Nanoencapsulation of Alpha-linolenic Acid with Modified Emulsion Diffusion Method

Nanocapsules of alpha-linolenic acid (α-LA) were prepared by a modified emulsion diffusion technique with encapsulation efficiency of 93%. Polylactic acid (PLA) was used as the encapsulating polymer with acetone and ethyl acetate as organic solvents, and Tween 20, gelatin and Pluronic-F68 in water as stabilizers. Two ratios of organic to aqueous phases were used with each solvent and stabilizer. Nanocapsule dispersions with a particle size less than 100 nm and a zeta potential as high as 33 mV were obtained as verified by scanning electron microscopy and the dynamic light scattering technique respectively. Both particle size and zeta potential were influenced by such preparation conditions as the type of stabilizer, type of organic solvent and the organic to aqueous phase ratio. Acetone was superior to ethyl acetate, and Tween 20 was superior to each of Pluronic-F68 and gelatin in obtaining smaller, less aggregated nanocapsules. An organic to aqueous phase ratio of 1:5 was shown to be more suitable for the formation of smaller nanocapsules, particularly when acetone was used as the organic solvent.     

A unique approach to predict accurate heavy oil density with new three parameter cubic equation of state

A unique approach is proposed to predict the heavy oil density using a recently developed three parameter cubic equation of state for heavy pure components. It predicts the heavy oil density with an AAD of 2.5%. The new model does not require any experimental density data for its tuning. The basic assumption in this work is that heavy oil is a mixture of n‐alkanes and aromatics as the most prominent groups. Critical pressure characterisation for pseudo fractions is done by tuning a perturbation factor (f_c), also representing the aromaticity, to match the predicted saturation pressure with the experimental pressure. The parameter ‘u’ for the pseudo fractions is adjusted using another parameter ‘S’ which was found to vary linearly with f_c.     

Performance of a MANET directional MAC protocol with angle‐of‐arrival estimation

The use of directional antennas in mobile ad hoc networks (MANETs) has shown to offer large throughput gains relative to omnidirectional antennas. When used in ad hoc networks, directional medium‐access‐control (DMAC) protocols usually require all nodes, or part of nodes, to be aware of their exact locations. This location information is typically provided using a global positioning system (GPS). Although GPS systems are designed to be as nearly accurate as possible, there are still estimation errors that can cause a relatively large deviation from the actual GPS receiver position. In this paper, we investigate the effect of inaccurate node position estimation on the throughput of these protocols. Our results clearly indicate that the advantages of DMAC protocols diminish if the available position information is not accurate enough. As an alternative, we propose an efficient DMAC protocol that utilizes signal parameter estimation via the rotational invariance technique (ESPRIT) for direction‐of‐arrival (DOA) estimation; alleviating the need for GPS and, hence, avoiding the degrading associated with typical GPS position estimation errors. Moreover, unlike GPS‐based protocols, our protocol is suitable for both outdoor and indoor applications. Under different operating conditions and channel models, our simulation results show the throughput improvement achieved using the proposed protocol relative to the IEEE 802.11. Copyright © 2007 John Wiley & Sons, Ltd.     

A validated HPLC method for separation and determination of promethazine enantiomers in pharmaceutical formulations

A simple, rapid, and validated method for separation and determination of promethazine enantiomers was developed. Promethazine was separated and quantitated on a Vancomycin Chirobiotic V column (250 x 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1%, by volume) as a mobile phase at 20 degrees C and at a flow rate of 1 mL/min. The UV-detector was set to 254 nm. Acetyl salicylic acid (Aspirin) was used as an internal standard. The applied HPLC method allowed separation and quantification of promethazine enantiomers with good linearity (r > .999) in the studied range. The relative standard deviations (RSD) were 0.29 and 0.36 for the promethazine enantiomers with accuracy of 100.06 and 100.08. The limit of detection and limit of quantification of promethazine enantiomers were found to be 0.04 and 0.07 microg/mL, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of promethazine in pharmaceutical formulations.     

Isolation and characterization of the volatile aroma compounds from the concrete headspace and the absolute of <Emphasis Type="Italic">Jasminum sambac</Emphasis> (L.) Ait. (Oleaceae) flowers grown in Egypt

The composition of the volatile fraction of Egyptian Jasminum sambac (L.) Ait. (Family: Oleaceae) flowers picked in July (the climax of the flowering season), was studied using GC/MS. The flowers’ concrete headspace (HS) volatiles had been analyzed by SPME (solid phase microextraction) and compared with those from the flowers’ absolute. The main volatile constituents of the concrete HS and the absolute, respectively, were: benzyl acetate (23.7 and 14.2%), indole (13.1 and 13.4%), E-E-α-farnesene (15.9 and 13.1%), Z-3-hexenyl benzoate (4.9 and 9.4%), benzyl alcohol (7.7 and 8.4%), linalool (10.6 and 6.3%), and methyl anthranilate (5.0 and 4.7%). The major volatile constituents of Egyptian J. sambac absolute are almost qualitatively similar but quantitatively different from those grown in other geographical regions. The proportion of some major volatile constituents at this investigation are also different from those reported in a previous investigation for Egyptian J. sambac. The study also revealed that, headspace-solid phase microextraction (HS-SPME), equipped with a polydimethylsiloxane (PDMS) fiber, can give an indication about the composition of some of the major volatile constituents of J. sambac, e.g., indole, methyl anthranilate and E-E-α-farnesene, directly from the concrete HS.     

