Tailoring the ionic transfer characteristics of polyvinyl chloride-based heterogeneous ion exchange membranes by embedding carboxy methyl cellulose in membrane channels

Polyvinyl chloride-based heterogeneous cation exchange membranes were modified by embedding carboxy methyl cellulose in ionic transfer channels of membrane. The effect of CMC to PVC blend ratios on properties of membranes was studied. SOM images showed uniform distribution and surfaces for prepared membranes relatively. The SEM images showed uniform and dense structure for the membranes. The XRD pattern also demonstrated amorphous structure for the membranes. Membrane water content was improved from 25 to 39 % by increase of CMC concentration up to 32 %wt. Similar trend was found for membrane surface hydrophilicity. The membrane ion exchange capacity, fixed ion concentration, membrane potential, charge density, transport number, permselectivity, and ionic flux were enhanced initially by increase of CMC ratio up to 16 %wt and then began to decrease by increase in CMC concentration from 16 to 32 %wt. The membrane oxidative stability and areal electrical resistance showed decreasing trends by utilizing of carboxy methyl cellulose in the membrane matrix. Membrane transport number and selectivity were also increased by increase of electrolyte concentration. Similar trend was found for the membrane electrical conductivity by increase of electrolyte concentration. Also prepared membranes showed higher transport number, selectivity, and areal electrical resistance at pH 7 compared to other pH values.     

Parameters optimization of recombinant hepatitis B antigen adsorption–desorption in purification process on three different kinds of diatomaceous earth matrix

The purpose of this study was to compare adsorptive capacity of three kinds of celite for r-HBsAg. The experimental design methodology was used to optimize the parameters which affect adsorption efficiency. The examined parameters were the adsorption/desorption temperature, pH, time, agitation speed and antigen concentration.     

A novel organic gas steam-liquid extraction method for the selective extraction of cobalt from water samples

In this work, for the first time, organic gas steam-liquid extraction (OGS-LE) technique was developed as a promotion in the liquid–liquid extraction (LLE) method, by the use of a special homemade extraction cell that was designed to facilitate the traditional LLE method, without emulsification and with high extraction efficiency by a small amount of organic solvent in one step. This method is fast, simple and efficient, and was employed for the selective extraction and determination of cobalt (II) from water samples. The efficiency of the OGS-LE method was compared with the LLE method. The obtained results revealed that by using the OGS-LE technique, the extraction efficiency of cobalt from a synthetic mixture was over 90%, much higher than the traditional LLE method (34%).     

Statistical Analysis of Cognitive Radio Operation in a Periodic Pattern of Sensing and Transmission

A Cognitive Radio must sense the channel to detect spectrum holes. To this end, it senses the channel for $T_S$ and transmits its data for $N T_S$ , if the channel is not occupied by Primary User. It is expected that the more frequent arrivals of PU, characterized by the arrival rate $\lambda $ , provides CR with less opportunity. The aim of this paper is two-fold: analysis of the interaction between $N$ and $\lambda $ , as well as the access time of CR on the one hand and study of the possible benefits a variable decreasing modulation order might provide for CR on the other. In both cases, data rate of CR and the interference it causes for PU are considered as the performance measures.     

Global virtual engineering teams (GVETs): A fertile ground for research in Australian construction projects context

Implementation of global virtual engineering teams (GVETs) commenced since at least two decades ago, but construction has been behind other industries in terms of harnessing this new paradigm. Nevertheless, GVETs are receiving increasing attention within the construction context due to numerous potential benefits they can bring about for the projects. On the other hand, the research about GVETs in Australia is still in its embryonic stages. Australian scholars noticeably have paid scant attention to GVETs in comparison to their colleagues in other developed countries. This paper assumes the process of implementation of a GVET as an isolated project. The study then highlights the well-known main areas of necessary knowledge for managing a GVET project within the construction context based on a project lifecycle approach. Recognizing the weaknesses of existing literature, the paper sets out an agenda for further research within Australian construction projects.     

