Characterization of antioxidant chitosan film incorporated with Zataria multiflora Boiss essential oil and grape seed extract

Antioxidant chitosan based edible films were developed incorporated with Zataria multiflora Boiss essential oil (ZEO) (5 and 10 g/L) and grape seed extract (GSE) (10 g/L) alone and in combination. The physico-mechanical, wettability, swelling index, color, total phenol and antioxidant characteristics of the films were investigated. Films without any agents were used as control sample. All films, with the exception of 10 g/L GSE + 10 g/L ZEO film, exhibited lower strength and elongation values, and only the addition of 10 g/L ZEO to GSE film improved the water vapor transmission rate of chitosan films. Only GSE containing films had higher swelling index. The incorporation of GSE and ZEO into chitosan film increased the wettability of the surface, total phenol and antioxidant activity. Neat chitosan and ZEO incorporated films had a light yellowish color, whereas GSE + ZEO films were gray.     

In situ growth of carbon nanotubes in alumina–zirconia nanocomposite matrix prepared by solution combustion method

In this work successful synthesis of multiwall carbon nanotube (CNT) using solution combustion and chemical vapor deposition (CVD) methods are reported. Ceramic nanocomposite samples of (Al_2?xFe_xO₃)–(y)ZrO₂ formula with x = 0.017, 0.034 and 0.17 and y = 0.15 were initially prepared. These were then subjected to CVD process during which the in situ reduction of iron oxide to metallic iron (Fe/Fe₃C) phase/s provided the necessary catalyst for the CNT formation. The formation of long flexible filaments with a smooth and regular surface bridging between alumina–zirconia (AZ) grains could be detected. The diameters of the formed filaments were in the range of ～70 to ～320 nm and length of the order of some tens of micrometers. However, transmission electron microscope (TEM) examinations also revealed the existence of small amounts of Bamboo-like carbon along with more or less straight CNTs. This could be related to the lack of strong interactions between the metallic iron phase/s and the nanocomposite support.     

Failure Analysis of a Drilling Wire Rope

The failure of a multistrand wire rope used in drilling rig hook is investigated in this case study. The wire rope failed during the raising of the rig and caused some serious damage to the rig structure. Throughout its short time of service, the wire had been used a few times for rig up and rig down. The failure investigation is performed by metallurgical examinations and computational analyses utilizing the finite element method. The wire rope was made of AISI 1095 steel. Its chemical composition, ferrite?Cpearlite structure, and high hardness indicate that the wire is a type of extra extra improved plow steel (EEIPS) grade. The morphologies of fractured surfaces indicate tensile overloading of wires. Finite element analysis confirms the overload in core and strands, and compressive contact stresses between wires, and between wires and sheave surface. The results show that high tensile stresses due to the overload and small ratio of sheave-to-rope diameter were responsible for the failure.     

Minimizing the makespan and the system unavailability in parallel machine scheduling problem: a similarity-based genetic algorithm

This paper is devoted to ponder a joint production and maintenance problem. For solving the problem, a genetic algorithm named similarity-based subpopulation genetic algorithm (SBSPGA) is introduced. SBSPGA is presented based on a well-known evolutionary algorithm, the subpopulation genetic algorithm II (SPGA-II). Compared with the SPGA-II, the innovation of the SBSPGA could be divided into two parts: (1) using a similarity model for the elitism strategy and (2) performing the algorithm in just one stage. To tackle the maintenance aspect, reliability models are employed in this paper. The aim of this paper was to optimize two objectives: minimization of the makespan for the production part and minimization of the system unavailability for the maintenance part. To execute our proposed problem, two decisions must be made at the same time: achieving the best assignment of n jobs on m machines to minimize the makespan and determining the time at which the preventive maintenance activities must be performed to minimize the system unavailability. The maintenance activity numbers and the maintenance intervals are not fixed in advanced. Promising the acquired results, a benchmark with tremendous number of test instances (more than 5,000) is employed.     

