The emulsifying properties of a polysaccharide isolated from the fruit of Cordia abyssinica

Polysaccharide was isolated from Cordia abyssinica and its effect, at differing concentrations, on its emulsifying ability was determined. Emulsions of vegetable oil containing up to 1% of the polysaccharide in phosphate pH 7.4 buffer, were prepared by using a hand piston homogenizer. Emulsification was assessed by diluting samples of the emulsions in sodium dodecyl sulphate and measuring absorbance at 500 nm. Addition of increasing concentrations of the polysaccharide up to 1% enhanced emulsification and emulsion stability. Above 1% concentration the polysaccharide solutions were too viscous for making emulsions conveniently. At a constant concentration of the polysaccharide, addition of up to a 1% concentration of salt enhanced emulsion formation. Further addition of salt above 1% resulted in no further changes in emulsifying ability, but the stability of the emulsions formed decreased on increasing the concentration of salt above 1%. The effect of pH on emulsifying ability was investigated by preparing emulsions using buffers of different pH, from pH 3 to pH 13. The polysaccharide had poor emulsifying ability below pH 7. Emulsifying ability increased with pH between pH 7 and 11. At pH above 11 there was a decrease in emulsifying ability.     

Characterization of 1.55-μm pulses from a self-seededgain-switched Fabry-Perot laser diode using frequency-resolved opticalgating

The intensity and frequency chirp of picosecond pulses from a self-seeded gain-switched Fabry-Perot laser diode have been directly measured using the technique of frequency-resolved optical gating. Measurements over an output sidemode suppression ratio (SMSR) range of 15-35 dB show that higher SMSR's are associated with an increasingly linear frequency chirp across the output pulses. This complete pulse characterization allows the conditions for optimum pulse compression to be determined accurately, and indicates that transform-limited, pedestal free pulses can be obtained at an SMSR of 35 dB     

Friction studies of tough pitch copper using a hollow punch-torque method

A hollow punch-torque method was used to measure friction between tough pitch copper and three different lubricants. The tests indicated that the coefficient μ is not a function of the applied pressure, while the friction factorm is. Both μ andm depend only slightly on the degree of prior deformation. The range of pressure investigated was that encountered in drawing operations and is below that for lubricated sliding surfaces where sublayer plastic flow occurs.     

Energy savings by reduced mixing in aeration tanks: results from a full scale investigation and long term implementation at Avedoere wastewater treatment plant

The aim of this project was to investigate the potential of reducing number of mixers in the biological treatment process and thereby achieve energy and economical savings and contribute to cleaner environment. The project was carried out at Avedoere wastewater treatment plant and a full scale investigation was conducted to study the effect of reduced mixing on flow velocity, suspended solid sedimentation, concentration gradients of oxygen and SS with depth and treatment efficiency. The only negative effect observed was on flow velocity; however the velocity was above the critical velocity. The plant has been operating with 50% of its designed number of mixers since September 2007 and long term results also confirm that reduced mixing did not have any negative effect on treatment efficiency. The estimated yearly electricity saving is 0.75 GWh/year.     

Superconducting gap in PrxY1?xBa2Cu4O8 and YBa2?ySryCu4O8 probed by infrared phonon self-energies

We report a reflectivity study of thez-polarized TO-phonons of Pr _x Y_1–x Ba₂Cu₄O₈ and YBa_2–y Sr _y Cu₄O₈ alloys in the temperature range 10–300 K. Anomalies of the frequency and linewidth of the plane-oxygen vibration at300 cm^–1 due to the opening of the superconducting gap are found to occur upon crossing the superconducting transition temperatureT _c . Phonon self-energy effects are strongly dependent onT _c , providing evidence for a relative shift of the gap with respect to the energy of phonon.On leave from the Institute for Semiconductor Physics, Ukrainian Academy of Sciences, 252650 Kiev-28, Ukraine.     

Gender-differences in Self-efficacy ICT related to various ICT-user profiles in Finland and Norway. How do self-efficacy,gender and ICT-user profiles relate to findings from PISA 2006

In this paper, we explored the relationship between self-efficacy, Information and Communication Technology (ICT) user profiles, and gender. Self-efficacy is an important theoretical and empirical concept to identify and describe how students perceive their own ability to solve a task. ICT user profiles were developed as an empirical framework to identify and categorize students based on how frequent they use ICT. In this paper, we have chosen six ICT user profiles in order to distinguish between leisure activities and school activities. Each ICT user-profile was computed by combining two dimensions (frequency of ICT use for leisure purposes and frequency of ICT use for school purposes). We tried to identify how students’ perception of their ability to solve a task is related to both their gender and how frequently they use ICT. The results showed that student’s self-efficacy varied between the ICT user profiles. The findings showed how an increased level of self-efficacy in ICT High-level tasks is related to both an increased level of leisure use and with an increased level of educational use. Further, our findings provided evidence in support of positive relationships (for both males and the females) between Self-efficacy in ICT and the ICT user profiles.     

Local effects in the vicinity of inserts in sandwich panels

The paper considers local bending effects induced in the vicinity of inserts in sandwich panels. Such local bending effects are associated with an increase of bending stresses in the sandwich faces and normal and shear stresses in the sandwich core. An earlier developed analytic model [Proceedings of the Sixth International Conference on Sandwich Structures (ICSS-6) (2002) 551] is adapted for the case of a sandwich panel with circular insert, with elastic properties differing from those of the core. The locally induced stresses in the faces and core due to presence of the insert are expressed via simple analytic relations (and charts) enabling an estimation of these local stresses. Finite element analysis is employed to demonstrate the applicability of the analytic model, and a good correspondence between the numerical and the analytical data is found. A study case related to marine applications, namely a circular insert in a sandwich deck panel used for mounting of a rigging fixture, is considered, and optimization of an existing design is carried out.     

An improved model for the prediction of intra-cell buckling in CFRP sandwich panels under in-plane compressive loading

Local instability in the form of “intra-cell buckling” or “dimpling” is a well-known failure mode in honeycomb-cored sandwich panels with very thin faces. Most work reported on the subject suggests relatively simple design formulae for the estimation of the intra-cell buckling load. It is however widely known that these classical design formulae in some cases considerably underpredict the intra-cell buckling load. In this paper a series of experimental results obtained for different CFRP/honeycomb sandwich panel configurations loaded in compression are presented. The results confirm that the “classical” design formulae provide overly conservative results. During the tests the intra-cell buckling patterns were monitored carefully, and it was observed that the hitherto assumed buckling patterns did not correspond to the experimental observations. Based on these findings a new simplified design formula is suggested, which for the investigated CFRP/honeycomb sandwich panels provides significantly more accurate predictions than the “classical” design formulae.     

Solidification of SiMo Nodular Cast Iron for High Temperature Applications

During the 1960s and 70s research was aimed at developing a material withstanding the ever higher temperatures in a combustion engine. This work resulted in what have later been named SiMo and D5S. SiMo is a nodular cast iron typically containing 4?C6?% Si and 0.5?C2?% Mo and can be used in temperatures up to 850?C860?°C. D5S is a nickel base material. High silicon and silicon?Cmolybdenum content improves the dimensional stability of ductile iron. Silicon increases the transformation temperature where austenite transforms to ferrite. Molybdenum partly segregates and freezes in intercellular regions, promoting carbides while during the solid state transformation molybdenum particles precipitate around grain boundaries. The solidified material shows a range of interesting structures and phases which will be presented.