A new frequency compensation technique for three stages OTA by differential feedback path

A new single Miller capacitor for frequency compensation of three‐stage amplifier is proposed in this paper. In this scheme, a differential stage in which its negative and positive inputs are connected to the output and input nodes of third stage with a cascade capacitor forms the compensation block of a conventional three‐stage amplifier. Analysis shows that this configuration significantly improves the frequency domain performances of total circuit such as phase margin (PM) and gain‐bandwidth product (GBW) with just a very small amount of compensation capacitor. A three‐stage amplifier has been simulated with and without a differential feedback path in a 0.18 µm complementary metal–oxide–semiconductor (CMOS). The simulated amplifier with a 100 pF capacitive load achieved more than 9 MHz GBW and 83° PM while the compensation is less than 0.2% of load capacitor. An amplifier based on conventional nested Miller compensation can just achieve less than 0.23 MHz GBW with the same load, while using more than 100 pF as compensation capacitor. So this method shows an improvement of a factor of 40 in GBW and reduction of a factor of 550 in the size of compensation capacitor. It is a suitable strategy for ON‐CHIP compensation in comparison to other methods. Copyright © 2014 John Wiley & Sons, Ltd.     

A UWB receiver with modified CS-CG LNTA: Noise and nonlinearity analysis

A modified common source-common gate (CS-CG) low-noise transconductance amplifier (LNTA) with an improved noise figure (NF), operational bandwidth, and power consumption are analyzed in this paper. The common source (CS) stage of the modified LNTA is utilized for noise cancellation and transconductance enhancement of the common gate (CG) transistor. Using these, NF, bandwidth, and power consumption are improved without using extra active elements. Noise analyses show the modified CS-CG LNTA has lower NF than conventional CS-CG LNTA. The linearity of the modified CS-CG LNTA is calculated by Taylor series expression. Besides, a design procedure is proposed based on the obtained equations for linearity and NF. Finally, an ultra-wideband (UWB) surface acoustic wave (SAW-less) direct-conversion receiver is designed in 65 nm complementary metal-oxide-semiconductor (CMOS) technology. NF and third-order intercept point (IIP3) of the designed receiver are simulated as 5 dB and −2 dBm, respectively. The receiver consumes 18.4 mA from a 1.8 V supply voltage.     

Application of paraffin and silver coated titania nanoparticles in polyethylene nanocomposite food packaging films

In this work, 3% and 5% TiO₂/Ag nanoparticles were dispersed in low‐density polyethylene through melt blending process, and subsequently nanocomposite films were prepared by hot pressing. Paraffin was used for the first time in this work as compatibilizer agent. The effect of TiO₂/Ag nanoparticle content, as well as compatibilizer dosage on the antimicrobial, morphological, mechanical, and optical performance of the nanocomposite films was investigated. Improved mechanical properties of the nanocomposite films were found on using paraffin as compatibilizer in comparison with the neat low‐density polyethylene (LDPE) films. The optical study results also showed that the addition of TiO₂/Ag to the LDPE films does not drastically change the film appearance other than making them more reddish. The fabricated nanocomposites presented in this study could be a suitable choice for food packaging (subject to further investigation of the food packaging behavior). The results showed that both TiO₂/Ag nanoparticle and compatibilizer are needed to prevent the bacteria growth in the film. The best result was obtained by using 5% nanoparticle and 4% paraffin compatibilizer where the bacteria growth rate was significantly reduced by 95%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45913.     

Proposing channel coordination and horizontal cooperation in two competitive three‐echelon reverse supply chains

Considering and analyzing various kinds of cooperation among supply chain members is an option for better managing each channel. It is noteworthy that in many real‐world cases, each of vertical and horizontal cooperation has an important role in the success of supply chains. Nevertheless, only vertical cooperation in most previous research is considered. This paper addresses both vertical and horizontal cooperation in two competitive reverse supply chains, each of which includes one collector, one remanufacturer, and one retailer. Our primary concern is to analyze quality improvement competition between the remanufacturers. Moreover, retail price competition between the retailers and the quality competition are simultaneously considered in the extended model. In this research, the investigated system has been analyzed under different structures including decentralized, centralized, horizontal cooperation, and coordinated decision‐making models. The results show that when the remanufacturers cooperate horizontally, the profit of each collector and that of the retailer will decrease compared with those in the decentralized structure. To overcome this problem, a new coordination contract named multiple‐link two‐part tariff is proposed to simultaneously coordinate the members of each chain. The proposed contract effectively convinces the remanufacturers to participate in the coordination model instead of the horizontal cooperation. Moreover, it provides a win–win–win condition for all chain members and improves the quality level of the remanufactured products. The results indicate the proper performance of the proposed contract in improving the benefits of the competing chains, especially when there exists no intense competition between the remanufacturers (i.e., when the market sensitivity to the quality of the remanufactured products is low and consequently less effort is needed to increase the quality of the remanufactured products). Moreover, the proposed contract not only is able to simultaneously increase both remanufactured products demand and of end‐of‐life products supply but also involves both economic and environmental benefits.