Fatty acid and phytosterol accumulation during seed development in three oilseed species

This study was carried out to compare the kinetic accumulation of bioactive lipids during seed development in three oil crops rapeseed, sunflower and woad. Field experiments were conducted under organic conditions during 3 years. After flowering, seeds were collected each 4–5 days until harvest. The three species differed by the quantity and quality of both fatty acids and sterols. Higher levels of phytosterols and fatty acids were reached between 20 and 40 days after flowering (DAF) in sunflower, 40 and 60 DAF in rapeseed and 25 and 45 DAF for woad. The modification of lipid composition during the grain filling depends on species. Knowledge of the composition and accumulation of fatty acids and phytosterols in sunflower, rapeseed and woad seeds would assist in efforts to achieve industrial applications. These seeds may give an interesting source of bioactive lipids.     

Effects of genotype and sowing date on phytostanol–phytosterol content and agronomic traits in wheat under organic agriculture

Cereals are an important source of sterols and stanols in the human diet. The present study underlines the effect of genotype and weather conditions in bread wheat, on total sterol and stanol content (TSS), agronomic traits, proteins and ash content under organic conditions. Variations in TSS as well as other characters between two sowing dates were observed. A broad genotypic variability was also reported since extreme genotypes differed by more than 30 mg 100 g⁻¹ DW for TSS, with total stanol content varying twofold. Moreover, two groups of genotypes that differed in agronomic production, ash and protein content were depicted, based on their response to an increase in temperature. This result suggests that the genotypic factor prevails over the sowing date factor for determining sterol and stanol traits in wheat cultivated under organic conditions. Nevertheless, a strong interaction exists between the two factors, which can be used to drive bioaccumulation of these molecules.     

Web search enhancement by mining user actions

Search engines are among the most popular as well as useful services on the web. There is a need, however, to cater to the preferences of the users when supplying the search results to them. We propose to maintain the search profile of each user, on the basis of which the search results would be determined. This requires the integration of techniques for measuring search quality, learning from the user feedback and biased rank aggregation, etc. For the purpose of measuring web search quality, the “user satisfaction” is gauged by the sequence in which he picks up the results, the time he spends at those documents and whether or not he prints, saves, bookmarks, e-mails to someone or copies-and-pastes a portion of that document. For rank aggregation, we adopt and evaluate the classical fuzzy rank ordering techniques for web applications, and also propose a few novel techniques that outshine the existing techniques. A “user satisfaction” guided web search procedure is also put forward. Learning from the user feedback proceeds in such a way that there is an improvement in the ranking of the documents that are consistently preferred by the users. As an integration of our work, we propose a personalized web search system.     

Coupled Eulerian Lagrangian finite element modeling of friction stir welding processes

A 3-dimensional localized finite element model (FEM) is developed to predict likely conditions that result in defect generation during friction stir welding (FSW). The workpiece is modeled using Eulerian formulation, while the tool is modeled using Lagrangian. Coulomb's frictional contact model is adopted to define the tool workpiece interaction, while the welding speed is defined by material inflow and outflow velocities. The numerical results show that the coefficient of friction has a major effect on void formation; the lower the friction coefficient is applied, the larger the void is formed. Furthermore, welding using force control (FC) at lower welding speed results in smaller void size and wider plastic zone, leading to higher quality weld.     

Finite element evaluation of clearance effect on tube-to-tubesheet joint strength

Tube-to-tubesheet joint strength is measured in terms of residual contact pressure between the tube's outer surface and the tubesheet hole surfaces. The joint integrity is affected by several design parameters, including the type of material and the initial radial clearance.

The present work complements an experimental program on the effect of over-tolerance on heat exchanger tube-to-tubesheet joint strength. Finite element analyses address the effect of initial clearance on contact pressure and percent tube wall reduction. Results show that for low strain hardening materials the initial clearance effect is negligible. However, higher levels of strain hardening have a significant effect on residual stress and percent wall reduction. For low clearances, the calculated residual contact pressure compares well with an analytical result and with that inferred from the experimentally measured pull out force. The variation of the percent wall reduction with initial clearance is found to be similar to that measured.     

Dimerization of native myosin LC2(RLC)-free subfragment 1 from adult rabbit skeletal muscle

We reinvestigated whether the native myosin LC2-free-subfragment 1 (S1) dimer exists by using viscometry, capillary electrophoresis, and laser light scattering. We found that the intrinsic viscosity of the monomer is [eta]m = 6.7 cm3/g and its translation diffusion coefficient is (c = 0) = 4.43 x 10(-)7 cm2/s. For the dimer, [eta]d = 19.8 cm3/g and (c = 0) = 2.54 x 10(-)7 cm2/s. Using the Svedberg equation and introducing the values of the sedimentation coefficients (5.05 S for the monomer and 6.05 S for the dimer), we find the following molecular weights: Mr,m = 108 000 Da and Mr,d = 213 000 Da, which agree well with previous determinations. Capillary electrophoresis successfully separated S1(A1) and S1(A2), in a monomer buffer, and S1(A1) and S1(A2) and a heterodimer S1(A1)-S1(A2), in a dimer buffer. An interesting feature of the monomer-dimer equilibrium is the presence of temperature transitions, whose positions and widths depend upon the buffer conditions. At low temperatures, a pure dimer was observed, whereas at high temperatures only the monomer was present. The dimerization site on both myosin and S1 is extremely labile.     

