAlMCM-41(75) has higher catalytic activity than other solid acid catalysts, washed ZnAlMCM-41(75)/W-ZnAlMCM-41(75) was prepared using an efficient chemical treatment method and used with various reaction parameters to find an optimal parameter for the highly selective synthesis of 4-PDO. W-ZnAlMCM-41(75) was also used in the Prins cyclization of olefins with PFCHO and formalin (FN, 37% aqueous solution of formaldehyde (FCHO)) under different reaction conditions to obtain 1,3-dioxanes, which are widely used as solvents or intermediates in organic synthesis. Based on the nature of catalysts used under different reaction conditions, a reasonable plausible reaction mechanism for the Prins cyclization of SE with PFCHO is proposed. Notably, it can be seen from the catalytic results of all catalysts that the W-ZnAlMCM-41(75) catalyst has higher 4-PDO selectivity with exceptional catalytic activity than other microporous and mesoporous catalysts.
The present work was undertaken to investigate the effect of different packaging materials, namely polyethylene terephthalate (PET) and aluminium laminated polyethylene (ALP) on the physicochemical properties and microbiological stability of spray-dried honey jackfruit powder over seven weeks of storage at 38 ± 2°C and 90% relative humidity. The moisture content of honey jackfruit powder packaged in PET was doubled (12.32%) than of those packaged in ALP (5.31%). The water activity (aw) of the powders were lower than 0.6 for both packaging materials, thus considered shelf-stable. Hygroscopicity increased up to 42.44 and 39.84% for powder packaged in PET and ALP, respectively. The angle of repose for powders flowability increased to 19° (ALP) and 28° (PET), which indicated that the powders flowabili- ty significantly decreased upon storage. The degree of caking for powder packaged in ALP (43.69%) was much less severe than that of PET (84.51%). Powder packaged in ALP showed good solubility (81.07 - 99.01%) and satisfactory microbiological results (< log 2.58 CFU/g). The results recommended that ALP packaging was better suited for keeping spray-dried honey jackfruit powder.
Hydrotalcite-like inorganic layers of Zn-Al, a host containing an organic moiety, 2,4-dichlorophenoxy-acetate, as a guest, was prepared by the spontaneous self-assembly method from an aqueous solution for the formation of a new layered organic-inorganic hybrid nanocomposite material. In this synthesis, the host- and guest-forming species were simultaneously included in the mother liquor, aged, and separated. Various Zn/Al ratios (R = 2, 3, and 4), concentrations of 2,4-dichlorophenoxyacetic acid (0.03-0.1 M), and pH (7 and 10) were studied to optimize the formation of the layered nancomposite. It was found that the optimum conditions for the formation of the nanocomposite were R = 4, pH 7, and concentration of 2,4-dichlorophenoxyacetic acid = 0.08 M. X-ray diffraction shows that this sample affords a nanolayered structure with a basal spacing of 24.6 A.
This study was conducted to compare the total antioxidant activity (TAA), total phenolic content (TPC) and total flavonoid content (TFC) from the different parts of papaya tree including their ripe and unripe fruit, seeds and the young leaves. Two methods namely DPPH radical scavenging activity and ß-carotene bleaching assay were used to determine the TAA, whereas TPC was determined by Folin-Ciocalteu’s method while TFC by aluminium trichloride (AlCl3). For these purposes, methanolic extracts (80%) were prepared. The results showed that the highest antioxidant activity through ß-carotene bleaching assay was observed in unripe fruit (90.67 ± 0.29%) followed by young leave, ripe fruit and the seed. In other hand, young leaves exhibited a significant higher scavenging effect compared to others and the dose required in reducing the absorbance of DPPH control solution by 50% (EC50) was calculated at 1.0 ± 0.08mg/ml. The EC50 values were 4.3 ± 0.01mg/ml, 6.5 ± 0.01mg/ml and 7.8 ± 0.06mg/ml for unripe fruit, ripe fruit and seeds respectively. Interestingly, both TPC and TFC also showed that young leaves had the highest antioxidant content (424.89 ± 0.22mg GAE/ 100 g dry weight and 333.14 ± 1.03mg rutin equivalent/ 100 g dry weight, respectively). Statistically, Pearson correlation showed there were positive correlations between TPC and TFC with antioxidant activity assayed by DPPH radical scavenging assay (r=0.846 and r=0.873, respectively). However there was no correlation between TPC and TFC with ß-carotene bleaching activity. In brief, taken into account all the parameters measured, antioxidants were highly remarkable in the sequence of young leaves > unripe fruit > ripe fruit > seed. Nevertheless, further investigation for isolation and identification of the phytoconstituents responsible for antioxidant activity is desirable.
