Effect of Microstructure on Exhaust Manifold Cracks Produced From SiMo Ductile Iron

Ductile cast irons are used as high temperature materials in internal combustion engines,because they are microstructurally stable at high operating temperatures.SiMo granular graphite cast irons contain Fe2 MoC and M6C carbide precipitates due to their higher concentration of both silicon and molybdenum.The microstructure of these cast irons consists of carbides dispersed within the ferrite matrix.The microstructural change and the crack formation mechanism in manifolds produced from SiMo ductile iron are studied.Chemical analysis,optical and scanning electron microscope studies have been completed and evaluated.     

Biomass Energy and Biochemical Conversion Processing for Fuels and Chemicals

Biomass, mainly in the form of wood, is the oldest form of energy used by humans. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles, and providing process heat for industrial facilities. Biomass potential includes wood and animal and plant wastes. Biomass, mainly now represents only 3% of primary energy consumption in industrialized countries. World production of biomass is estimated at 146 billion metric tons a year, mostly wild plant growth. Energy from biomass fuels is used in the electric utility, lumber and wood products, and pulp and paper industries. Biomass conversion may be conducted on two broad pathways: chemical decomposition and biological digestion. The conversion technologies for utilizing biomass can be separated into four basic categories: direct combustion processes, thermochemical processes, biochemical processes, and agrochemical processes. Biological processes are essentially microbic digestion and fermentation.     

Application of microwave plasma to the oxidation of ceramic material under conditions of atmospheric re-entry

Study of the physicochemical behaviour of ceramic materials for space applications requires the implementation of specific simulations. We have developed a testing bench, called MESOX, to simulate the atmospheric re-entry conditions of space planes, which associates a solar radiation concentrator with a microwave plasma generator. Oxidation experiments were done under molecular and dissociated air on sintered ceramics (SiC). The results were compared, and we found differences between the two environments in the conditions for the formation of a passive oxide layer.     

Preparation and characterization of polyvinyl borate/polyvinyl alcohol (PVB/PVA) blend nanofibers

In this study, it was aimed to prepare polyvinyl borate/polyvinyl alcohol blend nanofibers by electrospinning process. Polyvinyl borate was synthesized by the condensation reaction of polyvinyl alcohol and boric acid. Polyvinyl borate itself was not suitable for electrospinning process. To improve fiber formation capability, polyvinyl borate was blended with polyvinyl alcohol before electrospinning process. A series of nanofibers with various polyvinyl borate concentrations in polyvinyl alcohol were prepared. Homogeneous and highly porous mat containing 100–250 nm diameter nanofibers were obtained by electrospinning process. According to the FTIR results, boron atoms were found to be integrated into the polymer network. There is not any significant effect of polyvinyl borate content on fiber morphologies according to SEM images. The blend composition with the highest polyvinyl borate content was found to be suitable for thermally stable nanofiber formation according to the TGA results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Progress in biodiesel processing

Biodiesel is a notable alternative to the widely used petroleum-derived diesel fuel since it can be generated by domestic natural sources such as soybeans, rapeseeds, coconuts, and even recycled cooking oil, and thus reduces dependence on diminishing petroleum fuel from foreign sources. The injection and atomization characteristics of the vegetable oils are significantly different than those of petroleum-derived diesel fuels, mainly as the result of their high viscosities. Modern diesel engines have fuel-injection system that is sensitive to viscosity change. One way to avoid these problems is to reduce fuel viscosity of vegetable oil in order to improve its performance. The conversion of vegetable oils into biodiesel is an effective way to overcome all the problems associated with the vegetable oils. Dilution, micro-emulsification, pyrolysis, and transesterification are the four techniques applied to solve the problems encountered with the high fuel viscosity. Transesterification is the most common method and leads to monoalkyl esters of vegetable oils and fats, now called biodiesel when used for fuel purposes. The methyl ester produced by transesterification of vegetable oil has a high cetane number, low viscosity and improved heating value compared to those of pure vegetable oil which results in shorter ignition delay and longer combustion duration and hence low particulate emissions.     

