Discrete Fourier Transform as applicable technique in electrochemical detection of hydrazine using multi-walled carbon nanotube/polyacrylonitrile ceramic fiber as working electrode

Effect of “Discrete Fourier Transform” (DFT) is studied for electrochemical detection of some electroactive species using multi-walled carbon nanotube/polyacrylonitrile ceramic fiber as ultra micro electrode. Based on DFT theory, two independent phases i.e. the imaginary and real phases are evaluated during the oxidation/reduction of the quasi-reversible or irreversible electroactive species, revealing the independent components of imaginary (I_Imaginary) and real (I_Real) currents. The results show that, in different electrochemical modes such as cyclic voltammetry (CV), the contribution of DFT to the electrochemical signals significantly improves the detection limit of the electrochemical technique. More sensitive signals are obtained at high scan rates according to the combination of electrochemical techniques with the DFT theory. The reliability of DFT algorithm was evaluated for rapid determination of trace amount of hydrazine (N₂H₄) at a scan rate up to 800 V s^? 1. In this study, the amounts of phase and amplitude were estimated to 1.69 and 31.57, respectively. The detection limit of hydrazine was 4.13 × 10^? 9 M. The application of this technique was also evaluated for determination of hydrazine in different industrial wastewater samples.     

Employing secure coding practices into industrial applications: a case study

Industrial Control Systems (ICS) are the vital part of modern critical infrastructures. Recent attacks to ICS indicate that these systems have various types of vulnerabilities. A large number of vulnerabilities are due to secure coding problems in industrial applications. Several international and national organizations like: NIST, DHS, and US-CERT have provided extensive documentation on securing ICS; however proper details on securing software application for industrial setting were not presented. The notable point that makes securing a difficult task is the contradictions between security priorities in ICS and IT systems. In addition, none of the guidelines highlights the implications on modification of general IT security solutions to industrial settings. Moreover based on the best of our knowledge, steps to develop a successful real-world secure industrial application have not been reported. In this paper, the first attempts to employ secure coding best practices into a real world industrial application (Supervisory Control and Data Acquisition) called OpenSCADA is presented. Experiments indicate that resolving the vulnerabilities of OpenSCADA in addition to possible improvement in its availability, does not jeopardize other dimensions of security. In addition, all experiments are backed up with proper statistical tests to see whether or not, improvements are statistically significant.     

Spray-Drying Microencapsulation of Anthocyanins by Natural Biopolymers: A Review

There has been an increased interest in the development of food colorants from natural sources as alternatives to synthetic dyes because of both legislative actions and consumer concerns. Anthocyanins are of great interest for the food industry since they give a wide range of colors as well as nutraceutical activities. Nevertheless, due to their low stability to environmental conditions during processing and storage, introducing those compounds into foods is challenging. Microencapsulation may be an efficient way to introduce such compounds into those products. An important step in developing microcapsules is the selection of a biopolymer (wall material) which meets the required criteria. Hence, this review will focus on microencapsulation of anthocyanins with different biopolymers through spray drying to develop natural colorant pigments which possess high stability, solubility, and dispersibility. Our goal is to give updated information regarding microencapsulation of anthocyanins by spray drying, as well as its effectiveness, developments, and optimized conditions which will be discussed.     

Effect of the preparation conditions on the morphology and performance of poly(imide) hollow fiber membranes

Poly(imide) (PI) hollow fiber membranes were prepared by using classical phase inversion process. Effects of different external coagulation bath temperatures (ECBT) and various bore flow rates (BFR) on the morphology and separation performance of the membranes were studied. Cross‐section, inner and outer structures were characterized by using scanning electron microscope and atomic force microscopy (AFM). Mean pore size, pore size distribution, and mean roughness of the PI hollow fibers surfaces were estimated by AFM. It was found that the hollow fibers morphology composed of sponge‐like and finger‐like structures with different ECBT and BFR. A circular shape of the nodules with different sizes was observed in the outer surface of the PI hollow fibers. Mean pore size of the outer surface increases with increasing ECBT and BFR. The important result observed in this study is that the ECBT clearly has the largest effect on hollow fiber PI membrane roughness compared with the BFR. Pure water permeability of the PI hollow fibers was improved with increase of ECBT and BFR. The solute rejection (R%) was reduced when the ECBT and BFR was increased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40428.     

