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Volume 2, Number 2, March 1999

CONTENTS

Supercritical fluid extraction of biomass (1999) Volume(issue) 2(1): 62-67.

M. M. Küçük1 and M. Tunç2

1 Y. Yıl University Educational Faculty, 65080, Van, Turkey

2 Y. Yıl University Science Faculty, 65080, Van, Turkey

Verbascum and sunflower stalks mill were converted to liquid products by using organic solvents (methanol, ethanol and acetone) with catalysts (% 10 NaOH) and without catalyst in an autoclave at temperatures of 533 and 553 K for verbascum and 523 and 563 K for sunflower. The liquid products were extracted by liquid-liquid extraction (benzene and diethyl ether). The yields from supercritical methanol, ethanol and acetone conversions were 40.6, 29.8 and 42.4 (at 553 K, for verbascum stalk) and 40.0, 45.6 and 47.8 (at 563 K, for sunflower stalk) % , respectively. In the catalytic runs with methanol and ethanol extracts were 44.0 and 36.0 (at 553 K, for verbascum stalk) and 58.5 and 54.2 % (at 563 K, for sunflower stalk) respectively.


Fatty acids from erythrocyte membranes of man with and without margarine (1999) Volume(issue) 2(2): 69-75.

N. Yılmaz1, E. Keha2, M. Aktaş3, and A. Demirbaş4

1Department of Biology, Gaziosmanpaşa University, Tokat, Turkey

2Department of Biochemistry, Karadeniz Technical University, Trabzon, Turkey

3Department of Biology Education, Atatürk University, Erzincan, Turkey

4Department of Chemical Education, Karadeniz Technical University, 61335, Akçaabat, Trabzon, Turkey

Fatty acid composition were determined in 8 different oil samples normally used in margarine manufacture. Concentrations of trans fatty acids (TFA) were determined in 6 soft-type and 6 hard-type Turkish margarines. Methyl esters of the fatty acids were analyzed on a Tracor 570 model gas chromatograph equipped with flame ionization detector (FID) and Restek Rtx-2330 capillary column (50 m long and 0.2 mm inside diameter) by programming and as isothermal for 40 minutes. The samples in soft-type users had total TFA concentration of 5.28%, while margarines in hard-type users contained total TFA concentration of 12.38%. Average trans monoenoic-acid concentrations in soft- and hard-type margarine users, and non-margarine users were 2.94 and 11.74, and 8.68%, respectively. Average trans dienoic-acid concentrations in soft- and hard-type margarine users, and non-margarine users were 2.18 and 0.50, and 1.84%, respectively.


Calculation of compressive strengths of concrete from cement with admixture (1999) Volume(issue) 2(2): 77-80.

A. Demirbaş1, N. Yazıcı2, and A. Şahin2

1P. K. 216, TR-61035 Trabzon, Turkey

2Karadeniz Technical University, Fatih Education Faculty, 61335 Akçaabat, Turkey

In this article, the compressive strengths of concrete from Portland cement mixes were determined experimentally and calculated as a function of age by developing equations:

CS = 7.5905 + 3.7722t - 0.1654t2 + 2.7485x10-3t3 - 1.4809x10-5t4

for which the correlation coefficient (r) is 1.000. The compressive strengths calculated from this equation showed a mean difference of only 0.28 %. Mathematical equations have been developed to calculate the compressive strengths of concrete from Portland cement and/or Portland cement mixes. The compressive strengths calculated from these new correlation show a mean difference from the measured values of 0.14 to 1.82 %.


Recovery of boric acid from boronic wastes (1999) Volume(issue) 2(2): 83-89.

