Powder material parameters establishment through warm forming route

This paper presents the establishment of the properties of powder materials through experimentation at elevated temperature ranging from room temperature (30 °C) to 150 °C. Uniaxial die compaction experiments were conducted to establish the powder properties such as densification, Young’s modulus, spring-back, plastic index, elastic index, and plastic hardening coefficient. Shearing experiments were conducted to establish the temperature dependent friction coefficient. Iron powder ASC 100.29, manufactured by Höganäs AB Company was used during the experiment. The results showed that the deformation properties of powder materials especially iron powder are temperature dependent. The values of some properties are increased as the compaction temperature increased and vice versa.     

Investigation of a New 3D Intelligent Ray-Tracing Model

While characterizing the wireless network, it is critical to predict the exact signal propagation paths in an efficient way for three dimensional (3D) indoor environment. In this paper, a new 3D intelligent ray-tracing (IRT) model based on the modified binary angle division (MBAD) technique is presented. The MBAD algorithm can launch the minimum amount of rays by identifying the invalid regions, which can skip the processing of the unnecessary signals. To further accelerate the MBAD algorithm feasible for the 3D environment, virtual surface technique and efficient polygon test are used. Besides, the amount of time for intersection test is reduced by using the surface skipping technique. Moreover, different radio signal propagation paths, such as reflection, refraction, and diffraction from 3D objects along with infinitesimal rays with very small wavefront are considered. The results obtained from this study show the superiority of the proposed model in terms of higher prediction accuracy (29.21 %) and better computational time (58.78 %) than other well-known techniques. Finally, this work also analytically examines the measured and the simulated results for the proposed IRT model and evaluates the effectiveness. The experimental results are compared with the simulated results obtained from IRT model and good agreement (accuracy of about 97 to \(>\) 99 %) demonstrated.     

Production of bacterial endoglucanase from pretreated oil palm empty fruit bunch by bacillus pumilus EB3

In this study, endoglucanase was produced from oil palm empty fruit bunch (OPEFB) by a locally isolated aerobic bacterium, Bacillus pumilus EB3. The effects of the fermentation parameters such as initial pH, temperature, and nitrogen source on the endoglucanase production were studied using carboxymethyl cellulose (CMC) as the carbon source. Endoglucanase from B. pumilus EB3 was maximally secreted at 37 degrees C, initial pH 7.0 with 10 g/l of CMC as carbon source, and 2 g/l of yeast extract as organic nitrogen source. The activity recorded during the fermentation was 0.076 U/ml. The productivity of the enzyme increased twofold when 2 g/l of yeast extract was used as the organic nitrogen supplement as compared to the non-supplemented medium. An interesting finding from this study is that pretreated OPEFB medium showed comparable results to CMC medium in terms of enzyme production with an activity of 0.063 U/ml. As OPEFB is an abundant solid waste at palm oil mills, it has the potential of acting as a substrate in cellulase production.     

Congenital dyserythropoietic anaemia: report of three cases

Between January 1985 and June 1992, the Paediatric Department of Hospital Universiti Sains Malaysia has diagnosed congenital dyserythropoietic anaemia in three children, two of whom were siblings. The age of onset ranged from 1 to 3 years. All of them became transfusion-dependent before the age of 4 months. One of them was successfully treated with bone marrow transplantation.     

Chemical modification of kenaf fibers

The interest in using natural fibers in composites has increased in recent years due their lightweight, non-abrasive, combustible, non-toxic, low cost and biodegradable properties. However, lack of good interfacial adhesion, low melting point and poor resistance to moisture absorption make the use of natural fiber reinforced composites less attractive. Chemical treatment of the fiber can clean the fiber surface, chemically modify the surface, stop the moisture absorption process and increase the surface roughness. In this study, kenaf bast fibers, supplied by MARDI, for use in fiber-reinforced composites, were modified using NaOH of different concentrations. Morphological and structural changes of the fibers were investigated using scanning electron microscopy (SEM). A series of fiber bundle tensile tests were also performed to evaluate the effect of the treatments on the fiber tensile strength. It has been found that the alkalization treatment has improved the mechanical properties of the kenaf fiber significantly as compared to untreated kenaf fiber. It is also interesting to note that 6% NaOH yields the optimum concentration of NaOH for the chemical treatment.     

