Removal of phenols from aqueous solutions by emulsion liquid membranes

The present study deals with the extraction of phenols from aqueous solutions by using the emulsion liquid membranes technique. Besides phenol, two derivatives of phenol, i.e., tyrosol (2-(4-hydroxyphenyl)ethanol) and p-coumaric acid (4-hydroxycinnamic acid), which are typical components of the effluents produced in olive oil plants, were selected as the target solutes. The effect of the composition of the organic phase on the removal of solutes was examined. The influence of pH of feed phase on the extraction of tyrosol and p-coumaric was tested for the membrane with Cyanex 923 as an extractant. The use of 2% Cyanex 923 allowed obtaining a very high extraction of phenols (97-99%) in 5-6 min of contact time for either single solute solutions or for their mixtures. The removal efficiency of phenol and p-coumaric acid attained equivalent values by using the system with 2% isodecanol, but the removal rate of tyrosol was found greatly reduced. The extraction of tyrosol and p-coumaric acid from their binary mixture was also analysed for different operating conditions like the volume ratio of feed phase to stripping phase (sodium hydroxide), the temperature and the initial concentration of solute in the feed phase.     

An Integrated Software Environment For Powertrain Feasibility Assessment Using Optimization And Optimal Control

With the increase in automotive powertrain complexity, an upfront assessment of powertrain capability in meeting its design targets is important early on in the development programs. The optimization of control policy based on powertrain simulation models can facilitate this assessment and establish limits of achievable performance for a given powertrain configuration and parameters. The paper discusses several computational optimization and user interface solutions for deploying a numerical optimal control approach in a user‐friendly software environment.     

Optimal Cycle Times in a Two-Stage Serial System With Set-Up and Inventory Costs

Two 2-stage serial production systems under constant average demand rate and infinite horizon are considered. The first and the simpler system assumes zero final product inventory; while the second assumes it nonzero but with a continuous demand. The stages have finite production rates greater than or equal to the demand rate and operate with periodic start-ups and shutdowns. No stock-outs are allowed in the inventories. Analytical results for determining a cyclic schedule with the minimum sum of set-up and inventory costs are presented. The optimal lot sizing policy for the first system involves integer splitting/merging of lots; however noninteger split/merge policy may be optimal in some instances of the second.     

Performance characterization of a non‐linear system as both an adaptive notch filter and a phase‐locked loop

The behaviour of a non‐linear dynamical system is described. The system may be characterized as an adaptive notch filter, or alternatively, as a phase‐locked loop. Either way, the system has the inherent capability of directly providing estimates of the parameters of the extracted sinusoidal component of its input signal, namely its amplitude, phase and frequency. The structure and mathematical properties of the system are presented for two cases of fixed‐frequency and varying‐frequency operation. The effects of parameter setting of the system on its performance are studied in detail using computer simulations. Transient and steady‐state behaviour of the system are studied in the presence of noise. Simplicity of structure, high noise immunity and robustness and the capability of direct estimation of amplitude, phase and frequency are the salient features of the system when envisaged as an adaptive notch filter or a phase‐locked loop. Copyright © 2004 John Wiley & Sons, Ltd.     

Universal bio-molecular signal transduction-based nano-electronic bio-detection system

The development of rapid and ultra-sensitive detection technologies is a long-standing goal for researchers in the bio-detection fields. Nanowire field-effect transistor (nano-FET) devices have shown great promise in label-free and ultra sensitive detection of biological agents. However, critical application problems in using this technology have not been addressed, particularly the difficulties of FET sensing surface modification for various targets and lower detection specificity in real biological samples. A novel molecular signal transduction system reported herein overcomes such problems. With this system, various complicated bio-molecular interactions are “translated” into simple signal molecules with universal sequences. These signal molecules are captured on the sensing surface of nano-FET devices through sequence-specific recognition and generate detectable electronic signals. Using this system, nano-FET devices become universal for detecting almost any bio-agents. Staphylococcus aureus was used as the target to demonstrate the detection of DNA, RNA and protein on the same nano-FET device. Detection sensitivity was achieved at 25 fM levels in pure sample.     

