A complementary study on novel PdAuCo catalysts: Synthesis,characterization, direct formic acid fuel cell application,and exergy analysis

At present, Pd containing (10–40 wt%) multiwall carbon nanotube (MWCNT) supported Pd monometallic, Pd:Au bimetallic, and PdAuCo trimetallic catalysts are prepared via NaBH₄ reduction method to examine their formic acid electrooxidation activities and direct formic acid fuel cell performances (DFAFCs) when used as anode catalysts. These catalysts are characterized by advanced analytical techniques as N₂ adsorption and desorption, XRD, SAXS, SEM-EDX, and TEM. Electronic state of Pd changes by the addition of Au and Co. Moreover, formic acid electrooxidation activities of these catalysts measured by CV indicates that particle size changes in wide range play a major role in the formic acid electrochemical oxidation activity, ascribed the strong structure sensitivity of formic acid electrooxidation reaction. PdAuCo (80:10:10)/MWCNT catalyst displays the most significant current density increase. On the other hand, lower CO stripping peak potential obtained for PdAuCo (80:10:10)/MWCNT catalyst, attributed to the awakening of the Pd-adsorbate bond strength down to its optimum value, which favors higher electrochemical activity. DFAFCs performance tests and exergy analysis reveal that fuel cell performances increase with the addition of Au and Co which can be attributed to synergetic effect. Furthermore, temperature strongly influences the performance of formic acid fuel cell.     

Processing and properties of modified polyamide 66-organoclay nanocomposites

Binary polyamide 66 nanocomposites containing 2 wt % organoclay, polyamide 66 blend containing 5 wt % impact modifier, and ternary polyamide 66 nanocomposites containing 2 wt % organoclay and 5 wt % impact modifier were prepared by melt compounding method. The effects of E-GMA and the types of the organoclays on the interaction between the organoclay and the polymer, dispersion of the organoclay, morphology, mechanical, flow, and thermal properties of the nanocomposites were investigated. Partial exfoliation and improved mechanical properties are observed for Cloisite® 15A and Cloisite® 25A nanocomposites. On the other hand, the organoclay was intercalated or in the form of tactoids in Cloisite® 30B nanocomposites. Components of the nanocomposites containing Cloisite® 15A and Cloisite® 25A were compounded in different addition orders. Mixing sequence of the components affected both the dispersion of the organoclay and the mechanical properties drastically. SEM analyses revealed that homogeneous dispersion of the organoclay results in a decrease in the domain sizes and promotes the improvements in the toughness of the materials. Melt viscosity was also found to have a profound effect on the dispersion of the organoclay according to MFI and XRD results. Crystallinity of the nanocomposites did not change significantly. It is only the type of the constituents and their addition order what dramatically influence the nanocomposite properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

An investigation of Al2O3–ZrO2 ceramic composite-coated engine parts using plasma spray method on a diesel engine

ABSTRACT

In this study, the surfaces of the piston, cylinder head and valve parts of the combustion chambers for a single-cylinder diesel engine were coated at 250?µm thick ceramic composite Al₂O₃–ZrO₂ (20–80%) main coating material and 100?µm NiCrAl interlayer material. Also, B6 and B12 biodiesel fuels were produced. Fuel blends were tested on a diesel engine with thermal barrier-coated surfaces for 50?h under the same conditions. When the SEM images and the EDS analysis results of the pistons covered with the ceramic composite main coating material are examined, it has been seen that the coating material permeates the surfaces in a very homogeneous manner and allows to work with high performance without causing any deterioration on the surfaces during working. At high temperatures, the working periods of 50?h and the formation of smoke did not cause any damage to the main material and the coating material.     

Force Transmission Error Analysis for a High-Pressure Single-Sinker Magnetic Suspension Densimeter

The magnetic suspension densimeter (MSD) is a sophisticated, state-of-the-art device that provides extremely accurate results for density measurements. The MSD uses a magnetic technique to couple a mass inside a measurement cell with an external mass balance for mass measurement. This article presents a force transmission error (FTE) analysis for a high-pressure, single-sinker MSD. Due to the magnetic working principle of the apparatus, magnetic properties of the high-pressure cell and external magnetic fields affect the measurements slightly. For the analysis, McLinden et al. suggest making measurements using two different sinkers, a titanium sinker and a copper sinker, having the same mass. The measurements cover densities for methane, ethane, carbon dioxide and nitrogen over the temperature range from 265 K to 450 K (±5 mK stability) up to 180 MPa (uncertainty of 0.01 % full scale: 200 MPa). Comparing and manipulating the measurements permit determination of apparatus and fluid specific effects that contribute to the FTE. For this MSD, the apparatus effect is about 200 ppm, which effectively masks any fluid specific effect. A comprehensive analysis of the FTE produces a uniform deviation for density values of about 0.05 % at 2σ across the full range of pressure.     