This study aimed to compare the antioxidant content and antioxidant capacity of pulp and peel of two varieties of pomelo fruit (Tambun White and Tambun Pink). Antioxidants including total phenolic content, total flavonoid content and ascorbic acid content were determined using Folin-Ciocalteu reagent assay, aluminium chloride colorimetric assay and AOAC method, respectively. Antioxidant capacity of pomelo pulp and peel was measured using ferric reducing antioxidant potential and trolox equivalent antioxidant capacity assays. The peels of both pomelo fruits had higher antioxidant content and capacity than their pulps. Moreover, the white variety of pomelo had higher antioxidant content and capacity compared to the pink counterpart. Trolox equivalent antioxidant capacity of the samples was positively high correlated with total phenolic content (r = 0.978) and total flavonoid content (r = 0.959), except for ascorbic acid. Therefore, pomelo peel from white variety possessed higher antioxidant properties and it is potentially rich sources of natural antioxidants.
In this study, low-bandgap polymer poly{[4,4-bis(2-ethylhexyl)-cyclopenta-(2,1-b;3,4-b')dithiophen]-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl} (PCPDTBT) nanostructures have been synthesized via a hard nanoporous alumina template of centrifugal process. Centrifuge has been used to infiltrate the PCPDTBT solution into the nanoporous alumina by varying the rotational speeds. The rotational speed of centrifuge is directly proportional to the infiltration force that penetrates into the nanochannels of the template. By varying the rotational speed of centrifuge, different types of PCPDTBT nanostructures are procured. Infiltration force created during the centrifugal process has been found a dominant factor in tuning the morphological, optical, and structural properties of PCPDTBT nanostructures. The field emission scanning electron microscopy (FESEM) images proved the formation of nanotubes and nanowires. The energy-dispersive X-ray spectroscope (EDX) analysis showed that the nanostructures were composed of PCPDTBT with complete dissolution of the template.
Synthesis of palm oil based-urethane acrylate (POBUA) resins was carried out by acrylation of epoxidizedpalm oil (EPOP) using acrylic acid in the presence of a catalyst and followed by isocyanation to obtainthe POBUA. Using the monomer as a diluent in the formulation, 4% of photoinitiator and incorporationof organoclay (1-5% wt), nanocomposites were obtained upon UV irradiation. The X-ray DiffractoryXRD study revealed that the nanocomposites obtained were of the exfoliation type. The presence ofthe clay improved the hardness and did not affect the thermal stability. Similarly, it increased the glasstransition temperature Tg but reduced the modulus as the clay content was increased. The improvementof the tensile strength was only obtained when the clay concentration was 5 phr.