Mitogen-activated protein kinase is activated during IgG-mediated phagocytosis, but is not required for target ingestion

This meta-analysis quantitatively summarized the developmental influence and the effects of locomotor experience as well as the benefits of locomotor practice, locomotor assistance, and active searching patterns on children's search performance. Based on specific criteria, a search of a database and reference lists identified 19 studies, including 1,029 children (510 boys and 519 girls) from 4 to 144 months of age. Outcome measures of spatial performance were converted to 83 effect sizes that reflected the effects of specific experimental characteristics. Analyses of variance indicated that with older children, locomotor activities are more important to their spatial searching. Locomotor status, searching patterns, locomotor assistance, test conditions, and test reliability were identified as moderator variables. In addition, locomotor training significantly improved children's spatial search. The results supported the hypothesis that children's development of spatial search skills is influenced by locomotor experience.     

Supply chain redesign through optimal asset management and capital budgeting

Manufacturing and inventory facilities along with the materials present in them are the physical assets of a company. Companies strive to maximize their shareholder values by managing these assets through a variety of business decisions. In this work, we present a new mixed-integer linear programming model for asset management and capital budgeting, which can aid the decision-making process for supply chain redesign. The decisions include facility location, relocation, investment, disinvestment, technology upgrade, production–allocation, distribution, supply contracts, capital generation, etc. To the best of our knowledge, this model is the first to address disinvestment, technology upgrade, material supply contracts, and loans and bonds for capital generation, while including strategic asset management and tactical planning, capacity planning, financial/regulatory factors, and production–distribution. We illustrate the impact of ignoring disinvestment and/or relocation decisions as a 14% decrease in profit for an example case study.     

Operational modeling of multistream heat exchangers with phase changes

Multistream heat exchangers (MSHE) enable the simultaneous exchange of heat among multiple streams, and are preferred in cryogenic processes such as air separation and LNG. Most MSHEs are complex; proprietary and involve phase changes of mixtures. Although modeling MSHE is crucial for process optimization, no such work exists to our knowledge. We present a novel approach for deriving an approximate operational (vs. design) model from historic data for an MSHE. Using a superstructure of simple 2‐stream exchangers, we propose a mixed‐integer nonlinear programming (MINLP) formulation to obtain a HE network that best represents the MSHE operation. We also develop an iterative algorithm to solve the large and nonconvex MINLP model in reasonable time, as existing commercial solvers fail to do so. Finally, we demonstrate the application of our work on an MSHE from an existing LNG plant, and successfully predict its performance over a variety of seasons and feed conditions. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Development of electrically conductive hybrid nanofibers based on CNT‐polyurethane nanocomposite for cardiac tissue engineering

Conductive nanofibers have been considered as one of the most interesting and promising candidate scaffolds for cardiac patch applications with capability to improve cell–cell communication. Here, we successfully fabricated electroconductive nanofibrous patches by simultaneous electrospray of multiwalled carbon nanotubes (MWCNTs) on polyurethane nanofibers. A series of CNT/PU nanocomposites with different weight ratios (2:10, 3:10, and 6:10wt%) were obtained. Scanning electron microscopy, conductivity analysis, water contact angle measurements, and tensile tests were used to characterize the scaffolds. FESEM showed that CNTs were adhered on PU nanofibers and created an interconnected web‐like structures. The SEM images also revealed that the diameters of nanofibers were decreased by increasing CNTs. The electrical conductivity, tensile strength, Young's modulus, and hydrophilicity of CNT/PU nanocomposites also enhanced after adding CNTs. The scaffolds revealed suitable cytocompatibility for H9c2 cells and human umbilical vein endothelial cells (HUVECs). This study indicated that simultaneous electrospinning and electrospray can be used to fabricate conductive CNT/PUnanofibers, resulting in better cytocompatibility and improved interactions between the scaffold and cardiomyoblasts.