Enrichment of ω‐3 fatty acids in flax seed oil by alkaline lipase of Aspergillus fumigatus MTCC 9657

Flax seed oil obtained from the seeds of flax plant (Linum usitatissimum, L.) is an unexploited source which contains ω‐3 and ω‐6 fatty acids. Flax seed oil is hydrolysed with a novel alkaline lipase from Aspergillus fumigatus MTCC 9657 for the removal of unwanted fatty acids and enrichment of ω‐3 fatty acids. An appropriate balance of ω‐3 and ω‐6 polyunsaturated fatty acids and enzymatic enrichment of polyunsaturated fatty acids in diet promote nutrition and health. Fatty acid composition shows that flax seed oil contains about 26.80%, 13.5% and 25.45% of ω‐3 and ω‐6 fatty acids in triglyceride (TG), diglyceride (DG) and monoglyceride (MG), respectively. After 8 h of hydrolysis, ω‐3 content was increased to 39% in TG, showing that unwanted saturated fatty acids are removed. ω‐6 content of triglycerides in flax seed oil also showed 54.76% increase after 8 h of hydrolysis. An enzymatic method of hydrolysis by fungal lipase was developed by this study and achieved to concentrate the essential fatty acids linoleic acid (LA) and α‐linoleic acids (ALA).     

Nutritional and nutraceutical comparison of Jamaican Psidium cattleianum (strawberry guava) and Psidium guajava (common guava) fruits

Psidium cattleianum (strawberry guava) is one of many underutilised edible fruits that grow wild in Jamaica, and could potentially be commercially exploited to yield health and economic benefits. In this study, the total phenolics, proximate contents, and antioxidant, anti-inflammatory, and antimicrobial activities of P. cattleianum and P. guajava (common guava), a well-known species, were compared. Strawberry guavas were found to be superior to common guavas in antioxidant and antimicrobial activities, total phenolics and vitamin C content. They also possessed relatively high fibre content (24.9%). The hexane and ethyl acetate extracts of strawberry guavas showed cyclooxygenase-2 enzyme inhibitory activities of 18.3% and 26.5%, respectively (250 μg/mL), indicating anti-inflammatory activity. The EtOAc and MeOH extracts of P. guajava showed 56.4% (COX-2) and 44.1% (COX-1) inhibitory activity, respectively. Additionally, nine compounds were isolated from strawberry guava fruits, some of which demonstrated anti-inflammatory activity. These results indicate that strawberry guavas are beneficial for health.     

Numerical and experimental evaluation of performance of centrifugal seals

‘Centrifugal seals’ or ‘Slinger seals’ offer an attractive choice as non-contact-type sealing in fluid machinery. These seals utilize the radial pressure gradient caused by centrifugal forces in a rotating fluid ring, to create a sealing of the working fluid. Basic construction of a typical seal consists of a rotating disc inside a stationary casing; one side of the disc (sealing side) is provided with a set of slots (Type-1) or vanes (Type-2) to enhance the tangential velocity of the fluid. The other side of the disk (back side) in both the configurations is exposed to high pressure liquid being sealed. Both numerical and experimental investigations of the performance of Type-1 seal (with slots) have been carried out so as to optimize the seal configuration to achieve maximum sealing capacity, with minimum power consumption. A comparison of the performance of Type-1 seal has been made with that of conventional one (Type-2) in view of economy of construction and better sealing with minimal expense of power consumption. A test rig that allows for varying the major geometrical and operating parameters was designed and tests were conducted with water as the medium. Influence of major geometric parameters like dimensions and number of slots, axial/radial clearances and major operating parameters like rotational speed, inlet pressure and sealing fluid bypass flow rate has been investigated. Apart from various pressure, temperature, flow and torque measurements, the interface between the sealing and working fluid for the experiments was captured and recorded using a high speed camera at ~26,000 frames per second. Geometrical configuration for the slots that maximizes the sealing capacity is arrived through 3D numerical simulations using commercial CFD solver ANSYS Fluent^®. A good agreement is obtained with respect to experimental results. In view of economy of construction and better sealing with minimal expense of operating power, a modified version of Type-1 seal termed as Type-3 seal is investigated. A simple 1D model for prediction of the interface radius during the seal operation, which could be used as a quick design guide, is also presented.     

Transported snapshot model order reduction approach for parametric,steady-state fluid flows containing parameter-dependent shocks

A new model order reduction approach is proposed for parametric steady-state nonlinear fluid flows characterized by shocks and discontinuities whose spatial locations and orientations are strongly parameter dependent. In this method, solutions in the predictive regime are approximated using a linear superposition of parameter-dependent basis. The sought-after parametric reduced bases are obtained by transporting the snapshots in a spatially and parametrically dependent transport field. Key to the proposed approach is the observation that the transport fields are typically smooth and continuous, despite the solution themselves not being so. As a result, the transport fields can be accurately expressed using a low-order polynomial expansion. Similar to traditional projection-based model order reduction approaches, the proposed method is formulated mathematically as a residual minimization problem for the generalized coordinates. The proposed approach is also integrated with well-known hyper-reduction strategies to obtain significant computational speedups. The method is successfully applied to the reduction of a parametric one-dimensional flow in a converging-diverging nozzle, a parametric two-dimensional supersonic flow over a forward-facing step, and a parametric two-dimensional jet diffusion flame in a combustor.     

