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        • A novel high performance configuration of electrochemical cell to produce alkali for sequestration of carbon dioxide

          Mehmood, A.,Iqbal, M.I.,Lee, J.Y.,Hwang, J.,Jung, K.D.,Ha, H.Y. Pergamon Press 2016 ELECTROCHIMICA ACTA Vol.219 No.-

          We propose a new configuration of a 3-compartment electrochemical cell for producing alkali that is subsequently utilized for mineralization of carbon dioxide. In this new membrane configuration, a second cation exchange membrane (CEM) replaces the anion exchange membrane (AEM) employed in a standard cell configuration. The electrochemical cell comprising of two cation exchange membranes (a CEM-CEM system) eliminates the issues associated with the AEM such as low ionic conductivity and inferior mechanical strength. All of tested CEM-CEM combinations exhibit superior electrochemical performance with considerable reduction of energy requirement for NaOH production in comparison to the standard AEM-CEM configuration. The optimized two-CEMs-based system presents a remarkable enhancement of output current density by 2.5-fold and a substantial input energy savings up to 740kWhton<SUP>-1</SUP> for mineralization of carbon dioxide to produce sodium carbonate.

        • SCIESCOPUSKCI등재

          An Untraceable ECC-Based Remote User Authentication Scheme

          Mehmood, Zahid,Chen, Gongliang,Li, Jianhua,Albeshri, Aiiad Korean Society for Internet Information 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

          Recent evolution in the open access internet technology demands that the identifying information of a user must be protected. Authentication is a prerequisite to ensure the protection of user identification. To improve Qu et al.'s scheme for remote user authentication, a recent proposal has been published by Huang et al., which presents a key agreement protocol in combination with ECC. It has been claimed that Huang et al. proposal is more robust and provides improved security. However, in the light of our experiment, it has been observed that Huang et al.'s proposal is breakable in case of user impersonation. Moreover, this paper presents an improved scheme to overcome the limitations of Huang et al.'s scheme. Security of the proposed scheme is evaluated using the well-known random oracle model. In comparison with Huang et al.'s protocol, the proposed scheme is lightweight with improved security.

        • Comparative Analysis of Consumer's Impulse Buying Behavior with Different Household Incomes : Empirical Evidence from Faisalabad

          Mehmood, Sana,Hamid, Kashif East Asia Business Economics Association 2017 East asian journal of business management Vol.5 No.2

          In today's highly unpredictable marketing environment, where the consumer demands and behaviors are continuously and rapidly changing therefore various factors of consumer impulse buying behavior are proving to be challenging for the existing and new business organizations. Shopping has become a relaxing and rejoicing activity for the consumers making impulsive buying as a socially acceptable and common practice. So by taking into account all these aspects, the objective of this study was to understand the factors affecting impulse buying behavior of the consumer. Store atmosphere and fashion involvement were selected as independent variables while consumer impulse buying behavior was taken as dependent variable for this study. Likewise, impulse buying behavior of consumers with different monthly household income was also analyzed in this study. Primary data was collected through a questionnaire from 250 respondents of district Faisalabad, and then it was analyzed by using various statistical techniques. The results indicated a significant positive impact of store atmosphere and fashion involvement on consumer impulse buying behavior. The study also revealed that among consumer groups with different household incomes; at least one group differed from others in impulse buying behavior. These results were consistent with previous literature. These results could provide information to the marketers and retailers for planning and execution of various marketing techniques. Moreover, educators could expand on the findings by developing new studies examining consumer impulse buying behavior.

        • SCIESCOPUSKCI등재

          New Butyrylcholinesterase Inhibitory Triterpenes from Salvia santolinifolia

          Mehmood Sajid,Riaz Naheed,Nawaz Sarfraz Ahmed,Afza Nighat,Malik Abdul,Choudhary Muhammad Iqbal The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.3

          Slavins A (1) and B (2), the new amyrin type triterpenes, have been isolated from the chloroform soluble fraction of Salvia santolinifolia and assigned structures on the basis of spectral studies including 2D NMR. Both the compounds displayed inhibitory potential against the enzyme butyrylcholinesterase.

        • Performance restoration of direct methanol fuel cells in long-term operation using a hydrogen evolution method

          Mehmood, Asad,Ha, Heung Yong Elsevier 2014 APPLIED ENERGY Vol.114 No.-

          <P><B>Abstract</B></P> <P>A detailed study has been carried out to investigate the changes taking place in the electrodes of a direct methanol fuel cell (DMFC) upon their exposure to the hydrogen gas that is electrochemically evolved <I>in situ</I> in the electrodes. It is found that the individual, as well as the combined, H<SUB>2</SUB> evolution treatment of both the anode and the cathode for a short amount of time causes a substantial improvement in the cell performance, which is attributed to their improved catalytic activities. The exposure of Pt and PtRu catalysts to evolved H<SUB>2</SUB> is beneficial in reducing the surface oxides that are formed during DMFC operation. The performance losses originating from the catalyst oxidation in a continuous operation are successfully recovered by the H<SUB>2</SUB> evolution method, and the DMFC has experienced a voltage loss of only 15mV during a 1383h durability test. These results show the effectiveness of using the H<SUB>2</SUB> evolution method to reduce catalyst oxides and recover the performance losses of a DMFC. Various physical and electrochemical analyses are carried out to fully understand the mechanism and the consequences of the H<SUB>2</SUB> evolution treatment in DMFCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen gas is electrochemically evolved <I>in situ</I> in DMFC electrodes. </LI> <LI> DMFC performance is considerably improved after H<SUB>2</SUB> evolution treatment. </LI> <LI> Exposure of Pt and PtRu catalysts to H<SUB>2</SUB> gas can reduce their surface oxides. </LI> <LI> H<SUB>2</SUB> evolution is used as a new approach to recover performance losses in DMFC. </LI> </UL> </P>