Temperature compensation of Gm-C filters using resistive bridge

A new technique for temperature compensation of G_m-C filters is presented. Using negative feedback the G_m-cells' transconductance is locked to the reciprocal of a resistance array. Temperature dependency of the G_m/C ratio, which determines the unity-gain frequency, is minimised by arranging the temperature dependency of the resistors. Unique properties of a proposed resistive bridge allow for the synthesis of temperature coefficients beyond the range of coefficients of constituent elements. With a set of practical elements a variation of only 0.66% in G_m/C has been achieved over -40 to 120degC.     

Incremental dynamic analysis of steel frames equipped with NiTi shape memory alloy braces

This paper determines the seismic performance of four‐storey concentrically braced frames equipped with either steel buckling‐restrained braces or buckling‐restrained superelastic shape memory alloy (SMA) braces through incremental dynamic analysis. The incremental dynamic analysis technique is used to examine the behaviour of four‐storey braced frames with four different bracing configurations (including diagonal, split‐X, chevron‐V and inverted‐V) under 20 different ground motion records. The study reveals a satisfactory performance at the design intensity level for both types of braced frames. The results show that the SMA braces lead to a uniform distribution of inelastic response over the height of the buildings, as well as mitigating seismic response in terms of maximum inter‐storey drift and residual roof displacement. By comparing the responses of SMA and buckling‐restrained braced frames under higher intensities of earthquake loading, it is found that the SMA braces can be more beneficial especially under severe ground motion excitations. Copyright © 2014 John Wiley & Sons, Ltd.     

An Overview of MAI Effect on the Uplink Performance of the UMTS Air Interface

Universal Mobile Telecommunications System (UMTS) is the main standard of the third generation of mobile communications and its air interface is called WCDMA. This paper considers the effect of multiple access interference (MAI) on the uplink performance of a simple WCDMA system. The transmitted signal of a defined user is destroyed by interferences from other users and executable resolves are presented and applied. The performance measure is the probability of error, BER, for different number of users. The results indicate that an increase in the number of users would degrade system performance considerably. Furthermore, the channel effect on the signal quality is a problem in transmission that should be considered. The goal of this paper is the observation of uplink performance in presence of MAI. Finally, we represent all ways for resolving the MAI as an undesired effect. FDD mode has been chosen as the operation mode of transmission as well. We consider an identical user's power of received signals at the base station. Hassan Moradi received his B.S. degree in Electrical Engineering from Shiraz University, Shiraz, Iran in 1998 and the M.S. in communications systems from K.N. Toosi University of Technology, Tehran, Iran in 2001. He joined the Iran Telecommunications Research Center (ITRC) as an assistant researcher of wireless communications in 2001. Also, he is currently a member of technical staff of ITRC. His current research interests are in Mobile Communications Network, Radio Transmission and Signaling Protocols. He has authored several papers in the wireless communications field especially about access network of CDMA-based systems. Moreover, after finishing Mobile Switching Center (MSC) project in ITRC, he now works and manages the Implementation Switch Lab project at ITRC. Mahdi Samie received his B.S. in Computer Engineering from Isfahan University of Technology (IUT), Isfahan, Iran, in 1996, and M.S. in Computer System Architecture from Iran University of Science and Technology (IUST), Tehran, Iran in 2001. Since 1999 he is teaching at the department of Computer Engineering in IUST. He joined the Iran Telecommunications Research Center (ITRC) in September of 2001, where he is currently pursuing research on communication protocols for mobile networks as a Research Assistant. His research interest includes Signaling Protocols, Mobile Network Protocols, mobile IP, Digital Transmission and Database in Telecommunication Networks. Maryam Fallah-Pour received the B.S. degree in Electrical Engineering from K.N. Toosi University of Technology (KNTU), Tehran, Iran in 2003. Her primary current research interests are Industrial Control, Instrumentation, Control of Communication Systems, Software and Hardware design of PLC systems, analysis and modeling of control systems. In addition, she is interested in simulation and implementation of communications protocols. Now, addition to working at Patsa Industry group in Tehran, she is continuing his studies as a M.Sc. student at KNTU.     