Influence of adjunct cultures on angiotensin‐converting enzyme (ACE)‐inhibitory activity,organic acid content and peptide profile of kefir

The angiotensin‐converting enzyme (ACE)‐inhibitory activities, peptide profiles and organic acid contents in kefir produced by kefir grains plus lactic acid bacteria as adjunct cultures were determined. All the kefir samples showed almost similar peptide profiles as detected by RP‐HPLC, but quantitative differences were observed during storage. The ACE‐inhibitory activities of different lactic cultures did not exhibit a linear tendency during storage period. After 7 days of storage, there was a significant increase in ACE‐inhibitory activity of the sample fermented with Lactobacillus helveticus. However, a kefir sample containing Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis exhibited a higher ACE‐inhibitory activity (92.23%) compared to the other samples.     

Dissolution kinetics of borogypsum in di-ammonium hydrogen phosphate solutions

This work examines the dissolution kinetics of borogypsum in di-ammonium hydrogen phosphate solutions ((NH₄)₂PO₄) in a batch reactor. The parameters selected were the reaction temperature (15–53 °C), di-ammonium hydrogen phosphate concentration (1–4 M), stirring speed (50–800 rpm), and solid/liquid ratio (1/50–1/5). The dissolution rate increased by increasing the temperature (from 0.32 to 0.82), di-ammonium hydrogen phosphate concentration (from 0.35 to 0.821), and by decreasing solid-to-liquid ratio (from 0.77 to 0.24). The dissolution rate increased up to stirring speed of 600 rpm (from 0.135 to 0.56), and then decreased with increasing stirring speed (from 0.56 to 0.351). The dissolution rate was described by first-order pseudo-homogeneous reaction model. The activation energy of this study was calculated as 42.103 kJ mol^?1. A kinetics model including the used parameters in this study was suggested as follows:

$?\ln \left(1?X\right)=223.63C^{0.911}{\left(S/L\right)}^{?0.7689}{W}^{0.6212}{e}^{\left(?5064.2/T\right)}t$

     

Energy consumption and economic growth in Turkey during the past two decades

The Turkish economy has undergone a transformation from agricultural to industrial, enhanced by rapid urbanization, especially after 1982. Turkey's gross national production has grown at an average annual rate of 5% since 1983, ranking it at the top of the OECD countries, although the growth pattern has been uneven. Economic growth in recent years has been associated with the privatization of public enterprises. Turkey's energy demand has risen rapidly as a result of social and economic development. The country's energy consumption has grown considerably since the beginning of the 1980s. The Turkish government encourages foreign and Turkish private sector investors to implement the energy projects and is currently working on a new investment model for the construction of new generation plants to create the additional capacity needed. The Turkish energy sector, with its current size of 30 billion US dollars and projected size of 55 billion US dollars by 2015, as well as the fundamental restructuring process it has been going through since 2001, attracts both local and foreign investors. The sector needs an investment amount of approximately 130 billion US dollars by 2020. The aim of the present paper is to investigate the increasing of Turkish energy demand with the growth of the economy and utilization of domestic energy sources and the case of investments and imports in Turkey during the past two decades.     

Graft copolymerization of methyl methacrylate upon gelatin initiated by benzoyl peroxide in aqueous medium

The graft copolymerization of methyl methacrylate upon gelatin was studied using benzoyl peroxide as an organic initiator in aqueous medium. The grafting reactions were carried out within the 65–90°C temperature range, and the effect of monomer and initiator concentrations on the graft yield were also investigated. The maximum graft yield was obtained at a benzoyl peroxide concentration of 0.20 × 10⁻² mol/L and the optimum temperature was 80°C. Thermogravimetric analysis showed that the thermal stability of gelatin increased as a result of grafting. Further, such changes in the properties of methyl methacrylate‐grafted gelatin as density, moisture regain, and water uptake were also determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1547–1556, 1999