Rolling element bearing design through genetic algorithms

The design of rolling element bearings has been a challenging task in the field of mechanical engineering. While most of the real aspects of the design are never disclosed by bearing manufacturers, the common engineer is left with no other alternative than to refer to standard tables and charts containing the bearing performance characteristics. This paper presents a more viable method to solve this problem using genetic algorithms (GAs). Since the algorithm is basically a guided random search, it weakens the chances of getting trapped in local maxima or minima. The method used has yielded improved performance parameters than those catalogued in standard tables.     

Ternary Solvent System to Control the Morphology of Active Blend in Inverted Organic Solar Cells

Bulk heterojunction blend of poly(3-hexylthiophene)–[6,6]-phenyl-C₆₁-butyric acid methyl ester prepared using the ternary solvent mixture was used as the active layer of an inverted organic solar cell. The ternary solvent mixture consisted of a good solvent such as ortho-dichlorobenzene and two marginal solvents such as cyclohexanone and toluene offering limited solubility to the poly(3-hexylthiophene) component. Power conversion efficiency of inverted device was found to decrease from 2.74?±?0.05% in the unmodified device to 2.64?±?0.07% in the modified device. UV–visible measurement revealed less efficient photoabsorption in the mixed cosolvent-casted active layer due to insufficient and disordered crystallization of poly(3-hexylthiophene) domains.     

Production of soya milk containing low flatulence‐causing oligosaccharides in a packed bed reactor using immobilised α‐galactosidase

Peanut α‐galactosidase was immobilised in calcium alginate beads and used to hydrolyse the flatulence‐causing oligosaccharides, raffinose and stachyose, in soya milk in batch and in packed bed reactor with recycle. The immobilised enzyme exhibited a slightly lower activity than the free enzyme. The activity yield of immobilised α‐galactosidase was 75.1% and the immobilisation yield was 82.6%. Batch hydrolysis using immobilised enzyme at 55 °C resulted in 96% reduction in the oligosaccharides after 12 h. For the continuous process, a packed bed reactor with recycle was used. More than 98% of the oligosaccharides were hydrolysed after 6 h of reaction at 55 °C. The immobilised enzyme also proved to be stable up to three repeated hydrolysis reactions.     

Frequency-reconfigurable antennas for multiradio wireless platforms

Looking to increase the functionality of current wireless platforms and to improve their quality of service, we have explored the merits of using frequency-reconfigurable antennas as an alternative for multiband antennas. Our study included an analysis of various reconfigurable and multiband structures such as patches, wires, and combinations. Switches, such as radio-frequency microelectromechanical systems (RFMEMS) and p-i-n diodes, were also studied and directly incorporated onto antenna structures to successfully form frequency-reconfigurable antennas.     

Study and Analysis of the Effect of Harmonics on the Hot Spot Temperature of a Distribution Transformer Using Finite-Volume Method

Transformers are critical components in power systems and their failure can cause long interruption of power supply. The condition of a transformer can be monitored by performing thermal analysis. The use of non-linear devices, such as rectifiers and converters, draws harmonic currents that increase losses in transformers, thereby increasing their operating temperature. In this article, a new numerical approach is presented for determining the rise in hot spot temperature in a 5-kVA, 400/400-V dry-type three-phase transformer laboratory prototype. The key novelty is that the additional winding eddy current loss due to non-linear loads is considered in the numerical modeling. The winding eddy current loss corresponding to harmonic distortion is estimated by conducting experiments and calculations. Numerical simulations are carried out for a wide range of non-linear loads using a commercial computational fluid dynamics package, FLUENT 6.3. The proposed numerical methodology is validated by performing experiments on the transformer for possible non-linear loads and comparing the measured hot spot temperature with the simulated values. Correlation equations for rise in hot spot temperature as a function of total harmonic distortion are presented, which can be used for estimating the life of transformers when connected to different types of loads.     

Material properties and operating configurations of membrane reactors for propane dehydrogenation

A modeling‐based approach is presented to understand physically realistic and technologically interesting material properties and operating configurations of packed‐bed membrane reactors (PBMRs) for propane dehydrogenation (PDH). PBMRs composed of microporous or mesoporous membranes combined with a PDH catalyst are considered. The influence of reaction and membrane transport parameters, as well as operating parameters such as sweep flow and catalyst placement, are investigated to determine desired “operating windows” for isothermal and nonisothermal operation. Higher Damköhler (Da) and lower Péclet (Pe) numbers are generally helpful, but are much more beneficial with highly H₂‐selective membranes rather than higher‐flux, lower‐selectivity membranes. H₂‐selective membranes show a plateau region of conversion that can be overcome by a large sweep flow or countercurrent operation. The latter shows a complex trade‐off between kinetics and permeation, and is effective only in a limited window. H₂‐selective PBMRs will greatly benefit from the fabrication of thin (～1 µm or less) membranes. © 2014 American Institute of Chemical Engineers AIChE J, 61: 922–935, 2015