Effect of various processing techniques on digestibility of starch in Red kidney bean (Phaseolus vulgaris) and two varieties of peas (Pisum sativum)

The effect of common domestic processing methods, such as splitting, soaking, boiling and pressure-cooking on the nutritionally significant starch fractions such as rapidly and slowly digestible starches (RDS and SDS), resistant starch (RS) and total starch (TS) in two legumes, Red kidney bean (Phaseolus vulgaris) and Yellow and Green peas (Pisum sativum) were studied. The legumes had comparatively high amount (>30%, dry basis) of RS. Soaking of all legumes resulted in reduced starch fractions, possibly due to leaching of soluble fractions. Ordinary cooking of soaked as well as unsoaked seeds led to a significant (P < 0.01) decrease in RS and increase in RDS, SDS and TS. Pressure-cooking led to even greater reduction in RS and a greater increase in RDS. Cooking of legumes gelatinizes the starch and opens up the starch structure which makes them vulnerable to α-amylase hydrolysis. Splitting of legumes markedly affects the digestibility as well as RS content of raw as well as processed legumes indicating that the seed coat plays a key role in the digestibility of starches in these seeds. Overall, the enzyme resistant starch fraction of legumes was rendered more digestible by all the domestic cooking methods used.     

Creep deformation behavior of Sn–Zn solder alloys

Creep properties of three Sn–Zn solder alloys (Sn–9Zn, Sn–20Zn, and Sn–25Zn, wt%) were studied using the impression creep technique. Microstructural characteristics were examined using a scanning electron microscope. The alloys exhibited stress exponents of about 5.0. The activation energy for creep was calculated to be ~50–75 kJ/mol with a mean value of 66.3 kJ/mol. The likely creep mechanism was identified to be the low temperature viscous glide of dislocations.     

Continuum Bed Model for Estuarine Sediments Based on Nonlinear Consolidation Theory

The goal of this note is to examine a continuum theory that describes the evolution of sediment beds when subjected to time-dependent shearing forces resulting from surface water movement. The bed was conceptualized as a medium with continuously varying properties such as shear strength and void ratio. The nonlinear equation describing finite strain consolidation, and the complicated nature of the shearing forces acting on top of the bed, preclude the possibility of analytical solutions. Ramifications of linearizing the governing flow equations were explicitly evaluated for applications in bed modeling. Numerical solutions were obtained for the linear and nonlinear models under transient boundary conditions. Model results indicated that the linear model typically predicts lower void ratios, and consequently underestimates the amounts of sediment eroded from the bed as compared to the nonlinear model.     

Improved operating policies for multipurpose use: A case study of Bhadra Reservoir

The operation of Bhadra reservoir project is studied using optimization (overyear and within year storage model) and simulation (with both historic and synthetically generated monthly streamflows) based on a 52-year record of monthly inflow data for irrigation and hydropower generation. Bed turbine operation is found to be the key issue in maximizing the total hydropower production. The reservoir operation is studied for thirteen different policies of bed turbine operation using simulation. These simulation runs are carried out for a specified irrigation demand with historic data. The probability distribution of the maximum possible hydropower production is arrived at by simulating the reservoir operation with 4 different sets of synthetically generated monthly streamflows, each having sequences of different lengths, for two promising policies. A comparison of results made with the actual operation over a 11-year period shows that substantial increase in the total hydropower generation is possible with the identified policies without undue deficits in meeting the specified irrigation demands.     

An investigation into the mechanical and tribological properties of plasma electrolytic oxidation and hard-anodized coatings on 6082 aluminum alloy

A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2-3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed.     

