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Öğe Antibacterial activity of new [(2-hydroxypropyl)-n-oximino]pyridines(ASIAN JOURNAL OF CHEMISTRY, 2008) Sen, Nejdet; Kar, Yakup; Kurbanov, Sultan; Uyanik, ArzuThe synthesized [(2-hydroxypropyl)-n-oximino]pyridine derivatives has been tested against the pathogenic four Gram-positive bacteria Bacillus cereus (ATCC 11778), Staphylococcus aureus (ATCC 6538), Sarcina lutea (ATCC 934 1) and Streptococs mutans (UCTC 10499) and three Gram-negative bacteria Salmonella typhimurium (1,4,5,12:;: 1,2), Pseudomonas aeruginosa (ATCC 27853) and Escherichia coli (ATCC 29998). Generally, all synthesized compounds (IVa-c) showed strong activity compared to antibiotic drug (cefalexin). However, among this compounds (IVa) showed excellent activity against Bacillus cereus (ATCC 11778), Sarcina lutea (ATCC 9341), Salmonella typhimurium (1,4,5,12:;: 1,2) and Escherichia coli (ATCC 29998) compared to cefalexin.Öğe Calculation of higher heating values of hydrocarbon compounds and fatty acids(TAYLOR & FRANCIS INC, 2018) Demirbas, Ayhan; Ak, Namik; Aslan, Avni; Sen, NejdetHydrocarbon compounds are formed by carbon and hydrogen elements. The higher heating values (HHVs) of the hydrocarbon compounds can be calculated based on the carbon (C) and hydrogen (H) contents of the chemical structures. HHVs (MJ / kg) as a function of the carbon (C) and hydrogen (H) fractions of N-saturated hydrocarbons can be calculated by the following equation: According to this Equation, the HHV is a function of the percentages of the carbon (C) and hydrogen (H) of pure n-saturated hydrocarbon compounds. This Equation represents the correlation obtained by means of regression analysis. It is found that the calculated values shows mean difference of 0.18%. The correlation coefficient is 0.9955.HHVs as a function of the iodine value (IV) and the saponification value (SV) of fatty acids can be calculated by the following equation: HHV(MJ/kg) = 49.43 - 0.015(IV)-0.041(SV)Öğe Catalytic pyrolysis of the oily seeds of Styrax officinalis L. for bio-fuels and valuable industrial chemicals(WILEY, 2012) Kar, Yakup; Sen, NejdetThe catalytic pyrolysis of the oily seeds of Styrax officinalis L., which was carried out using two catalysts in a fixed-bed reactor. As a catalyst, expanded perlite was firstly used according to the best current knowledge. Pyrolysis experiments were performed under at 450 degrees C temperature and 25 degrees C/min heating rate. The results showed that both catalyst materials had approximately the same effect on the bio-oil yields. By using the natural zeolite and expanded perlite at a ratio of 30 wt %, the maximum bio-oil yields were achieved as 38.07 wt % and 37.49 wt %, respectively. The oxygen content is important to bio-oil and upgrading oil. High oxygen content causes poor heating value and instability. The use of a catalyst greatly reduced the oxygen content of the bio-oil, such that the 30 wt % of oxygen content for noncatalytic oil decreased to 16.34 wt % and 18.35 wt % with use of natural zeolite and expanded perlite, respectively. Higher heating values (34.84 and 33.48 MJ/kg) and H/C atomic ratios (1.47 and 1.51) for the catalyzed bio-oils were very close to those of petroleum, which are 40 MJ/kg and 1.5:1.9, respectively. In addition, the oxygenated species decreased and also the quantities of alkyl and alkenyl substituted aromatic compounds and paraffinic alkanes in the catalyzed bio-oils were notably higher than those of noncatalyzed bio-oils when using a catalyst. The use of catalysts in the pyrolysis not only increased the yield of bio-oil, but also produced higher quality oil with higher calorific value, lower oxygen content, higher carbon, and hydrogen contents etc. (C) 2011 American Institute of Chemical Engineers Environ Prog, 2011Öğe Enhancing Effect of Calix[4]arene Amide Derivatives on Lipase Performance in Enantioselective Hydrolysis of Racemic Arylpropionic Acid Methyl Esters(TAYLOR & FRANCIS LTD, 2016) Uyanik, Arzu; Sen, Nejdet; Yilmaz, MustafaCalix[4]arene amide derivatives were employed as new additives within the sol-gel encapsulation of lipase from Candida rugosa (CRL) to improve its catalytic properties. Evaluation of catalytic activity of the encapsulated lipases was acheived by enantioselective hydrolysis of both racemates, Naproxen methyl ester and 2-phenoxypropionic acid methyl ester, in aqueous buffer solution/isooctane reaction system. Results show that enantioselectivity was improved by using calix[4]arene amide derivatives-based encapsulated lipases. The reaction of naproxen methyl ester resulted in 47.6% conversion (x) in 24h with 88.9% enantiomeric excess of substrate (ee(s)), analogous to an enantioselectivity (E) value of 297 (E = 137 for the encapsulated free enzyme). The conversion of 2-phenoxypropionic acid methyl ester, obtained was 48.4% with E value of 327, enantiomeric excess of substrate (ee(s)) of 92% for the reaction time of 1h (E = 211 for the encapsulated free enzyme).Öğe Gasoline- and diesel-like products from heavy oils via catalytic pyrolysis(TAYLOR & FRANCIS INC, 2017) Demirbas, Ayhan; Al-Ghamdi, Khalid; Sen, Nejdet; Aslan, Avni; Alalayah, Walid M.Heavy oil is less expensive than light crude oil, but heavy oil is more expensive to obtain light oil products. Conventional light crude oil resources are decreasing, therefore heavy oil resources will be needed more in the future. There are huge differences from field to field for heavy oil deposits. In terms of final productive use, heavy oil is considered as an unconventional resource. Heavy oil upgrading depends on four important factors: catalyst selection, heavy oil classification, process design, and production economics. Heavy and extra-heavy oils are unconventional reservoirs of oil. Globally, 21.3% of total oil reserves are heavy oil. Heavy oil is composed of long chain organic molecules called heavy hydrocarbons. The thermal degradation of the heavy hydrocarbons in heavy oil generates liquid and gaseous products. All kinds of heavy oils contain asphaltenes, and therefore are considered to be very dense material. The most similar technologies for upgrading of heavy oils are pyrolysis and catalytic pyrolysis, thermal and catalytic cracking, and hydrocracking. The amount of liquid products obtained from pyrolysis of heavy oil was dependent on the temperature and the catalyst. Pyrolytic oil contains highly valuable light hydrocarbons as gasoline and diesel components range. The constant increase in the use of crude oils has raised prices of the most common commercial conventional products and consequently seeking for new alternative petroleum resources, like some unconventional oil resources, becomes an interesting issue. The mass contents of gasoline, diesel, and heavy oil in the crude oil are 44.6%, 38.3%, and 17.1%, respectively. The gasoline yield from the heavy oil catalytic (Na2CO3) pyrolysis is higher than the diesel efficiency for all conditions. The yield of gasoline products increases with increasing pyrolysis temperature (from 230 degrees C to 350 degrees C) and percentage of catalyst (from 5% to 10%). The yields of gasoline-like product are from 21.5% to 39.1% in 5% catalytic run and from 32.5% to 42.5% in 10% catalytic run. The yields of diesel-like product are from 9.3% to 29.8% in 5% catalytic run and from 15.5% to 33.7% in 10% catalytic run.Öğe Improvement of catalytic activity of lipase from Candida rugosa via sol-gel encapsulation in the presence of calix(aza)crown(ELSEVIER SCI LTD, 2011) Uyanik, Arzu; Sen, Nejdet; Yilmaz, MustafaLipase from Candida rugosa (CRL) was encapsulated within a chemically inert sol-gel support in the presence of calix(aza)crowns as the new additives. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yields of the calix(aza)crown based encapsulated lipases were higher than that of the free lipase. Improved enantioselectivity was observed with the calix(aza)crown-based encapsulated lipases as compared to encapsulated free lipase. The reaction of Naproxen methyl ester resulted in 48.4% conversion for 24 h and 98% enantiomeric excess for the S-acid, corresponding to an E value of > 300 (E = 166 for the encapsulated free enzyme). Moreover, the encapsulated lipases were still retained about 18% of their conversion ratios after the sixth reuse in the enantioselective reaction. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Methane production from anaerobic treatment of volatile organic compounds(MULTI SCIENCE PUBL CO LTD, 2006) Ozdemir, Celalettin; Dursun, Sukru; Sen, NejdetWorldwide increasing energy problems prompts researchers to find new and renewable energy sources. There are many new studies on energy investigation using different materials and technology. These studies were quite important for continuing development, comfortable life and industrial improvement. This investigation considers the removal of volatile organic compounds frequently found in many wastewaters and methane production following the wastewater treatment. The study was performed on the up flow anaerobic condition sludge blanket reactors. Used volatile organic compounds are trichloroethylene, chloroform, dichloromethane, and TCE. Removal ratio of these compounds were 87.8% trichloroethylene, 96.5% chloroform, 67.1% dichloromethane, and 97.3% tetrachlorethylene. Methane ratios in the gas production were 67.1% for TCE, 72.4% for chloroform, 69.6% dichloromethane and 69.8% tetrachlorethylene.Öğe Methane production from anaerobic treatment of volatile organic compounds (VOC)(MULTI-SCIENCE PUBL CO LTD, 2006) Ozdemir, Celalettin; Dursun, Sukru; Sen, NejdetWorldwide increasing energy problems guided to workers to find new and renewable energy sources. There are many new studies on energy investigation using different materials and technology. These studies were quite important for continuing development, comfortable life and industrial improvement. This investigation is considerable for removal of volatile organic compounds (VOC) frequently found in many wastewaters and methane production behind the wastewater treatment. The study performed in the up flow anaerobic condition sludge blanket (UASB) rectors. Used VOC's are trichloroethylene, chloroform, dichloromethane and tetrachlorethylene. Removal ratio of these compounds were 87.8% trichloroethylene (TCE), 96.5% chloroform (CF), 67.1% dichloromethane (DCM) and 97.3% tetrachlorethylene (PCE). Methane ratios in the gas production were 67.1% for trichloroethylene (TCE), 72.4% for chloroform (CF), 69.6% dichloromethane (DCM) and 69.8% tetrachlorethylene (PCE).Öğe Pyrolysis of black cumin seed cake in a fixed-bed reactor(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Sen, Nejdet; Kar, YakupThe black cumin seed cake (BCSC) is a by-product obtained from the black cumin seeds with cold pressing. This by-product can be utilized as a biomass feedstock for conversion to bio-oil with pyrolysis process. The BCSC samples were initially pyrolyzed on a lab-scale pyrolysis system at different values in the ranges of 300-800 degrees C and 0.050-0.300 L min(-1) to determine the effects of operation temperature and N-2 flow rate on the yields on products, respectively. Then, the bio-oil in the highest yield (wB = 44.37%) which was obtained at pyrolysis final temperature (450 degrees C) temperature, heating rate (35 degrees C min(-1)) particle size (dp > 850 mu m), and sweeping flow rate of 0.200 L min(-1) was characterized by Fourier Transform infra-red (FT-IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS) and column chromatography. Consequently, it was shown that the operating temperature and N-2 gas flow rate parameters were effective on the product yields. Also, the important some physico-chemical properties of the pyrolytic oil obtained in high yield were determined as the calorific value of 38.48 MJ kg(-1), the empirical formula of CH1.651O0.105N0.042S0.001, the rich chemical content containing many different chemical groups, and the density of 970.25 kg m(-3), and the viscosity of 63.42 mm(2) s(-1). Based on the determined properties of the pyrolytic oil, it was decided that the use of pyrolytic oil derived from the BCSC may possible be for the production of the alternative liquid fuels and finely chemicals after the necessary improvements. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Reaction kinetics and removal of COD with treatment of TCE with the synthetic wastewater in UASB reactors(SILA SCIENCE, 2012) Ozdemir, Celalettin; Sen, Nejdet; Kalipci, ErkanThe aim of this work was to treat chloroforms (CFs) by upflow anaerobic sludge bed reactors (UASB) and to determine Chemical Oxygen Demand (COD) % removal. The aim of this study was to investigate biological treatment of CFs in high flow rate reactors. Resistance capacity of microorganisms was investigated in a UASB designed as automated control system by feeding with addition of co-substrate, by loading different ratio of organic matter and VOCs, hydraulic retention time, at stable condition of Chemical Oxygen Demand (COD), Volatile Fatty Acids (VFA), pH, alkalinity, temperature (35 degrees C) etc. during the anaerobic treatment. The resulting removal rates for chloroform ranged between 60-70% of COD. The chloroform decomposition ratio was approximately 96%. The highest methane ratio in the obtained biogas was 68.6% for CF. Also inhibition concentrations (IC) in 24 hour were determined as IC50; 27.8 mg/L and IC25; 7.4 mg/L.Öğe The Synthesis and Reactions of Novel Pyrazole Derivatives by 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione Reacted with Some Hydrazones(CHIMINFORM DATA S A, 2017) Erdem, Ahmet; Genc, Hasan; Sen, Nejdet; Kilincarslan, Rafet; Erdem, EminWe report some novel pyrazole derivatives taking 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione, I. For this, 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione, 1 was reacted with benzaldehyde (2- or 4-fluorophenyl)hydrazone to give 4-benzoyl-1-(2- or 4-fluorophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid 2a,b. Pyrazol derivative containing 2-fluorophenyl group 2a was converted into carboxylic chloride derivative 3a by thionyl chloride and then the compound 4a was obtained from reaction ammonia with compound 3a. In the next step, 4-benzoyl-1-(2-fluorophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid 2a was reacted with MeOH/H2SO4, EtOH/H2SO4, 2-nitrophenylhydrazine and 3-nitrophenylydrazine to give 5a,b and 6a,b pyrazol derivatives, respectively. The structures regarding all compounds synthesized were determined by the IR, NMR and elemental analysis method.Öğe TREATMENT OF COD WITH REMOVAL OF DICHLOROMETHANE AND CARBON TETRACHLORIDE IN THE WASTEWATER WITH UASB(INT SCIENTIFIC CONFERENCE SGEM, 2008) Ozdemir, Celalettin; Sen, Nejdet; Dursun, Sukru; Tezcan, HayrunnisaLow concentration of chlorinates maybe found in wastewater, contaminated soils and air due to different industrial sources. Low level of Volatile Organic Compounds (VOC)'s could be removed by adsorption, incineration and biofiltration methods. These methods have some disadvantages such as removal efficiency or high operation cost. Chlorine has been removed from the chlorinated aliphatic compounds under anaerobic conditions. The aim of this study was to investigate biological treatment of DCM and CT in high flow speed reactors. Resistance capacity of microorganisms was investigated ill a designed UASB auto control system by feeding with addition of co-substrate, by loading different ratio of organic matter and VOC's, hydraulic retention time, at stable condition of COD, Volatile Fatty Acids (VFA), pH, alkalinity, temperature (35 degrees C) etc. during the anaerobic treatment. In this study, removals of DCM and CT were approximately 60 - 70 % and 98 %, respectively. At different DCM and CT doses, the highest removal efficiencies were 77,4% COD for DCM and 99,5% COD for CT, respectively.