The effect of solid solution treatment on semisolid microstructure of Zn-22Al with developed dendrites was investigated. Zn-22Al is a zinc-based alloy with aluminium as its main alloying element. Producing Zn-22Al product by semisolid metal processing (SSM) offers significant advantages, such as reduction of macrosegregations, porosity and low forming efforts. Meanwhile, thermal and microstructure analyses of Zn-22Al alloy were studied using differential scanning calorimeter (DSC) and Olympus optical microscope. Solidus and liquidus of the alloy can be determined by DSC analysis. In addition, changes to the microstructures in response to solid solution treatments were also analyzed. The major effort of all the semi-solid technologies is the generation of small and spherical morphologies. Prior to the generation of spherical morphologies, the fine grains should be first produced. The as-cast samples were isothermally held at 315°C, ranging from 0.5 to 5 hours before they were partially re-melted at semisolid temperature of 438°C to produce solid globular grains structure in liquid matrix. The results indicated that a non-dendritic semisolid microstructure could not be obtained if the traditionally cast Zn-22Al alloy with developed dendrites was directly subjected to partial remelting. After solid solution treatment at 315°C, the black interdendritic eutectics were dissolved and gradually transformed into ß structure when the treatment time was increased. The microstructure of the solid solution treated sample changed into a small globular structure with the best shape factor of 0.9 and this corresponded to 40±16µm when the sample was treated for 3 hours, followed by directly partial remelting into its semi solid zone.
The present investigation deals with the development of ethanol-vapour-sensing materials coated with the semiconducting oxide TiO2. Thick films of anatase TiO2 were deposited using the sol-gel dip-coating technique on alumina substrates by conventional alkoxide sol and modified sol added with Degussa P-25 as the sensing medium. It was shown that crystallised TiO2 anatase was obtained at the annealing temperature of 500oC. The fabricated TiO2 sensors exhibited highest sensitivity at the sensing temperature of 350 ºC. Sensitivity towards the ethanol vapour was further increased with UV light effect. The enhancement of the sensitivity of the modified catalytic pellet can be explained by the crystallite of anatase TiO2 and the effect of the photocatalytic of TiO2. The high sensitivity of the TiO2 film deposited with modified sol revealed that the modified sol could be a new alternative in the development of a TiO2 ethanol sensor.
Tailing sand is the residue mineral from tin extraction that contains between 94% and 99.5% silica, which can be used as moulding sand. It is found in abundance in the Kinta Valley in the state of Perak, Malaysia. Adequate water content and clay in moulding sand are important factors for better strength and
casting quality of products made from tailing sand. Samples of tailing sand were investigated according
to the American Foundrymen Society (AFS) standard. Cylindrical test pieces of Ø50 mm×50 mm in height from various sand-water ratios were compacted by applying three ramming blows of 6666g each using a Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using a Ridsdale-Dietert universal sand strength machine. Before the tests were conducted, moisture content of the tailing sand was measured using a moisture analyser. A mixture bonded with 8% clay possesses higher green compression strength compared to samples bonded with 4% clay. The results also show that in order to achieve maximum green compression strength, the optimum allowable moisture content for mixtures bonded with 8% clay is ranged between 3.75 and 6.5% and for mixtures bonded with 4% clay is 3-5.5%.
Aluminium (Al) is a low cost, lightweight and corrosion resistant material, which corrodes when exposed to pitting agents. Palm olein exhibits characteristics, which indicate its suitability as a corrosion inhibitor. Tween 20, hexane and diethyl triamine were used as additives to Palm olein to form the inhibitor formulation POT2OHA. The inhibition efficiency (IE) and behaviour of the POT2OHA were determined using potentiodynamic polarization in which Al 6061 samples were immersed in a 1 M HC1 solution at 26, 50 and 70 °C in the presence of different POT2OHA concentrations: 0, 0.03, 0.07, 0.10, 0.13 and 0.17 M The IE increased with increasing POT2OHA concentration, but decreased with increasing temperature. The work presented indicates that POT2OHA is a mixed-type inhibitor capable of inhibiting both corrosive anodic and cathodic reactions. According to the Langmuir isotherm results POT2OHA adsorbs on the A16061 surface through semiphys iosorption and/or semi-chemisorption. The POT2OHA adsorption mechanism on Al 6061 takes through the protonation of micelles by the HC1 solution, whereby protonated micelles in the presence of chloride ions adsorb on both cathodic and anodic surface corrosion sites.