        • SCISCIESCOPUS

          Tailoring cathode structure of catalyst coated membranes for performance enhancement in direct methanol fuel cells

          Mehmood, A.,An, M.,Ha, H.Y. Pergamon Press 2016 International journal of hydrogen energy Vol.41 No.46

          <P>In this study, we demonstrate how the formulation of colloidal catalyst ink and fabrication conditions affect the cathode microstructure of catalyst coated membranes (CCMs) prepared via decal technique. The CCMs based on conventional and high concentration cathode inks are compared in a direct methanol fuel cell (DMFC). It is found that the cathode catalyst layer made with a high concentration ink possesses superior porosity, leading to an improved DMFC performance. The temperature of roll-press used for preparing CCM is varied ranging from 170 to 210 degrees C in order to determine the optimal fabrication conditions for high concentration ink-based cathode. The CCM hot-pressed at 200 degrees C (advanced CCM) retains a significantly higher pore volume and outperforms' the conventional CCM by delivering an excellent DMFC performance with a maximum power density of 155 mW cm(-2), which is 20% higher than that of the conventional CCM. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</P>

        • Corroborating social media echelon in cancer research

          Mehmood, A.,On, B. W.,Lee, I.,Park, H. W.,Choi, G. S. Springer Science + Business Media 2018 Quality & quantity Vol.52 No.2

          <P>Worldwide medical facilities differ, and for this reason, the causes of death can vary. Cancer is considered the second leading cause of death after heart disease worldwide, and the same causes of death are observed in the United States (US). Therefore, the purposes of this study are to explore worldwide research levels in the field of cancer and the social collaboration of researchers and institutions in this field. This article examines the structural patterns of international co-authors and co-institutions in science citation index papers in cancer research. The study uses measures from the social network analysis method, including degree centrality, betweenness centrality, eigenvector centrality, and effectiveness, to investigate the effects of social networks in the area of cancer research. Empirical analysis results identify the US is the most central country, followed by Germany, Italy, France, and China, in terms of co-authored networks in this research field. Institutional analysis results indicate that the University of Milan is at the top in terms of degree centrality. The Gustave Roussy Cancer Campus in France and German University of Dusseldorf occupy the second and fourth positions, respectively. The University of California in Los Angeles and Harvard University, both in the US, are at third and fifth positions, respectively.</P>

        • SCISCIESCOPUS

          An efficient decal transfer method using a roll-press to fabricate membrane electrode assemblies for direct methanol fuel cells

          Mehmood, A.,Ha, H.Y. Pergamon Press ; Elsevier Science Ltd 2012 International journal of hydrogen energy Vol.37 No.23

          This study has focused on the development of a roll-press based decal transfer method to fabricate membrane electrode assemblies (MEAs) for direct methanol fuel cells (DMFCs). This method exhibits an outstanding transfer rate of catalyst layers from substrates to the membrane, despite hot-pressing at a considerably lower pressure and for a much shorter duration than the flat-press based conventional decal method. The MEA produced by a roll-press (R-MEA) delivers an excellent single-cell performance with power densities more than 30% higher than that fabricated using a flat-press (F-MEA). The new method considerably improves catalyst active sites in both electrodes and renders a high cathode porosity. The superior pore structure of the cathode makes the R-MEA more efficient in terms of performance and operation stability under lower air stoichiometries. Moreover, MEAs can be prepared in a continuous mode using this new method due to the unique design of the roll-press. All these advantages demonstrate the superiority of this method over the conventional flat-press decal method and make it suitable for use in the commercial manufacturing of MEAs for direct methanol fuel cells.

        • Physical degradation of cathode catalyst layer: A major contributor to accelerated water flooding in long-term operation of DMFCs

          Mehmood, A.,An, M.G.,Ha, H.Y. Applied Science Publishers 2014 APPLIED ENERGY Vol.129 No.-

          This study presents a comprehensive investigation on the water flooding of direct methanol fuel cells (DMFCs) during long-term testing with regard to the structural changes of the catalyst layer and gas diffusion layer (GDL) of the cathode. Two separate durability operations of DMFCs are conducted for 1000 and 1261h in order to determine the relative contributions of the cathode catalyst layer and the GDL to time-dependent water flooding during the aging process. The voltage decay rates caused by flooding and non-flooding degradation phenomena are calculated and compared. DMFCs undergo serious voltage decay due to water accumulation in the cathode, and the rate of flooding degradation multiplies approximately every 500h during the duration of testing. The cathode catalyst layer is found to be severely deformed due to surface wrinkling and cracking during the aging of the membrane electrode assembly (MEA). The morphological alteration of the cathode catalyst layer, particularly the formation of wide and deep cracks is identified as the main reason for the acceleration of water flooding, while degradation of the cathode GDL is minor. This demonstrates that during the long-term operation of DMFCs, the physical disintegration of the cathode catalyst layer is a crucial issue affecting water management, which should be carefully addressed.

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