Optimization Research: Enhancing the Robustness of Large-Scale Multiobjective Optimization in Construction

Many construction planning problems require optimizing multiple and conflicting project objectives such as minimizing construction time and cost while maximizing safety, quality, and sustainability. To enable the optimization of these construction problems, a number of research studies focused on developing multiobjective optimization algorithms (MOAs). The robustness of these algorithms needs further research to ensure an efficient and effective optimization of large-scale real-life construction problems. This paper presents a review of current research efforts in the field of construction multiobjective optimization and two case studies that illustrate methods for enhancing the robustness of MOAs. The first case study utilizes a multiobjective genetic algorithm (MOGA) and an analytical optimization algorithm to optimize the planning of postdisaster temporary housing projects. The second case study utilizes a MOGA and parallel computing to optimize the planning of construction resource utilization in large-scale infrastructure projects. The paper also presents practical recommendations based on the main findings of the analyzed case studies to enhance the robustness of multiobjective optimization in construction engineering and management.     

Production of (S)-2-chloropropionate by asymmetric reduction of 2-chloroacrylate with 2-haloacrylate reductase coupled with glucose dehydrogenase

(S)-2-Chloropropionate is a synthetic intermediate for phenoxypropionic acid herbicides. We constructed a system for asymmetric reduction of 2-chloroacrylate to produce (S)-2-chloropropionate with recombinant Escherichia coli cells producing 2-haloacrylate reductase from Burkholderia sp. WS and an NADPH regeneration system. The system provided 37.4 g/l (S)-2-chloropropionate in more than 99.9%e.e.     

Synthesis,characterization, and thermal analysis of two polymeric chromium ternary complexes with nitrilotriacetic acid and alanine or glycine

Two chromium ternary complexes with nitrilotriacetic acid as a primary ligand and alanine or glycine as secondary ligand were prepared in slightly acidic medium. The structure of these two complexes was characterized using elemental, thermal analysis, FTIR spectra, and the two complexes mass spectra. The spectroscopy data suggest that these two complexes were in polymeric form and have the monomeric unit H[Cr(HNTA)(Hala)(SO₄)] and H[Cr(HNTA)(Gly)(SO₄)] in which sulfate group act as a bidentate ligand linked between each monomeric unit for the same complex. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Near-Surface-Mounted Composite System for Repair and Strengthening of Reinforced Concrete Columns Subjected to Axial Load and Biaxial Bending

This paper aims to examine the effectiveness of near-surface-mounted (NSM) glass fiber-reinforced polymer (GFRP) composite rebars in combination with external confinement with carbon fiber-reinforced polymer (CFRP) composite sheets to repair and strengthen reinforced concrete (RC) columns exposed to axial load and biaxial bending. Nine columns with a square cross section of 150×150??mm were constructed and tested under biaxial eccentric loading with equal eccentricity along each principal axis. Test parameters included load eccentricity, concrete grade, and level of the CFRP confinement used in combination with the NSM-GFRP reinforcement. The effectiveness of the NSM-GFRP reinforcement was greatly affected by the CFRP-confinement level and the load eccentricity. For columns with a high level of CFRP confinement, the gain in the load capacity attributable to the NSM-GFRP reinforcement was higher at a lower eccentricity. For columns with a low level of CFRP confinement, the gain in the load capacity attributable to the NSM-GFRP reinforcement was higher at a higher eccentricity. The enhancement in the load capacity was more pronounced in the columns with a lower concrete grade. An analytical model for predicting the load capacity of RC columns strengthened with NSM-GFRP rebars in combination with CFRP confinement under axial load and biaxial bending is introduced. The model accounts for the nonlinear behavior of materials and the change in geometry under biaxial eccentric loading. The model accuracy is demonstrated by comparing the model predictions with the experimental results.     

Adaptive steering‐based HDTC algorithm for PMSM

This paper introduces sensorless hysteresis direct torque control for permanent magnet synchronous motors to provide a reduced torque pulsation profile, which leads to a smaller mechanical vibration. The suggested algorithm utilizes the principle of vehicle steering, which continuously fixes the direction of the vehicle in the track. Moreover, the algorithm efficiently employs the output of torque and the output of flux error controllers used in basic hysteresis direct torque control to select two nonzero adjacent vectors. The initial switching time for the selected vectors is determined by a function that considers the absolute magnitude of the torque error and the magnitude of the flux error in addition to the space angle position of the stator flux. To reduce the processing time in the control signal flow, a suggested structure for switching the initial time of the selected vectors is developed. The final switching time of the vectors is adaptively adjusted according to the minimum required stator voltage to drive the load and according to the stored rotor energy that arises due to the inertia of the mechanical load connected to the motor shaft. The simulation results along with the experimental results show a fast dynamic response of torque, relatively reduced torque ripples, and reduced current harmonics compared to the basic hysteresis direct torque control.