Heat treatment was introduced onto the aluminum coated low carbon steel to promote the formation of thin layer of oxide for enhancement of oxidation protection of steel. This process has transformed the existing intermetallic layer formed during hot dip aluminizing process. Experiment was conducted on the low carbon steel substrates with 10mm x 10mm x 2mm dimension. Hot dip aluminizing of low carbon steel was carried out at 750 ºC dipping temperature in a molten pure aluminum for 5 minutes. Aluminized samples were heat treated at 600 ºC, 700 ºC, 800 ºC, and 900 ºC for 1 hour. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and EDAX were used in investigation. From the observation, it showed the intermetallic thickness increased with the increase in temperature. The result of EDAX analysis revealed the existence of oxide phase and the intermetallics. The XRD identified the intermetallics as Fe2Al5 and FeAl3.
Al-Si/SiC composites with the fraction of 5 and 15 wt. % fine SiC particles were fabricated using stir casting process by which SiC powders were poured into aluminium melt and cast in a stainless steel mould to form ingot. Characterization by X-ray diffraction (XRD) analysis showed the presence of constituent and intermetallic materials in the composites. Microstructure study revealed that both fine and course particles scattered in the Al-Si matrix. The characterization of thermal properties showed that the thermal conductivity and coefficient of thermal expansion decreased with the increase in SiC content. The conductivity and expansion behavior is correlated to the microstructure and weight fraction of the SiC particles. Meanwhile, the hardness of the composite increased with the increasing of SiC particles in the composites.
The corrosion behaviour of ternary aluminium alloy sacrificial anodes with small amount addition of tin as depassivating element in natural seawater was studied by means of conventional DC electrochemical measurements. Metallurgical microscope was employed in order to observe the changing of microstructure caused by tin present in ternary alloys. The relationship between microstructure and electrochemical results was examined and particular attention paid to the cause of the electrochemical efficiency of anode performance. The results indicate that the proper precipitates uniformly distributed of tin are influence on improving electrochemical performance of alumnium alloy anode.
Being an imperative material for man either used as building materials, pottery or as components in material industry and technology, knowledge of clays elemental contents is important. In the present study ten clay samples obtained from various locations in North-West Peninsular Malaysia were used. Majority of the clays were economically manufactured to be used as building materials or pottery. The objective of study was to determine the main elemental contents of the samples, and relate the results to the types of minerals, as well as to compare them with clays from other studies. In the study X-ray Fluorescence (XRF) coupled to samples dilution method and standard calibration samples was used. The elements detected in the study were Si, Al, Fe, Ti, K and Ca. Depending on locations, the percentage concentration ranged between 24.8 – 32.4 for Si, 10.8 – 19.0 for Al, 0.09 – 2.12 for Fe, 0.08 – 1.13 for Ti, 0.45 – 3.39 for K and trace amount of Ca and P. However, Mg that normally found in typical clay was not found in the studied samples. Comparing the oxide of the major elements with other studies, it was found that the clay samples contained mixtures of kaolinite (two-layered structure) and illite (three-layered structure).
Radon-222 emanation from selected locally produced samples of building materials, used in Malaysia were measured using the Professional Continuous Radon Monitor Model 1027, which is a patented electronic detecting-junction photodiode sensor to measure the concentration of radon gas. Each sample was placed for 72 hours inside a 3.11 x 10 -2 m 3 sealed container. It was found that the average radon concentration Bqm -3 of air for concrete bricks, concrete brick with cemented coatings, concrete brick with cemented coatings and paint samples were, 303.7 Bq/m 3, 436.6 Bqm -3, and 410.7 Bqm -3, respectively. (Bqm -3 ) for brown clay brick, brown clay brick with cemented coatings, brown clay brick with cemented coatings and paint were 166.5 Bqm -3, 166.5 Bqm -3, and 148 Bqm -3, respectively. (Bqm -3 ) for sample of compact ceramic tile was 0 Bqm -3. The findings show that concrete brick samples are important source of radon emanation, while brown clay brick have been accepted as the recommendation of the U.S. Environmental Protection Agency (EPA), and ceramic tiles had no emanation of radon gas due to their compact surface, or the glazed layer created on the tile surface during the manufacturing process, which blocks radon emanation. A positive correlation between radon emanation and radium content has been observed for both brown clay brick and concrete brick samples whereas a negative correlation for ceramic tile has been observed. Consequently from the findings, in order to reduce radon emanation and radon exposure in house dwellings and in addition to EPA recommendation of sealed cracks and established good ventilation, we recommend concrete walls to be painted and concrete floors to be paved with ceramic tiles.