Evaluation of occupational exposure to naturally occurring radioactive materials in the Iranian ceramics industry

Zircon contains small amounts of uranium, thorium and radium in its crystalline structure. The ceramic industry is one of the major consumers of zirconium compounds that are used as an ingredient at ～10-20 % by weight in glaze. In this study, seven different ceramic factories have been investigated regarding the presence of radioactive elements with focus on natural radioactivity. The overall objective of this investigation is to provide information regarding the radiation exposure to workers in the ceramic industry due to naturally occurring radioactive materials. This objective is met by collecting existing radiological data specific to glaze production and generating new data from sampling activities. The sampling effort involves the whole process of glaze production. External exposures are monitored using a portable gamma-ray spectrometer and environmental thermoluminescence dosimeters, by placing them for 6 months in some workplaces. Internal routes of exposure (mainly inhalation) are studied using air sampling, and gross alpha and beta counting. Measurement of radon gas and its progeny is performed by continuous radon gas monitors that use pulse ionisation chambers. Natural radioactivity due to the presence of 23?U, 232Th and ??K in zirconium compounds, glazes and other samples is measured by a gamma-ray spectrometry system with a high-purity germanium detector. The average concentrations of 23?U and 232Th observed in the zirconium compounds are >3300 and >550 Bq kg?1, respectively. The specific activities of other samples are much lower than in zirconium compounds. The annual effective dose from external radiation had a mean value of ～0.13 mSv y?1. Dust sampling revealed the greatest values in the process at the powdering site and hand weighing places. In these plants, the annual average effective dose from inhalation of long-lived airborne radionuclides was 0.226 mSv. 222Rn gas concentrations in the glaze production plant and storage warehouse were found to range from 10 to 213 Bq m?3. In this study, the estimated annual effective doses to exposed workers were <1 mSv y?1.     

Rapid Analysis of Styrene in Drinking Water and Tea Samples Using Dispersive Liquid-Liquid Microextraction Combined with Liquid Chromatography-Ultraviolet Detection

In this project, a simple, low-cost and rapid procedure based on dispersive liquid–liquid microextraction (DLLME) technique coupled with high performance liquid chromatography-ultraviolet detector (HPLC-UV) has been used for the extraction and determination of styrene in aqueous solutions. Several factors, such as type of extraction and dispersive solvents and their volumes, salt addition, and pH were optimized. Under optimal conditions, the recoveries of styrene for tea and water samples spiked with 10 and 15 ng mL^?1 were in the range of 91.4–97.8 %, whereas the temperature was set at 0, 4, 20, 70 and 91 °C for 15, 30, 60, 1440, and 14,400 min. The linear range was obtained in the interval of 1.86–50 ng mL^?1. The limits of detection (S/N = 3) and quantitation (S/N = 10) were 0.6 and 1.86 ng mL^?1, respectively. The relative standard deviations (RSDs) for three replicated analysis of styrene in aqueous samples ranged from 0.01 to 0.3 %.     

An investigation on linear optical properties of dilute Cr doped ZnO thin films synthesized via sol-gel process

Cr doped ZnO thin films were prepared via sol-gel method. The effects of dopant concentration (0%, 1.5% and 3%) annealing temperature and film thickness on UV-Vis spectra of prepared films were investigated. Also, the thickness and surface topology of thin films were investigated by thickness profile meter (DEKTAK) and Atomic Force Microscopy (AFM), respectively. In addition, the band gap and Urbach energy of prepared films were calculated completely for the samples. The results showed that by increasing the dopant concentrations, the microstrain of the prepared thin film structures also increases while the band-gap values decrease. Meanwhile, an increase in annealing temperature makes a decrease in band gap and microstrain of thin films. The increase in thickness resulted in red shift in band gap and reduction in interior microstrains.