Geopolitics of European natural gas demand: Supplies from Russia, Caspian and the Middle East

This paper addresses issues of natural gas which raise questions about European energy security. It first focuses on the rising gas demand of the EU27 and elaborates alleged risks of dependence on Russia such as Gazprom's disagreement with Ukraine, which became an international gas crisis in January 2006 and also more recently in January 2009. Incentives and barriers of Europe's further cooperation with selected Caspian (Azerbaijan, Kazakhstan and Turkmenistan) and Middle Eastern (Iran, Iraq and Egypt) countries are discussed. Supplies from Caspian are analyzed with a particular focus on Russia's role and the vested interests in the region. Supplies from the Middle East are elaborated with regard to Iran's huge and Iraq's emerging potentials in terms of natural gas reserves and foreign direct investments in the energy sector. The geopolitical analysis leads to a conclusion that the best strategy, and what seems more likely, for the EU is to include at least two countries from Azerbaijan, Turkmenistan, Iran and Iraq within its natural gas supply system.     

Biogenic Amine Content of Beers Consumed in Turkey and Influence of Storage Conditions on Biogenic Amine Formation

The biogenic amine content of beers available in Turkey, both domestic production and imported products, was investigated. A total of 17 domestic and 13 imported beers were evaluated in terms of 8 different biogenic amines (histamine, tyramine, spermine, spermidine, 2‐phenylethylamine, putrescine, tryptamine and cadaverine). HPLC methodology with pre‐column derivatization and photodiode array detection after derivatization with dansyl chloride was used for quantification. In addition, the evolution of important amines such as histamine, tyramine, putrescine and cadaverine were investigated during different storage conditions by response surface methodology. The results indicated that both storage temperature and storage time were important factors affecting biogenic amine content. Histamine and putrescine increased during storage, but then decreased after reaching a maximum level after six weeks. With the biogenic amines tyramine and cadaverine, the amounts increased during the entire storage period. At higher storage temperatures, the formation of biogenic amines increased.     

Selecting the suitable material handling equipment in the presence of vagueness

Selection of the suitable material handling equipment (MHE) is a very difficult task for the manufacturing companies because of the considerable capital investment required. There are many tangible and intangible factors for choosing the suitable MHE. Multiple criteria decision making (MCDM) has been found to be a useful approach to analyze these conflicting factors. The evaluation of MHE alternatives within the frame of various subjective criteria and the weights of the criteria are usually expressed in linguistic terms. This makes fuzzy logic a more natural approach to this kind of problems. This paper proposes a combined MCDM methodology for evaluation and selection of MHE types for a company in the steel construction industry in Istanbul, Turkey. Fuzzy analytic network process (FANP) is utilized for assigning weights of the criteria for MHE selection and fuzzy technique for order preference by similarity to ideal solution (TOPSIS) is used to determine the most proper system alternative using the criteria weights attained by FANP. The selection is based on the compatibility between MHE and production characteristics. Objective is to select the most efficient MHE considering also the cost efficiency. The study was followed by the sensitivity analyses of the results.     

The effects of text structure and prior knowledge of the learner on computer-based learning

This study is an attempt to investigate the effects of document structure and knowledge level of the reader on reading comprehension, browsing, and perceived control. Four types of texts are distinguished, differing in structure (linear text, hierarchical hypertext, mixed hypertext, and generative text). All the materials were on a PC. In all conditions, participants were allowed 1 h to read through the document. After completing the reading part of the experiment, they were asked to fill out the perceived control questionnaire followed by the reading comprehension test. As far as reading comprehension was concerned, knowledgeable participants had higher reading comprehension scores than non-knowledgeable participants only in the linear text. In addition, there were no significant differences in terms of the reading comprehension scores of the knowledgeable participants among the four topologies. However, the performance of non-knowledgeable participants differed with respect to the type of the topology. In particular, non-knowledgeable participants in the hierarchical and generative conditions performed better than those in the other two conditions. With respect to perceived control, the performance of knowledgeable and non-knowledgeable participants was equivalent in all four conditions. The results are discussed in terms of their implications for the computer-based learning.     

Parametric analysis of flare edge rolling throat bending and asymmetric flare effects for H-plane horn radiator

In this paper, radiation characteristics of H-plane sectoral horn antenna are treated systematically by investigation of main structural design parameters and, flare edge rolling, throat bending and asymmetric flare effects. The analytical regularization method (ARM) is used to solve the problem of E-polarized wave diffraction in a fast and accurate way. The numerical procedure is initially verified by the analytical solutions, and then the calculated directivity gain patterns are demonstrated for the modeled horn antenna configurations. Proper choices of the antenna parameters, such as horn depth, aperture length, feeder waveguide width, flare angle, wall thickness, flare edge rolling and throat bending are proposed for the designers to reach high directivity gain, narrow beam width, suppressed side lobe levels, increased front-to back ratio and improved aperture efficiency.