Influence of Polishing-Induced Surface Hardening on the Adhesion of Oxide Scales Grown on a Ferritic Stainless Steel

The influence of surface preparation on the stress and adhesion of oxide scales formed on the ferritic stainless steel AISI 441 was studied. Steel coupons were surface-finished to different degrees of surface roughness from 400-grit SiC through to 1-micron diamond, and were also electropolished to remove the work hardened surface. Initial metal roughness was measured by optical profilometry. Oxidation was carried out at 800 °C under synthetic air for 100 h. Oxide residual stress was derived from the Raman shift of the main chromia line, and adhesion of oxide scales was quantitatively obtained using forced spallation by tensile straining. The results show that surface hardening is the most influential factor on adhesion, with the high dislocation-containing mirror-polished samples exhibiting the lowest adhesion energy (~4 J m^?2), and the electropolished samples with non-mechanically affected surface exhibiting the highest adhesion energy (17 J m^?2). Recrystallisation of the subsurface zone during heating to the oxidation temperature is thought to be the most influential factor reducing scale adhesion.     

Analytical Analysis of Applying Packet Fragmentation Mechanism on Both Basic and RTS/CTS Access Methods of the IEEE 802.11b DCF Network Under Imperfect Channel and Finite Load Conditions

The mathematical modeling and performance evaluation of the IEEE 802.11 network in all its various extensions (802.11b, 802.11a, 802.11g, 802.11e, 802.11n, etc.) have already been widely explored over the past years. However, the Packet Fragmentation Mechanism (PFM), which is proposed by the IEEE work group to enhance the MAC sub-layer of the IEEE 802.11 standard in an error-prone channel, has been missed in the available literature. Yet, the PFM is the only existing solution to reduce the influence of bit error rate and the length of data packets on the packet error rate, and consequently on the performances of IEEE 802.11 networks. In this paper, we propose a new three-dimensional Markov chain in order to model, for the first time in the literature, the PFM in both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions. Then, we develop mathematical models to derive a variety of performance metrics, such as: the overall throughput, the average packet delay successfully transmitted, the average packet drop time, the delay jitter and the packet delay distribution. Performance analysis of applying PFM on both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions shows original results and leads to new conclusions that could not be intuitively expected.     

Boosted PTS Method with Mu-Law Companding Techniques for PAPR Reduction in OFDM Systems

Wireless Personal Communications - This paper proposes an enhanced PAPR reduction technique which combines an enhanced PTS method with Mu-Law companding. The enhanced PTS method improves...     

Circular discontinuities detection in welded joints using Circular Hough Transform

Conventional radiography is one of the common non-destructive testing which employs manual image interpretation. The interpretation is very subjective and depends much on the inspector experience and working conditions. It is therefore useful to have pattern recognition system in order to assist human interpreter in evaluating the quality of the radiographed sample, especially radiographic image of welded joint. This paper describes a system to detect circular discontinuities that are present in the joints. The system utilizes together two different algorithms, which are separability filter to identify the best object candidate and Circular Hough Transform to detect the presence of circular shape. The result of the experiment shows a promising output in recognition of circular discontinuities in a radiographic image. This is based on 81.82–100% of radiography film with successful circular detection by using template movement of 10 pixels.     

Microstructure and Texture of Milk Coagulum of Streblus asper Leaf Extract

Microstructure, texture, and syneresis of Streblus asper leaf extract, calf rennet, and Fromase made milk coagula were investigated. Microstructure of the milk coagulum was assessed by scanning and transmission electron microscopy. Milk coagulum produced with Streblus asper showed a sponge-like structural network and a denser casein network compared with calf rennet and Fromase produced coagula. Streblus asper made coagulum displayed low porosity, low strength, and low syneresis than those of calf rennet and Fromase made coagula. The spong-like structure, low porosity, and low syneresis were attributed to the high proteolytic nature of Streblus asper leaf extact and to interactions of its phenolic compounds.     

Purification of a novel protease enzyme from kesinai plant (Streblus asper) leaves using a surfactant–salt aqueous micellar two-phase system: a potential low cost source of enzyme and purification method

Serine protease from kesinai leaves was purified for the first time by a surfactant–polymer aqueous micellar two-phase system. The effectiveness of different types and concentrations of non-ionic surfactants (Pluronic series and X-114) on the partitioning behaviour of the protease was evaluated. The results showed that the enzyme preferentially partitioned into the bottom surfactant-rich phase, while the hydrophilic amino acid preferred the top aqueous phase. This distribution of the enzyme is due to the hydrophobic interaction of the serine protease with the hydrophobic lid of the micelle core in the bottom phase. The influence of different types of salts (K₂SO₄, KH₂PO₄, KCl and KNO₃) on the purification and selectivity of the enzyme was determined. The protease partitioning in the bottom phase increased in the presence of KNO₃, which confirmed that the salt was able to improve the protein solubility in bottom phase and increase the hydrophobic interaction between the two phases. In addition, the protease from the bottom phase was re-extracted to a new aqueous phase solution to remove and recycle the surfactant. Addition of potassium thiocyanate led to the partitioning of the enzyme in top aqueous phase due to high ionic strength of SCN^?, which forced the lighter micellar phase toward the upper position of the system. A high purification factor (10.3) and yield of 92 % of the enzyme were achieved in a solution of 31 % of Pluronic L61 using 0.3 % KNO₃ and 50 % crude feedstock at pH 7.0.     