Heat transfer inside a horizontal channel with an open trapezoidal enclosure subjected to a heat source of different lengths

The heat transfer phenomena inside a horizontal channel with an open trapezoidal enclosure subjected to a heat source of different lengths was investigated numerically in the present work. The heat source is considered as a local heating element of varying length, which is embedded at the bottom wall of the enclosure and maintained at a constant temperature. The air flow enters the channel horizontally at a constant cold temperature and a fixed velocity. The other walls of the enclosure and the channel are kept thermally insulated. The flow is assumed laminar, incompressible, and two‐dimensional, whereas the fluid is considered Newtonian. The results are presented in the form of the contours of velocity, isotherms, and Nusselt numbers profiles for various values of the dimensionless heat source lengths (0.16 ≤ ε ≤ 1). while, both Prandtl and Reynolds numbers are kept constant at (Pr = 0.71) and (Re = 100), respectively. The results indicated that the distribution of the isotherms depends significantly on the length of the heat source. Also, it was noted that both the local and the average Nusselt numbers increase as the local heat source length increases. Moreover, the maximum temperature is located near the heat source location.     

Effects of friction on roller expanded tube–tubesheet joint strength

Roller expansion of new tubes in enlarged heat exchanger tubesheet holes requires higher rolling torques which may result in over-thinning of the tube wall. This affects adversely the tube–tubesheet joint strength, which is measured in terms of residual contact pressure between the expanded tube and tubesheet. The axial force required to cause the mechanical failure of the tube–tubesheet joint has therefore been considered as an indication of the integrity of the joint. This force is influenced by several parameters such as the type of tube and tubesheet materials, the initial clearance and coefficient of friction. In the present work, an axisymmetric finite element (FE) model is used to evaluate the combined effects of friction between tube and tubesheet, initial clearance and tube material strain hardening on the strength of the tube–tubesheet joint. The FE results show that the increase in friction between tube and tubesheet results in higher residual contact stress and lower cutoff clearances. The residual contact stress also increased linearly with increasing tube material strain hardening level for all friction coefficients.     

Higher-order finite element modelling of laminated composite plates

P-version finite elements based on higher-order theory are developed for the two-dimensional modelling of general bending and cylindrical bending of thin-to-thick laminated composite plates. In the case of general laminated plate elements, three displacement fields are used. In the special case of cylindrically bent laminated plate elements, two displacement fields are needed. In each case the displacement is expressed as the product of two functions—one in terms of out-of-plane co-ordinates alone and the other in terms of in-plane co-ordinates. The shape functions used to build the displacement fields are based on integral of Legendre' polynomials. The quality and performance of the elements are evaluated in terms of convergence characteristics of displacements and stresses. The predicted response quantities are compared with those available in the published literature based on analytical as well as conventional finite element models.     

UHMWPE Hybrid Nanocomposites for Improved Tribological Performance Under Dry and Water-Lubricated Sliding Conditions

To tap the full potential of polymers to be used as tribo-materials under water lubrication, it is very important to improve their resistance to water uptake on the one hand and improve their strength and load bearing capacity on the other so that their performance under these conditions is not deteriorated. Hence, a unique approach of fabricating a hybrid polymer nanocomposite reinforced with nanoclay for improving the resistance to water uptake and carbon nanotubes (CNTs) to improve the mechanical/tribological properties is undertaken. Ultrahigh molecular weight polyethylene (UHMWPE) hybrid nanocomposites were fabricated via ball milling followed by hot pressing method. Functionalized multi-wall CNTs and C15A organoclay were used as nanofillers in UHMWPE matrix. Hybrid nanocomposites were developed with CNT loadings of 0.5, 1.5 and 3.0 wt% while keeping C15A organoclay content fixed at an optimized value of 1.5 wt%. Initially, the hybrid nanocomposites were optimized under dry sliding conditions whereby a loading of 1.5 wt% of CNTs and 1.5 wt% C15A organoclay resulted in the maximum reduction in the specific wear rate by about 64% as compared to pristine UHMWPE. Later, tribological performance of the optimized hybrid nanocomposite was compared with pristine UHMWPE and its UHMWPE nanocomposites under water-lubricated conditions sliding against a 440C stainless steel ball for 150,000 cycles. The specific wear rate showed a reduction by ~46% for the 1.5 wt% CNTs hybrid nanocomposites as compared to pristine UHMWPE under water lubrication. The improved resistance to wear was attributed to the uniform dispersion of both the nanofillers, namely CNTs and C15A organoclay which effectively increased the load bearing capacity of UHMWPE. Moreover, the excellent barrier properties of the platelet-like structure of C15A clay which presented a torturous path for the diffusion of the water molecule in UHMWPE reduced the softening of the surface layer leading to better resistance to wear under water lubrication.