Molecularly imprinted solid-phase extraction of diazepam and its metabolites from hair samples

An anti-diazepam, molecularly imprinted polymer (MIP) has been synthesized and used to extract diazepam and other benzodiazepines from hair samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. Optimum retention of diazepam on the MIP columns was achieved using an apolar solvent, and the binding capacity of the polymer toward diazepam was found to be 110 ng of diazepam/mg of polymer. The recovery of a 50 ng diazepam standard spiked into blank hair was 93%, with good precision (RSD = 1.5%). The LOD and LOQ of diazepam in spiked hair samples were 0.09 and 0.14 ng/mg, respectively. The MISPE method was demonstrated to be applicable to the analysis of diazepam metabolites and other benzodiazepine drugs, in addition to diazepam itself. The application of the extraction method to postmortem hair samples yielded results that were in good agreement with the corresponding ELISA data (from blood samples) and data arising from the analysis of the same blood samples using a validated in-house SPE-LC-MS-MS method.     

Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature

The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal α-amylase and glucoamylase at 35 °C for 24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization temperature (60 °C for 30 min). The dextrose equivalent (DE) value of heat-treated starch increased significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch, respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and solubility showed insignificant increase for both starches. Evidently, heating treatment below gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch.     

Effect of blending and emulsification on thermal behavior, solid fat content, and microstructure properties of palm oil-based margarine fats

The ability of palm oil (PO) to crystallize as beta prime polymorph has made it an attractive option for the production of margarine fat (MF). Palm stearin (PS) expresses similar crystallization behavior and is considered one of the best substitutes of hydrogenated oils due to its capability to impart the required level of plasticity and body to the finished product. Normally, PS is blended with PO to reduce the melting point at body temperature (37 °C). Lipid phase, formulated by PO and PS in different ratios were subjected to an emulsification process and the following analyses were done: triacylglycerols, solid fat content (SFC), and thermal behavior. In addition, the microstructure properties, including size and number of crystals, were determined for experimental MFs (EMFs) and commercial MFs (CMFs). Results showed that blending and emulsification at PS levels over 40 wt% significantly changed the physicochemical and microstructure properties of EMF as compared to CMF, resulting in a desirable dipalmitoyl-oleoyl-glycerol content of less than 36.1%. SFC at 37 °C, crystal size, crystal number, crystallization, and melting enthalpies (ΔH) were 15%, 5.37 μm, 1425 crystal/μm(2), 17.25 J/g, and 57.69J/g, respectively. All data reported indicate that the formation of granular crystals in MFs was dominated by high-melting triacylglycerol namely dipalmitoyl-oleoyl-glycerol, while the small dose of monoacylglycerol that is used as emulsifier slowed crystallization rate. Practical Application: Most of the past studies were focused on thermal behavior of edible oils and some blends of oils and fats. The crystallization of oils and fats are well documented but there is scarce information concerning some mechanism related to crystallization and emulsification. Therefore, this study will help to gather information on the behavior of emulsifier on crystallization regime; also the dominating TAG responsible for primary granular crystal formations, as well as to determine the best level of stearin to impart the required microstructure properties and body to the finished products.     

Effect of chemical treatments on the mechanical,flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites

This study was performed with commercially available phenyl trimethoxysilane (PTMS) and neoalkoxytitanate [i.e., neopentyl(diallyl)oxytri(dioctyl)phosphato titanate (LICA 12)] as coupling agents. PTMS and LICA 12 were used to treat talc and kaolin to compare their effects with untreated fillers upon incorporation into polypropylene (PP). Single‐filler PP composites (containing either talc or kaolin) and hybrid‐filler composites (containing a mix of both talc and kaolin) were compounded in a twin‐screw extruder and subsequently injection‐molded into dumbbells. The incorporation of PTMS and LICA 12 slightly decreased the tensile and flexural properties in terms of modulus and strength but increased the elongation at break for both single‐filler and hybrid‐filler composites. There was also a significant improvement in the impact strength of the composites, particularly those treated with LICA 12. The hybrid composites, through the synergistic coalescence of positive characteristics from talc and kaolin with the aid from chemical treatment provided an economically advantageous material with mechanical properties comparable to those of the single‐filler‐filled PP composites. Further investigations on flow and morphological properties were also done to correlate the mechanical properties of the single‐ and hybrid‐filler‐filled PP composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008