Optimization of Lipase-Catalyzed Fractionation of Two Conjugated Linoleic Acid (CLA) Isomers

The separation of two isomers of conjugated linoleic acid is highly significant since each exhibits different biochemical properties. The aim of this study was to investigate and optimize several factors affecting the esterification of l-menthol with the c9,t11-CLA isomer in an organic solvent-free system using lipase from Candida rugosa (Lipase AY-30). D-optimal design with 5 factors and 3 levels were employed to evaluate the effects of synthesis parameters; reaction time (8–24 h), temperature (30–50 °C), enzyme content (2–20 U/ml), substrate molar ratio of conjugated linoleic acid oil to l-menthol (2:1–1:2) and pH (6–8) on esterification of c9,t11-CLA with l-menthol. Based on the analysis of the residual amount of c9,t11-CLA in the free fatty acid fraction after just one-step esterification, the optimum synthesis conditions were as follows: reaction time 23.12 h, temperature 32.65 °C, enzyme amount 135.40 U, molar ratio of CLA oil to l-menthol at 1:1.7 and pH at 7.7; the lowest purity of c9,t11-CLA in free fatty acid fraction based on the total content of c9,t11 and t10,c12-CLA isomers was 8.6 %.     

Reliable modeling of discharge process for adsorbed natural gas storage tanks

Natural gas consumption has doubled in the last fifteen years. Among all storage techniques, adsorbed natural gas (ANG) provides a reliable vehicle for safe utilization of natural gas. Despite all favorable characteristics of the ANG process, thermal adverse effects during charge and discharge processes are the most challenging issues facing adsorbed natural gas applications, especially for automotive usage. Mathematical modeling of an ANG tank can provide a reliable method to analyze and solve such problems. A robust and lumped model is presented to mimic the discharge process of an ANG tank storing pure component. The proposed model is very convenient compared to other available conventional models that require extensive computational efforts. Two experimental measurements and two simulation data sets (borrowed from literature) are recruited to validate the model predictions. The simulation results indicate proper agreement between the proposed model predictions and the validation data.     

On‐Chip Fabrication of Paclitaxel‐Loaded Chitosan Nanoparticles for Cancer Therapeutics

The use of solvent‐free microfluidics to fine‐tune the physical and chemical properties of chitosan nanoparticles for drug delivery is demonstrated. Nanoparticle self‐assembly is driven by pH changes in a water environment, which increases biocompatibility by avoiding organic solvent contamination common with traditional techniques. Controlling the time of mixing (2.5–75 ms) during nanoparticle self‐assembly enables us to adjust nanoparticle size and surface potential in order to maximize cellular uptake, which in turn dramatically increases drug effectiveness. The compact nanostructure of these nanoparticles preserves drug potency better than previous nanoparticles, and is more stable during long‐term circulation at physiological pH. However, when the nanoparticles encounter a tumor cell and the associated drop in pH, the drug contents are released. Moreover, the loading efficiency of hydrophobic drugs into the nanoparticles increases significantly from previous work to over 95%. The microfluidic techniques used here have applications not just for drug‐carrying nanoparticle fabrication, but also for the better control of virtually any self‐assembly process.     

Three decades of urban growth in the city of Shiraz, Iran: A remote sensing and geographic information systems application

Although remotely sensed images have been used to study urban growth patterns the world over, very few studies have employed these methods to examine the growth of Iranian cities. Shiraz is perhaps the most important city in the southern part of Iran and, thus, was selected for this study. We used satellite images of the study area from the period between 1976 and 2005, and population censuses of Shiraz. By applying classification methods to the satellite images four main types of land use were extracted: water, built-up, vegetation and bare land. Then, the area coverage for all the land use types at different points in time were measured and coupled with population data. The results demonstrate that, over the entire study period, development in Shiraz cannot be characterized as sprawl. Since 2000, however, one can see evidence of sprawl. These results are also supported by calculations using Shannon’s entropy. A further finding is that vegetation growth did not keep pace with that of population or the built-up area; more recently, vegetation has greatly declined. It is advisable that future plans for the city give serious consideration to the preservation of available vegetation and, when possible, the restoration of vegetation that was destroyed in the past.