Neuro-fuzzy system in partitioned client-side Web cache

This paper proposes a novel contribution in Web caching area, especially in Web cache replacement, so-called intelligent client-side Web caching scheme (ICWCS). This approach is developed by splitting the client-side cache into two caches: short-term cache that receives the Web objects from the Internet directly, and long-term cache that receives the Web objects from the short-term cache. The objects in short-term cache are removed by least recently used (LRU) algorithm as short-term cache is full. More significantly, when the long-term cache saturates, the neuro-fuzzy system is employed efficiently in managing contents of the long-term cache. The proposed solution is validated by implementing trace-driven simulation and the results are compared with least recently used (LRU) and least frequently used (LFU) algorithms; the most common policies of evaluating Web caching performance. The simulation results have revealed that the proposed approach improves the performance of Web caching in terms of hit ratio (HR), up to 14.8% and 17.9% over LRU and LFU. In terms of byte hit ratio (BHR), the Web caching performance is improved up to 2.57% and 26.25%, and for latency saving ratio (LSR), the performance is better with 8.3% and 18.9% over LRU and LFU, respectively.     

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.     

A hybrid approach for learning concept hierarchy from Malay text using artificial immune network

A concept hierarchy is an integral part of an ontology but it is expensive and time consuming to build. Motivated by this, many unsupervised learning methods have been proposed to (semi-) automatically develop a concept hierarchy. A significant work is the Guided Agglomerative Hierarchical Clustering (GAHC) which relies on linguistic patterns (i.e., hypernyms) to guide the clustering process. However, GAHC still relies on contextual features to build the concept hierarchy, thus data sparsity still remains an issue in GAHC. Artificial Immune Systems are known for robustness, noise tolerance and adaptability. Thus, an extension to the GAHC is proposed by hybridizing it with Artificial Immune Network (aiNet) which we call Guided Clustering and aiNet for Learning Concept Hierarchy (GCAINY). In this paper, we have tested GCAINY using two parameter settings. The first parameter setting is obtained from the literature as a baseline parameter setting and second is by automatic parameter tuning using Particle Swarm Optimization (PSO). The effectiveness of the GCAINY is evaluated on three data sets. For further validations, a comparison between GCAINY and GAHC has been conducted and with statistical tests showing that GCAINY increases the quality of the induced concept hierarchy. The results reveal that the parameters value found by using PSO significantly produce better concept hierarchy than the vanilla parameter. Thus it can be concluded that the proposed approach has greater ability to be used in the field of ontology learning.     

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.     

Mycelium-bound lipase from a locally isolated strain of Aspergillus flavus link: Pattern and factors involved in its production

Aspergillus flavus produces a lipase (EC 3.1.1.3) which is partly bound to the mycelium during growth. The production of the mycelium-bound lipase is concomitant with growth, and declines when growth ceases. Maximum productivity of the enzyme is obtained when the culture is incubated at 30°C, an initial culture pH of 6·5 and with 2% (w/v) each of corn oil and yeast extract as carbon and organic nitrogen source. Yeast extract affects not only the production of lipase but also the secretion of proteases into the culture medium. Production of the latter enzymes, which inactivate the free lipase, is enhanced by adding yeast extract (1–2%, w/v) to the culture medium. However, at 5% (w/v) yeast extract concentration, proteolytic activity is not detected and consequently, the activity of free lipase may easily be measured. Free lipase activity can easily be detected when 0·001 mol dm⁻³ EDTA is added to the culture medium. The presence of the chelating agent enhances the production and maintains the stability of the extracted mycelium-bound lipase.     

Crystallisation regime of w/o emulsion [e.g. multipurpose margarine] models during storage

Multipurpose margarine (MPM) or water-in-oil (w/o) emulsion systems were prepared using palm oil (PO)/palm stearin (PS) blends as continuous phases and stabilized by monoacylglycerol (90% monoester) as emulsifier. Experimental analyses of three out of six models of MPM showed that MPM1, MPM2 and MPM3 had low workability force and weaker network structure. As results the solid fat content (SFC) at 28 °C, consistency, storage modulus (G′) and softness were 25%, 15.5 × 10² kPa, 2.62 × 10² kPa and 30 mm ease of cone penetration, respectively. Furthermore, examination microscopy of the images concerning MPM1, MPM2 and MPM3 revealed the presence of symmetrical crystals after 60 days of storage, whereas the MPM4, MPM5 and MPM6 models exhibited asymmetrical crystals during same incubation time. These results indicated that the diminution of PS versus PO contents induced the retardation of phase transition from less stable beta-prime (β′) crystals to the more stable beta (β) crystals during storage.     

Polyphenoloxidase from guava (Psidium guajava L.)

Polyphenoloxidase (PPO) was isolated from guava (Psidium guajava L., cv. Kampuchea). Purification by acetone precipitation and dialysis of the Amicon concentrate resulted in 4.9-fold and 17.2-fold purification of the dialysed crude extract respectively. Polyacrylamide gel electrophoresis indicated that PPO had a molecular weight in the region of 120000–140000. The pH optimum of the enzyme was found to be 7.2. Heat inactivation studies showed that heating for 1.1, 3.5, and 10.1 min at 75, 65 and 55°C respectively caused a 50% loss in enzymic activity. The enzyme-catalysed browning reaction was significantly inhibited in the presence of sodium metabisulphite, L-cysteine hydrochloride and ascorbic acid.