Prebiotics as functional foods: A review

Prebiotics are short chain carbohydrates that are non-digestible by digestive enzymes in humans and selectively enhance the activity of some groups of beneficial bacteria. In the intestine, prebiotics are fermented by beneficial bacteria to produce short chain fatty acids. Prebiotics also render many other health benefits in the large intestine such as reduction of cancer risk and increase calcium and magnesium absorption. Prebiotics are found in several vegetables and fruits and are considered functional food components which present significant technological advantages. Their addition improves sensory characteristics such as taste and texture, and enhances the stability of foams, emulsions and mouthfeel in a large range of food applications like dairy products and bread. This contribution reviews bioactives from food sources with prebiotic properties. Additionally, food application of bioactive prebiotics, stimulation of the viability of probiotics, health benefits, epidemiological studies, and safety concerns of prebiotics are also reviewed.     

Study of the effects of beta-myrcene on rat fertility and general reproductive performance

beta-Myrcene (MYR) is a monoterpene found in the oils of a variety of aromatic plants including lemongrass, verbena, hop, bay, and others. MYR and essential oils containing this terpenoid compound are used in cosmetics, household products, and as flavoring food additives. This study was undertaken on investigate the effects of MYR on fertility and general reproductive performance in the rat. MYR (0, 100, 300 and 500 mg/kg) in peanut oil was given by gavage to male Wistar rats (15 per dose group) for 91 days prior to mating and during the mating period, as well as to females (45 per dose group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal day 21. On day 21 of pregnancy one-third of the females of each group were submitted to cesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed, and cleared and stained with Alizarin Red S for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal day 21. Mortality, weight gain and physical signs of postnatal development were evaluated. Except for an increase in liver and kidney weights, no other sign of toxicity was noted in male and female rats exposed to MYR. MYR did not affect the mating index (proportion of females impregnated by males) or the pregnancy index (ratio of pregnant to sperm-positive females). No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. Only at the highest dose tested (500 mg/kg) did MYR induce an increase in the resorption rate and a higher frequency of fetal skeleton anomalies. No adverse effect of MYR on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were slightly delayed in the exposed offspring. On the basis of the data presented in this paper the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance can be set at 300 mg of beta-myrcene/kg body weight by the oral route.     

Oil price shocks: Sectoral and dynamic adjustments in a small-open developed and oil-exporting economy

The recent uptrend in oil prices represents both an opportunity and a challenge for small-open developed and oil-exporting countries. Using Canada as a study case and in contrast to most studies that use aggregate models, this paper employs a multi-sector, intertemporal general equilibrium model to provide perspectives on the sectoral, aggregate and dynamic adjustments of a sustained increase in oil prices. It highlights the transmission channels through which the rise in oil prices affects the domestic economy. The simulation results suggest that the shock would have positive aggregate impacts, but would also spur the reallocation of resources and would therefore induce disparities in sectoral adjustments. The suggested contraction in some industries could not however be attributed to a pure Dutch disease phenomenon because of, among other factors, the cost-push effect induced by the increase in oil prices.     

Viability and Activity of Bifidobacteria During Refrigerated Storage of Yoghurt Containing Mangifera pajang Fibrous Polysaccharides

Abstract: The viability and activity of Bifidobacterium pseudocatenulatum G4, B. longum BB 536 and yoghurt cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) were studied in yoghurt containing 0.75%Mangefira pajang fibrous polysaccharides (MPFP) and inulin. Growth of probiotic organisms, their proteolytic activities, the production of short chain fatty acids (lactic, acetic and propionic) and the pH of the yoghurt samples were determined during refrigerated storage at 4 °C for 28 d. B. pseudocatenulatum G4 and B. longum BB 536 showed better growth and activity in the presence of MPFP and inulin, which significantly increased the production of short chain fatty acids as well as the proteolytic activity of these organisms. Practical Application: This is the first study reported on produce synbiotic yoghurt as a functional food for specified health uses contains bifidobacteria and M. pajang fibrous polysaccharides. M. pajang fibrous polysaccharides can be used as a prebiotic particularly in dairy products to increase the viability and activity of bifidobacteria which can be used as probiotic to exert health benefit to the human by yoghurt that is considered common use in society; thus, the benefits of synbiotic yoghurt are readily accessible to the member of society.