Effect of applied voltage on jet electric current and flow rate in electrospinning of polyacrylonitrile solutions

BACKGROUND: In the electrospinning process, through subjecting a pendent drop of a polymer solution to a high electric field, a fluid jet is ejected from the drop. To have a stable process, the rate at which the fluid is forced into the drop and the rate at which the fluid is carried away by the jet must be equal. A method is reported to find the point at which the flow into the drop is equal to the flow out of the drop. RESULTS: In the electrospinning of polyacrylonitrile solutions, by applying different voltages at a constant solution feed rate, two jet regimes were observed: stable jet and fluctuating jet regimes. The stable jet regime occurred at low voltages where the jet flow rate was lower than the feed rate, and the fluctuating jet regime occurred at higher voltages where the jet flow rate exceeded the feed rate. The highest voltage in the stable jet regime was the point where the jet flow rate was equal to the feed rate. This point was determined for different feed rates. CONCLUSION: By applying various voltages at different feed rates, and investigating the jet current, a curve showing stable processing points can be obtained. Copyright © 2008 Society of Chemical Industry     

Studies on phenoplasts by pyrolysis gas chromatography

A new technique of pyrolysis gas chromatography was used for the investigation of pyrolysis of phenol formaldehyde polycondensates and useful information about the nature of the chemical bonds and their relative strengths in these polycondensates were obtained. It was also found that by identifying only one of the pyrograms of a series of homologous compounds produced by the pyrolysis of polycondensates, all the pyrograms of the series were easily characterized and correspondingly the number of components in each series were identified.     

Life cycle GHG assessment of fossil fuel power plants with carbon capture and storage

The evaluation of life cycle greenhouse gas emissions from power generation with carbon capture and storage (CCS) is a critical factor in energy and policy analysis. The current paper examines life cycle emissions from three types of fossil-fuel-based power plants, namely supercritical pulverized coal (super-PC), natural gas combined cycle (NGCC) and integrated gasification combined cycle (IGCC), with and without CCS. Results show that, for a 90% CO₂ capture efficiency, life cycle GHG emissions are reduced by 75–84% depending on what technology is used. With GHG emissions less than 170 g/kWh, IGCC technology is found to be favorable to NGCC with CCS. Sensitivity analysis reveals that, for coal power plants, varying the CO₂ capture efficiency and the coal transport distance has a more pronounced effect on life cycle GHG emissions than changing the length of CO₂ transport pipeline. Finally, it is concluded from the current study that while the global warming potential is reduced when MEA-based CO₂ capture is employed, the increase in other air pollutants such as NO_x and NH₃ leads to higher eutrophication and acidification potentials.     

Solving infinite horizon nonlinear optimal control problems using an extended modal series method

This paper presents a new approach for solving a class of infinite horizon nonlinear optimal control problems (OCPs).In this approach,a nonlinear two-point boundary value problem (TPBVP),derived from P...     

UV–Visible Spectrometry and Multivariate Calibration as a Rapid and Reliable Tool for Simultaneous Quantification of Ternary Mixture of Phenolic Acids in Fruit Juice Samples

Phenolic compounds are biologically important molecules existed in many different plants and fruits. There is a need for a reliable analytical method possessing speedy monitoring, ease of operation, and simple instrumentation. We have developed a fast and reliable spectrophotometric method for simultaneous determination of p-hydroxybenzoic (PHBA), vanillic (VA), and caffeic (CA) acids in fruit juice samples. To overcome the severe spectral overlapping, partial least squares (PLS) regression as a multivariate calibration method was successfully developed for the simultaneous determination of PHBA, VA, and CA in ternary solutions. The experimental calibration matrix was designed with 25 ternary mixtures of these compounds, and the calibration models were validated with six synthetic mixtures. Calibration graphs were linear in the range of 0.0–6.0, 0.0–12.0, and 0.0–12.0 μg mL^?1; limit of detections (LODs) were found to be 0.092, 0.1 l7, and 0.107 μg mL^?1 for PHBA, VA, and CA, respectively. The root-mean-square errors of prediction (RMSEPs) for the same order of target compounds were 0.084, 0.146, and 0.114. The accuracy of the method was confirmed with the recoveries ranging between 84 and 107 %. The relative standard deviations (RSDs) for the analytes in the analysis of fruit juice samples were lower than 4 %. The PLS results were found to be in good agreement with those obtained by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) method. Such a chemometrics-based protocol may be a promising tool for more analytical applications in real sample monitoring, due to its advantages of simplicity, rapidity, and accuracy.     

ANFIS modeling of carbon dioxide capture from gas stream emissions in the petrochemical production units

Amino acid salt, especially sodium glycinate, was known as a new class of environment-friendly solution that is now being studied as a favorable alternative to amines. In the present collaboration, the Adaptive Network-based Fuzzy Inference System (ANFIS) was employed to estimate CO₂ loading capacity in the presence of aqueous sodium glycinate solution under broad ranges of temperature and pressure. The outcomes of suggested ANFIS model indicated their brilliant agreement with corresponding experimental values. The calculated values of mean relative error and R-squared were 2.93 and 0.988, respectively. Our suggested model can be of huge value for process engineers to have a simple and accurate tool in order to have rapid estimations of CO₂ solubility as a function of temperature, pressure, and mass composition of sodium glycinate solution.     

New Schiff Base Cationic Surfactants: Surface and Thermodynamic Properties and Applicability in Bacterial Growth and Metal Corrosion Prevention

A new series of cationic Schiff bases was synthesized and their chemical structures were confirmed using elemental analysis, infrared spectra and nuclear magnetic resonance. The surface properties of the surfactant solutions including surface tension, effectiveness, efficiency, critical micelle concentration, maximum surface excess and minimum surface area were calculated using surface tension-log concentration profiles. The surface parameters were strongly dependent on the hydrophobic chain length. The thermodynamic properties of the surfactants in their solutions showed the spontaneous behavior of both adsorption and micellization processes. The thermodynamic data revealed that the adsorption of the surfactant molecules at the air/water interface was more favorable than the micellization in the bulk of their solutions. The synthesized surfactants were evaluated with regard to their preventing the corrosion reaction of carbon steel in acidic media and also their acting as antibacterial biocides to inhibit bacterial growth. The data of corrosion and antibacterial evaluations showed the high efficiency and applicability of these compounds in these uses.     

Degradation of the antimicrobial triclocarban (TCC) with ozone

Triclocarban (TCC) has been used as an antimicrobial compound for many decades due to its sanitising properties. Recent studies showed that TCC is toxic and causes disruption to the endocrine system. In this work, ozone oxidation of TCC was studied in 70% acetonitrile:30% water solutions. Ozone degraded TCC effectively and the reaction rates increased substantially with ozone gas concentration, pH and temperature. Second-order-reaction kinetics was suitable to describe the chemical reaction. The effect of temperature was described by the Arrhenius equation and the activation energy was found equal to 31.0 kJ/mol. The stoichiometry of the reaction was one and the value of the rate constant at pH 7 was 5 × 10³ M⁻¹ s⁻¹.     

NLR-OP: a high-performance optical router based on North-Last turning model for multicore processors

The Journal of Supercomputing - Regarding the increase in the number of cores in the electronic network-on-chip, they may not be an ideal choice in the response of needing latency, power, and...