CFB combustion of low-grade lignites: Operating stability and emissions

This work presents the results of a comprehensive experimental investigation on the combustion of the low grade Turkish lignites in a 30 kW_th circulating fluidized bed combustor. This is the first study of this kind has ever been undertaken on these coals. Eighteen lignite samples procured from various lignite sites of Turkey have been burned under similar combustion conditions in order to access to their combustion stability and to determine the emissions of the major pollutants such as CO, NO_X and SO₂ in the flue gas from combustor. The qualities of lignites were evaluated based on van Krevelen graph which was highly scattered and diverse in respect to the degree of ageing. A steady and stable combustion was observed in the temperature range of 725–950 °C with an average operating temperature of around 850 ± 50 °C for all lignites. Under the operating condition applied in the study, CO, NO_X and SO₂ emissions varied mostly in the ranges of 120–600 mg/Nm³, 90–420 mg/Nm³ and 1100 mg/Nm³ - 18000 mg/Nm³, respectively. From the experimental results it seems that the most challenging problem may be faced during the CFB combustion of most of these lignites will be SO₂ emissions.     

SentiTurkNet: a Turkish polarity lexicon for sentiment analysis

Sentiment analysis aims to extract the sentiment polarity of given segment of text. Polarity resources that indicate the sentiment polarity of words are commonly used in different approaches. While English is the richest language in regard to having such resources, the majority of other languages, including Turkish, lack polarity resources. In this work we present the first comprehensive Turkish polarity resource, SentiTurkNet, where three polarity scores are assigned to each synset in the Turkish WordNet, indicating its positivity, negativity, and objectivity (neutrality) levels. Our method is general and applicable to other languages. Evaluation results for Turkish show that the polarity scores obtained through this method are more accurate compared to those obtained through direct translation (mapping) from SentiWordNet.     

Perceived overqualification and its outcomes: The moderating role of empowerment.

Research shows that perceived overqualification is related to lower job attitudes and greater withdrawal behaviors but to higher supervisor ratings of performance. Drawing upon relative deprivation theory, the authors proposed and tested empowerment as a moderator of the relationship between perceived overqualification and job satisfaction, intentions to remain, voluntary turnover, and objective sales performance to examine if negative outcomes could be lessened while stimulating even higher performance. Hierarchical linear modeling results from a sample of 244 sales associates working in 25 stores of a Turkish retail chain show that empowerment ameliorated the negative effects of perceived overqualification on job satisfaction, intentions to remain, and voluntary turnover. Empowerment did not affect the positive relationship between perceived overqualification and objective sales performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differentiated leader–member exchanges: The buffering role of justice climate.

The leader–member exchange (LMX) literature has established that leaders differentiate among their followers. Yet little is known about the effects of LMX differentiation (within-group variation in LMX quality). In this study, we contend that the effects of LMX differentiation on the employee outcomes of work attitudes, coworker relations, and employee withdrawal behaviors will be contingent upon the level of procedural and distributive justice climate. Data from 276 employees working in 25 stores of a retail chain in Turkey supported our hypotheses such that LMX differentiation was related to more negative work attitudes and coworker relations, and higher levels of withdrawal behaviors only when justice climate was low. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ion imprinted cryogel-based supermacroporous traps for selective separation of cerium(III) in real samples

This study demonstrates the preparation and characterization of a novel ion imprinted cryogel which exhibits high affinity and selectivity towards Ce(III) ions in aqueous solutions and bastnäsite ore samples. 2-Hydroxyethyl methacrylate (HEMA) and N-methacryloylamido antipyrine (MAAP) were used as functional monomers for the preparation of Ce(III) imprinted cryogel. The effects of various factors such as initial Ce(III) concentration, flow rate, pH, interaction time and ionic strength on the Ce(III) binding to the prepared ion imprinted cryogels were also studied. The binding equilibrium for Ce(III) is obtained in 30 min at the flow rate of 0.5 mL/min. The maximum binding capacity of the prepared ion imprinted cryogel towards Ce(III) is obtained as 36.58 mg/g at optimum conditions. The selectivity of the prepared ion imprinted cryogel towards Ce(III) in the presence of other possible interfering lanthanide ions such as La(III) and Nd(III) were also performed. The obtained results showed that the prepared ion imprinted cryogel exhibits high selectivity and sensitivity towards Ce(III) ions. The limit of detection (LOD) was found as 50 μg/L.     

The influence of pectolytic enzyme addition and prefermentative mash heating during the winemaking process on the phenolic composition of Okuzgozu red wine

The effects of pectolytic enzyme addition and mash heating prior to fermentation on the phenolic component of Okuzgozu red wine during the winemaking and ageing processes were investigated. In general, the highest concentration of total phenolics was found in the mash-heated wines, whereas the total flavan-3-ol and total anthocyanin contents in all of the wines, decreased notably during the winemaking and ageing processes. As determined by HPLC, hydroxycinnamic acids were the major phenolic acids in the red wines. After 6 months in the bottle, the enzyme-treated wines had lower phenolic acid concentrations than had the control and mash-heated wines, but no significant (p < 0.05) differences were found in the concentration of total phenolic acids between the control and mash-heated wines. All of the phenolic acid levels decreased with the winemaking and ageing processes whereas only gallic acid increased. The wines treated by the pectolytic enzyme addition had a lower monomeric flavan-3-ol content than had the other wines, and the amount of monomeric anthocyanins extracted did not increase with the addition of enzymes.     

Electropolymerization of m-aminophenol on mild steel and its corrosion protection effect

Poly-m-aminophenol (PMAP) films were synthesized using cyclic voltammetric (CV), chronoamperometric (CA) and chronopotentiometric (CP) methods in basic hydro-alcoholic medium on mild steel (MS). The structure and properties of these films were characterized by FTIR, UV–vis and scanning electron microscopy (SEM). SEM microphotographs reveal that the surface of MS was coated with PMAP films using CV, CP and CA methods. Some pinholes were seen in the SEM microphotograph of PMAP films prepared using CP method. The anti-corrosion behavior of PMAP films synthesized by CV, CA and CP has been investigated in 3.5% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that PMAP films synthesized by CV and CA methods are much more effective in reducing the corrosion of MS than PMAP films synthesized by CP method. Corrosion performance of these films arises from the barrier effect for the diffusion of O₂.     

Numerical Investigation of the Air-Side Thermal Hydraulic Performance of a Louvered-Fin and Flat-Tube Heat Exchanger at Low Reynolds Numbers

In this study, the air-side heat transfer and fluid flow characteristics of a louvered-fin and flat-tube type heat exchanger used in the household refrigerators were investigated numerically. Louver angles of 20°, 24°, 28°, and 32° and fin pitches of 1.50, 2.00, and 2.50 mm were tested. To represent domestic refrigeration systems, the simulations were conducted for low Reynolds numbers, between 223 and 573. The results were evaluated using the volume goodness factor for the air side. The best performance was obtained with louver angle of 20° and fin pitch of 1.50 mm at Reynolds number of 229 over the investigated cases. It was demonstrated that the Colburn j-factor, friction factor, Stanton number, and volume goodness factor did not change linearly with respect to the parameters considered.