At present, soil and mineral based building material such as bricks are one of the main components in building construction in Malaysia. This building material is a direct source of radiation exposure since it contains naturally occurring radioactive materials (NORM). In this study, clay brick samples used were obtained from 7 factories in Selangor and Johore, Malaysia. The activity concentrations of 226 Ra, 232 Th and 40 K in these samples of clay bricks were determined using a comparative method and was analysed using gamma spectrometry with HPGe detector. The mean values of activity concentrations for 226 Ra, 232 Th and 40 K were found to be in the range of 39.04 ± 0.88 Bqkg-1 - 73.61 ± 5.32 Bqkg-1, 43.38 ± 2.60 Bqkg-1 - 73.45 ± 1.51 Bqkg-1, and 381.54 ± 11.39 Bqkg-1 - 699.63 ± 15.82 Bqkg-1, respectively. The radiation hazard of NORM in the samples was estimated by calculating the radium equivalent activity (Raeq), external hazard index (Hex) and internal hazard index (Hin). Radium equivalent activity (Raeq) determined was in the range of 151.90 Bqkg-1 - 194.22 Bqkg-1 which is lower than the limit of 370 Bqkg-1 (equivalent to 1.5 mSvyr-1 ) recommended in the NEA-OECD report in 1979, whereas external hazard index (Hex) and internal hazard index (Hin) were between 0.20 – 0.26 and 0.52 - 0.71 respectively. The annual effective dose rate exposure to a dweller received from the clay bricks was calculated to be in the range of 0.35 ± 0.18 mSvy-1 - 0.43 ± 0.09 mSvy-1.
A co-deposition of nickel-phosphorus-alumina (NiPA) composite coatings were obtained from an ordinary sulphate-based plating bath consisting of 5 g/l alumina (Al2O3) particles. The particles were dispersed by using mechanical agitation at 125 rpm. The presence of Ni3P and Al2O3 phases in the coatings was confirmed by XRD analysis. SEM/EDX results indicated that a smooth Ni3P coating was obtained and Al2O3 particles were embedded into the coating. Microscopic observation showed that the bonding between the Ni3P metal matrix and the Al2O3 ceramic particles was compact.
Clay has been regarded as very important natural industrial materials. All these industries exploit the properties that clay can be molded into any shape and fired to dry without losing its form. A study was carried out on clay samples from eight sites in the north-eastern part of Peninsular Malaysia. The study was accomplished by using X-ray diffraction (XRD) technique. The x-ray diffraction spectra obtained enable the determination of the lattice spacing associated with the types of clay and nonclay minerals present in the samples. Results of the study shows that the major components of clay minerals present in all samples studied are kaolinite and illite. The presence of kaolinite is confirmed by firing test in which the kaolinite diffraction peaks disappeared upon heating the samples at 600 o C. The presence of non-clay minerals such as quartz, mica, feldspar and chlorite are also observed.
Boundary element method (BEM) is a numerical technique that used for modeling infinite domain as is the case for galvanic corrosion analysis. The use of boundary element analysis system (BEASY) has allowed cathodic protection (CP) interference to be assessed in terms of the normal current density, which is directly proportional to the corrosion rate. This paper was present the analysis of the galvanic corrosion between Aluminium and Carbon Steel in natural sea water. The result of experimental was validated with computer simulation like BEASY program. Finally, it can conclude that the BEASY software is a very helpful tool for
future planning before installing any structure, where it gives the possible CP interference on any nearby unprotected metallic structure.