Electrical properties of conductive Ge nanocrystal thin films fabricated by low temperature in situ growth

Thin films composed of Ge nanocrystals embedded in an amorphous SiO(2) matrix (Ge-NC TFs) were prepared using a low temperature in situ growth method. Unexpected high p-type conductivity was observed in the intrinsic Ge-NC TFs. Unintentional doping from shallow dopants was excluded as a candidate mechanism of hole generation. Instead, the p-type characteristic was attributed to surface state induced hole accumulation in NCs, and the hole conduction was found to be a thermally activated process involving charge hopping from one NC to its nearest neighbor. Theoretical analysis has shown that the density of surface states in Ge-NCs is sufficient to induce adequate holes for measured conductivity. The film conductivity can be improved significantly by post-growth rapid thermal annealing and this effect is explained by a simple thermodynamic model. The impact of impurities on the conduction properties was also studied. Neither compensation nor enhancement in conduction was observed in the Sb- and Ga-doped Ge-NC TFs, respectively. This could be attributed to the fact that these impurities are no longer shallow dopants in NCs and are much less likely to be effectively activated. Finally, the photovoltaic effect of heterojunction diodes employing such Ge-NC TFs was characterized in order to demonstrate its functionality in device implementation.     

MICROBIOLOGICAL PROFILE OF MURCHA STARTERS AND PHYSICO-CHEMICAL CHARACTERISTICS OF POKO, A RICE BASED TRADITIONAL FERMENTED FOOD PRODUCT OF NEPAL

Poko is a traditional rice based fermented food of Nepal prepared using murcha as the starter. The microbiological evaluation of eleven murcha starters showed that the lactic acid bacteria and yeast were dominant at 5×10⁵ to 1.0×10⁹ cfu g^-1 range while fungi were present at 2×10⁵ to 1.0×10⁷ cfu g^-1. Coliforms (1×10² to 1.4×10⁵ cfu g^-1), E. coli (1×10³ cfu g^-1), and. S. aureus (1×10² g^-1) were present in some of the murcha starters. Bacillus cereus was absent in all the starters. The microbial succession during poko fermentation suggested that it was primarily a mixed fermentation of yeasts, molds and lactic acid bacteria. The quality poko product obtained after two days and three days of fermentation at 30°C had a pH, acidity, reducing sugar, total sugar, and alcohol in the range of 3.2-3.0, 1.1-1.3 (% LA), 14.4-15.6 (%), 14.6-18.2 (%) and 1-1.6 (%) respectively. These critical ranges of biochemicals in the poko, due to the fermentation process imparted desirable organoleptic characteristics to the product. Saccharomyces cerevisiae, Candida versatilis, Lactobacillus spp, Pediococcus spp and Rhizopus spp were the dominant microorganisms identified from the poko fermentation. The results suggest that the quality of poko depends upon the microbial flora of the traditional murcha starters.     

Comparative studies on electronic transport due to the reduced dimensionality at the heterojunctions of GaAs/A1xGa(1−x)As and GaxIn(1−x)As/InP systems at low temperatures

Comparative studies on ac/dc mobility due to the reduced dimensionality of spatially confined low dimensional systems, at the heterojunctions of GaAs/A1_xGa_(1−x)As and Ga_xIn_(1−x)As/InP forming quasi-two dimensional (Q2D) and quasi-one dimensional (Q1D) systems have been made. The effect of various low temperature nonphonon scattering mechanisms such as ionized impurity, alloy disorder scattering and surface roughness scattering mechanisms; and phonon scattering mechanisms such as acoustic phonon via deformation potential and piezoelectric scattering mechanisms on the systems has been studied. It is found that the surface roughness scattering mechanism dominates in Q2D system whereas acoustic phonon scattering mechanism dominates in Q1D system due to which the nature and magnitude of the temperature dependent dc/ac mobility curves shows significant variation. Whereas, it is observed that the confinement does not change the nature of the frequency dependent real and imaginary parts of ac mobility curves. However, the mobility is found to be enhanced with effective mass and also due to the confinement, i.e. the mobility for Q1D system is higher than that for Q2D system.     

Enhancing power engineering education through the use of designmodules

This paper describes the main features of four design modules that form part of the curriculum for the final year power engineering students at the Nanyang Technological University, Singapore. Through the use of these modules, the students gain an insight into the various aspects of power engineering-including power electronics and drives-and this will hopefully help them in a better understanding of the practical aspects of power engineering, and therefore make them better engineers in the power industry. The four modules described are Generating Capacity Expansion Planning, Rectifier and DC Motor Control, Power Systems Operations Planning, and Security Enhancement using Optimal Power Flow