A. Demirbaş

P. K. 216, TR-61035 Trabzon, Turkey

Boronic wastes such as borogypsum, reactor waste, boronic sludges, waste mud and concentrator waste obtained from different boron industries were investigated. B2O3 was recovered from the waste samples by leaching processes using distilled water, sulfur dioxide- or carbon dioxide-saturated water. In the leaching processes; temperature, stirring time and solid-to-liquid ratio were taken as parameters. The amount of B2O3 leached increased with increasing the temperature and stirring time and it also increased with decreasing the solid-to-liquid ratio, but the increase was less than those of the increases of the leaching temperature and the stirring time. Water-saturated by SO2 is a higher effective leaching solvent than that of CO2 for the boronic wastes. End of the experiments, more than 90% B2O3 recovery was found as boric acid.


Phospholipids from erythrocyte membranes of margarine users and non-users (1999) Volume(issue) 2(2): 91-96.

M. Aktaş1, E. Keha2, N. Yılmaz3, and A. Demirbaş4

1Department of Biology Education, Atatürk University, Erzincan, Turkey

2Department of Biochemistry, Karadeniz Technical University, Trabzon, Turkey

3Department of Biology, Gaziosmanpaşa University, Tokat, Turkey

4Department of Chemical Education, Karadeniz Technical University, 61335, Akçaabat, Trabzon, Turkey

 The effect of diet application with and without margarine on membrane phospholipids, phospholipid fatty acids, cholesterol/phospholipid and sphingomyelin/phosphatidylcholin ratios, which is a significant criteria of membrane fluidity, were compared between two groups of thirty persons with the same age. In general, the saturated phospholipid saturated fatty acids were found at higher levels in non-margarine users. The values of phospolipids fractions in the non-margarine users were as percentage: phosphatidylcholin (PC) 32.95± 2.78, phosphatidyl ethanolamine (PE) 28.23± 1.96, phosphatidylserine (PS) 14.41± 0.97, and sphingomyelin (SM) 22.84± 2.00. Total phospholipid (PL) and the membrane cholesterol (Chol) levels were found as 2.93± 0.13 mg and 1.17± 0.10 mg per 1010 cell, respectively. The percentage distribution of the phospholipid types in the margarine users was determined as PC 31.00± 1.57, PE 25.57± 1.60, PS 16.23± 1.57, SM 25.28± 1.09. Total PL and the membrane Chol levels were found as 3.13± 0.12 mg and 1.29± 0.09 mg per 1010 cell, respectively.


Dissolution kinetics of phosphate from calcinated bone in hydrochloric acid solutions (1999) Volume(issue) 2(2): 99-106.

A. Demirbaş

P. K. 216, TR-61035 Trabzon, Turkey

In this study, recovery of phosphate from calcinated bone by dissolution with hydrochloric acid solutions was investigated in a batch reactor. The overall average values of the apparent activation energy (E) was 47.7 kJ mol-1, the pre-exponential factor (A) was 5.1x1011 min-1, the reaction order (n) was 1.1 and the rate constant (k) was 5.0x102 min-1 for dissolving processes of the calcinated bone samples. The effective parameters on dissolving can be given the hydrochloric acid concentration, the dissolution temperature, the solid-to-liquid ratio and the dissolution time respectively.


Supercritical fluid extraction of phenolic acids in snowdrop (1999) Volume(issue) 2(2): 107-112.

A. Demirb1, M. Tüzen2, and M. Özdemir1

1Karadeniz Technical University, Education Faculty, 61335-Akçaabat, Trabzon, Turkey

2Gaziosmanpaşa University, Chemistry Department, Tokat, Turkey

The acids are present as free and esterfied forms in snowdrop. Supercritical extraction of dried and powdered snowdrop sample (30 g used for each run) by acetone (300 g used for each run) was carried out in a one-liter autoclave for 30 minutes at 513 K and 6.0-6.5 MPa Dried extract was percolated 3 x 60 cm silica gel column. Combined fractions were dissolved in methanol for HPLC analysis. The yield of acids in average from all elute fractions are: p-hydroxy benzoic, 26.9 %; vanilic, 17.3 %; ferrulic, 16.6 %; p-coumaric, 15.1 %; caffeic, 15.8 %; and cinnamic, 8.3 %. among the organic acids from snowdrop extracts p-hydroxy benzoic acid was the major constituent followed by vanilic and ferrulic acids.


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